Thermo-Responsive Polymer Grafted Aluminum Surface to Actively Modulate Water Wettability

Thermo-responsive wettability is studied for adaptive surface, which can potentially help to enhance the performance of thermal devices under various operation conditions. Poly(N-isopropylacrylamide) or PNIPAAm polymer brush can be grafted onto solid surfaces so that at temperatures below the lower critical solution temperature (LCST), the surface is hydrophilic, while at temperatures above LCST, it automatically becomes more hydrophobic. In this study, PNIPAAm is grafted on to aluminum alloy 6061, which is a multipurpose alloy commonly used in thermal mechanical systems. It is demonstrated by water static contact angle experiment at varies temperature that, the surface is hydrophobic at temperatures above LCST, and hydrophilic below LCST. The results are compared with bare aluminum surface at similar temperatures. Grafting PNIPAAm polymer brush on roughened aluminum surface would result in the ability to automatically switch between superhydrophobic state and superhydrophilic state in response to temperature change.