Synthesis and characterization of recyclable chemically-crosslinked shape memory materials

SYNTHESIS AND CHARACTERIZATION OF RECYCLABLE

CHEMICALLY-CROSSLINKED SHAPE MEMORY MATERIALS

Dubois2_{, Christine Jérôme}1_{, Michaël Alexandre}1

1 _{Center for Education and Research on Macromolecules (CERM), University of Liege,}

Building B6a, 4000 Liege, Belgium

2 _{Laboratory of Polymeric and Composite Materials, Center of Innovation and Research in}

Materials and Polymers (CIRMAP), University of Mons, Place du Parc 23, 7000 Mons, Belgium

Amongst current trends in the design of new polymer and composite materials, the use of particular organic reactions that are able to create and reversibly disrupt chemical bonds upon an external stimulus (change in temperature, irradiation at various wavelength,…) is currently gaining more and more attention as it can lead to applications in various areas such as remendable materials, drug delivery systems, stimulus-degrading materials or recyclable materials. In this frame, photochemically (2+2) or thermally (4+2) reversible cycloadditions present interesting features such as the creation of robust bonds and well defined reversibility conditions. Amongst (4+2) reversible cycloaddition, the formation/cycloreversion of furan/maleimide adducts are actively studied due to the range of temperature (90-120°C) at which cycloreversion occurs.

Poly(-caprolactone) (PCL)-based shape memory materials have been prepared by mixing in stoechiometric amounts 4-arm furan-functionalized and 4-arm maleimide-functionalized PCL in a twin-screw mini extruder at 105°C and compression molding the resulting material at 65°C for 72h. A crosslinked PCL film was obtained, as evidenced by swelling experiments. This film exhibits shape memory properties around the melting/crystallization transitions of PCL, as determined by mechanical testing and reversible crosslinking through cycloreversion at 105°C, as demonstrated by rheology and by recycling experiment.