Carbohydrate-based polycarbonates.: Synthesis, structure, and biodegradation studies

Linear homo- and co-polycarbonates have been prepared from the sugar-based diols 2,3,4-tri-O-methyl-L-arabinitol and 2,3,4-tri-O-methylxylitol. Statistical co-polycarbonates were obtained from molar feed ratios of sugar:bisphenol A of 1:1 and 2:1. The polycarbonates were stable up to similar to 280 C with maximum decomposition rate above 345 degrees C. The arabinitol-based homopolymer was found to be semicrystalline whereas the xylitol-based one was amorphous. All the copolymers were amorphous with T-g ranging between 60 and 80 degrees C. Both homo- and co-polycarbonates showed high resistance to chemical hydrolysis; however, they were enzymatically degraded in different degree. The xylitol-based polycarbonates were the more easily degraded by lipase B from Candida antarctica in acetonitrile at 70 degrees C-this enzyme showing a high selectivity toward the configuration of the sugar-based moiety.