Thermal-responsive hydrogel surface: tunable wettability and adhesion to oil at the water/solid interface

Abstract

We present a thermal-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogel, which can responsively and reversibly control the wettability and adhesion to oil at water/solid interface. The hydrogel surface can switch from a superoleophobic and low adhesive state below the PNIPAM lower critical solution temperature (LCST, ∼32 °C) to an oleophobic and high adhesive state above its LCST. Moreover, the thermal-responsive wettability and adhesion to oil at the water/solid interface can be tailored by designing and constructing ordered micro-structures on the surface. We demonstrated the thermal-responsive changing of the topography on PNIPAM hydrogel surface by atomic force microscopy and proposed a mechanism of inter-molecular to intra-molecular hydrogen binding transitions. We believe the reported material has promising utilizations in micro fluidics, control of bio-relevant adhesion and under-water antifouling materials.