Synthesis and Characterization of Poly(glyceric Acid Carbonate): A Degradable Analogue of Poly(acrylic Acid)

The synthesis and characterization of a degradable version of poly(acrylic acid), poly(glyceric acid carbonate), are reported. Specifically, atactic and isotactic poly(benzyl glycidate carbonate)s are obtained via the ring-opening copolymerization of rac-/(R)-benzyl glycidate with CO2 using a bifunctional rac-/(S,S)-cobalt salen catalyst in high carbonate linkage selectivity (>99%) and polymer/cyclic carbonate selectivity (similar to 90%). Atactic poly(benzyl glycidate carbonate) is an amorphous material with a T-g (glass transition temperature) of 44 degrees C, while its isotactic counterpart synthesized from enantiopure epoxide and catalyst is semicrystalline with a T-m (melting temperature) = 87 degrees C. Hydrogenolysis of the resultant polymers affords the poly(glyceric acid carbonate). Poly(glyceric acid carbonate) exhibits an improved cell cytotoxicity profile compared to poly(acrylic acid). Poly(glyceric acid carbonate)s also degrade remarkably fast (t(1/2) approximate to 2 weeks) compared to poly(acrylic acid). Cross-linked hydrogels prepared from poly(glyceric acid carbonate) and poly(ethylene glycol) diaziridine show significant degradation in pH 8.4 aqueous buffer solution compared to similarly prepared hydrogels from poly(acrylic acid) and poly(ethylene glycol) diaziridine.