Synthesis and characterization of copolymer hydrogels having hydrophobic comonomer

In this thesis, N-vinylimdazole (VIm) based copolymeric hydrogels containing hydrophobic lauryl methacrylate (LM) with different mole ratio (5, 10 and 15%) were synthesized and characterized by various instrumental methods. Swelling experiments were carried out with respect to some parameters such as pH, temperature and ionic strength. Swelling tests were also performed in some organic solvents. It was seen that swelling capacity in aqueous media decreased with increasing LM content of the gels, while this value increased in organic solvents. While the equilibrium swelling ratio (Smax,e) for the copolymer containing %15 mole LM at pH 6.2 was 0.47 g water/g gel, Smax,e in dimethylsulfoxide and dichloromethane were 1.67 and 2.24 g solvent/g gel, respectively. Also, the presence of LM provided thermal responsivity for copolymers. Depending on LM content, Smax,e increased approximately by the ratio of 32% with increasing temperature. On the contrary, pH sensitivity of the copolymers were lower than that of homopolymer. "Salting-in effect" was observed for swelling processes carried out in salt solutions and Smax,e generally increased with increasing ionic strength. Hydrogels showed swelling behavior 5 times without loss of Smax,e. In deswelling tests at 25°C, it was observed that copolymers released 80-90% of their water in 1440 minutes depending on their LM content, while homopolymer lost almost all of water in the same period.