Effect of surface tension on elastocapillary wrinkling of interfacially adsorbed hydrogel disks with photothermally programmed swelling profiles

In this work, we study the influence of surface tension on light-induced wrinkling of hydrogel disks containing patterned regions of photothermally-active gold nanoparticles at the air-water interface. The disks, which are initially radially stretched by the air-water surface tension, undergo wrinkling under illumination through a radially nonuniform photothermal deswelling. By tuning the surface tension of the surrounding air-water interface through variations in concentration of a poly(vinyl alcohol) surfactant, we observe a critical threshold for wrinkling, followed by a monotonic decrease in wrinkle number with decreasing surface tension. Finite element simulations performed to better understand this behavior reveal qualitatively similar trends as the experiments. The insights provided into elastocapillarity-mediated wrinkling may guide future efforts to control interfacial behaviour of reconfigurable and shape-morphing films.

Automated summary

This study investigates the effect of surface tension on the light-induced wrinkling of hydrogel disks containing photothermally-active gold nanoparticles. By changing the surface tension through the concentration of a poly(vinyl alcohol) surfactant, a critical threshold for wrinkling is observed, followed by a decrease in wrinkle number with decreasing surface tension. Finite element simulations show similar trends as the experiments. The findings provide insights into controlling the interfacial behavior of reconfigurable and shape-morphing films.