Photocurable shape-memory polyether-polythioether/graphene nanocomposites and the study of their thermal conductivity

Herein a method is described to prepare photocurable thermally-conductive shape memory epoxy/ graphene composites. By photopolymerizing the epoxy resin diglycidyl ether of bisphenol A with an allyl-functionalized ditertiary amine as the curing agent, jointly with a multifunctional thiol, a crosslinked polyether-polythioether co-network was obtained. The presence of a soft domain like the flexible polythioethers enable the co-network to display shape memory properties. By varying the polyether to polythioether ratio it was possible to modulate the shape memory characteristics of the composite. The effect of the concentration of graphene nanoplatelets (GNP) in the composite was also investigated. Shape memory performances revealed excellent values of shape recovery and shape fixity with maximums of 98 and 99% respectively. The temporary- shaped composites with higher concentration of polythioethers and GNP regained their permanent shapes in 2–3 s when heated above the programming temperature. The thermal conductivity in the composites reached 0.39 W/m°K for the composite with 15% w/w of GNP. The presence of the polythioethers in the co-network enhanced the toughness of the composite as revealed by the impact resistance analysis.