10:00 AM - SM1.1.02
Polymer-Dispersed Liquid Crystal Elastomers
Valentina Domenici 1,Jerneja Milavec 2,Andraz Resetic 2,Bostjan Zalar 2
1 Universita di Pisa Pisa Italy,2 Jozef Stefan Institute Ljubljana Slovenia
Show AbstractWe are introducing polymer-dispersed liquid crystal elastomers (PDLCEs) as a new anisotropic soft material suitable for future applications in the fields of thermomechanical actuation and additive manufacturing [1,2]. With our novel synthesizing method, we were able to produce thermomechanically active, macroscopically sized soft devices which can be molded into practically any arbitrary shape and can thus go beyond any imposed geometrical and size limitations that hinders the use of other similar recently proposed materials [3,4].
Our PDLCEs were prepared by dispersing microparticles of conventional liquid crystal elastomers (LCEs) into a polymer matrix and then cured in an external magnetic field, present for the orientation of LCE microparticles’ average domain nematic director during the curing process. After curing, the thermomechanical response is coupled with the surrounding polymer network and a binary soft-soft PDLCE composite is produced.
Thermomechanical properties can be custom tuned by simply changing LCE concentrations and/or use of LCEs with different thermomechanical characteristics. PDLCEs have also an advantage of being further functionalized by using different dopants dispersed into the polymer network. Unlike regular LCEs that poses difficulties with their synthetisation method, trying to uniformly disperse additional micro- or nanoparticles throughout their volume [5,6], the PDLCEs uses LCEs as inclusions and additional elastomer functionalization can be achieved by mixing additional particles in the composite polymer matrix. This opens many new ways of producing elastomers with custom-made properties that can satisfy diverse industrial needs.
References:
[1] H. Lipson and M. Kurman, Fabricated: The New World of 3D Printing, 1 edition (John Wiley & Sons, Indianapolis, Indiana, 2013).
[2] C. J. Camargo, H. Campanella, J. E. Marshall, N. Torras, K. Zinoviev, E. M. Terentjev, and J. Esteve, J. Micromech. Microeng. 22, 075009 (2012).
[3] Z. Pei, Y. Yang, Q. Chen, E. M. Terentjev, Y. Wei, and Y. Ji, Nat Mater 13, 36 (2014).
[4] T. H. Ware, M. E. McConney, J. J. Wie, V. P. Tondiglia, and T. J. White, Science 347, 982 (2015).
[5] J. E. Marshall, Y. Ji, N. Torras, K. Zinoviev, and E. M. Terentjev, Soft Matter 8, 1570 (2012).
[6] A. Kaiser, M. Winkler, S. Krause, H. Finkelmann, and A. M. Schmidt, J. Mater. Chem. 19, 538 (2009).
3:00 PM - SM1.2.02
Total Reflection of Electrically Induced Band Gap Changes in Polymer Stabilized Cholesteric Liquid Crystals
Vincent Tondiglia 2,John Binzer 2,Kyung Min Lee 2,Timothy Bunning 2,Timothy White 2
1 Azimuth Beavercreek Township United States,2 USAF AFRL WPAFB United States,2 USAF AFRL WPAFB United States
Show AbstractElectrically induced deformations of the pitch structure within polymer stabilized cholesteric liquid crystal (PSCLC) prepared with negative dielectric anisotropy nematic liquid crystal gives rise to large tuning or broadening of the reflection band gap of more than 800 nm. Notably, the electrically induced changes in the reflective properties of the PSCLC material system are proportional to the strength of the applied DC field (<3 V/µm) and reversible, relaxing to the original bandwidth and position when the DC field is removed. In this examination, we report on the optical response of PSCLC material systems that exhibit large range tuning or broadening at offset incident angles to light propagation. For a large range of incident angles with respect to the helical axis of the cholesteric liquid crystal, a reasonable approximation to the propagation mode is still the normal solution of circularly polarized light. At large incidence angles (>350) this is no longer the case and at extremely high incidence (
3:15 PM - SM1.2.03
Bimesogen-Mediated Flexoelectro-Optical Behavior of Cholesteric Liquid Crystals
Andrii Varanytsia 1,L.C. Chien 1
1 Kent State Univ Kent United States,
Show AbstractWe explore flexoelectro-optic effect in polymer stabilized cholesteric liquid crystals (CLC) with uniform lying helix (ULH) texture. A method to control the flexoelectric properties of the CLC mixture by mixing nematic liquid crystal constituents with large and small flexoelastic coefficients is demonstrated. By adding a bimesogenic LC dimer CB7CB into a low dielectric anisotropy commercial NLC mixture MLC-2048 the maximum of flexoelectrically driven in-plane rotation angle of the helical axis in a well-aligned ULH texture was increased from 3.5° to 73.2°. Prototype samples demonstrated a submillisecond flexoelectric response time both for switching between electric field on and off states, and the change of polarity of applied electric field, with typical contrast ratio of 150:1. Our findings identified quality of ULH alignment, and material miscibility challenges, and will be useful for material design of future CLC mixtures for applications in flexoelectro-optic displays.
3:30 PM - SM1.2.04
Morphology of Polymer Structure in Polymer-Stabilized Blue Phase
Hui-Yu Chen 1,Che-Kai Wu 2,Fang-Chi Chen 2,Chia-Sheng Chen 2
1 National Chung Hsing University Taichung Taiwan,2 Feng Chia University Taichung Taiwan
Show AbstractBlue phases (BPs) have been recognized as a fast optical isotropic/anisotropic switching liquid-crystal (LC) material in recent years, and they have become a possible candidate in fast-display, three-dimensional laser and photonics applications after improving their thermal stability. For most LC materials, BPs are usually stable within a very narrow temperature range between the isotropic liquid phase and the cholesteric phase with strong chirality. I In terms of the defect theory, in BPI and BPII, DTCs have a lower elastic free energy than a uniaxially twisted director field in chiral nematic LC. Those DTCs self-assemble as three-dimensional cubic lattice structures, leading to the appearance of a disclination network. These disclination lines can be considered as cylinders filled with the isotropic liquid phase, and thus have a higher enthalpy and an additional interfacial energy, which causes the narrow temperature range of BPs. In order to extend this temperature range, the most useful way is to introduce the polymer network into the BP declination lines to help achieve a temperature of more than 60 K, due to the pinning effect. Polymer-stabilized BP (PSBP) is a key for next generation display and photonics application.
A previous study showed that the thermal stability of BP enhancement is related to the polymer component accumulating in the disclination lines, reducing the enthalpic contribution from the isotropic liquid and the interfacial energy. The sort and the concentration of reactive monomers are important for extending the BP temperature range. Another key point for achieving the stabilized effect is that the photo-polymerization process should be completed during the BP phase. It indicates that we should examine other polymerization conditions to control the morphology of the polymer network, and then discuss their influence on the thermal stability of BPI.
In this study, we would like to investigate the influences of the LC phase, the intensity of the UV irradiation, and the photo-polymerization time on the BP temperature ranges. The morphology of the polymer network formed in BPLC is studied by SEM. We prepared PSBP samples, where the polymer network is constructed in cubic BPI, amorphous BPIII and the chiral nematic phase, with the intention of comparing the temperature range of the blue phases in these samples. From these SEM photographs, the radius of the polymer chain becomes tiny when the photo-polymerization temperature and the intensity of the UV irradiation are increased. These experimental results show that the different LC phases will affect the morphology of the polymer network. Referring to the free-energy density of BP, the temperature range of BP will depend inversely on the square of the disclination diameter, as well as the polymer-chain diameter. We can obtain experimental results which agree with this theoretical prediction.
3:45 PM - SM1.2.05
Topology-Mediated Electro-Optical Behaviour of a Wide-Temperature Liquid Crystalline Amorphous Blue Phase
Min Su Kim 1,L.C. Chien 1
1 Kent State Univ Kent United States,
Show AbstractA wide-temperature liquid crystalline amorphous blue phase based on polymer network stabilization exhibits high thermodynamic stability with an extended temperature ranging from a few 1C to more than 80oC.[1] Analyses using confocal laser scanning microscopy show that the polymer network imitates the aperiodic disclination-entangled structure of an amorphous blue phase and involves a highly intertwined interaction with liquid crystal molecules. The stabilized amorphous blue phase manifests tens of microseconds response time, a consistent achromatic dark state and it is intrinsically hysteresis-free during the application of an electric field. The topological and electro-optical features of the stabilized amorphous blue phase are further compared with the stabilized isotropic and cubic blue phases. These results not only provide a physical perspective on the electro-optical response of a liquid crystal and polymer composite but also open up a new direction for electro-optical device applications.
[1] M. S. Kim and L.-C. Chien, Soft Matter, 11, (2015) DOI: 10.1039/c5sm01918d
4:30 PM - *SM1.2.06
Electrooptics of Nematics and Cholesterics with Oblique Helicoidal Structure
Oleg Lavrentovich 1
1 Kent State Univ Kent United States,
Show AbstractLiquid crystals formed by mesogenic dimers with two rigid rod-like units connected by a flexible aliphatic bridge feature unusual structural organization, with an oblique helicoidal local director. The pitch of the oblique helicoid ranges from nanometers in the twist-bend nematic (Ntb) to micrometers in cholesterics (Ch) formed by mesogenic dimers in presence of chiral dopants and external electric field (the so-called cholesteric with oblique helicoidal structure, or Choh). Both structures lead to unusual electro-optics discussed in the presentation: first order structural transition in the Ntb and electrically-controlled selective reflection of light tunable in an extraordinary broad range, from ultraviolet to visible and to infrared, in Choh. The work is supported by NSF DMR-1410378 and IIP-1500204.
5:00 PM - SM1.2.07
Controlling the Electronic Properties in Liquid Crystal Conjugated Small Molecules for Application in Electronics
Nadine Tchamba 4,Peer Kirsch 3,Juergen Parisi 4,Elizabeth von Hauff 1
4 Carl von Ossietzky Universität Oldenburg Oldenburg Germany,2 Merck KGaA, Liquid Crystals Ramp;D Chemistry Darmstadt Germany,3 Albert Ludwigs Universität Freiburg Freiburg Germany1 Vrje Universiteit Amsterdam Amsterdam Netherlands
Show AbstractOrganic semiconductors offer numerous advantages for electronic and opto-electronic applications such as chemical flexibility, good optical properties, low material usage, low cost processing via solution processing. However, carrier mobilities in organic semiconductors are generally orders of magnitude lower than those in inorganic semiconductors. This is a major bottle neck for increasing device efficiency. The electrical properties are additionally strongly dependent on thin film structure and morphology which is challenging to control in solution deposited films.
In this contribution we study structure-function relationships in a novel small molecule which demonstrates liquid crystal properties. The molecular films demonstrate phase changes from the crystalline to nematic to isotropic phases at temperatures of 140 C, 165 C and 250 C, respectively. By controlled film preparation we can manipulate the film crystallinity and thereby influence the electrical and optical properties. We demonstrate the influence of temperature on the structural properties of solution processed films with cross polarized microscope (CPM) and X-ray diffraction (XRD). Electrical measurements were performed on single carrier devices using current-voltage measurements and impedance spectroscopy. We found that after annealing the films to temperatures above the crystalline – nematic phase change and subsequently cooled, the mobility can be increased from (as prepared) to 10-3 . We investigated the electric field dependence of the mobility on the dispersion of the carrier transport and demonstrated that controlled structural manipulation of the film can be used to reduce electronic disorder. These results demonstrate the potential of liquid crystal conjugated materials in organic electronic applications.
5:15 PM - SM1.2.08
The Influence of Polymer Network Development on the Electro-Optic Response of Polymer Stabilized Cholesteric Liquid Crystals
Kyung Min Lee 2,Vincent Tondiglia 2,Claire Middleton 2,Timothy Bunning 1,Timothy White 1
1 Air Force Research Laboratory Wpafb United States,2 Azimuth Corp. Dayton United States,1 Air Force Research Laboratory Wpafb United States
Show AbstractWe have recently reported on dynamic electro-optic responses of the reflection band of polymer stabilized cholesteric liquid crystal (PSCLC) formulations prepared with negative dielectric anisotropy nematic liquid crystal hosts including bandwidth broadening, switchable scattering, red-shifting tuning, and now blue-shifting tuning. Here, we report our current understanding of the influence of polymer network development on the resulting electro-optic response of these PSCLCs. This understanding was developed through a recently completed systematic structure-property examination focused on the influence of the photopolymerization conditions (initiator concentration, light intensity, curing time) as well as the monomer formulation/composition. Based on the electromechanical distortion of the structurally chiral polymer stabilizing network, the kinetics of the network development as well as the distribution/uniformity of the properties are shown to be critical.
SM1.3: Liquid Crystals in Displays and Beyond—Materials Synthesis
Session Chairs
L.C. Chien
Helen Gleeson
Ivan Smalyukh
Timothy White
Wednesday PM, March 30, 2016
PCC North, 200 Level, Room 231 A
5:30 PM - SM1.3.01
Design and Properties of SmAPF Liquid Crystal Materials
Eva Korblova 1,David Walba 1,Edward Guzman 1,Maria Kolber 1,Joseph Maclennan 1,Matthew Glaser 1,Renfan Shao 1,Yongquiang Shen 1,Per Rudquist 4,Noel Clark 1
2 Dept. Chem. Biochem University of Colorado Boulder Boulder United States,1 Soft Materials Research Center Boulder United States,3 Physics University of Colorado Boulder Boulder United States,1 Soft Materials Research Center Boulder United States4 Bio Nano System Lab Chalmers University Goteborg Sweden
Show AbstractThe first reported SmAPF phase, obtained from the mesogen W586, exhibited interesting and useful electrooptics.(1) Specifically, upon application of an electric field, a significant increase in birefringence is observed without rotation of apparent optic axis. Further study demonstrates great promise for this phase in applications requiring fast phase-only electrooptic modulation.
In order to tune properties of SmAPF materials for such applications, a search for new mesogens providing wider phase temperature ranges and improved modulation depth (birefringence change with field) alone or in mixtures, is in progress.
Several surprising and interesting discoveries have derived from this work. For example, a dramatic and unexpected odd-even effect in homologues of W586, which possesses a tricarbosilane-terminated alkoxy tail, provides insights into the nature of nanophase segregation in smectics.
In addition, new classes of SmAPF mesogens have been prepared in an effort to produce materials for applications. Details of the characterization and EO properties of the new materials will be presented.
Another key development is the ability to obtained uniform bookshelf geometry by applying an electric field between interdigitated electrodes as the molecules cool from the SmA to SmAPF. Uniform alignment is necessary to demonstrate the unique analog phase only modulation observed in the SmAPF molecules. [2]
(1) a) Reddy, R. A.; Zhu, C.; Shao, R.; Korblova, E.; Gong, T.; Shen, Y.; Garcia, E.; Glaser, M. A.; Maclennan, J. E.; Walba, D. M.; Clark, N. A. "Spontaneous ferroelectric order in a bent-core smectic liquid crystal of fluid orthorhombic layers," Science 2011, 332, 72-77. b) Korblova, E.; Walba, D.; Gong, T.; Reddy, A.; Zhu, C.; Shao, R.; Maclennan, J.; Glaser, M.; Clark, N. "Design and synthesis of an achiral ferroelectric smectic liquid crystal," Proc. SPIE 2011, 8114, (1), 81140X-1 - 81140X-9.
(2) Shen, L. Goodhew, R. Shao, M. Moran, E. Korblova, D.M. Walba, N.A. Clark, J.E. Maclennan, and P. Rudquist. “Field alignment of bent-core smectic liquid crystals for analog optical phase modulation,” Appl. Phys. Lett., 2015, 106, 191191
5:45 PM - SM1.3.02
Transflective Properties in Amorphous Liquid-Crystal BPIII
Hui-Yu Chen 1,Sheng-Feng Lu 2
1 National Chung Hsing University Taichung Taiwan,2 Feng Chia University Taichung Taiwan
Show AbstractThree blue phases, BPI, BPII and BPIII, exist between the chiral nematic phase and the liquid phase. Compared with the electro-optical properties of BPI and BPII, BPIII is a fast response photonic device with no residual birefringence, less hysteresis effect and low driving voltage when an in-plane electric field is applied [5]. However, the thermal stability of BPs is usually low. In terms of the free energy of the blue phase, the thermal stability of the blue phase is decided by the balance between the free energies of the disclinations and the double-twisted cylinders. Of the three BPs, BPIII usually occupies a narrow temperature range of ~0.1K just below the isotropic phase when the chirality is high enough. There have been many suggestions for widening the BP temperature range. Among those, the most effective way to extend the temperature range of BPI or BPII is polymer stabilization. However, the polymer network cannot obviously stabilize the amorphous BPIII in a wide temperature range. Transflective devices that incorporate both transmissive and reflective functions in the one device are attractive for outdoor image readability in portable displays. Their power consumption is lower than transmission display, because they use the sunlight as the light source in outdoor applications. Many methods have been proposes to produce a transflective nematic liquid-crystal displays. Polymer-stabilized blue phase I (PSBPI) has been suggested as a replacement for NLC materials due to its fast response, optical isotropy, insensitivity to the cell gap with the application of an in-plane switching field, and the fact that no alignment layers are needed. Thus, a single-cell-gap PSBP with bumpy reflectors on one of the glass substrates is made as a transflective display.
In this paper, our purpose is to demonstrate the BPIII can be a tranflective device. In our BPIII material, we do not need to use a polymer network or add any nanoparticles to widen the temperature range, because the temperature range of BPIII in our sample is over 10°C and covers room temperature. Due to the structure of BPIII, a perfect optically isotropic dark state can be obtained in a null field. An in-plane electric field is applied to the BPIII cell through interdigital transparent electrodes on one of the substrates. Here, no reflectors are used in our cell. Measuring the light efficiencies of transmission and reflection, they are almost equal. Moreover, the transmitting and reflecting light are independent of the incident wavelength and the total response time of the IPS-BPIII cell is less than 2 ms. These experimental results exhibit that BPIII can be a potential candidate for use in transflective devices, even for use on a transparent display.
SM1.4: Poster Session
Session Chairs
Thursday AM, March 31, 2016
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - SM1.4.01
Electric-Field Induced Reorientation of Reflective Microplatelets Dispersed in a Nematic Liquid Crystal Host
Aubrey Steele 1,Douglas Krein 3,Vincent Tondiglia 4,Timothy White 2,Jonathan Vernon 2
2 Materials and Manufacturing Directorate Air Force Research Beavercreek United States,1 SOCHE Wright Patterson AFB United States,2 Materials and Manufacturing Directorate Air Force Research Beavercreek United States,3 General Dynamics Information Technology Dayton United States2 Materials and Manufacturing Directorate Air Force Research Beavercreek United States,4 Azimuth Corporation Dayton United States2 Materials and Manufacturing Directorate Air Force Research Beavercreek United States
Show AbstractThe investigation of electric-field induced reorientation of dispersions containing reflective particles is motivated by the desire to produce low-power reflective displays, transflective displays, color tunable/switchable mirrors/windows for privacy control, and tunable/switchable optical filters. Cholesteric liquid crystal (CLC) microplatelets have been shown to reorient under application of electric field when dispersed in an isotropic, moderately conductive propylene carbonate host.[1,2] This work evaluates and contrasts the stimuli-responsive behavior of inorganic and organic microplatelets dispersed in both propylene carbontate and nematic liquid crystal hosts. In isotropic hosts, such reorientation can be explained by the Maxwell-Wagner polarization effect via charge accumulation at the host fluid / microplatelet interface. However, changing from isotropic to nematic liquid crystal hosts adds complexity to the forces (e.g., torque) acting on particles both with and without the presence of electric field.[3] Understanding the mechanisms of reorientation for miroplatelets exhibiting diverse chemical and topological surface properties should elucidate distinct mechanisms that enable dynamic optical elements.
9:00 PM - SM1.4.02
Asymmetric Organic-Inorganic Hybrid Polyhedral Oligomeric Silsesquioxane Nanoparticles for Vertical Alignment of Liquid Crystals
Joo-kyoung Hwang 1,Daseal Jung 1,Yu-Jin Choi 1,Kwang-Un Jeong 1
1 Polymer-Nono Sci and Tech Chonbuk National University Jeonju Korea (the Republic of),
Show AbstractPolyhedral oligomeric silsesquioxane (POSS) nanoparticles have been considered as useful giant molecules for the formation of vertical alignment (VA) of liquid crystal (LC). However, due to their poor compatibilities and weak interactions with LC host molecules, the pristine POSS nanoparticles were highly aggregated themselves in the LC media and formed the macroscopic particles, resulting in severe light scattering. To overcome this problem, we successfully synthesized the cyanobiphenyl monosubstituted POSS giant molecule (POSS-CBP1), which showed an excellent dispersion in nematic (N) LC media and formed the perfect VA of LC without using conventional polymer-based VA layers. On the basis of the systematic experiments and careful analysis, we revealed that the cyanobiphenyl part chemically attached to the pristine POSS with an alkyl chain can play a key role in improving the initial solubility and interaction with LC media. The finely tuned POSS-CBP1 was gradually diffused onto the substrate for the formation of VA layer without forming the macroscopic aggregations.
Therefore, the novel POSS-CBP1 VA layer can allow us to develop electro-optical applications and to cut the manufacturing cost. This work was supported by the BK21 Plus, the BRL 2015042417, and MOTIE/KDRC 10051334.
9:00 PM - SM1.4.03
Optically Isotropic Liquid Crystal Medium Prepared by Doping Star-Shaped Liquid Crystal Surfactants in Twin Nematic Liquid Crystals
Joo-kyoung Hwang 1,Daseal Jung 1,Yumin Lee 1,Kwang-Un Jeong 1
1 Chonbuk National University Jeonju Korea (the Republic of),
Show AbstractOptically isotropic liquid crystal (LC) media were prepared by doping the star-shaped cyclic oligosiloxane LC molecular surfactants (SiLC) into the rod-shaped twin LC host molecules (DiLC). The phase diagram was constructed by differential scanning calorimetry (DSC). The phase diagram of the SiLC/DiLC mixtures showed the broad coexistence regions such as smectic A + crystal (SmA1 + Cr2), liquid + crystal (L1 + Cr2) and liquid + nematic (L1 + N2) at the intermediate compositions along with the narrow single phase crystal (Cr2), smectic (SmA1) and nematic (N2) regions. The morphologies and structures of these coexistence regions were investigated by polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). At the 80/20 SiLC/DiLC composition, the optical anisotropy was induced under an alternating current (AC) electric field above its isotropization temperature. The fabricated optically isotropic LC medium in mixtures of the SiLC molecular surfactants and nematic LC host opens new doors for the electro-optical devices. This work was supported by the BK21 Plus, the BRL 2015042417, and MOTIE/KDRC 10051334.
9:00 PM - SM1.4.04
Dual Photo-Functionalized Amphiphiles for Photo-Reversible Liquid Crystal Alignments
Daseal Jung 1,Joo-kyoung Hwang 1,Yumin Lee 1,Kwang-Un Jeong 1
1 Chonbuk National University Jeonju Korea (the Republic of),
Show AbstractWithout the conventional polymer-based liquid crystal (LC) alignment process, a newly synthesized dual photo-functionalized amphiphile (ADMA
1) was successfully applied as a robust photo-reversible LC alignment layer by self-assembly and photo-polymerization. The LC alignment layer constructed by directly adding dual photo-functionalized amphiphiles into LC media can cut the manufacturing cost as well as open new doors for the fabrication of novel electro-optical devices. The chemical structure of ADMA
1 was determined by
1H nuclear magnetic resonance spectroscopes (NMR),
13C NMR, MALDI-ToF, and elemental analysis. The dual photochemical behavior of ADMA
1 was identified by ultraviolet-visible spectroscopy. The homeotropic alignment of nematic LC was investigated by both orthoscopic and conoscopic polarized optical microscopy. The self-assembled ADMA
1 monolayer was investigated by atomic force microscopy to analyze the surface morphological changes of the ADMA
1 layer according to light irradiation. From the combined the experimental results, it was realized that ADMA
1 gradually diffused onto the substrate of LC cell and formed monolayered ADMA
1 protrusions by lateral self-assembly. This work was supported by the BK21 Plus, the BRL
2015042417">2015042417, and MOTIE/KDRC 10051334.
9:00 PM - SM1.4.05
Reversible Actuating and Writing Behaviors of a Head-to-Side Connected Main-Chain Photochromic Liquid Crystalline Polymer
Daseal Jung 1,Joo-kyoung Hwang 1,Yu-Jin Choi 1,Dae-Yoon Kim 1,Kwang-Un Jeong 1
1 Chonbuk National University Jeonju Korea (the Republic of),
Show AbstractA photochromic liquid crystalline (LC) polymer {4-butoxy-2’-(4-hex-5-enyloxy)-4’-(4-hex-5-enyl-oxybenzyl-oxy)azobenzene, abbreviated as PLCP} was newly synthesized via the acrylic diene metathesis polymerization. Utilizing the combined techniques of differential scanning calorimetry, cross-polarized optical microscopy, and wide-angle X-ray diffraction (WAXD), it was realized that PLCP formed a nematic (N) phase below the isotropization temperature and the N phase turned to the glassy N phase below the glass transition temperature. From the two-dimensional (2D) WAXD fiber pattern, it was realized that PLCP forms the N LC ordered phase containing the synclinically tilted smectic C (SmC)-type cybotactic clusters, in which the molecular packing structure is related to the head-to-side connected chemical structure of PLCP. By using light and heat, we successfully demonstrated the rewritable UV-patterned PLCP film as well as the reversible mechanical deformation of the uniaxially oriented PLCP microfiber. Due to the wireless remote controllability of reversible actuating and patterning behaviors of PLCP polymer, PLCP can be applied as a key material in optoelectronic and bio-mimetic devices. This work was supported by the BK21 Plus, the BRL 2015042417, and MOTIE/KDRC 10051334.
9:00 PM - SM1.4.06
Bistable and Photoswitchable Diffraction Grating Based on Electric Field-Induced Cholesteric Bubbles
Andrii Varanytsia 1,L.C. Chien 1
1 Liquid Crystal Institute, Kent State University Kent United States,
Show AbstractWe demonstrate a bistable and photoswitchable diffraction grating based on self-assembled bubble domain (BD) texture of cholesteric liquid crystals (CLC). The BD texture is generated in CLCs confined into a cell with homeotropic surface anchoring when equilibrium helical pitch p is approximately equal to the cell gap thickness d, d/p~1.0. An applied electric field is used to switch the CLC between transparent homeotropic and light scattering BD textures. The optical density of scattering BD texture is controlled in a wide range by introducing a light-sensitive azo-benzene type chiral dopant and a dichroic dye into the CLC mixture. Light illumination induced reversible trans-cis isomerization of the chiral dopant enables fine tuning of the CLC pitch, providing photoswitching with a bistability between transparent HO and opaque BD optical states, and a spatial photopatterning using a shadow mask. Dichroic dye dopant creates a bistable guest-host effect based on the BD and homeotropic textures. All optical states are stable in rest after applied electric field or light excitations are removed and the switching is completed. Due to the ability to modulate a broad range of the wavelength of light from UV to near-IR a bistable BD texture dye-doped systems provide promising applications for the wide range of diffractive photonic devices, optical light shutters or light extractors.
9:00 PM - SM1.4.07
Phase Behaviors of Tapered Dendritic Liquid Crystals with Photochromic Azobenzene Mesogens
Yu-Jin Choi 1,Dae-Yoon Kim 1,Joo-kyoung Hwang 1,Yumin Lee 1,Kwang-Un Jeong 1
1 Chonbuk National University Jeonju Korea (the Republic of),
Show AbstractDue to the unique structural properties and chemical multi-functionalities of dendritic molecules, dendrimers have been considered to be promising materials for the advanced applications in nano- and bio-technologies. We newly designed and synthesized a ribbon-shaped chiral liquid crystal (LC) dendrimer containing photochromic azobenznes and an isosorbide chiral center (abbreviated as AZ3DLC). Based on the diffraction experiments combined with thermal and morphological results, it was realized that AZ3DLC formed a low-ordered chiral smectic LC phase at a high-temperature phase region. The pitch length of the spontaneously formed helical superstructure can be precisely controlled by tunning the wavelength of light. This work was supported by the BK21 Plus, the BRL 2015042417, and MOTIE/KDRC 10051334.
9:00 PM - SM1.4.08
Bilayered Composite Materials Based on Liquid Crystalline Elastomers: Experiments and Simulations
Valentina Domenici 1,Jerneja Milavec 3,Andraz Resetic 3,Giuseppe Romano 2,Alexie Kolpak 2,Blaz Zupancic 3,Bostjan Zalar 3
1 Dipartimento di Chimica e Chimica Industriale Università di Pisa Pisa Italy,3 Jozef Stefan Institute Ljubljana Slovenia2 Department of Mechanical Engineering Massachusetts Institute of Technology Boston United States
Show AbstractLiquid crystal elastomers are very interesting soft materials due to the large changes in their microscopic and macroscopic properties at the isotropic-nematic phase transition. The possibility to have a controlled, tunable and reversible shape variation induced by thermal energy has been deeply investigated both on the theoretical and experimental point of view [1]. In order to induce a similar shape variation by applying an external stimulus, such as an electric or magnetic field, several attempts have been recently adopted [2,3].
In this report, we focus on a particular bi-layered system, composed by a Liquid Single Crystal Elastomers (LSCE) film covered by a thin layer of gold [4]. As previously reported for similar systems [3], the thickness of the film can produce either the formation of micron-sized wrinkles or macroscopic bending actuation via direct Joule heating of the composite material.
In this work, we present an experimental study of the thermo-mechanic, thermo-elastic and the Joule heating actuation behavior. Our findings have been supported by continuum elasticity modeling based on finite elements. The simulation takes into account the temperature map throughout the sample and the stress induced by polymer alignment. The change in the elastic properties have been computed by first-principle calculations.
Acknowledgements:
V.Domenici, G. Romano and A. Kolpak thank the MIT-UNIPI project for collaboration between University of Pisa (Italy) and MIT (Boston), project titled: "Energy Storage Devices and Actuators based on Composites of Liquid Crystal Elastomers".
References:
[1] Warner, M. & Terentjev, E. M. Liquid crystal elastomers. (Oxford Univ. Press, 2007).
[2] Agrawal, A., Yun, T.-H., Pesek, S. L., Chapman, W. G. & Verduzco, R. "Shape-responsive liquid crystal elastomer bilayers". Soft Matter 10, 1411-1415 (2014).
[3] Greco, F., Domenici,V., Mattoli, V., Desii, A., Sinibaldi, E., Mazzolai, M., Zupancic, B, Zalar, B. “Liquid single crystal elastomer/conducting polymer bilayer composite actuator: Modelling and experiments”. Soft Matter, 9, 11405-11416 (2013).
[4] Zupancic, B., Zalar, B, Remskar, M., Domenici, V. “Actuation of Gold-Coated Liquid Crystal Elastomers”. Appl. Phys. Express, 6, 021701 (2013).
9:00 PM - SM1.4.09
Enhanced Optical and Electro-Optical Properties of Nano-Ceria Dispersed Ferroelectric Liquid Crystals for Display Applications
Puja Goel 1,Manju Arora 2
1 G.B. P.U.A.T. Pantnagar India,2 NPL Delhi India
Show AbstractThe research in the field of developing nanomaterials-Ferroelectric Liquid Crystals (FLCs) based composites is rapidly growing with the notion of tailoring their physical properties and possibility of entering in to novel multidisciplinary applications of Liquid Crystal materials. Current study deals with the in-depth investigation of physical properties of CeO2 nanoparticles (NPs)-FLC composites with varied Ceria NPs concentration. In previous studies on nanomaterials based LC composites, physical property changes were understood considering the core properties of guest and host materials. However in our present study, the mechanism behind significant changes in dielectric behavior and electro-optic parameters of nanocomposites will be discussed in correlation with structural deformation of functional group present in FLC and lattice straining induced by dispersed NPs using infrared transmission spectroscopy. The temperature and frequency dependence of dielectric permittivity exhibits a gradual increase dielectric constant with CeO2 NPs addition. The increase in saturated spontaneous polarization (Ps) and switching at a lower bias was also observed in these nanocomposites. IR transmission peaks pertaining to uC=O and uC-O stretching modes of FLC’s ester functional group showed shift in peak positions and appearance of new weak intensity C=O bonded chiral group vibrational mode at 1718 cm-1 after Ceria dispersion. These variations are attributed to stress induced and coordinated bond formation between planar polar ester C=O group and Ce3+ ion through lone pairs of oxygen by CeO2 NPs present in the interstitial sites of FLC’s polar component. Apart from this, the mechanisms involved in the changes of the Photoluminescence spectrum of FLC–ceria nanocomposites with varying ceria concentration and excitation wavelengths are studied in detail. These studies will provide important information in designing and tailoring properties of FLCs for luminescent display device application.
9:00 PM - SM1.4.10
Brightness Enhancement Films Based on Quantum Dot Doped Nanoscale Polymer Dispersed Liquid Crystals
Sahil Sandesh Gandhi 1,L.C. Chien 1
1 Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University Kent United States,
Show AbstractWe propose a simple way to fabricate highly transparent nanoscale polymer dispersed liquid crystal (nano-PDLC) films between glass substrates and investigate their incident angle dependent optical transmittance properties with both collimated and Lambertian intensity distribution light sources. We also demonstrate that doping nano-PDLC films with 0.1 % InP/ZnS core/shell quantum dots (QD) results in a higher optical transmittance. This work lays the foundation for such nanostructured composites to potentially serve as roll-to-roll coatable light extraction or brightness enhancement films in emissive display applications, superior to complex nanocorrugation techniques proposed in the past.
9:00 PM - SM1.4.11
Preparation and Characterization of New Photochromic Polymers Containing Side Chain Azo-Diphenyl Diacetylene
Jinsoo Kim 2,Jae-Won Ka 2,Mihye Yi 1,Yun Ho Kim 1,Hye In Jung 1,Sun-Jung Do 2
1 KRICT Daejeon Korea (the Republic of),2 Chemical Convergence Materials Korea University of Science and Technology Daejeon Korea (the Republic of),1 KRICT Daejeon Korea (the Republic of)
Show AbstractNew photoresponsive polymers containing photoisomerizable azo and high birefringence diphenyl diacetylen mesogenic units in the side chain have been designed and synthesized to achieve enhanced photosensitivity such as modulation of refractive index and diffraction efficiency. Newly synthesized polymers were studied by spectral methods (NMR, UV-Vis, IR) and thermal analysis (DSC, POM, TGA). The photochromic behavior of the polymer films was evaluated by observing trans-cis isomerization process of azo-groups. Refractive-index modulation of the new photochromic polymers for developing rewritable hologram media will be discussed.
9:00 PM - SM1.4.12
Structure Property Relationship in Liquid Crystal Nanoinclusion Hybrids
Clare Mahoney 1,Christopher Grabowski 1,Kyoungweon Park 1,Timothy White 1,Richard Vaia 1
1 Materials and Manufacturing Directorate Air Force Research Lab Dayton United States,
Show AbstractThe incorporation of anisotropic nanomaterials such as gold nanorods in liquid crystal media provides avenues towards enhancing current liquid crystal properties as well as the creation of novel hybrid material systems sensitive to external fields, temperature, and other stimuli. In this presentation, the delicate relationship between nanoinclusion parameters, photoresponsive materials, and liquid crystalline media will be discussed.
9:00 PM - SM1.4.13
Responsive Optical Elements Prepared from Liquid Crystal Elastomers
Benjamin Kowalski 1,Timothy White 1
1 Mat amp; Mfg Directorate Air Force Research Lab Wright Patterson AFB United States,
Show AbstractLiquid crystal elastomers have attracted recent interest for their capacity to undergo complex and reversible mechanical responses. The topology inputs to generate these mechanical responses are similar or identical to those used to fabricate high-performance optical components, such as diffractive waveplates. In this contribution, we assimilate the mechanical and optical functionalities into a responsive optical element capabile of being reconfigured by actuation of the material. The versatility of this approach is illustrated with various diffractive optical elements, and their performance is characterized.
9:00 PM - SM1.4.14
Structure-Performance Relation of Liquid Crystal Photoalignment with in situ Formation of Protection Layers
Kai-Han Chang 1,L.C. Chien 1
1 Liquid Crystal Institute and Chemical Physics Interdisciplinary Program Kent State University Kent United States,
Show AbstractPhotoalignment and photopatterning of photosensitive materials have become a subject of intensive fundamental and application studies. The issues associated with azobenzene-based photoalignment layers (PALs) are the vulnerability to thermal stress and exposure to short wavelength ultraviolet light. Furthermore, weak surface anchoring of PAL is also an obstacle for practical applications. In this work, an in-situ protection formation on PALs has been demonstrated. We studied both the structure-property and concentration effects of reactive monomers (RMs) on the morphology of the protection on PAL. The morphological studies show that both the molecular structure and concentration of RM play important roles in the protection achievements. We will present the enhanced stability of PAL, increased anchoring strength and improved electro-optical properties of the photoaligned liquid crystal cells.
Symposium Organizers
Timothy White, Air Force Research Laboratory
L.C. Chien, Kent State University
Helen Gleeson, University of Leeds
Ivan Smalyukh, University of Colorado
SM1.5: Liquid Crystals in Displays and Beyond—Property Enhancement with Nanoinclusions
Session Chairs
L.C. Chien
Helen Gleeson
Ivan Smalyukh
Timothy White
Thursday AM, March 31, 2016
PCC North, 200 Level, Room 231 A
9:30 AM - SM1.5.01
Topological Nanocolloids with Facile Electric Switching of Plasmonic Properties
Ye Yuan 1,Ivan Smalyukh 1
1 University of Colorado Boulder Boulder United States,
Show AbstractCombining topology and plasmonics paradigms in nanocolloidal systems may enable new means of pre-engineering desired composite material properties. Here we design and realize orientationally ordered assemblies of noble metal nanoparticles with genus-one topology and unusual long-range ordering mediated by their interactions with the surrounding nematic fluid host. Facile electric switching of these composites is reminiscent to that of pristine liquid crystals but provides a means of reconfiguring the nanoparticle assembly and thus also the ensuing composite medium’s optical properties. Our findings may lead to formation of new molecular-colloidal soft matter phases with unusual optical properties as well as novel types of optical metamaterials.
9:45 AM - SM1.5.02
Development of 3D Nano-Assembled Gold Micro-Shells for Plasmon Driven Optical and Therapeutic Applications
Makiko Quint 1,David Quint 2,Som Sarang 1,Kerwyn Huang 3,Ajay Gopinathan 2,Linda Hirst 1,Sayantani Ghosh 1
1 Department of Physics University of California Merced Merced United States,2 Department of Bioengineering Stanford University Stanford United States2 Department of Bioengineering Stanford University Stanford United States,3 Department of Microbiology and Immunology Stanford University Stanford United States
Show AbstractWe use thermotropic nematic liquid crystal (LC), 4-Cyano-4'-pentylbiphenyl (5CB), doped with low concentration (1.2 wt %) of mesogen-functionalized gold nanoparticles (AuNPs) to generate nano-assembled micro-shells (NAMs). The assembly process is driven by the isotropic-nematic phase transition. In the isotropic phase, the functionalized AuNPs are uniformly dispersed in the LC mixture. When the mixture is cooled from the isotropic phase to the nematic phase, it separates into LC–AuNP rich isotropic droplets and ordered 5CB rich regions. As the functionalized AuNPs move into the rapidly shrinking isotropic domains during this process, local crystallization of the mesogenic ligands leads to the formation of a dense spherical wall of AuNPs. We show that these NAMs are capable of encapsulating chemical substances without leakages for several months. Additionally, these NAMs demonstrate strong localized surface plasmon resonance (LPSR) and when excited with resonant excitation, the plasmonic heating causes them to rupture at excitation powers as low as 1.5 mW over a time period of a few seconds. Our results exhibiting the capture and optically-regulated release of encapsulated substances can be exploited to enhance a cargo drug releasing system and photothermal therapy.
This work is supported in by National Science Foundation DMR-1056860 and ECC-1227034, and a University of California Merced Faculty Mentor Fellowship.
10:00 AM - SM1.5.03
Tunable Surface Plasmon Resonance From Assembled Nanorods in the Topological Defects of Nematic Liquid Crystals
Elaine Lee 2,Yu Xia 2,Robert Ferrier 3,Hye-Na Kim 2,Mohamed Gharbi 4,Kathleen Stebe 3,Randall Kamien 5,Russell Composto 3,Shu Yang 3
1 Engineering Lawrence Livermore National Laboratory Livermore United States,2 Materials Science and Engineering University of Pennsylvania Philadelphia United States,2 Materials Science and Engineering University of Pennsylvania Philadelphia United States3 Chemical and Biomolecular Engineering University of Pennsylvania Philadelphia United States4 Physics McGill University Montreal Canada5 Physics and Astronomy University of Pennsylvania Philadelphia United States2 Materials Science and Engineering University of Pennsylvania Philadelphia United States,3 Chemical and Biomolecular Engineering University of Pennsylvania Philadelphia United States
Show AbstractControl over the assembly of functional, nanostructured materials is an essential ingredient in creating novel, responsive nanodevices. Efforts have focused on the assembly of metal nanoparticles due to their many applications. However, because of challenges in achieving dynamic assembly and disassembly of metal nanoparticles on cue through a specific stimulus, the full potential of responsive metal nanoparticle-based devices has yet to be achieved. Here, we present a method to direct the assembly of gold nanorods (AuNRs) in nematic liquid crystals (LCs) confined within micropillar arrays by controlling the LC director field to achieve tunable localized surface plasmon resonance properties. The peak absorbance wavelength can be reversibly shifted over a range exceeding 100 nm by varying temperature, an order of magnitude greater than previously observed for AuNRs/LCs nanocomposites. We attribute this much enhanced shift to the formation of well-ordered LC defects surrounding the pillars. In contrast, random defect structures were formed surrounding planar anchored pillars, resulting in indistinguishable plasmon peaks with no peak shift as the sample is cooled. The assembly and actuation of PS-AuNRs demonstrated is achieved through several factors, including the surface functionalization of AuNRs with PS brushes, which allowed for nanorod dispersion in 8CB without aggregation, the periodic arrangement of the surface topography at the microscale, the manipulation of LC surface anchoring through surface functionalization and geometry to form well-ordered defect structures, and the reversible compression/relaxation of the LC director field tuned by temperature. Flexible modulation of the optical properties of metal nanoparticles offers a new route in the quest for active plasmonic devices.
Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344.
10:15 AM - SM1.5.04
Electrically Tunable Nematic Colloidal Dispersions of Upconversion Nanorods
Haridas Mundoor 1,Ivan Smalyukh 3
1 Department of Physics University of Colorado Boulder United States,1 Department of Physics University of Colorado Boulder United States,2 Renewable and Sustainable Energy Institute Boulder United States,3 Department of Electrical, Computer, and Energy Engineering, Materials Science and Engineering Program, and Liquid Crystal Materials Research Center University of Colorado Boulder United States
Show AbstractA promising approach of designing mesostructured materials with novel physical behavior is to combine unique optical and electronic properties of solid nanoparticles with long-range ordering and facile response of soft matter to weak external stimuli. We design, practically realize, and characterize orientationally ordered nematic liquid crystalline (LC) dispersions of rod-like upconversion nanoparticles (UCNP). We synthesized rod shaped β-NaYF4 particles doped with lanthanide ions Erbium (Er3+) and Thulium (Tm3+) using hydrothermal method and dispersed in a nematic LC by suitably modifying the surface functionalization of the particles. Boundary conditions on particle surfaces, defined through surface functionalization, promote spontaneous unidirectional self-alignment of the dispersed rod-like nanoparticles in thermotropic nematic LC. Since the particles are mechanically coupled to the molecular ordering direction of the LC host, UCNP-LC composites inherit unique optical properties of individual UCNP nanoparticles and facile response and ordering of the LC host matrix at the same time, yielding tunable upconversion and polarization dependent luminescence properties. LC switching and polarization dependent properties of the UCNP-LC composite are correlated with the crystal structure of the host matrix of the rod-like UCNPs. We study novel polarization-dependent, electrically switchable optical properties of the UCNP-LC mesostructured composite and explained our findings considering LC switching that causes rotation of rod-like particles while following the LC host reorientation, as well as the crystal symmetry of NaYF4.
References
H. Mundoor, I. I. Smalyukh, “Mesostructured composite materials with electrically tunable upconverting properties” Small, 11, 5572 (2015).
Q. Liu, Y. Yuan, I. I. Smalyukh. “Electrically and optically tunable plasmonic guest-host liquid crystals with long-range ordered nanoparticles” Nano Lett., 14, 4071 (2014).
Y. Zhang, Q. Liu, H. Mundoor, Y. Yuan, I. I. Smalyukh, “Metal nanoparticle dispersion, alignment and assembly in nematic liquid crystals for applications in switchable plasmonic color filters and E-polarizers” ACS Nano, 9, 3097 (2015).
10:30 AM - SM1.5.05
“Michel-Levy” Bands in Nanoplate Suspensions: Use of Gravity and Magnetic Field to Control Orientation of Colloidal Nanoplates
Zhengdong Cheng 1,Chong Ye 2,Ying Chen 2,Abhijeet Shinde 3
3 Artie McFerrin Department of Chemical Engineering Texas A amp; M University College Station United States,1 Department of Material Science and Engineering Texas A amp; M University College Station United States,2 Soft Matter Center, Guangdong Province Key Laboratory on Functional Soft Condensed Matter, School of Materials and Energy Guangdong University of Technology Guangzhou China3 Artie McFerrin Department of Chemical Engineering Texas A amp; M University College Station United States
Show AbstractLiquid crystals of two dimensional materials are of great importance from a fundamental colloidal physics standpoint and they are also being viewed as next generation display materials. Aqueous dispersions of α-Zirconium Phosphate exfoliated with tetra-(n) butyl ammonium hydroxide shows liquid crystalline phases. A vertically-positioned tube containing such a dispersion kept under influence of normal gravity for few hours yielded a vertical density gradient. Birefringence pattern, same as Michel-Levy chart, was observed to have produced when magnetic field was applied to such a sample. Each band had a single color corresponding to the retardation in the path of light which increases in the direction of gravity due to increasing density of particles. After removal of magnetic field, the texture returned back to the original state consisting of small nematic domains oriented in different directions. Magnetic field orients all the nematic domains. This “Michel-Levy” band phenomenon was also observed without application of magnetic field but it needed a few months of domain merging under the influence of gravity.
SM1.6: Liquid Crystals in Displays and Beyond—Light and Alignment
Session Chairs
L.C. Chien
Helen Gleeson
Ivan Smalyukh
Timothy White
Thursday PM, March 31, 2016
PCC North, 200 Level, Room 231 A
11:00 AM - *SM1.6.01
Light-Controlled Topological Charge in a Nematic Liquid Crystal
Igor Musevic 2,Gregor Posnjak 1
1 Jozef Stefan Institute Ljubljana Slovenia,2 Faculty of Mathematics and Physics University of Ljubljana Ljubljana Slovenia,1 Jozef Stefan Institute Ljubljana Slovenia
Show AbstractCreating, imaging, and transforming the topological charge in a superconductor, a superfluid, a system of cold atoms, or a soft ferromagnet is a difficult—if not impossible—task, because of the shortness of the length-scales and lack of control. The length scale and softness of defects in liquid crystals allow for the easy observation of charges, but it is difficult to control charge creation. Recently, we demonstrated [1,2] full control over the creation, manipulation and analysis of topological charges that are pinned to a microfibre in a nematic liquid crystal. Oppositely charged pairs are created via the Kibble-Zurek mechanism by applying a laser-induced local temperature quench in the presence of symmetry-breaking boundaries. The pairs are long-lived, oppositely charged rings or points that either attract and annihilate, or form a long-lived, charge-neutral loop made of two segments with a fractional topological charge. This indicates the sensitivity of the Kibble-Zurek mechanism and the coarsening dynamics of entangled defects at late times to the connectedness of space and symmetry-breaking boundary conditions which might have implications also on the cosmological level. Furthermore, we show that any even number of topological charges could be deliberately created on topologically simple objects, which opens new routes to the design and assembly of topologically complex colloidal structures.
[1] M. Nikkhou, M. Škarabot, S. Čopar, M. Ravnik, S. Zumer and I. Muševič, Nature Physics 11, 183 (2015), doi:10.1038/nphys3194.
[2] M. Nikkhou, M. Škarabot, and I. Muševič, Eur. Phys. J. E 38: 23 (2015), doi:10.1140/epje/i2015-15023-6.
11:30 AM - *SM1.6.02
Designing the Chemomechanical Response of Liquid Crystal Elastomers
Taylor Ware 1,Hyun Kim 1,Jennifer Boothby 1
1 The University of Texas at Dallas Richardson United States,
Show AbstractBiological materials derive function from spatial and hierarchical control of structure and composition. In synthetic materials, programmable control of shape, modulus, and porosity is needed to better interface with complex natural tissues. Liquid crystal elastomers mimic some of the behaviors of natural materials due to the coupling of molecular order to an elastic polymer network. This coupling results in behaviors such as soft elasticity and anisotropic actuation in response to thermal and chemical stimuli. Here we design this mechanical response to yield flat films that morph from flat to 3D in shape in response to both organic solvents and water. For example, torsional actuators capable of peak rotational velocities of up to 400 RPM are demonstrated. Finally we will discuss efforts to use surface-aligned mixtures of liquid crystal monomers to spatially align porogens, yielding microstructured actuators. These active, designed monoliths may be leveraged in applications such as smart implantable devices.
12:00 PM - SM1.6.03
Three-Dimensional Patterning of Solid Microstructures through Laser Reduction of Colloidal Graphene Oxide in Aqueous Liquid-Crystalline Dispersions
Bohdan Senyuk 2,Natnael Behabtu 2,Angel Martinez 1,Taewoo Lee 1,Dmitri Tsentalovich 2,Matteo Pasquali 3,Ivan Smalyukh 5
1 Physics University of Colorado Boulder United States,2 Chemical and Biomolecular Engineering Rice University Houston United States,2 Chemical and Biomolecular Engineering Rice University Houston United States1 Physics University of Colorado Boulder United States2 Chemical and Biomolecular Engineering Rice University Houston United States,3 Chemistry Rice University Houston United States1 Physics University of Colorado Boulder United States,4 Electrical, Computer, and Energy Engineering, Materials Science and Engineering Program University of Colorado Boulder United States,5 Soft Materials Research Center University of Colorado Boulder United States
Show AbstractGraphene materials and structures have become an essential part of modern electronics and photovoltaics. However, despite many production methods, applications of graphene-based structures are hindered by high costs, lack of scalability and limitations in spatial patterning. Here we produce three-dimensional functional solid microstructures of reduced graphene oxide in an lyotropic nematic liquid crystal of graphene oxide flakes dispersed in water using a pulsed near-infrared laser. The proposed method is mask-free, does not require special chemical reduction agents, and can be implemented at ambient conditions starting from aqueous graphene oxide flakes. Orientational ordering of graphene oxide flakes in self-assembled liquid-crystalline phases enables laser patterning of complex, three-dimensional reduced graphene oxide structures and colloidal particles. These graphene oxide structures and particles are mechanically rigid and range from hundreds of nanometers to millimeters in size, as needed for applications in colloids, electronics, photonics and display technology.
12:15 PM - SM1.6.04
Nanoscale Etched Surfaces for Arbitrary and Robust Liquid Crystal Alignment
Jeffrey Chou 1,Lalitha Parameswaran 1,Vladimir Liberman 1,Brian Kimball 2,Mordechai Rothschild 1
1 MIT Lincoln Laboratory Lexington United States,2 U.S. Army Natick Soldier Center Natick United States
Show AbstractThe electrical control of light via liquid crystals (LC) is by far the dominant form of light manipulation used today. To enable the functional use of liquid crystals, the orientation of the LC molecules across the device needs to be precisely defined. Current methods of defining the orientation of LC include either mechanical scratching or photoalignment methods. These methods limit the possible layouts of LCs to simple patterns such as large area single angle alignment or periodic patterns defined by interference lithography. As a result, entire families of complex 2D LC patterns are completely left out due to fabrication limitations.
In this paper, we will present LC devices fabricated with an electron-beam patterned etched indium tin oxide (ITO) surface. This lithography enables precise and deterministic alignment of LCs with arbitrary geometries. Once patterned, we assembled fully functioning LC cells operated under an applied AC bias. To verify our novel nanofabrication method, we prepared electrically switchable cycloidal diffractive waveplate patterns with etched periodic ITO nanostructures just 60 nm wide. We measure polarization diffraction efficiency of 87% and 76% for periods of 2.7 μm and 1.8 μm, respectively, under 405 nm wavelength light. Since these patterns are mechanically defined by etched grooves, they are environmentally robust and will not degrade under standard environmental variations such as temperature, humidity, and prolonged sun exposure.
This new method of LC alignment control opens new opportunities for LC cell designs, as arbitrary patterns of LC alignment can now be formed. To illustrate these new concepts, we show finite-difference time-domain (FDTD) far-field simulations of computer-aided designs of novel 2D LC cells and their unique optical properties. Our simulations use standard commercially available liquid crystal properties and take into account the LC cell thickness to illustrate fully realizable devices. One design of interest is a wide-angle diffraction pattern with 0th order suppression for efficient beam steering applications. Another advantage of arbitrary LC designs is that it allows for custom patterns to be generated to minimize non-ideal effects such thick LC cells, broadband dispersion, and undesired diffraction modes.
Our successful demonstration of the nanoscale etched surfaces for LC control allows for completely new design paths never considered previously and will enable novel optical devices for use in commercial, medical, industrial, and defense applications.
The Lincoln Laboratory portion of this work was sponsored by the United States Air Force under Air Force Contract number FA8721-05-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the authors, and not necessarily endorsed by the United States Government.
12:30 PM - *SM1.6.05
Chirogyral Effect on Microfibres in Nematic Cells
Simon Copar 1,Pawel Pieranski 2,Maria Helena Godinho 3,Slobodan Zumer 1
1 Univ of Ljubljana Ljubljana Slovenia,2 Université Paris-Sud Paris France3 Faculdade de Ciências e Tecnologia Caparica Portugal
Show AbstractFibres of thickness on the sub-millimetre scale, down to a few micrometres, are ubiquitous in nature and man-made materials. The process of creation of the fibres, their molecular structure, which usually consists of polymer chains, and mechanical or abrasive action upon them, impose certain order on the fibres' surface. In a nematic host, the surface order can orient the nematic director in different ways, producing different elastic deformations, visible on polarized micrographs.
Glass fibres with perpendicular director alignment on the surface, immersed in a cell with planar surface alignment, were shown to produce interesting states of topological defects [1]. Nematic droplets were also used to explore the surface of biological fibres, such as cellulose and spider silk, which induce different defects and different optical transmission images [2]. In this talk, we present the behaviour of fibres that have the surface anchoring oriented not exactly along the fibre, but with a helical twist around it [3]. In a nematic cell with homeotropic (perpendicular) anchoring, we find that the metastable defect rings, that would usually enclose the fibre symmetrically, tilt in response to the chirality of the fibre surface. This chirogyral effect, which is approximately linear, is measured experimentally and with numerical simulations. An analytical model is also constructed to explain the elastic mechanism behind the effect, and to qualitatively predict the relationship between the defect tilt and the pitch of the fibre. This effect can be seen as an instance of a more general concept of chiral symmetry breaking having an observable geometric effect on the system.
The coupling can be seen either as a sensory mechanism for detection of fibre chirality, or as means of manipulating the defects via mechanical actuation on the fibre.
[1] M. Nikkhou, M. Škarabot, S. Čopar, M. Ravnik, S. Zumer and I. Muševič, Light-controlled topological charge in a nematic liquid crystal,
Nature Phys. 11, 183 (2015).
[2] Luis E. Aguirre, Alexandre de Oliveira, David Seč, Simon Čopar, Pedro L. Almeida, Miha Ravnik, Maria Helena Godinho and Slobodan Zumer,
Sensing surfaces morphology of bio-fibers with nematic micro droplets: from spider silk to cellulosic fibers, submitted.
[3] Simon Čopar, David Seč, Luis E. Aguirre, Pedro L. Almeida, Mallory Dazza, Miha Ravnik, Maria H. Godinho, Pawel Pieranski and Slobodan Zumer,
Sensing and tuning microfibre chirality with nematic chirogyral effect, submitted.
SM1.7: Liquid Crystals in Displays and Beyond—Fibers and Self Assembly
Session Chairs
L.C. Chien
Helen Gleeson
Ivan Smalyukh
Timothy White
Thursday PM, March 31, 2016
PCC North, 200 Level, Room 231 A
2:30 PM - *SM1.7.01
Topological Defects in Liquid Crystals as Templates for Molecular Self-Assembly
Nicholas Abbott 1
1 Univ of Wisconsin Madison United States,
Show AbstractTopological defects present in liquid crystals (LCs) have been widely used to organize colloidal dispersions and template polymerizations, leading to a range of assemblies, elastomers and gels with complex mechanical and optical properties. However, little is understood about molecular-level assembly processes within defects, although within the nanoscopic cores of singular topological defects the ordering of mesogens is known to be diminished relative to the bulk LC. Herein, we report that nanoscopic environments defined by LC topological defects can selectively trigger processes of molecular self-assembly. By using fluorescence microscopy, cryogenic transmission electron microscopy and super-resolution optical microscopy, key signatures of molecular self-assembly of amphiphilic molecules in topological defects are observed - including cooperativity, reversibility, and controlled growth of the molecular assemblies. By using amphiphiles that can be photocrosslinked, we also demonstrate preservation of molecular assemblies templated by defects, including nanoscopic “o-rings” synthesized from “Saturn-ring” disclinations. Our results reveal that topological defects in LCs are a versatile class of three-dimensional, dynamic and reconfigurable templates that can direct processes of molecular self-assembly in a manner that is strongly analogous to other classes of macromolecular templates (e.g., polymer—surfactant complexes).
3:00 PM - *SM1.7.02
Micro/Nano Filaments Morphologies Revealed by Nematic Liquid Crystals
Maria Helena Godinho 1,Pedro Almeida 1,Simon Copar 2,Pawel Pieranski 3,Slobodan Zumer 2,Miha Ravnik 2
1 Universidade Nova de Lisboa Caparica Portugal,2 University of Ljubljana Ljubljana Slovenia3 Université Paris-Sud Paris France
Show AbstractMicro/nano filaments are ubiquitous in Nature and can be found in plants as well as in the animal kingdom. They play a crucial role on the plants feed and mechanical performance [1, 2] and are determinant in the survival of spider species, which make use of webs to hunt preys [3]. The establishment of relations between structure/properties of these micro/nano threads are thus relevant and also to perform their characterization in order to determine their interaction with the environment. In this work we focus on the use of a nematic liquid crystal to sense the surface of diverse micro/nano filaments. The morphology of the outer surface of the fibers was determined by scanning electron microscopy (SEM) and polarizing optical microscope (POM) was used to observe the interaction between the threads and the liquid crystal. The nematic structures identified were correlated to the filaments morphologies and numerical simulations were performed in order to clarify the experimental data obtained. This work describes a very simple but powerful procedure, which takes profit of the excellent sensitivity of liquid crystals to reveal the outer surface morphology of natural micro/nano fibers.
Acknowledgements: D.S., M.R. and S.Z. acknowledge funding from Slovenian Research Agency Grant No. Z1-5441 and Programme P1-0099. M.R. acknowledges support from EU FP7 MC CIG FREEFLUID. D.S. is thankful to Simon Čopar for the help with visualization of numerical results. L.A., P.L.A. and M.H.G. acknowledge funding from FEDER through the COMPETE 2020 Program and National Funds through FCT-Portuguese Foundation for Science and Technology under projects UID/CTM/50025/2013 and PTDC/CTM-POL/1484/2012.
[1] B.A. Meylan, B.G. Butterfield, Wood Sci Technol, 12, 219-222 (1978).
[2] D.G. Gray, Cellulose, 21(5), 3181-3191 (2014).
[3] S.W. Cranford et al., Nature, 482(7383), 72-76 (2012)
3:30 PM - *SM1.7.03
Liquid Crystalline Polymer Vesicles: Thermotropic Phases in Lyotropic Structures and Their Potential Bio-Based Applications
Min-Hui Li 2
1 Chimie ParisTech - PSL Research University - CNRS Institut de Recherche de Chimie Paris (IRCP) Paris France,2 International Research Center for Soft Matter Beijing University of Chemical Technology Beijing China,
Show AbstractIn this talk I will present our research work on the liquid crystalline (LC) polymer vesicles (polymersomes), where the thermotropic nematic and smectic phases are displayed in the lyotropic membrane of polymer bilayer. LC polymersomes possess the properties of both liquid crystals and polymers, the two essential soft matters. LC polymersomes offer, on the one hand, novel examples of the interplay between the orientational order and the curved geometry of a two dimensional membrane. Spherical, ellipsoidal and tetrahedral vesicles will be discussed. On the other hand, LC polymersomes enable novel design of stimuli-responsive polymersomes using intramolecular conformational transition from nematic to isotropic phase of LC blocks. Photo-responsive polymersome bursting will be highlighted. At the end, reduction-responsive biocompatible LC polymersomes will be discussed.
References:
[1] Jia L., Li M.-H. “Liquid crystalline polymer vesicles: thermotropic phases in lyotropic structures” Liq. Cryst. 2014, 41, 368-384. (for pdf: http://arxiv.org/abs/1503.00904)
[2] Xing X., Shin H., Bowick M. J., Yao Z., Jia L., Li M.-H., “Morphology of Nematic and Smectic Vesicles”, Proc. Natl. Acad. Sci. U. S. A., 2012, 109, 5202-5206.
[3] Jia L., Lévy D., Durand D., Impéror-Clerc M., Cao A., Li M.-H., “Smectic Polymer Micellar Aggregates with Temperature-Controlled Morphologies”, Soft Matter, 2011, 7, 7395-7403.
[4] Mabrouk E., Cuvelier D., Brochard-Wyart F., Nassoy P., Li M.-H., “Bursting of sensitive polymersomes induced by curling”, Proc. Natl. Acad. Sci. U. S. A., 2009, 106, 7294-7298.
[5] Hocine S., Cui D., Rager M.-N., Di Cicco A., Liu J.-M., Wdzieczak-Bakala J., Brûlet A., Li M.-H., “Polymersomes with PEG Corona: Structural Changes and Controlled Release Induced by Temperature Variation”, Langmuir 2013, 29, 1356-1369.
[6] Jia L., Cui D., Bignon J., Di-Cicco, A., Wdzieczak-Bakala J., Liu J., Li M.-H. “Reduction-Responsive Cholesterol-Based Block Copolymer Vesicles for Drug Delivery”, Biomacromolecules 2014, 15, 2206–2217.
[7] Ferji K., Nouvel C., Babin J., Li M.-H., Gaillard C., Nicol E., Chassenieux C., Six J.-L. "Polymersomes from amphiphilic glycopolymers containing polymeric liquid crystal grafts." ACS Macro Lett. 2015, 4,1119-1122.
4:30 PM - SM1.7.04
Guiding Liquid Fibers of Smectics
Francesca Serra 1,Hye-Na Kim 1,Randall Kamien 1,Kathleen Stebe 1,Shu Yang 1
1 University of Pennsylvania Philadelphia United States,
Show AbstractLiquid crystals, a soft anisotropic material, offer new ways to direct light through their assemblies. Droplets of cholesteric liquid crystals, for example, have been exploited as microlasers [1] and smectic liquid crystal defects are used to create compound eye-like microlenses [2]. Bahr and Musevic have recently demonstrated the possibility of creating liquid fibers that work as optical fibers entirely made of smectic liquid crystals and float in a water-surfactant solution [3].
One of the challenges to make these fibers useful for practical applications, however, is controlling their alignment, orientation, and direction without the use of external micromanipulation such as optical tweezers. To this end, we confine a large drop of smectic liquid crystal, 4-octyl-4’-cyano-biphenyl (8CB), in a cell in which one of the substrates has topographical features such as micro-pillars, wrinkles or grooves, made of SU8 or poly(dimethylsiloxane). When the droplet comes in contact with the water-surfactant solution, the fibers start to form. We show that these fibers can follow the topographical features: they tend to wrap around the pillars and they align with the microgrooves and wrinkles, even when these are very shallow compared to the diameter of the fibers. The fibers are able to bend to a certain extent and to form kinks along the microwrinkles. After about 20 minutes from the loading of the sample, fibers are aligned over large areas and relatively stable. The fibers can be all contained in one single wrinkle, if their diameter is small enough; they can also span across two or three adjacent wrinkles, while retaining the capability of being aligned by the wrinkles. We characterize the optical waveguiding properties in such prepared smectic fibers.
Further, we show that smectic fibers can be coupled to the smectic microlens arrays to create a soft, all-liquid crystal optical system via self-assembly.
[1] M. Humar, I. Musevic, Opt. Express 18, 26995 (2010)
[2] F. Serra, M.A. Gharbi, Y. Luo, I. B. Liu, N. D. Bade, R. D. Kamien, S. Yang, K. J. Stebe, Adv. Opt. Mater. 3, 1287 (2015)
[3] K. Peddireddy , V.S. Jampani, S. Thutupalli, S. Herminghaus, C. Bahr, I. Musevic, Opt. Express 21, 30233 (2013)
4:45 PM - SM1.7.05
Responsive Liquid Crystalline Cellulose Networks
Susete Fernandes 1,Joao Avo 1,Maria Helena Godinho 1
1 I3N/CENIMAT, Department of Materials Science, Faculty of Sciences and Technology, Universidade NOVA de Lisboa Caparica Portugal,
Show AbstractCellulose, the most abundant biopolymer on earth, is one of the main constituents of the plant cell walls. It has unique properties, which makes it an ideal starting point for transforming it into a wide range of materials and derivatives. Cellulose derivatives are mainly produced by chemical reaction of the free hydroxyl groups in the β-D-glucopyranose units, often in heterogeneous conditions yielding, in many cases, average degrees of substitution less than 3 per glucose unit. [1] Amongst the very interesting properties of cellulose and its wide range of derivatives some can present liquid crystalline behavior, either in the presence of a solvent or on its own. Here we take profit of the richness of these systems and different assembly conditions to built up from similar nano structures, different nano structures lamellas and filaments that show dissimilar response when subjected to UV irradiation. Nanocrystalline cellulose and a thermotropic liquid crystalline cellulose derivative were modified with azobenzene or spiropyran substituents. [2-3] Different structures were obtained from these cellulose derivatives by using spin-coating, Langmuir-Blodgett, as well as shear or solvent casting techniques. The nano structures obtained presented a high surface-to-volume ratio, which can be freestanding or grown off a substrate leading to organic tunable interfacial templates, that response to external stimuli, as light, giving rise to materials with distinct properties (E.g. wettability).
Acknowledgements: The Portuguese Science and Technology Foundation (FCT) supported this research through contract UID/CTM/500025/2013. The NMR spectrometers are part of The National NMR Facility, supported by FCT through contract RECI/BBB-BQB/0230/2012. SN Fernandes acknowledges FCT for grant SFRH/BPD/78430/2011.
References: [1] RJ Moon, A Martini, J Nairn, J Simonsen, J Youngblood, Chem. Soc. Rev. 40, 3941–3994, 2011; [2] LFV Pinto, S Kundu, P Brogueira, C Cruz, SN Fernandes, A Aluculesei, MH Godinho, Langmuir 27(10):6330-6337, 2011. [3] R. Klajan, Chem. Soc. Rev. 43, 148-184, 2014.
SM1.8: Liquid Crystals in Displays and Beyond—Energy
Session Chairs
L.C. Chien
Helen Gleeson
Ivan Smalyukh
Timothy White
Thursday PM, March 31, 2016
PCC North, 200 Level, Room 231 A
5:00 PM - *SM1.8.01
Ion-Conductive Liquid-Crystalline Assemblies: Orientation Control of Ionic Channels and Approaches to Energy Applications
Takashi Kato 1
1 Univ of Tokyo Tokyo Japan,
Show AbstractHerein we describe design of functional liquid crystals that form nanoscale self-organized structures. The use of nanostructures of bicontinuous cubic, smectic, and columnar liquid crystals having ionic moieties leads to the development of new transport materials forming well-controlled nano-scale 3D, 2D, and 1D channels.[1-8] They serve as new electrolytes that transport ions and protons efficiently.[1-5] It is important to control of the orientation of ionic channels. Recently, photocontrol of the direction of ion conductive paths has been achieved for the ionic liquid crystals with photochromic moieties.[5] Switching of the ion conductivities have been observed for an ionic liquid crystal on columnar-columnar phase transition.[6] Liquid-crystalline (LC) ion-conductive materials are applied for energy devices.[7,8] For example, lithium-ion batteries[8] and dye-sensitized solar cells (DSSCs)[8] are developed using these nanostructured LC electrolytes. Smectic LC electrolytes have been used as thermally stable electrolytes for DSSCs.[8]
Partial financial support by CREST, JST is gratefully acknowledged.
[1] Kato, T. Angew. Chem. Int. Ed. 2010, 49, 7847.
[2] Kato, T. Science, 2002, 295, 2414.
[3] Ichikawa, T.; Yoshio, M.; Hamasaki, A.; Taguchi, S.; Liu, F.; Zeng, X,; Ungar, G.; Ohno, H.; Kato, T. J. Am. Chem. Soc. 2012, 134, 2634.
[4] Soberats, B.; Yoshio, M.; Ichikawa, T.; Taguchi, S.; Ohno, H.; Kato, T. J. Am. Chem. Soc. 2013, 135, 15286.
[5] Soberats, B.; Uchida, E.; Yoshio, M.; Kagimoto, J.; Ohno, H.; Kato, T. J. Am. Chem. Soc. 2014, 136, 9552.
[6] Soberats, B.; Yoshio, M.; Ichikawa, T.; Zeng, X.; Ohno, H.; Ungar, G.; Kato, T. J. Am. Chem. Soc. 2015, 137, 13212.
[7] Sakuda, J.; Hosono, E.; Yoshio, M.; Ichikawa, T.; Matsumoto, T.; Ohno, H.; Zhou, H.; Kato, T. Adv. Funct. Mater. 2015, 25, 1206.
[8] Hogberg, D.; Soberats, B.; Uchida, S.; Yoshio, M.; Kloo, L.; Segawa, H.; Kato, T. Chem. Mater. 2014, 26, 6496.
5:30 PM - SM1.8.02
Discotic Liquid Crystalline Hole Transport Layers: Towards Capillary Filled Organic-Inorganic Photovoltaic Devices
Ammar Khan 1,M A Bin Kamarudin 1,Malik Qasim 1,Mojtaba-Abdi Jalebi 2,Timothy Wilkinson 1
1 Engineering (Div B) University of Cambridge Cambridge United Kingdom,2 Cavendish Laboratory, Department of Physics University of Cambridge Cambridge United Kingdom
Show AbstractRecent improvements in the power conversion efficiencies of perovskite and dye sensitized solar cells have generated significant interest1,2. While the efficiencies of the best perovskite devices are now comparable to poly-crystalline silicon solar cells, large scale commercialization is still an open challenge that suffers from scalability and stability3. One challenge is the use of solution-processing techniques such as spin-coating, which is not suitable for large area panels. The high melting points (m.p) of commonly used hole transport layers (HTLs), (for example a m.p ~248°C in the case of Spiro-OMeTAD4) make melt-processing difficult. In addition, the use of Lithium salts to catalyze oxidative doping of spiro based HTLs affects repeatability and standardization.
In this research we aim to develop small molecule p-doped, low-temperature melt processed HTLs through the use of a Triphenylene based discotic liquid crystal (DLC); 2, 3, 6, 7, 10, 11 Hexakishexyloxytriphenylene (HAT6) . Discotic liquid crystalline organic molecules typically comprise of fused poly-aromatic core rings with substituted long alkyl chains5. The electron rich aromatic cores exhibit π- π stacking forming long-range hole conducting molecular columns6, and the alkyl chains act as insulating spacers between the hole conducting columns, allowing 1-D charge carrier conduction.
Pure HAT6 is initially doped with a p-type molecular dopant 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) to increase hole concentration and then mixed with Spiro-OMeTAD in varying wt.% . The ternary mixtures are then characterised using polarizing optical microscopy (POM) , Differential Scanning Calorimetry (DSC) and current-voltage (IV) measurements. Effects on alignment and conductivity of the columnar mesophases upon mixture formation are discussed in the context of device applications. Our results show doping with F4TCNQ and Spiro-OMeTAD increases the hole conductivity of HAT6 by almost three orders of magnitude, while still preserving mesophase characteristics. The mixtures are then used to fabricate photovoltaic devices and the performance is characterised.
1 B. E. Hardin, H. J. Snaith and M. D. McGehee, Nat. Photonics, 2012, 6, 162–169.
2 N. G. Park, J. Phys. Chem. Lett., 2013, 4, 2423–2429.
3 M. a. Green, A. Ho-Baillie and H. J. Snaith, Nat. Photonics, 2014, 8, 506–514.
4 C. D. Bailie, E. L. Unger, S. M. Zakeeruddin, M. Grätzel and M. D. McGehee, Phys. Chem. Chem. Phys., 2014, 16, 4864.
5 R. J. Bushby and O. R. Lozman, Curr. Opin. Colloid Interface Sci., 2002, 7, 343–354.
6 S. Sergeyev, W. Pisula and Y. H. Geerts, Chem. Soc. Rev., 2007, 36, 1902–29.
5:45 PM - SM1.8.03
Thermotropic Ionic Liquid Crystals as Single-Ion Conducting Lithium-Battery Electrolytes: Investigation of the Structure-Transport Interplay
Melody Leclere 2,Dominic Bresser 1,Laurent Bernard 1,Patrice Rannou 1,Hakima Mendil-Jakani 1,Sandrine Lyonnard 1,Lionel Picard 2
2 Liten CEA Grenoble Grenoble France,1 CEA-INAC-SPrAM Grenoble France
Show AbstractLithium-ion batteries are currently gaining increasing importance for (hybrid) electric vehicles as well as stationary energy storage. However, a major issue towards their implementation in these large-scale applications concerns their safety. Commonly utilized liquid organic electrolytes containing, e.g., LiPF
6 as conducting lithium salt entail the risks of thermal instability, high flammability, sensitivity towards hydrolysis, high toxicity, and leakage
[1].
Consequently, solid electrolytes are presently considered as most promising to overcome these safety issues
[1-4]. Nevertheless, the state-of-the-art polyethylene oxide-based electrolytes suffer from insufficient ionic conductivities (10
-4-10
-5 S cm
-1) while polymer gel electrolytes (inactive polymer host comprising a conducting liquid electrolyte) do not provide a terminal solution for the aforementioned issues
[4,5].
Recently, two very promising strategies have emerged to enhance both chemical and electrochemical characteristics: block copolymer ionomers
[6,7], providing the advantage of being single-ion conductors (transference number (T) = 1), and Thermotropic Ionic Liquid Crystals (in combination with a lithium salt), offering tunable self-assembly and very high Li
+ conductivities (ca. 10-3 S.cm-1)
[8-10].
With the objective to combine the advantages of both, we have successfully developed
a new class of single-ion conducting Thermotropic Ionic Liquid Crystals (Polymers) (TILC(P)s) (2 patents) which potentially allow superior Li
+ conductivities and, thus, enable the realization of high performance, safer lithium-ion batteries.
Herein, we will present their
structural, morphological and electrochemical characterization, highlighting the interplay of nanostructure and ionic conductivity. In addition, we will present our first results concerning their application as lithium-ion electrolyte.
References:
[1] J. Kalhoff, G.G. Eshetu, D. Bresser, S. Passerini
ChemSusChem 2015,
accepted manuscript.
[2] W. Fergus
J. Power Sources 2010,
195,
4554-4569.
[3] E. Quartarone, P. Mustarelli
Chem. Soc. Rev. 2011,
40,
2525-2540.
[4] B. Scrosati, J. Garche
J. Power Sources 2010,
195,
2419-2430.
[5] B. Scrosati, C.A. Vincent
MRS Bull. 2000,
25, 28-30.
[6] H. Sinha, J.K. Maranas
Macromolecules 2011,
44,
5381-5391.
[7] K.-J. Lin, J.K. Maranas
Macromolecules 2012,
45,
6230-6240.
[8] H. Shimura, M. Yoshio, A. Hamasaki, T. Mukai, H. Ohno, T. Kato
Adv. Mater. 2009,
21, 1591-1594.
[9] T. Ichikawa, M. Yoshio, A. Hamasaki, J. Kagimoto, H. Ohno, T. Kato
J. Am. Chem. Soc. 2011,
133,
2163-2169.
[10] J. Sakuda, E. Hosono, M. Yoshio, T. Ichikawa, T. Matsumoto, H. Ohno, H. Zhou, T. Kato
Adv. Funct. Mater. 2015,
25, 1206-1212.