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Recyclable shape-memory materials based on photo or thermo-reversible crosslinking
Defize, Thomas; Riva, Raphaël; Wauters, Céline et al.
2014Polymer Networks Group Meeting & Gel Symposium
 

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Keywords :
shape memory; Diels Alder reaction; polyester; solid-state NMR
Abstract :
[en] Shape memory polymers (SMPs) are remarkable materials able to switch from a stressed deformed state (temporary shape) to their initial relaxed state (permanent shape) by the application of a stimulus, such as heat or light. Typically, the shape memory property is generally observed for chemically or physically cross-linked polymers that exhibit an elastomeric behavior above a phase transition, e.g. glass or melting transition. Cross-linked semi-crystalline poly(ε-caprolactone) (PCL) is already widely studied for the development of SMPs. However, the tensile strength of standard PCL-based SMPs remains quite low, limiting their use in some applications. A convenient way to enhance the strength of SMPs relies on the introduction of nanofillers, such as silica nanoparticles, leading to an enhancement of mechanical strength. Moreover, silica nanoparticles can be advantageously used as multifunctional crosslinking nodes, with the purpose to increase the cross-linking density of the material. As most of SMPs are irreversibly cross-linked material, their reprocessing is impossible preventing any recycling. Thereby, reversible reactions, allowing the formation/cleavage of the network, raise tremendous interest in macromolecular engineering. Recently, a reversibly cross-linked 4-arm star-shaped PCL-based SMP was prepared using the Diels-Alder (DA) reaction between furan and maleimide moieties, well-known to create reversible bonds. This shape memory material demonstrated to be implementable, and so recyclable, and was characterized by excellent fixity and recovery before and after recycling experiments. However, the relatively low retro-DA temperature of the furan- maleimide adducts led to an inelastic deformation during shape memory tensile cycles. In order to get rid of this drawback, two alternative approaches were investigated. Firstly, the substitution of the DA reaction by a photo-reversible reaction, typically the photo- induced (2+2) cycloaddition of coumarins, was proposed to crosslink the PCL matrix. The second approach is based on the use of surface functionalized silica nanoparticles as crosslinking nodes with the purpose to increase the crosslinking density of the material. The network formation and cleavage were studied by solid-state NMR and rheology.4 The resulting shape memory materials were characterized by excellent one-way and two-way shape memory properties as demonstrated by dynamical mechanical analysis.
Research center :
Center for Education and Research on Macromolecules (CERM)
Disciplines :
Chemistry
Materials science & engineering
Author, co-author :
Defize, Thomas ;  University of Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Riva, Raphaël ;  University of Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Wauters, Céline;  University of Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Thomassin, Jean-Michel ;  University of Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Alexandre, Michaël;  University of Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Tatton, Andrew ;  University of Liège (ULg), Department of Chemistry, Laboratory of Structural Biological Chemistry (CBS)
Lecomte, Philippe  ;  University of Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Damblon, Christian ;  University of Liège (ULg), Department of Chemistry, Laboratory of Structural Biological Chemistry (CBS)
Jérôme, Christine  ;  University of Liège - ULiège > Department of Chemistry > Center for Education and Research on Macromolecules (CERM)
Language :
English
Title :
Recyclable shape-memory materials based on photo or thermo-reversible crosslinking
Publication date :
11 November 2014
Event name :
Polymer Networks Group Meeting & Gel Symposium
Event place :
Tokyo, Japan
Event date :
10/11/2014 - 14/11/2014
Audience :
International
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
ULiège - Université de Liège [BE]
Commentary :
This poster was presented by Thomas Defize
Available on ORBi :
since 08 October 2015

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