Effect of adamantyl methacrylate on the thermal and mechanical properties of thermosensitive poly(N-isopropylacrylamide) hydrogels

A series of thermosensitive hydrogels containing adamantyl groups were fabricated by copolymerization of N-isopropylacrylamide and adamantyl methacrylate (AdMA). The thermal properties of such copolymeric hydrogels were studied by differential scanning calorimetry. The mechanical properties were emphasized through compression, tension, and dynamic mechanical analysis (DMA). Moreover, Rubber elasticity theory was used to evaluate the network parameters based on compressive stressstrain measurements. The results indicate that both the microstructure and physical properties strongly depend on the quantity of AdMA in the copolymeric gels. As the content of AdMA increases, the volume phase transition temperature of hydrogels decreases linearly, and the mechanical strength can be significantly improved, the effective crosslinking density (nu(e)) increases monotonously, while the polymer-water interaction parameter (chi) decreases first and then increases with AdMA content. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012