Infrared Scanning Near-Field Spectroscopic Studies of Self-Assembled Nanostructures Based on Photo-Crosslinkable Block Copolymers

When and Where

Nov 30, 2023
4:15pm - 4:30pm

Sheraton, Second Floor, Republic B



Nadine von Coelln1,Britta Weidinger1,Christian Huck1,Irene Wacker1,Rasmus Schroeder1,Eva Blasco1,Petra Tegeder1

Heidelberg University1


Nadine von Coelln1,Britta Weidinger1,Christian Huck1,Irene Wacker1,Rasmus Schroeder1,Eva Blasco1,Petra Tegeder1

Heidelberg University1
Block copolymers, i.e., chemically distinct polymer blocks which are covalently bond, are known for their ability to self-assemble into a variety of morphologies on the nanometer scale.<sup>[1]</sup> The self-assembly of block copolymers has been extensively investigated for 2D films,<sup>[2,3]</sup> however, less attention has been paid to 3D bulk morphologies as well as light-based 3D printed microstructures. To achieve long-range ordered samples in thermodynamic equilibrium, in this work, 3D bulk morphologies were prepared via solvent annealing and 3D printed microstructures were fabricated from pre-self-assembled block copolymer inks.<br/><br/>Infrared scanning near-field optical microscopy (IR-SNOM) offers the unique possibility of infrared chemical imaging and spectroscopy with a spatial resolution down to ∼20 nm.<sup>[4]</sup> When irradiating a well-defined diblock copolymer consisting of polystyrene and a methacrylate-based copolymer decorated with photo-crosslinkable units at an independently addressable absorption band of a polymer block, chemical imaging of the blocks’ nano-ordered spatial arrangement is possible.<br/><br/>Here, the internal nanostructure of self-assembled 3D bulk morphologies with lamellar nanostructures is studied by means of IR-SNOM. When selectively exciting each polymer block, a switch of the relative optical phase, related to the local absorption, is observed, revealing a strong phase segregation via spectroscopic contrast. A successful correlation with scanning electron microscopy (SEM) measurements, performed after post-staining with ruthenium tetroxide, furthermore demonstrates, that ruthenium tetroxide creates a specific metal stain for polystyrene. These studies are extended to cylindrical nanostructures as well as two-photon laser printed microstructures exhibiting complex geometry and hierarchically nano-ordered structures.<br/><br/>References:<br/>[1] Y. Mai <i>et al.</i>, <i>Chem. Soc. Rev.</i> <b>2012</b>, <i>41</i>, 5969-5985.<br/>[2] C. J. Hawker <i>et al.</i>, <i>MRS Bull.</i> <b>2005</b>, <i>30</i>, 952-966.<br/>[3] J. Kim <i>et al.</i>, <i>Spectrochim. Acta A</i> <b>2022</b>, <i>274</i>, 121095.<br/>[4] A. Centrone, <i>Annu. Rev. Anal. </i><i>Chem.</i> <b>2015</b>, <i>8</i>, 101-126.


polymer | scanning probe microscopy (SPM) | self-assembly

Symposium Organizers

Allison Beese, The Pennsylvania State University
A. John Hart, Massachusetts Institute of Technology
Sarah Wolff, Ohio State University
Wen Chen, University of Massachusetts Amherst

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MRS publishes with Springer Nature


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