Hydrophilic polymethacrylates containing cholic acid-ethylene glycol derivatives as pendant groups

In an effort to improve the hydrophilicity of bile acid containing polymers, we have synthesized new methacrylate monomers by incorporating ethylene glycol and oligo(ethylene glycol) spacers of different lengths between cholic acid and methacrylate residues. The monomers were subsequently polymerized by free radical reaction in solution. The methyl ester protecting groups on the cholic acid residue were selectively hydrolyzed to restore the carboxylic acid group of cholic acid. Water absorption tests showed that the hydrophilicity of the polymers was improved with increasing length of oligo(ethylene glycol) spacers and upon restoration of the carboxylic acid group of the cholic acid residue.