| Abstract: | Copolyesters containing pendent vinylidine groups were prepared in a one-step synthesis by reacting either chloro- or bromoacetic acid with 2-(bromomethyl)acrylic acid and triethylamine in diethyl ether. Polymers were characterized by IR, 1H- and 13C-NMR, DSC, and TGA. Copolymer formation supports a mechanism involving a triethylammonium carboxylate salt acting as an active nucleophilic species in a manner analogous to that seen in phase transfer catalysis involving carboxylate anions. Comparison of 13C-NMR spectra intensities indicates that 2-(bromomethyl)acrylic acid is much more reactive than the haloacetic acids leading to higher copolymer incorporation than in the monomer feed. Unsaturation in the copolymers provides a site for crosslinking during radical polymerization with an added vinyl monomer, similar to the way unsaturated polyesters function in commercial fiberglass formulations. This was confirmed by polymerization of both styrene and methyl methacrylate in the presence of an unsaturated copolymer giving insoluble semi-interpenetrating networks. These unsaturated copolymers are the first examples of soluble biodegradable glycolic acid polyesters containing such reactive functionality. |
