Ultralow-Temperature-Resistant Poly(ethylfluorophenylsiloxane) Elastomers Synthesized by Postpolymerization Macromolecular Chain Exchange Reaction

The research investigated the synthesis and characterization of poly(ethylfluorophenylsiloxane) elastomers, emphasizing the postpolymerization macromolecular chain exchange reaction and its implications for ultralow temperature performance. This innovative approach achieved the successful integration of five distinct siloxane linkages, namely, dimethyl, diphenyl, methyltrifluoropropyl, diethyl, and methylvinyl, into a single polymer chain, thereby addressing the challenges associated with traditional copolymerization methods that often fail to incorporate multiple siloxane linkages. Comprehensive analysis using 1H NMR, 29Si NMR, FT-IR, GPC, DOSY–1H NMR, and DSC verified the successful incorporation of these diverse siloxane linkages. It is worth noting that the incorporation of diethylsiloxane linkages led to a significant decrease in the glass transition temperature (Tg) down to −136 °C, which in turn enhanced the flexibility and low-temperature resistance of the elastomer. Mechanical characterization demonstrated that F-PDMEPMFS-80–5–5 exhibited remarkable elastic properties and structural stability, maintaining consistent performance even at cryogenic temperatures down to −120 °C. Furthermore, the material showed excellent stress relaxation recovery characteristics during cyclic loading tests conducted at −115 °C. These results highlight the efficacy of postpolymerization macromolecular chain exchange reaction in the development of advanced polysiloxane elastomers with superior ultralow temperature performance.