Synthesis and Characterization of Polymethylphenylsiloxane With Arbitrarily Tunable Phenylsiloxane Contents via Phosphazenium Salt/KOH Catalyzed Ring‐Opening Polymerization

ABSTRACT

Poly(dimethylsiloxane‐co‐methylphenylsiloxane) (P(DMS‐co‐MPS)) is an important polysiloxane with good thermal stability, low‐temperature resistance, and damping properties due to the phenyl groups in the polymer chain. However, there were limited studies on the synthesis and performance study of high molecular weight P(DMS‐co‐MPS) copolymers with different MPS contents. In this contribution, a series of P(DMS‐co‐MPS) copolymers with molecular weight up to 468.4 kg/mol and MPS contents varying by 10 mol% (9–92 mol%) were successfully synthesized by P₅Cl/KOH catalyzed ring‐opening copolymerization (ROCP) of octamethylcyclotetrasiloxane (D₄) and tetraphenyltetramethylcyclotetrasiloxane (D₄ ^Ph). The good random characteristic of the resulting P(DMS‐co‐MPS)s was fully verified by the ²⁹Si NMR, predictable T _gs, and good high‐temperature resistance. The low T _gs between −115.7°C and −26.8°C and the good damping performance at low temperature enabled P(DMS‐co‐MPS) copolymers as good candidates for applications as elastic materials under extreme conditions.