화학공학소재연구정보센터
Polymer, Vol.147, 67-73, 2018
An efficient synthesis of low-covered polyrotaxanes grafted with poly(epsilon-caprolactone) and the mechanical properties of its cross-linked elastomers
Advanced polyrotaxane elastomers were fabricated by the synthesis of poly(epsilon-caprolactone)-grafted polyrotaxanes with significantly lower coverage than previously achieved. The time course for the complexation of alpha-cyclodextrin with an end-functionalized polyethylene glycol (PEG) was analyzed by subsequent end-capping and polyrotaxane isolation, which revealed that the bulkiness of the PEG end group affects the time required for complex nucleation and the resulting coverage. Low-coverage poly(epsilon-caprolactone)-grafted polyrotaxanes were synthesized in a facile and large-scale manner by optimizing the simultaneous hydrolysis of the end-capping groups and the solubility of the product during the ring-opening polymerization of epsilon-caprolactone. Cross-linking the thermoplastic graft polyrotaxanes yielded elastomers that are much more extensible than conventional elastomers with fivefold higher coverages. Elastomers with lower coverages behave as ideal elastic bodies due to chain sliding through the crosslinks, which suggests that the arrangement entropy of the cyclic components, which counteracts chain sliding, is substantially decreased by reduced coverage. (C) 2018 Elsevier Ltd. All rights reserved.