Synthesis of high molecular weight non-peptidic polymer derivatives

An activated polymer derivative comprising said polymer derivative one (or more than one) first non-peptidic, water-soluble polymer segment having at least about 200 repeating units covalently attached through at least one binding moiety at least a second polymeric segment nonpeptide soluble in water, having no more than about 120 repeating units, wherein said units of said first and second polymeric segments may be the same or different, wherein said (to minus one) moiety does not substantially alter the properties of said polymer derivative, said derivative having polymer, at least one active moiety selected from the group consisting of electrophilic moieties and nucleophilic moieties, located in one of said first and second polymeric segments and wherein the first and second polymeric segments are independently selected from the group consisting of poly (alkylene glycol), poly (olefinic alcolhol), poly (vinylpyrrolidone), poly (hydroxyalkylmethacrylamide), poly (hydroxyalkylmethacrylate), poly (saccharides), poly (alpha-hydroxy acid), poly (vinyl alcohol), polyphosphazene, polyoxazoline, poly (N-acryloylmorpholine), and copolymers, terpolymers, and mixtures thereof.