Tailor-Made Functional Polymethacrylates with Dual Characteristics of Self-Healing and Shape-Memory Based on Dynamic Covalent Chemistry

New shape memory polymers with self-healing behavior are obtained by thermoreversible Diels-Alder (DA) cross-linking of a furfuryl group-containing star-block copolymer with 1,1 '-(methylenedi-4,1-phenylene)bismaleimide. The star-block copolymer consisting of a 3-arm polycaprolactone (PCL) core and a polyfurfuryl methacrylate shell is synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. For this, a 3-arm macro-RAFT agent based on PCL is converted with an appropriate amount of furfuryl methacrylate in the presence of a radical initiator. Films of the DA network are partly insoluble at ambient temperatures. After annealing at 120 degrees C the films become completely soluble because of the progressing retro-DA reaction. Evaporation of the solvent and subsequent annealing at 60 degrees C restores the original insoluble state of the material. By means of a scratch test and tensile tests on cut and subsequently mended samples it is shown that the retro-DA reaction facilitates self-healing. Additionally, the films show pronounced shape memory effects with reasonable shape recovery and fixity ratios, which are attributed to the melting and crystallization of the PCL phase.