Temperature-induced changes in the surface wettability of SBR plus PNIPA films

We report a novel rubber film made by a simple mixing method, which realizes a steep temperature dependence of the contact angle of water at a critical temperature of 41 degrees C. We mixed a common SBR with a known temperature-responsive PNIPA to make a thermo-responsive rubber. This rubber film distinctly showed a switch of surface wettability between hydrophilic below 41 degrees C and hydrophobic above 41 degrees C. The switching property is possibly controlled by the mixing ratio of PNIPA to SBR, preparation method, added chemicals, and so on. This mixing technique will be applied for the control of surface wetting properties by temperature on various SBR-like rubber materials, such as wet-brake performance of automobile tires on a rainy day.