Preparation of composite-crosslinked poly(N-isopropylacrylamide) gel layer and characteristics of reverse hydrophilic-hydrophobic surface

The composite-crosslinked poly(N-isopropylacrylamide) (PNIPAAm) gels were prepared by grafting N-isopropylacrylamide on the surface of glass plates modified by organosilanes. The glass plates as the substrate increase the mechanical strength of composite PNIPAAm gel layers. We investigated the effects of a series of organosilanes and the reaction time of organosilanes on surface characteristics, such as the static contact angle and the layer thickness. We discuss the equilibrium swelling ratio and the water release behavior of the gel layers in terms of the crosslinking density of the composite gels. The composite gels exhibit not only the characteristics of remarkable water release but also the reversed hydrophilic–hydrophobic surface properties. The gel layers are hydrophilic under 25°C and change to hydrophobic above 40°C. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1–11, 1999