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Influence of programming strain rates on the shape-memory performance of semicrystalline multiblock copolymers

  • Multiblock copolymers named PCL-PIBMD consisting of crystallizable poly(epsilon-caprolactone) segments and crystallizable poly[oligo(3S-iso-butylmorpholine-2,5-dione)] segments coupled by trimethyl hexamethylene diisocyanate provide a versatile molecular architecture for achieving shape-memory effects (SMEs) in polymers. The mechanical properties as well as the SME performance of PCL-PIBMD can be tailored by the variation of physical parameters during programming such as deformation strain or applied temperature protocols. In this study, we explored the influence of applying different strain rates during programming on the resulting nanostructure of PCL-PIBMD. Programming was conducted at 50 degrees C by elongation to epsilon(m)=50% with strain rates of 1 or 10 or 50 mmmin(-1). The nanostructural changes were visualized by atomic force microscopy (AFM) measurements and investigated by in situ wide and small angle X-ray scattering experiments. With increasing the strain rate, a higher degree of orientation was observed in the amorphousMultiblock copolymers named PCL-PIBMD consisting of crystallizable poly(epsilon-caprolactone) segments and crystallizable poly[oligo(3S-iso-butylmorpholine-2,5-dione)] segments coupled by trimethyl hexamethylene diisocyanate provide a versatile molecular architecture for achieving shape-memory effects (SMEs) in polymers. The mechanical properties as well as the SME performance of PCL-PIBMD can be tailored by the variation of physical parameters during programming such as deformation strain or applied temperature protocols. In this study, we explored the influence of applying different strain rates during programming on the resulting nanostructure of PCL-PIBMD. Programming was conducted at 50 degrees C by elongation to epsilon(m)=50% with strain rates of 1 or 10 or 50 mmmin(-1). The nanostructural changes were visualized by atomic force microscopy (AFM) measurements and investigated by in situ wide and small angle X-ray scattering experiments. With increasing the strain rate, a higher degree of orientation was observed in the amorphous domains. Simultaneously the strain-induced formation of new PIBMD crystals as well as the fragmentation of existing large PIBMD crystals occurred. The observed differences in shape fixity ratio and recovery stress of samples deformed with various strain rates can be attributed to their different nanostructures. The achieved findings can be relevant parameters for programming the shape-memory polymers with designed recovery forces. (c) 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1935-1943show moreshow less

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Metadaten
Author details:Wan Yan, Liang Fang, Ulrich NöchelGND, Karl KratzORCiD, Andreas LendleinORCiDGND
DOI:https://doi.org/10.1002/polb.24097
ISSN:0887-6266
ISSN:1099-0488
Title of parent work (English):Journal of polymer science : B, Polymer physics
Publisher:Wiley-Blackwell
Place of publishing:Hoboken
Publication type:Article
Language:English
Year of first publication:2016
Publication year:2016
Release date:2020/03/22
Tag:SAXS; WAXS; X-ray scattering; atomic force microscopy (AFM); crystal structures; crystallization; multiblock copolymer; shape-memory effect; stimuli-sensitive polymers
Volume:54
Number of pages:9
First page:1935
Last Page:1943
Funding institution:Helmholtz-Association; Helmholtz Graduate School for Macromolecular Bioscience [VH-GS-503]
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie
Peer review:Referiert
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