HYPERBRANCHED POLY(EPSILON-CAPROLACTONE)S

Novel hyperbranched poly(epsilon-caprolactone)s have been synthesized. The versatile synthesis utilizes AB(2) macromonomers and allows the t hermo-physical properties of the polymers to be tailored. The epsilon- caprolactone-based AB(2) macromonomers were synthesized through living ring opening polymerization, using aluminum benzyloxide as the initia tor. The aluminum benzyloxide initiated polymers were then functionali zed with benzylidene-protected 2,2'-bis(hydroxymethyl) propionic acid and subsequently deprotected to form the alpha-carboxylic-omega-dihydr oxy functional AB(2) macromonomers. The AB(2) polyesters were condense d into hyperbranched polymers through a room-temperature esterificatio n synthesis using dicyclohexylcarbodiimide (DCC) and 4-(dimethylamino) pyridinium 4-toluenesulfonate (DPTS). All polymers were characterized by H-1 NMR, SEC, and DSC. The degree of branching in the hyperbranched polymers was found, by H-1 NMR, to be 0.37 +/- 0.03, and to be indepe ndent of the macromonomer used. Significant flexibility exists in the new approach since the molecular weight and the type of macromonomer c an be varied.