Reference : Design of reprocessable poly(ɛ-caprolactone)-based shape-memory materials
Dissertations and theses : Doctoral thesis
Physical, chemical, mathematical & earth Sciences : Chemistry
Engineering, computing & technology : Materials science & engineering
http://hdl.handle.net/2268/211947
Design of reprocessable poly(ɛ-caprolactone)-based shape-memory materials
English
Defize, Thomas mailto [University of Liège (ULg), Complex and Entangled Systems from Atoms to Materials (CESAM), Center for Education and Research on Macromolecules (CERM) > > > >]
18-May-2017
Université de Liège, ​Liège, ​​Belgique
PhD in Science
220
Jérôme, Christine mailto
Monbaliu, Jean-Christophe mailto
Riva, Raphaël mailto
Vamvakaki, Maria
Lendlein, Andreas
Alexandre, Michaël
Raquez, Jean-Marie
[en] ring-opening polymerization (ROP) ; shape-memory ; polyester
[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.
CESAM Complex and Entangled Systems from Atoms to Materials (CESAM) ; Center for Education and Research on Macromolecules (CERM)
Researchers
http://hdl.handle.net/2268/211947

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