Patent ID: 8492505

Claim:
A process for the preparation of branched biodegradable polymers comprising of the steps of: (a) subjecting a first composition comprising at least one cyclic ester, cyclic carbonate and/or cyclic N-carboxyanhydride to ring opening polymerization conditions in the presence of a branching agent and optionally a catalyst to produce a second composition comprising a macromonomer, wherein the catalyst is an alkyl, an oxide, an alkoxide, a halide, or a carboxylate of a metal, wherein the branching agent has the following formula: (Z) x —R 1 (COOR 2 ) y wherein Z is a hydroxyl, thiol, primary or secondary amine group; (x+y)≧3; R 1 is an aliphatic or aromatic moiety with or without ester, ether, amide, and/or ketone functionality; R 2 is a hydrogen, (C 1 -C 6 )-alkyl optionally substituted with halogen, or aryl, such as phenyl, optionally substituted with halogen or (C 1 -C 6 )-alkyl; and (b) subjecting the second composition comprising the macromonomer produced in step (a) to polycondensation without an intermediate deprotection step; wherein the polycondensation occurs under conditions different from the ring opening polymerization conditions, wherein the cyclic esters and carbonates have the following general structures: in which h is from 2 to 16, i is from 1 to 4, j is from 0 to 4, and R 1 , R 2 , R 3 , R′ 1 and R′ 2 are the same or different and represent a hydrogen, or hydrocarbyl or substituted hydrocarbyl with protected O, N, and/or S functionality with a maximum of 30 carbon atoms; wherein the substituted hydrocarbyl with protected O, N and/or S functionality is CH 2 O—Bz, (CH 2 ) 4 —NH—Z 1 , and CH 2 —S-MBz wherein Bz is benzyl, Z 1 is benzyloxycarbonyl, and MBz is p-methoxybenzyl; and wherein the cyclic N-carboxyanhydride (NCA) has the following general structure in which R represents a hydrogen, or hydrocarbyl, or hydrocarbyl with (protected) O, N, and/or S functionality, or hydrocarbyl with protected carboxylic acid, or aromatic group such as —CH 2 Ph.