Fully Closed-Loop Recyclable Thermosetting Polythiourethane Microspheres and Their Application in Efficient Fabrication of Composites with Segregated Structures

Introducing dynamic covalent bonds into cross-linked polymer endows thermosetting polymers with thermoplastic properties such as reprocessability and recyclability, providing a solution to the environmental problems induced by thermosetting polymers. However, unlike thermoplastic polymers, the synthesis and molding processes of most thermosetting polymers with covalent adaptable networks still maintain together, affecting the development of industrial production. Herein, the cross-linked polythiourethane microspheres (PTUMs) with dynamic covalent bonds have been prepared by suspension polymerization. The PTUMs can be closed-loop-recycled and shows no significant performance degradation after recycling, paving an easy and efficient way for the recycling of cross-linked polymers. Furthermore, as with the thermoplastic film prepared from polymer pellets, a thermosetting polythiourethane film (PTUMF) can be obtained by simple compression molding of PTUMs. Importantly, by mixing PTUMs with fillers and then compression molding, the composites with a segregated structure and excellent electrical conductivity can be fabricated. Such composites can be used as wearable strain sensors to monitor human motions. Notably, the preparation and molding of thermosetting polymer materials in this work are separated, which may be conducive to the development of industrial production.