Self Wrinkling of UV-cured Polymer Films

We report~the~formation of surface wrinkle patterns associated with the curing of polymer films. Taking advantage of a thin layer of liquid on the surface of a polymer film, we swell the underlying substrate-constrained film, resulting in surface wrinkles due to the resulting compressive stress. The wrinkles evolve from isolated dimples at short times to elongated wrinkles with a defined length. ~The wavelength of the wrinkles is proportional to the film thickness and is stable at long times.~The wrinkle amplitude increases with time after curing due to~diffusion of the liquid, reaching a state of equilibrium swelling at long times. The characteristic time for amplitude evolution increases with increasing crosslink density.