Nitroxide-Mediated Polymerization of Vinyl Chloride at Low Temperature: Kinetic and Computational Studies

Abstract

The synthesis of poly(vinyl chloride) (PVC) by nitroxide-mediated polymerization (NMP) using the SG1-based BlocBuilder alkoxyamine at low temperature (30 and 42 °C) is reported. The reaction system was studied regarding the nature of the solvent, the monomer-to-solvent ratio, the polymerization temperature and the target molecular weight. First order kinetics and linear evolutions of the molecular weight with vinyl chloride (VC) conversion were obtained in dichloromethane (DCM) and dimethyl sulfoxide (DMSO) together with decreasing dispersities (Ð) down to 1.59-1.47. The resulting PVC was fully characterized by 1 H nuclear magnetic resonance spectroscopy (1 H-NMR), 31 P-NMR and size exclusion chromatography (SEC). The 1 H-NMR and 31 P-NMR revealed the existence of very small content of structural defects and the presence of chain-end functional groups (~91% SG1 chain-end functionality). Chain extension experiments were performed with VC, methyl methacrylate (MMA) and mixture of monomers (90% of MMA and 10% of styrene (S)) and confirmed the "livingness" of the PVC-SG1 macroinitiators, giving access to different PVC-based block copolymers. High level ab initio molecular orbital calculations suggested that the CO bond in the PVC-SG1 alkoxyamine is too strong to mediate the NMP of VC by simple "classic" activationdeactivation equilibrium, and is likely being mediated by a SG1-mediated dehydrochlorination mechanism. The results presented in this study established a new route to afford a wide range of new complex macrostructures based on PVC segments.

Synthesis of random and block copolymers of vinyl chloride and vinyl acetate by RAFT miniemulsion polymerizations mediated by a fluorinated xanthate

“…Abreu et al . conducted NMP of VC at low temperature using the commercially available SG1‐based alkoxyamine, and prepared PVC‐ b ‐PMMA and PVC‐ b ‐P(St‐ co ‐MMA) copolymers by the chain extension from SG1‐terminated PVC in dimethyl sulfoxide . Rosen and Percec developed the single‐electron transfer living radical polymerization (SET‐LRP) and single‐electron transfer degenerative chain transfer living radical polymerization (SET‐DTLRP) using Cu 0 or Na 2 S 2 O 4 as a catalyst, CHI 3 or CH 2 I 2 as an initiator, and confirmed the living nature of SET‐LRP and SET‐DTLRP of VC and acrylate monomers .…”

Molecular Radical Chain Initiators for Ambient‐ to Low‐Temperature Applications

“…[56] With initiator loadings of 1mol %a nd lower, the polymerization of n-butylacrylate and styrene could be conducted at temperatures as low as 50 8C. Vinyl chloride could be polymerized at 30 8Cb yu sing commercially available alkoxyamine 27, [57] which was also applied to the alternating copolymerization of an acrylate with vinyl acetate at 40 8C. [58] Photosensitive alkoxyamines have also been developed, which allow controlled polymerization reactions to be initiated by irradiation.…”

“…With initiator loadings of 1 mol % and lower, the polymerization of n‐butyl acrylate and styrene could be conducted at temperatures as low as 50 °C. Vinyl chloride could be polymerized at 30 °C by using commercially available alkoxyamine 27 , which was also applied to the alternating copolymerization of an acrylate with vinyl acetate at 40 °C …”

Nitroxide-mediated graft copolymerization of styrene from cellulose and its polymer/montmorillonite nanocomposite

“…This technique is particularly appealing mainly due to its applicability to a wider range of monomers (e.g. acrylates, acrylamides, and vinyl chloride) both in homogenous and heterogeneous media, 37,38 synthesis of copolymers with controlled molecular weight and well-defined architecture (e.g. block, star, and graft) in relatively mild condition, simple and feasible activation–deactivation equilibrium only by increasing of temperature for polymerization and cooling for quenching of reaction.…”