Biodegradable polymers based on renewable resources.: VII.: Novel random and alternating copolycarbonates from 1,4:3,6-dianhydrohexitols and aliphatic diols

Novel copolycarbonates containing 1,4:3,6-dianhydro-D-glucitol or 1,4:3,6-dianhydro-D-mannitol units, with various methylene chain lengths, were synthesized by bulk and solution polycondensations, of several combinations of carbonate-modified sugar derivatives and aliphatic diols. Bulk polycondensations of 1,4:3,6-dianhydro-2,5-bis-O-(phenoxycarbonyl)-D-glucitol or 1,4:3,6-dianhydro-2,5-bis-O-(phenoxycarbonyl)-D-mannitol with four alpha,omega-alkanediols having methylene chain lengths of 4, 6, 8, and 10, respectively, at 180 degreesC afforded the corresponding copolycarbonates with number-average molecular weight (M-n) values up to 19.(2) x 10(3). C-13 NMR analysis disclosed that these polymers had scrambled structures in which the sugar carbonate and aliphatic carbonate moieties were nearly randomly distributed along a polymer chain. However, solution polycondensations between 1,4:3,6-dianhydro-2,5-bis-O-(p-nitrophenoxycarbonyl)-D-glucitol or 1,4:3,6-dianhydro-2,5-bis-O-(p-nitrophenoxycarbonyl)-D-mannitol, and the alpha,omega-alkanediols in sulfolane or dimethyl sulfoxide at 60 degreesC gave well-defined copolycarbonates having regular structures consisting of alternating sugar carbonate and aliphatic carbonate moieties with M-n values up to 33.(8) x 10(3). Differential scanning calorimetry demonstrated that all the copolycarbonates were amorphous with glass-transition temperatures ranging from 1 to 65 degreesC, which decreased with increasing lengths of the methylene chain of the aliphatic diols. Additionally, all the copolycarbonates were stable up to 310-330 degreesC as estimated by thermogravimetric analysis. (C) 2003 Wiley Periodicals, Inc.