Fabrication and properties of thermosensitive organic/inorganic hybrid hydrogel thin films

We report on a facile method for fabricating thermosensitive organic/inorganic hybrid hydrogel thin films from a cross-linkable organic/inorganic hydrid copolymer, poly[ N-isopropylacrylamide- co-3-(trimethoxysilyl)propylmethacrylate] [P(NIPAm- co-TMSPMA)]. Fourier transform infrared (FT-IR) spectra confirmed the formation of hybrid hydrogel thin films after hydrolysis of the methoxysilyl groups (Si-O-CH 3) and subsequent condensation of the silanol groups (Si-OH). Atomic force microscopy (AFM) images revealed that the surface morphology of the hydrogel thin films depended on the supporting substrates. Microdomains were observed for the hydrogel thin films on a gold surface, which can be attributed to inhomogeneous network structures. The thermoresponsive swelling-deswelling behavior and the viscoelastic properties of the hydrogel thin films were investigated as a function of temperature (25-45 degrees C) by using a quartz crystal microbalance (QCM) operated in water. The high frequency shear modulus of the P(NIPAm- co-TMPSMA) hydrogel thin films was several hundred kilopascals.