Optically Active Polymer Via One-Pot Combination of Chemoenzymatic Transesterification and RAFT Polymerization: Synthesis and Its Application in Hybrid Silica Particles

Abstract

A novel strategy for the preparation of hybrid particles of optically active polymer and silica is developed via combination of chemoenzymatic transesterification, reversible addition-fragmentation chain transfer (RAFT) polymerization, and click reaction for the first time. During this procedure, Novozym 435 is employed to catalyze the transesterification between 2,2,2-trifluoethyl methacrylate monomer and 2-octanol to form the target monomer (R)-OMA, which synchronously participates in RAFT polymerization to obtain a new polymer with transformed optically active side groups. Compared with RAFT polymerization, the transesterification reaction is much faster, with conversion ratio reaching 93% after 7 h; subsequently, the polymerization is nearly homo-polymerization of (R)-OMA. The molar fraction of (R)-OMA in the final polymer is about 97.8% with controlled molecular weight (Mn ≈ 6840 g mol-1) and a narrow polydispersity index (≈1.25). Finally, the hybrid particles of silica and optically active polymer P((R)-OMA) are obtained by the thiol-ene click reaction. The Fourier transform infrared, X-ray photoelectron spectroscopy, and transmission electron microscopy results exhibit the successful graft of P((R)-OMA) polymer to the silica surface, and the P((R)-OMA) polymer in the hybrid particles is about 10 wt% from the TGA curves. These as-prepared hybrid particles combine excellent mechanical stability of silica and good chirality of polymer, making them promising for chromatographic resolution, catalytic synthesis, and (stereo-) selectivity applications. Using a novel combination of chemoenzymatictransesterification, reversible addition-fragmentation chain transfer (RAFT) polymerization, and click reactions, the preparation of hybrid particles of optically active polymer and silica is achieved. This process leads to faster transesterification than RAFT polymerization. The hybrid particles produced in this way are promising for in chromatographic resolution, catalytic synthesis, and (stereo-) selectivity applications.