Buckling instabilities in polymer films have received significant attention due to their well-defined and complex topological features. Wrinkled interfaces represent one class of buckling instabilities in thin films, with multiple examples apparent in nature (i.e. wrinkling in skin, grooves on cerebral cortex) and engineered polymer thin-film applications (i.e. flexible electronics, controlled adhesion, microfluidic devices). Surface wrinkles frequently occur from an in-plane compression (i.e. mechanical, thermal, or osmotic) of a bilayer film comprised of a thin, rigid skin layer attached to a semi-infinite, low modulus elastic substrate. Recent efforts have focused on stimuli-responsive wrinkle formation. Specifically, light-induced wrinkle formation represents an attractive stimulus because it enables morphological changes with high spatial resolution. Herein, we report a simple route to engineer wrinkled ultrathin poly(styrene-alt-maleic anhydride) (pSMA) brush surfaces using a simple post-polymerization modification (PPM) approach with an azobenzene crosslinker. The azobenzene moieties undergo a UV-induced photoisomerization transition from a trans to a cis-state enabling the design of ultra-thin pSMA surfaces with tunable and controlled morphological transitions.

Photoresponsive surface wrinkling in polymer brush thin films

255th National Meeting (2018)

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