Hydrosilylation-Promoted Group Transfer Polymerization of Ethyl Sorbate: A Controlled/Living System Applied to the Synthesis of an ?-End Functionalized Polymer and a Triblock Copolymer with a (Meth)acrylate Polymer

The polymerization method, preparation of well-defined (co)polymers, and controlled/living property of ethyl sorbate (ES) have been investigated using hydrosilylation-promoted group transfer polymerization (GTP). The GTP of ES with hydrosilane (R3SiH) was performed in a living manner to produce well-defined poly(ethyl sorbate) (PES) via two methods: single catalyst and catalyst switch. For the single catalyst method, B(C6F5)3 served as the catalyst for the hydrosilylation of ES and R3SiH, yielding silyl ketene acetal (SKA), as well as the polymerization of ES and PES with the trans structure. SKA was prepared using the catalyst switch method via equimolar hydrosilylation with B(C6F5)3, and the phosphazene base of t-Bu-P4 catalyzed the polymerization of ES, yielding PES with cis and trans structures. The kinetic experiments demonstrated that the propagation rate kp for t-Bu-P4-catalyzed GTP is significantly higher than that for B(C6F5)3. The alpha-end-functionalized PES was synthesized via the hydrosilylation-promoted GTP of ES using a sorbate ester with a functional group as the moisture-stable latent initiator via the catalyst switch method. Furthermore, the controlled/living property has enabled the hydrosilylation-promoted GTP of ES with MMA and n-butyl acrylate (nBA) to produce the AB-diblock copolymer and ABA-and ABC-triblock copolymers composed of PES, PMMA, and PnBA.