Patent ID: 7671164

Claim:
A method for the manufacture of an aliphatic polycarbonate, comprising: melt reacting an ester-substituted diaryl carbonate of the formula: wherein each R 4 is independently a C 1-20 aliphatic group, C 4-20 cycloaliphatic group,or C 4-20 aromatic group, each R 5 is independently a halogen atom, cyano group, nitro group, C 1-20 aliphatic group, C 4-20 cycloaliphatic group, or C 6-18 aromatic group, and each f is independently 0 to 4, with a multifunctional compound of the formula: wherein R 10 is a chemical bond, a C 1-40 hydrocarbon that can be unsubstituted or substituted with a hydroxy, carboxy, C 1 -C 22 alkoxycarbonyl, halogen, C 2-20 olefin,C 1-20 alkylether, or C 4 -C 30 polyoxyalkylene in which the alkylene groups each independently comprise 2 to 6 carbon atoms, R 11 and R 12 are each independently a hydrogen or a C 1 -C 40 hydrocarbon that can be unsubstituted or substituted with a hydroxyl, carboxy, C 1 -C 22 alkoxycarbonyl, halogen, C 1-20 olefin, C 1-20 alkylether, or C 4 -C 30 polyoxyalkylene functionality in which the alkylene groups contain 2 to 6 carbon atoms, and optionally wherein at least two of R 10 , R 11 , and R 12 together form a C 2 -C 40 monocyclic, bicyclic, or tricyclic ring system optionally substituted with a heteroatom in a ring, and R 9 is a hydroxy or C 1 -C 22 alkoxycarbonyl group; to form a first oligomer having a weight average molecular weight of 4,000 to 12,000 g/mol, measured using gel permeation chromatography using polystyrene standards, and comprising less than 2,000 ppm of an ester-linked terminal group of the formula: wherein each R 5 is independently a halogen atom, cyano group, nitro group, C 1-20 aliphatic group, C 4-20 cycloaliphatic group, or C 6-18 aromatic group, and f is 0 to 4, as determined by 1 H NMR; and melt polymerizing the first oligomer in the presence of a transesterification catalyst to form the aliphatic polycarbonate.