Highly Recyclable and Tough Elastic Vitrimers from a Defined Polydimethylsiloxane Network

JC Luo and X Zhao and H Ju and XJ Chen and S Zhao and Z Demchuk and BR Li and V Bocharova and JMY Carrillo and JK Keum and S Xu and AP Sokolov and JY Chen and PF Cao, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 62 (2023).

DOI: 10.1002/anie.202310989

Despite intensive research on sustainable elastomers, achieving elastic vitrimers with significantly improved mechanical properties and recyclability remains a scientific challenge. Herein, inspired by the classical elasticity theory, we present a design principle for ultra- tough and highly recyclable elastic vitrimers with a defined network constructed by chemically crosslinking the pre-synthesized disulfide- containing polydimethylsiloxane (PDMS) chains with tetra-arm polyethylene glycol (PEG). The defined network is achieved by the reduced dangling short chains and the relatively uniform molecular weight of network strands. Such elastic vitrimers with the defined network, i.e., PDMS-disulfide-D, exhibit significantly improved mechanical performance than random analogous, previously reported PDMS vitrimers, and even commercial silicone-based thermosets. Moreover, unlike the vitrimers with random network that show obvious loss in mechanical properties after recycling, those with the defined network enable excellent thermal recyclability. The PDMS-disulfide-D also deliver comparable electrochemical signals if utilized as substrates for electromyography sensors after the recycling. The multiple relaxation processes are revealed via a unique physical approach. Multiple techniques are also applied to unravel the microscopic mechanism of the excellent mechanical performance and recyclability of such defined network. We develop a novel network design principle for ultra-tough and highly recyclable elastic vitrimers, and a series of physical analysis is performed to provide a deep structure-property understanding for the excellent performance of the defined-network vitrimers.image

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