Defize, Thomas Thomassin, Jean-Michel Ottevaere, Heidi Malherbe, Cédric Eppe, Gauthier Jellali, Rachid Alexandre, Michaël Jérôme, Christine Riva, Raphaël Photo-Cross-Linkable Coumarin-Based Poly(ε-caprolactone) for Light-Controlled Design and Reconfiguration of Shape-Memory Polymer Networks Photochemically cross-linked shape-memory polymer (SMP) materials have been achieved by functionalizing chain-ends of star-shaped poly­(ε-caprolactone) (PCL) with 7-hydroxy­propoxy-4-methyl­coumarin followed by photodimerization of these end-groups. The kinetics of the network formation in function of the photosensitizer concentration has been studied by swelling experiments and rheology. Thanks to the design of a dedicated homemade mold, highly reproducible irradiation conditions have been achieved allowing to study the network formation and properties, especially the shape-memory properties, in relation to the coumarin dimerization degree as determined by Raman spectroscopy. In optimized conditions, PCL-based SMP materials exhibiting high fixity and recovery have been achieved in remarkably short irradiation time, typically 5 min. In addition, the precise control of the network cross-link density with the irradiation time, so as the high stability of the formed networks toward temperature variations was also demonstrated allowing the fine-tuning of the network properties by the irradiation process. Finally, the reversible character of the coumarin dimerization under light irradiation of appropriate wavelength has been quantified by Raman spectroscopy. The dimer photocleavage allows the photoreconfiguration of the networks offering the ability to modify the “permanent” shape of the SMP material, while preserving the excellent shape-memory properties. network cross-link density;irradiation time;Raman spectroscopy;Shape-Memory Polymer Networks Photochemically cross-linked shape-memory polymer;coumarin dimerization degree;network formation;shape-memory properties;PCL-based SMP materials 2018-12-28
    https://acs.figshare.com/articles/journal_contribution/Photo-Cross-Linkable_Coumarin-Based_Poly_-caprolactone_for_Light-Controlled_Design_and_Reconfiguration_of_Shape-Memory_Polymer_Networks/7528514
10.1021/acs.macromol.8b02188.s001