Buckling instabilities (wrinkles, creases, and folds) are ubiquitous in soft materials and can be exploited to define the shape, morphology, and function of complex systems – as exemplified by nature in the wrinkling of skin or folding of brain tissue. Following nature’s lead, strain-induced wrinkling of polymer thin films has emerged as a powerful bottom-up approach to engineer surfaces that exhibit complex ordered and disordered patterns at multiple length scales. Herein, we highlight out recent efforts to exploit ultrathin polymer brush surfaces (&lt;100nm) with wrinkled and creased morphologies using a simple postpolymerization modification (PPM) approach. Poly(styrene-alt-maleic anhydride) (pSMA) polymer brushes were synthesized via surface-initiated polymerization and then postmodified (crosslinked) under poor solvent conditions. Exposure of the partially crosslinked brushes to good solvent conditions preferentially swells the non-crosslinked regions to induce the buckling instability. Swelling ratio measurements were determined to investigate the onset of buckling of pSMA brush films. Additionally, time of flight secondary ion mass spectroscopy (TOF-SIMS) was utilized to obtain depth profiles of pristine pSMA and pSMA at discrete postmodification reaction times. The pSMA were exposed to sequential postmodification reactions to enable wrinkle-to-crease morphological transitions while endowing the brush with additional chemical functionality.

Wrinkling polymer brush surfaces via postpolymerization modification

253rd National Meeting (2017)

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