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|Title:||Star-shaped POSS-polycaprolactone polyurethanes and their shape memory performance|
|Citation:||Mya, K.Y., Gose, H.B., Pretsch, T., Bothe, M., He, C. (2011-04-07). Star-shaped POSS-polycaprolactone polyurethanes and their shape memory performance. Journal of Materials Chemistry 21 (13) : 4827-4836. ScholarBank@NUS Repository. https://doi.org/10.1039/c0jm04459h|
|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. © The Royal Society of Chemistry 2011.|
|Source Title:||Journal of Materials Chemistry|
|Appears in Collections:||Staff Publications|
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