Healable and recyclable multiblock polyurethanes with mechanical performance Tailorability based on hierarchical phase separation and dynamic bond interaction

Abstract

Thermoplastic polyurethanes (TPUs) have been demonstrated high versatility in widespread applications. In view of today's sustainable society, the advanced TPUs which combine both excellent mechanical properties and functionalities such as the self-healing and recyclability can extend utilization scope and service life. Herein, we reported a multiblock polyurethane with outstanding mechanical performance, self-healing capability and recyclability based on strong microphase-separated biocompatible polycaprolactone (PCL) semicrystalline segments and ultra-highly flexible polydimethylsiloxane (PDMS) segments. The mechanical performance of the designed PUs can be tuned from resilient elastomer to shape memory plastics by varying the molecular parameter of segments, and the fast self-healing was achieved through the synergetic effects of dynamic disulfide bond and hydrogen bonding interaction. The PUs with high PCL contents exhibit high tensile strength and high toughness (high up to 45 MPa, 511 MJ m−3, respectively) after thermal treatment and show shape memory effects, while these with high PDMS contents perform as ligament elastomer. We demonstrated the principles of high mechanical performance in the phase-separated multiblock PU, in which the hierarchical nanostructures including the microphase separation between PDMS and PCL blocks, the nanophase segregation of the carbamate segments as well as the semi-crystalline behavior of PCL segments endow these healable and recyclable PUs with high strength, high stretchability and high toughness. This work demonstrated tremendous potentials of utilizing strong microphase separated segments and dynamic bond chain extenders to design functional thermoplastic PU materials.