Hyperbranched Poly(ε-caprolactone)s

• Published in: Macromolecules Vol. 31; no. 11; pp. 3439 - 3445
• Main Authors: Trollsås, Mikael, Atthoff, Björn, Claesson, Hans, Hedrick, James L
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 02-06-1998
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Ring opening polymerization; End group; Branched polymer; Molecular structure; Self condensation; Deprotection; Condensation polymerization; Experimental study; Lactone polymer; Chemical modification; Hydroxyacid; Preparation; Hydroxyl group; Carboxyl group; Prepolymer; Polyol; Polycaprolactone
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma980241f

Novel hyperbranched poly(ε-caprolactone)s have been synthesized. The versatile synthesis utilizes AB2 macromonomers and allows the thermo-physical properties of the polymers to be tailored. The ε-caprolactone-based AB2 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 α-carboxylic-ω-dihydroxy functional AB2 macromonomers. The AB2 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 1H NMR, SEC, and DSC. The degree of branching in the hyperbranched polymers was found, by 1H 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.