A Poly(dimethyl-co-methylvinyl)siloxane-based elastomer with excellent ultra-low temperature elasticity driven by flexible alkyl branches

Elastomers that services under ultra-low temperature environments are of great strategic and technological importance. Among them, polysiloxanes are excellent precursors, however, the unfavorable crystallization greatly limits its ultra-low temperature application. Herein, we explore the synthesis, glass transition temperature (Tg), cross-linking behavior and long-time ultra-low temperature elasticity characterization of polydimethylsiloxane (PDMS) with flexible alkyl branches. The results demonstrated that the flexible alkyl branches play a dual role in PDMS, for it can not only unlock its ultra-low temperature elasticity by suppressing crystallization, but also provide more free radical attack sites to enhance the cross-linking activity. The resulting elastomer with a Tg lower than −120 °C exhibits excellent elasticity at such a low temperature down to −110 °C. Moreover, the facile and efficient one-step thiol-ene addition post-polymerization enables the large-scale preparation of this ultra-low temperature elastomer. The work demonstrated here reveals a general practical strategy to unlock PDMS ultra-low temperature performance, which is conducive to the development of cutting-edge scientific research.