Katia Bertoldi, Harvard University
Alan J. Jacobsen, HRL Laboratories, LLC
Christopher M. Spadaccini, Lawrence Livermore National Laboratory
Lorenzo Valdevit, University of California, Irvine
XX2: Processing I
Christopher M. Spadaccini
Monday PM, November 30, 2015
Sheraton, 2nd Floor, Republic B
2:30 AM - *XX2.01
Printing Architected Materials
Jennifer A. Lewis 1 2
1Harvard University Cambridge United States2Wyss Institute for Biologically Inspired Engineering Cambridge United StatesShow Abstract
3D printing opens new avenues for designing and fabricating architected materials in a scalable manner. Specifically, we fabricate tailored architectures by direct writing of soft, hard, and composite inks. Using digital assembly, we programmably encode the mechanical responses of interest, including bending, snap-through instabilities, specific stiffness, and Poisson&’s ratio. This talk will highlight multiple examples of novel architectures and their resulting mechanical properties created by this approach.
3:00 AM - XX2.02
Fabrication of Metal/Elastomer Hybrid Structure Using Site-Selective Folding Instabilit
Yemuk Choi 1 Pilnam Kim 1
1KAIST Daejeon Korea (the Republic of)Show Abstract
In this study, we suggest a new methodology to construct a 3D metal/elastomer hybrid microstructure by stiffness patterning and folding instability. Thin, layered elastomer undergoes the unstable process in the presence of the compression, creating the wrinkle or fold structure. Here, we adopted stiffness patterning method on the surface of the elastomer to control the position of fold structure. Subject to a compressive surface strain, the stiffness-patterned substrate could produce selective-deformation depending on substrate stiffness. Thus the folded structure appears on the softer part of the substrate. Using this approach, we constructed 3D metal-elastomer hybrid microstructure by site-selective folding instability combined with a wet transfer method. The folded metal-elastomer hybrid microstructure is reversibly stretched and compressed to large levels (200 %) of strain without damage in the metal structure. Moreover, our method opens the way to provide a new kind of microfabrication design like optical film or mechanical sensor.
3:15 AM - XX2.03
Insensitivity to Flaws Leads to Damage Tolerance in Brittle 3D Architected Meta-Materials
Lauren C. Montemayor 1 Wei Hin Wong 2 Yong-Wei Zhang 2 Julia R. Greer 1
1California Institute of Technology Pasadena United States2Institute for High Performance Computing Singapore SingaporeShow Abstract
Cellular solids are instrumental in creating lightweight, strong, and damage-tolerant engineering materials. By extending their feature size down to the nanoscale, we are able to simultaneously exploit the architecture and size effects to substantially enhance the structural integrity of architected meta-materials. We show that hollow-tube alumina nanolattices of 3D kagome geometry with and without pre-fabricated notches always fail at the same load when the ratio of notch length (a) to sample width (w) is no greater than 1/3, with no correlation between failure occurring at or away from the notch. For notches with (a/w) > 1/3, the samples fail at lower peak loads and this is attributed to the increased compliance as fewer unit cells span the un-notched region. Finite element simulations of the kagome tension samples show that the failure is governed by tensile loading for (a/w) < 1/3 but as (a/w) increases, bending begins to play a significant role in the failure. This work explores the flaw sensitivity of hollow alumina kagome nanolattices in tension, using experiments and simulations, and demonstrates that the discrete-continuum duality of architected structural meta-materials gives rise to their flaw insensitivity and fracture tolerance even when made entirely of intrinsically brittle materials.
3:30 AM - XX2.04
Realization of Hierarchically Porous and Three Dimensionally Ordered Mesoporous Materials (3DOm) via Templating
Daniel G Gregory 1 Mark Snyder 1
1Lehigh University Bethlehem United StatesShow Abstract
Sacrificial templating offers a versatile method of synthesizing new materials with hierarchically porous structures for use as catalysts and absorbents. This process facilitates precise tunability of pore size in order to produce materials with rationally designed pore structures spanning all porosity regimes (macroporous, mesoporous, and microporous). Such materials offer the ability to selectively engineer a catalyst or absorbent in order to obtain desirable transport properties during chemical processing. This work demonstrates the ability to produce three dimensionally ordered mesoporous materials (3DOm) including silica&’s, carbons, and transition metal oxides using various colloidal templating techniques. These materials demonstrated the ability to tune surface area and pore size via templating; while simultaneously stabilizing metastable oxide phases such as a-TiO2 and t-ZrO2 at elevated temperatures. The versatility of these hierarchically porous materials is demonstrated via the selective separation of sugars and the photocatalytic decomposition of methylene blue dye. To characterize the samples, precursor solutions were analyzed using DLS and SAXS prior to templating; while templated materials were characterized using N2 and Ar adsorption, SEM, HRTEM, XRD, SAXS, and XPS. The discussion will conclude with a review of these findings in order to highlight the appropriate selection of chemical precursor&’s, processing conditions, and potential pitfalls to consider when synthesizing future materials via templating.
3:45 AM - XX2.05
3D Printing Soft Architected Materials
Jordan Robert Raney 1 Katia Bertoldi 1 Jennifer A. Lewis 1
1Harvard University Cambridge United StatesShow Abstract
3D printing opens new avenues for designing and fabricating architected materials in a scalable manner. We use a 3D extrusion-based printing method, known as direct ink writing, to fabricate soft, reversibly-deformable architected materials. Specifically, silicone-based inks with tailored rheology are patterned into structures comprised of precise beam geometries. The aspect ratio and the tilting angle affect the mechanical response of the beams, which can include such phenomena as snap-through instabilities and multistability, leading to nonlinear wave propagation. Beam geometries can be programmably tuned to encode spatially-varying mechanical responses. Due to the soft architecture, the static and dynamic response of the architected material can be further tuned by applying static deformation. This talk will highlight multiple examples of novel architectures and mechanical responses created by this approach.
4:30 AM - *XX2.06
Textile Manufacturing of 3D Lattice Materials
Kevin J. Hemker 1 James K Guest 1 Stephen Ryan 1 Timothy P. Weihs 1 Longyu Zhao 1 Keith Sharp 2 David C Dunand 3 Dinc Erdeniz 3 Peter W. Voorhees 3 Richard Fonda 4 Andy Geltmacher 4 Amanda Levinson 4 Harold Kahn 5 Arthur Heuer 5
1Johns Hopkins Univ Baltimore United States2Saurtex Raleigh United States3Northwestern University Evanston United States4NRL Washington United States5Case Western Reserve University Cleveland United StatesShow Abstract
Recent advances in topological optimization methodologies for design of internal material architecture, coupled with the emergence of micro- and nanoscale fabrication processes, 3D imaging, and micron scale testing methodologies, now make it possible to design, fabricate, and characterize lattice materials with unprecedented control. This talk will describe a collaborative effort that employs scalable 3D textile manufacturing, location specific joining, and vapor phase alloying to produce metallic lattices with a wide range of internal architectures, alloy compositions, and mechanical and functional properties. Topology optimization allows properties to be decoupled and tailored for specific applications. Dramatic enhancements in permeability have been balanced with modest reductions in stiffness, and are being used to develop heat exchanger materials with high thermal transport, low impedance, low thermal gradients and high temperature strength. In a parallel effort, architectural designs to maximize both structural resonance and inter-wire friction are also being employed to develop metallic lattices capable of mechanical damping at elevated temperatures. These examples will be used to highlight the benefits to be gained by the design, manufacturing and characterization of metallic lattice materials with a wide range of tailorable properties.
5:00 AM - XX2.07
Electroplating 3D Printed Materials - Complimentary Processes Yield Unique Composites
Sean Wise 1
1RePliForm Inc. Baltimore United StatesShow Abstract
3D printing has opened the doors to design freedom such that just about anything that can be imagined and sketched up in CAD can be fabricated from plastics, metals and even ceramics. The plastic systems which have been around for more than 25 years, have been limited by the fact that it is difficult to incorporate reinforcement into the resins so mechanical properties are generally limited to neat resin stiffness and strengths. Additionally the layer by layer process of making parts often leads to weakness in the laminations. Metal AM parts on the other had have mechanical properties similar to wrought metal properties of the same composition but it is generally very expensive to build and finish metal AM parts limiting their application.
Electroplating additive manufactured organic resin parts can be a great complement to SLA, SLA, FDM and other 3D printing methods. Coating of copper and nickel can provide metallic properties such as heat dissipation, electromagnetic and optical reflectivity, barriers against harsh environments, improve thermal stability as well as stiffen and strengthen parts in a predictable way. This presentation will review the mechanics and methodology for applying the coatings for different purposes as well as simple design modifications, easily done with print on demand additive manufacturing, that facilitate making functional accurate metal clad plastic parts. Additionally, the issues encountered in working with the different AM systems will be covered along with how these can be dealt with and processed successfully.
5:15 AM - XX2.08
Dendrimer Mediated Synthesis and Self-Assembly of Colloidal Nanoparticles
Davit Jishkariani 1 Benjamin Diroll 1 Matteo Cargnello 1 Christopher B. Murray 1 Bertrand Donnio 1
1University of Pennsylvania Philadelphia United StatesShow Abstract
The collective physical properties of nanoparticle (NP) assemblies depend strongly on interparticle distance. Controlled tuning of interparticle spacings therefore offers the possibility to optimize the response of NP solids for applications including optical, magnetic and electronic devices.
In this series of projects, a variety of lipophilic, highly flexible, dendritic ligands (generations 0 to 4) was designed to bind colloidal nanocrystals and induce self-assembly properties. After ligand exchange, by controlling the solvent evaporation rate, the corresponding dendron-capped nanoparticle hybrids were found to self-organize into hexagonal close-packed (hcp) superlattices. The interparticular spacing can be progressively varied from 2.2 to 6.3 nm with increasing the dendritic generation, covering a range that is intermediate between commercial ligands and DNA-based ligand shells.
Dual mixtures of dendronized hybrids resulted in unprecedented superlatices (where both components have same size inorganic core, but different dendritic covering) which are isostructural with NaZn13 and CaCu5 crystals.
The synthetic and self-assembly details as well as latest results will be discussed.
5:30 AM - XX2.09
New Self-Assembly Method and Characterization of a Non-Close Packed Colloidal Lattice on a Water-Air Interface
Max Carlson 1 Ka-Yen Yau 1 Robert E. Simpson 2 Michael Short 1
1Massachusetts Institute of Technology Cambridge United States2Singapore University of Technology and Design Singapore SingaporeShow Abstract
Non-close packed colloidal lattices made by self-assembly can be used to fabricate a variety of large-scale nanostructures (honeycomb, nano-pillars) by nanosphere lithography, and devices such as photonic crystals and biosensors . This method has benefits over close-packed arrays due to greater applicability with tunable interparticle distance, and less susceptibility to particle size variation and solution contaminants. Multiple methods exist for self-assembly of close-packed polystyrene microspheres , but achieving control over microsphere spacing presently requires chemical and/or mechanical modifications of the substrate or the particles [1, 3]. We present an ultrasonic mist deposition approach that leads to robust, large-scale ordered structures of microspheres, with interparticle spacing above four particle diameters. Starting with a solvent-microsphere colloid, a piezoelectric element is used to generate a mist that passes through a gravity-buoyancy barrier to preferentially select mist particles containing individual microspheres before being transported onto a water surface. Upon landing on the water, at specific interparticle spacing an isotropic pair potential between the microspheres is established due to the combination of zeta potential, capillary, and surface tension forces at the water-air interface. Unlike the work of , the colloidal lattice is formed at a water-air interface and exhibits pair potential interactions without an applied electric field, suggesting a new mechanism for interparticle interaction at the observed spacing. Use of thisnew mist method, as opposed to traditional Langmuir-Blodgett or spin coating methods, enhances the fraction of microspheres deposited at the appropriate spacing to enter the ordered lattice potential well, while enabling straightforward extension to large scale deposition. No surface modifications to the microspheres or substrate are required, furthering the flexibility and ease of this approach. This work was supported by the SUTD-MIT International Design Center.
1. Jian-Tao Zhang, et al. Periodicity-Controlled Two-Dimensional Crystalline Colloidal Arrays. Langmuir vol. 27, 15230-15235 (2011).
2. Junhu Zhang, et al. Colloidal Self-Assembly Meets Nanofabrication: From Two-Dimensional Colloidal Crystals to Nanostructure Arrays. Advanced Materials vol. 22, 4249-4269 (2010).
3. Xiao Li, et al. Modulating Two-Dimensional Non-Close-Packed Colloidal Crystal Arrays by Deformable Soft Lithography. Langmuir vol. 26, 2930-2936 (2010).
4. Ke-Qin Zhang & Xiang Y. Liu. In situ observation of colloidal monolayer nucleation driven by an alternating electric field. Nature vol. 429, 739-743 (2004).
XX3: Poster Session
Monday PM, November 30, 2015
Hynes, Level 1, Hall B
9:00 AM - XX3.01
Fabrication of Multi-Layer 3D Nanostructures via Ion Assisted Aerosol Lithography (IAAL) and Studies on Its SERS Signals
Kiwoong Lee 1 Hoseop Choi 2 1 Dae Seong Kim 1 Min Seok Jang 1 Mansoo Choi 1 2
1Seoul National University Seoul Korea (the Republic of)2Seoul National University Seoul Korea (the Republic of)Show Abstract
A great deal of effort has been devoted to stack 2D planar nanostructures for the amplification of its own photonic functionality or the achivement of newly derived photonic behavior, such as chirality. In our experiment, we demonstrated to stack 3D nanostructures layer upon layer via repetitive execution of e-beam lithography and 3D assembly of nanoparticles via IAAL (Ion-Assisted Aerosol Lithography).
Our multi-layer 3D nanostructures were fabricated through following 3-step procedures. (1) We generated cross-shaped patterns with the size of 1.5mu;m#8553;1.5mu;m and the interval of 1.5mu;m on the silicon substrate via e-beam lithography. (2) Positively charged metal nanoparticles generated by spark discharge were blown onto the pattered silicon substrates where negative voltage was applied. nanoparticles assembled on the exposed silicon substrate and grew in the lateral directions, due to the nanoscopic electrostatic lens induced by the pre-deposited cations on e-beam resist. (3) 3D nanostructures were sintered and strengthened by e-beam irradiation to endure the spin-coating of e-beam resist for the upper layer patterns. Then, e-beam resist was spin-coated upon the nanostructure of the previous layer and patterns for the next layer which was aligned according to previous layer was fabricated via e-beam lithography. Through repetition of procedure (1)-(3), multi-layer 3D nanostructures were manufactured. Finally, e-beam resist was eradicated through O2 plasma ashing.
In order to demonstrate the photonic enhancement of multi-layer nanostructures, compared to mono-layer nanostructures, we measured the SERS signals of thiophenol molecueles chemisorbed onto the bi-layer nanostructures and the mono-layer nanostructures. It was observed that the peak intensities of the bi-layer nanostructures were significantly increased, compared to those of the mono-layer nanostructures. The bi-layer nanostructures exhibited 4-5 fold higher peak intensities, compared to the mono-layer nanostructures.
9:00 AM - XX3.02
Stress Transfer in Corrugation Reinforced Composite Materials
Mark Fraser 1 Hatem Zurob 1 Peidong Wu 1
1McMaster University Hamilton CanadaShow Abstract
This work examines the effect of corrugated architecture on stress transfer in metal matrix composite materials. Due to the fact that during unbending a corrugation exhibits a transition from bending dominated behaviour towards stretching dominated behaviour it is possible to construct a composite material that transitions from minimal stress transfer initially to large amounts of stress transfer upon further deformation. During the loading of a corrugation reinforced composite, the corrugation will unbend leading to an evolving reinforcement alignment and therefore evolving conditions for the transfer of stress. In this work, the stress transfer in composites with plastically deforming components is analyzed using an adapted shear lag model and Finite Element Modeling. Experimental investigations into strain distribution are also included.
9:00 AM - XX3.03
Vertically Aligned Silica Nano-Pillars Fabricated by Block Copolymer Lithography
Yuri Yamada 1 Atsushi Miura 1 Masashi Harada 1 Hiroaki Wakayama 1
1Toyota Central Ramp;D Labs., Inc Nagakute-City JapanShow Abstract
Recently, block copolymers (BCPs) have been investigated extensively for nanolithography applications to provide highly controlled structures with a simple and cost-effective method. Among various structures, vertically aligned pillars are one of the most prominent architectures for the emerging application, such as vertical transistor, light reflection controller, and chemical and biological sensor. Because of the easiness of surface modification, silica nano-pillars are promising candidate to realize these applications. In this presentation, we demonstrate a facile route to fabricate a well ordered vertically aligned silica nano-pillars making the most of self-assembled BCPs.
Polystyrene-block-polydimethylsiloxane (PS-b-PDMS; 31k-b-14.5k) was dissolved in cyclohexane, followed by spin coating on the Si substrate which was coated with PS brush in advance. The solvent annealing was conducted in chloroform vapor within 2 hours. The reactive ion etching (RIE) and the sequential calcination could easily provide silica nanostructures. The morphology of the obtained structures was observed by scanning electron microscope (SEM), whereas the composition was verified by Fourier transform infrared spectroscopy (FT-IR). Grazing-incidence small angle X-ray scattering (GISAXS) measurements were also conducted to investigate the morphological transition as well as the ordering of BCPs during annealing process. With increasing the annealing time, micro phase separation was induced and cylindrical PDMS became the dominant phase, leading to the optimum condition of 1.5 hours. Well aligned nano-pillars could be found throughout the substrate of 1 cm2. Over 2 hours, the structure gradually lost the regularity. In addition, we also investigated the effect of the vapor pressure, and drying speed of the solvent on the morphology of the samples. GISAXS measurements well agree the observation of SEM images. Some optical properties derived from fine structure of the fabricated nano-pillars will be presented.
9:00 AM - XX3.04
Controlled Fracture-Based Active Microfluidic System Inspired by Drinking-Mechanism of Desert Lizards
Junghwa Cha 1 Pilnam Kim 1
1KAIST Daejeon Korea (the Republic of)Show Abstract
Lizards living in desert have remarkable ability to collect and transport water through their skin to the mouth. The lizards drink water using specialized scaled integuments, semi-tubular capillary system, which consists of honeycomb-like scales as water reservoir, and interscalar channels as water transporter. Inspired from these unique integuments, we suggest that the lizard&’s water drinking system can be major components of open-closed hybrid microfluidic systems. Thus, we utilized a novel controlled fracture technique for a microfluidic system.
Although fractures or cracks are typically difficult to control precisely due to their randomness, crack formation can be controlled under the delicate conditions. In this study, we controlled the stress distribution throughout the surface at the predefined position. As expected, controlled cracks were created from the predefined notches as initiating points. When the extent of tensile strain became increased, the number of cracks formation was also increased. At the 75% of prestretched condition, the cracks were formed completely at almost of prepatterned