Function transformation of polymeric films through morphing of surface shapes

Abstract

The functions of materials are correlated with their shapes. Here, we propose a scheme of functional transformation of a polymeric film by changing the surface shape. After the preparation of straight shapes such as lines or rectangles on a substrate by conventional microfabrication methods, we transformed the shapes into laterally buckled or inversely tapered shapes. The change in surface shape induced stress dissipation or superomniphobic functions, which are difficult to obtain with straight shapes. To transform the shapes, we harnessed a method of swelling hydrogel shapes bonded to a substrate. We replicated the swollen shapes with functional materials by photopolymerization of liquid prepolymers filled within the cavities of the swollen hydrogel shapes. We investigated methods to hold water molecules within the hydrogel networks during photopolymerization by controlling the surface energy of the photocurable liquid prepolymer and removing air between the liquid prepolymer and the cavities for easy infiltration of the liquid prepolymer into the inversely tapered shapes. The proposed scheme of function transformation by using surface shape morphing can be a platform technology for developing unprecedented functions depending on shape.