Star polymer synthesis from ε-caprolactone utilizing polyol/protonic acid initiator

Three- and four-armed star-shaped poly(epsilon-caprolactone)s were synthesized from trimethylolpropane and pentaerythritol as initiators using fumaric acid as an activator of the monomer, respectively. Star-shaped poly(E-caprolactone)s could be satisfactorily obtained, which was confirmed by size exclusion chromatography equipped with low-angle laser light scattering and viscometer detectors. Comparing the melting points among the polymers with similar molecular weights, the order was as follows: linear poly(epsilon-caprolactone) > three-armed poly(epsilon-caprolactone) > four-armed poly(epsilon-caprolactone). On the other hand, poly(epsilon-caprolactone)s with similar arm length showed similar melting points irrespective of the arm numbers. Thermal decomposition temperature of poly(epsilon-caprolactone)s increased with the arm number.