Photodirected Formation and Control of Wrinkles on a Thiol-ene Elastomer.

Photopolymerization on a thiol-ene elastomer is a novel method to spatiotemporally control wrinkle formation gradients and complex patterns. Acrylate-rich elastomers, containing photoinitiator and photoabsorber, were strained and irradiated with UV light to generate wrinkles in as little as five seconds. The presence of the photoabsorber confines the UV light to a thin skin layer, facilitating wrinkle formation upon release of the strain. In conjunction with photomasks, wrinkles are confined and oriented with explicit boundaries defined by the irradiation pattern. Using a photoorthogonal photoiniator, we also demonstrate the ability to independently control the bulk modulus of the wrinkled elastomer. The wide array of thiol and ene monomers, photoinitiators, and photomask designs result in an alternative approach that is rapid, facile, and highly versatile, further enabling the a priori design and engineering of surface topography and shape of the material.