Preparation and characterization of copolymers of new monomers from bile acid derivatives with methacrylic monomers and selective hydrolysis of the homopolymers

Polymers have been prepared by solution-free radical polymerization from new monomers made from bile acid derivatives. Two approaches were used to improve the hydrophilicity of the polymers: first, the monomers were copolymerized with methacrylic monomers such as methacrylic acid and 2-hydroxyethyl methacrylate; second, the methyl ester groups on cholic acid of the homopolymers were also removed selectively by hydrolysis. The copolymers and the hydrolysed polymers were characterized by solid-state n.m.r. spectroscopy and differential scanning calorimetry. The copolymers were found to be random and the chemical composition in the final products was close to the original monomer composition prior to polymerization. It was also found that the methyl ester groups can be removed selectively by controlling the time of hydrolysis in a basic media while keeping the methacrylate ester bond mostly intact. The methacrylamide bond in the polymers was more resistant to hydrolysis than the methacrylate bond.