Issue 13, 2011

Star-shaped POSS-polycaprolactone polyurethanes and their shape memory performance

Abstract

Star-shaped polyhedral oligomeric silsesquioxane (SPOSS)-based multi-arm poly(ε-caprolactones) (PCLs) with various arm lengths were synthesized by ring opening polymerization of ε-caprolactone. Increasing the PCL arm lengths was observed to increase the melting temperature and also the melt crystallization temperature in SPOSS-PCLs. Star-shaped POSS-PCL polyurethanes (SPOSS-PUs) were then prepared by cross-linking SPOSS-PCLs with hexamethylene diisocyanate (HMDI) and their shape memory (SM) behaviour was determined. For this purpose two cyclic thermo-mechanical testing concepts with similar programming (deformation and shape fixing) but different recovery strategies (free strain versus fixed-strain constrained stress recovery) were used and the synthesized polymers were systematically investigated around the crystallization and melting temperatures of PCL. SPOSS-PU with the highest POSS content exhibited remarkable cycles-averaged (N = 2–5) shape fixities and strain recoverabilities of 98% and stress recoverabilities close to 100%. The main structural factors that were expected to reduce the SM performances with increasing PCL arm lengths were a lowering of cross-link density (content of octasubstituted POSS) and an increase in chain flexibility/molecular mobility.

Graphical abstract: Star-shaped POSS-polycaprolactone polyurethanes and their shape memory performance

Supplementary files

Article information

Article type
Paper
Submitted
20 Dec 2010
Accepted
25 Jan 2011
First published
21 Feb 2011

J. Mater. Chem., 2011,21, 4827-4836

Star-shaped POSS-polycaprolactone polyurethanes and their shape memory performance

K. Y. Mya, H. B. Gose, T. Pretsch, M. Bothe and C. He, J. Mater. Chem., 2011, 21, 4827 DOI: 10.1039/C0JM04459H

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