Patent ID: 6864327

Claim:
A polymer composition, comprising a mixture of a polymer derivative having the structure R-O-POLY-R′ and a polymer derivative having the structure R-O-POLY-O-R, wherein POLY is a water-soluble and non-peptidic polymer, R is alkyl and R′ is a functional group, wherein POLY is a poly(alkylene glycol), and wherein R′ is selected from the group consisting of hydroxyl, mesylate, tosylate, tresylate, —O—CO 2 R 3 wherein R 3 is H, alkyl or N-succinimidyl, —O—(CH 2 ) n —CO 2 R 3 wherein n is 1-6 and R 3 is H, alkyl or N-succinimidyl, —NHR 4 wherein R 4 is H or alkyl or an amine protecting group, —O—(CH 2 ) n —CH(ZR 5 ) 2 wherein n is 1-6, and Z is O or S, R 5 is H or alkyl, Ar—CH═CH—CH═CH—CO 2 —, wherein Ar represents a moiety selected from the group consisting of phenyl, substituted phenyl, biphenyl, substituted biphenyl, polycyclic aryls, substituted polycyclic aryls, and heterocyclic aryls, —O—(CH 2 ) n —CHO where n n is 1-6, —O 2 CCH 2 CH 2 CO 2 R 6 , wherein R 6 is H or N-succinimidyl. CH 2 ═CH—CO 2 —, and —O—CH 2 —CO 2 CH(CH 3 )CH 2 CO 2 —NHS. wherein NHS is N-succinimidyl.