Photocatalytic modular synthesis of functionalized cyclotetrasiloxane (D4) monomers toward tailored polysiloxanes

Abstract

Polysiloxanes possess immense utility across consumer and industrial sectors, yet conventional approaches to their functionalization remain constrained by reliance on platinum catalysts and limited group compatibility. We present a photocatalytic radical C–H functionalization strategy that enables direct, modular modification of octamethylcyclotetrasiloxane (D4) without noble-metal catalysts. This approach accommodates diverse functional groups, including cyano, pyridyl, sulfone, and phosphorus-based substituents, and facilitates efficient access to functionalized polysiloxanes via ring-opening polymerization. A streamlined one-pot protocol further enhances synthetic efficiency. The resulting modified polysiloxanes exhibit substantially improved thermal stability, underscoring the potential of this methodology to expand the landscape of high-performance silicone materials.