Polymers of methacrylate and methacrylamide derivatives of cholic acid were prepared by free radical polymerization in solution. To verify the stereoisomeric effect of the monomeric units, certain properties of the resulting polymers were compared, including conversion rate, molecular weight, and glass transition temperature. The 3B-epimers of the methacrylates and methacrylamides are to polymerize more easily than the 3a-epimers. Water absorption experiments showed that the methacrylamide polymers are more hydrophilic than the methacry late polymers and that the polymers from the 3B-epimers have higher hydrophilicity than those made from the 3a-epimers. The free acid forms of the polymers were also prepared by selective hydrolysis of the methyl ester group of the cholic acid moiety which resulted in improved hydrophilicity of the polymers.

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SUMMARY New copolymers were prepared from methacrylate and methacrylamide derivatives of cholic acid and methacrylic acid by free radical polymerization in solution. The copolymers were characterized by solid-state I3C NMR spectroscopy and differential scanning calorimetry. The copolymers all have a single glass transition temperature located between the glass transition temperatures of the two corresponding homopolymers. The copolymers were found to be random, and the chemical composition in the final products was close to the original monomer composition in the feed prior to polymerization. Water absorption measurements showed that the water absorption capacity of the copolymers increases from about 10% to about 35% with increasing molar ratio of methacrylic acid in the copolymers.