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Doctoral thesis (Dissertations and theses)
Design of reprocessable poly(ɛ-caprolactone)-based shape-memory materials
Defize, Thomas
2017
 

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Keywords :
ring-opening polymerization (ROP); shape-memory; polyester
Abstract :
[en] Shape-memory polymers (SMPs) are remarkable materials able to switch from a temporary shape to their initial permanent shape by crossing a thermal transition, e.g. glass or melting transition. Efficient shape-memory effect is notably observed for chemically cross- linked semi-crystalline polymers. Chemical networks of semi-crystalline poly(ε-caprolactone) (PCL) are widely studied for the development of SMPs especially when biomedical applications are foreseen. As these SMPs are irreversibly cross-linked material, their (re)processing is quite limited since they cannot be molten or solubilized after cross-linking. This prevents any recycling. Thereby, using reversible cross-linking reactions allowing the formation or cleavage of the network upon a selected stimulus raise tremendous interest for the development of smart SMPs. Chemically cross-linked but remarkably (re)processable shape-memory polymers (SMP) were designed by crosslinking poly(ε-caprolactone) (PCL) stars via reversible cycloaddition reactions. The thermo-reversible Diels-Alder (DA) reaction between furan and maleimide was investigated to crosslink the PCL matrix. However, the relatively low retro DA temperature of the furan-maleimide adducts led to some inelastic deformation during shape memory tensile cycles. In order to get rid of this drawback, two alternative approaches were investigated, i.e. the substitution of the DA reaction firstly by the efficient triazolinedione click chemistry, especially the very fast and reversible Alder-ene reaction of 1,2,4-triazoline-3,5- dione (TAD) with indole compounds and secondly by a photo-reversible reaction, typically the photo-induced (2+2) cycloaddition of coumarins. With these networks, the typical shape memory properties of PCL networks (high fixity and recovery ratios) were preserved while upon an external (light or stress) stimulus, the PCL network can be (re)processed efficiently.
Research center :
CESAM Complex and Entangled Systems from Atoms to Materials (CESAM)
Center for Education and Research on Macromolecules (CERM)
Disciplines :
Chemistry
Materials science & engineering
Author, co-author :
Defize, Thomas ;  University of Liège - ULiège > Complex and Entangled Systems from Atoms to Materials (CESAM), Center for Education and Research on Macromolecules (CERM)
Language :
English
Title :
Design of reprocessable poly(ɛ-caprolactone)-based shape-memory materials
Defense date :
18 May 2017
Number of pages :
220
Institution :
ULiège - Université de Liège
Degree :
PhD in Science
Promotor :
Jérôme, Christine  ;  Université de Liège - ULiège > Complex and Entangled Systems from Atoms to Materials (CESAM)
President :
Monbaliu, Jean-Christophe  ;  Université de Liège - ULiège > Département de chimie (sciences) > Center for Integrated Technology and Organic Synthesis
Secretary :
Riva, Raphaël ;  Université de Liège - ULiège > Complex and Entangled Systems from Atoms to Materials (CESAM)
Jury member :
Vamvakaki, Maria
Lendlein, Andreas
Alexandre, Michaël
Raquez, Jean-Marie
Available on ORBi :
since 19 June 2017

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