Hemisilicone (PM ₂ E) Elastomers: Assessing Prepolymer Synthetic Strategies

Hemisilicone, −(SiMe2–O–SiMe2–CH2CH2)n–(PM2E), represents a promising alternative to conventional silicone, polydimethylsiloxane (PDMS), for elastomer applications. In this study, we address a key challenge in PM2E synthesis by developing an anionic ring-opening polymerization (AROP) method that ensures precise control over both α- and ω-chain end functionalities through the in situ preparation of lithium silanolate-based initiators, generated by the reaction of disiloxanes with methyllithium. The propagation proceeds cleanly, without backbiting or chain transfer side reactions, resulting in a narrow molecular weight distribution. We compare the mechanical properties of elastomers prepared from PM2E prepolymers synthesized via different polymerization methods. Notably, PM2E synthesized by the AROP method enables the formation of elastomers with outstanding mechanical properties, including exceptional stretchability (>1000% strain) and excellent tear resistance. In contrast, elastomers prepared from equilibrated polydisperse PM2E exhibit comparable stretchability but significantly lower tear resistance. Overall, this polymerization approach offers a robust platform for producing high-performance, impurity-free silicone materials with well-defined architectures.