Graft copolymerization of epoxy-terminated poly(dimethylsiloxane) (PDMS) onto chitosan was reacted without using a catalyst. pH-sensitive hydrogels were obtained that are based on two different components: a natural polymer and a synthetic polymer, These PDMS substitutents provide the basis for hydrophobic interactions that contribute to the formation of hydrogels. Various graft hydrogels were prepared from different weight ratios of chitosan and PDMS. Swelling behavior of these hydrogels was studied by immersion of the gels in various buffer solution. Photocrosslinked hydrogels exhibited a high equilibrium water content (EWC). Particularly, the sample CP31 of the highest chitosan-PDMS weight ratio showed the highest EWC in time-dependent, temperature-dependent, and pH-dependent swelling behavior,