Macromolecules, Vol.31, No.11, 3439-3445, 1998
Hyperbranched poly(epsilon-caprolactone)s
Novel hyperbranched poly(epsilon-caprolactone)s have been synthesized. The versatile synthesis utilizes AB(2) macromonomers and allows the thermo-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 initiator. The aluminum benzyloxide initiated polymers were then functionalized with benzylidene-protected 2,2'-bis(hydroxymethyl) propionic acid and subsequently deprotected to form the alpha-carboxylic-omega-dihydroxy functional AB(2) macromonomers. The AB(2) polyesters were condensed into hyperbranched polymers through a room-temperature esterification 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 independent of the macromonomer used. Significant flexibility exists in the new approach since the molecular weight and the type of macromonomer can be varied.
Keywords:RING-OPENING POLYMERIZATION;PRIMARY AMINE POLY(EPSILON-CAPROLACTONE);EPSILON-CAPROLACTONE;ALIPHATIC POLYESTERS;ALUMINUM ALKOXIDES;END-GROUPS;POLYLACTONES;1;5-DIOXEPAN-2-ONE;DENDRIMERS;POLYMERS