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Polymerization of Vinyl Chloride at Ambient Temperature Using Macromolecular Design via the Interchange of Xanthate: Kinetic and Computational Studies

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journal contribution
posted on 23.12.2019, 20:37 by Carlos M. R. Abreu, Talita C. Rezende, Ana C. Fonseca, Tamaz Guliashvili, Cédric Bergerbit, Franck D’Agosto, Li-Juan Yu, Arménio C. Serra, Michelle L. Coote, Jorge F. J. Coelho
Reversible deactivation radical polymerization of vinyl chloride (VC) by methyl (ethoxycarbonothioyl)­sulfanyl acetate (MEA)-mediated macromolecular design via the interchange of xanthate (MADIX) polymerization at ambient temperature is reported. The polymerization system was studied using two conventional radical initiators (having very distinct half-life times at room temperature). The system was optimized regarding the nature of the solvent, the monomer concentration, the polymerization temperature, and the target molecular weight. The kinetic data showed linear first-order kinetics, the linear evolution of molecular weights with conversion, and polymers with narrow molecular weight distributions (Đ ≈ 1.2 to 1.3) using a low temperature (30–42 °C) and cyclopentyl methyl ether (CPME) as a “green” solvent. The resulting MEA-terminated poly­(vinyl chloride) (PVC) was fully characterized by 1H nuclear magnetic resonance spectroscopy that revealed the existence of a very small fraction of structural defects and the presence of chain-end functional groups. “One-pot” chain extension (with VC) and “one-pot” block copolymerizations (with vinyl acetate − VAc and N-vinylcaprolactam − NVCL) experiments confirmed the “livingness” of the MEA-terminated PVC chains, giving access to different PVC-based block copolymers. Computational studies confirm the results of the solvent screen and suggest that changes to the initial MADIX leaving or stabilizing groups could improve control. The computational data were further confirmed using methyl 2-(4-methoxyphenoxycarbonothioylthio)­acetate. This work establishes a new green route to afford a wide range of new complex macrostructures including high-value materials based on PVC segments.