H2O2-Initiated Reversible Addition-Fragmentation Chain Transfer Polymerization of Methyl Methacrylate Mediated by Peroxide-Labile Dithiobenzoate in O2-Rarefied N,N-Dimethylsulfoxide Under Aerobic Media

The effect of aerobic dioxygen (O 2 ) residues and hydrogen peroxide (H 2 O 2 ) on dithiobenzoate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) was studied. 2-cyano-2-propyl dithiobenzoate (CPDB) displayed excellent thermally oxidative stability against O 2 in O 2 -rarefied dimethylsulfoxide (DMSO) but was readily oxidized by H 2 O 2 . Azo-initiated CPDB-mediated RAFT polymerization of MMA in DMSO under different media led to multi-component products, consisting of PMMA macro-CTAs, MMA-terminated oligomers and low-MW byproducts, while nitrogen deoxygenating and headspace eliminating gave rise to a comparable CTA efficiency, higher than that headspace limiting. H 2 O 2 -initiated CPDB-mediated headspace-free RAFT polymerization of MMA smoothly proceeded in DMSO even at 50 °C, suggesting the co-initiation by CPDB, and also formed predominant PMMA macro-CTAs, negligible oligomers and some low-MW byproducts. H 2 O 2 -initiated CPDB-mediated headspace-free RAFT polymerization of MMA at 70 °C displayed well-controlled behaviors with 2–5 wt.% byproducts, and the high fidelity of the PMMA macro-CTAs was confirmed by the chain extension via azo-initiated RAFT polymerization and Cu I -catalyzed concurrent ATRP/RAFT polymerization. Graphical AIBN-initiated dithiobenzoate-mediated RAFT polymerization of MMA in O 2 -rarefied DMSO under headspace-free media led to well-controlled behaviors comparable to that under N 2 deoxygenating. H 2 O 2 -initiated RAFT polymerization manifested the unprecedented acceleration by dithiobenzoate; ascribed to its oxidation by H 2 O 2 ; and well-controlled polymerization behaviors.