Exceptionally recyclable, extremely tough, vitrimer-like polydimethylsiloxane elastomers via rational network design

Recently developed elastomers with an adaptable covalent network, e.g., elastic vitrimers, have great potential as sustainable materials, although most of them suffer from limited recyclability and unsatisfied mechanical properties. Here, we report a polydimethylsiloxane (PDMS)-based recyclable elastic network, combining permanent chemical and high-density dynamic physical crosslinks utilizing side-chain reactions, which provides energy dissipation for superb toughness and enables efficient chain rearrangement for excellent recyclability. The optimal elastic network achieves an unprecedented recyclability of 70 cycles, one order of magnitude higher than existing elastic vitrimers, extraordinary toughness of 66 MJ/m 3, significantly higher than previously reported PDMS elastomers, excellent chemical resistance, and vitrimer-like rheological behavior. Physical analysis is also performed to provide the accurate estimation of bond-exchange dynamics excluding the often-neglected chain dynamics and to offer insight into the superb performance. We anticipate that such a design principle enables an alternative approach for developing superior recyclable polymer networks.