RAFT Polymerization of Vinyl Esters: Synthesis and Applications

Abstract

This article is the first comprehensive review on the study and use of vinyl ester monomers in reversible addition fragmentation chain transfer (RAFT) polymerization. It covers all the synthetic aspects associated with the definition of precision polymers comprising poly(vinyl ester) building blocks, such as the choice of RAFT agent and reaction conditions in order to progress from simple to complex macromolecular architectures. Although vinyl acetate was by far the most studied monomer of the range, many vinyl esters have been considered in order to tune various polymer properties, in particular, solubility in supercritical carbon dioxide (scCO 2 ). A special emphasis is given to novel poly(vinyl alkylate)s with enhanced solubilities in scCO 2 , with applications as reactive stabilizers for dispersion polymerization and macromolecular surfactants for CO 2 media. Other miscellaneous uses of poly(vinyl ester)s synthesized by RAFT, for instance as a means to produce poly(vinyl alcohol) with controlled characteristics for use in the biomedical area, are also covered.

Influence of Polymer Chain Architecture of Poly(vinyl alcohol) on the Inhibition of Ice Recrystallization

“…NMR spectroscopy was performed on a Varian Mercury Vx 400 MHz and/or Varian 400MR, operating at 400 MHz for 1 H and 100 MHz for 13 C. Chemical shifts are reported in ppm (δ) values relative to tetramethylsilane (TMS) or residual solvent. Splitting patterns are labeled as s, singlet; d, doublet; dd, double doublet; t, triplet; q, quartet; q, quintet; m, multiplet; and b stands for broad.…”

“…Despite huge effort and commercial interest, control over both molecular weight and stereochemistry is still considered a synthetic challenge in the synthesis of PVA. [ 12,13 ] The signifi cance of polymer molecular weight, stereochemistry, and side group functionality on antifreeze activity is evident from studies on the antifreeze activity of AFGPs. AFGPs found in the blood of marine fi shes vary in molecular weight (2500-25 000 Da), of which the high molecular weight fraction is much more active.…”

Chain Transfer in Degenerative RAFT Polymerization Revisited: A Comparative Study of Literature Methods

“…[ 14,15 ] Such agent invokes a RAFT polymerization mechanism, as shown in Scheme 1 for a dithioester as RAFT CTA. [ 16 ] During RAFT polymerization, a propagating radical (R n ), formed upon chain initiation with a conventional radical initiator fragment I * , can add to the initial RAFT CTA (R 0 X) whereby an intermediate radical (INT-( n ,0)) is formed. Due to the instability of the formed adduct-radical, β-C-S-scission occurs, resulting in either the starting compounds ( k frag,0,a ) or a dormant RAFT polymer species with chain length n (R n X) and a RAFT CTA derived radical species (R 0 ) ( k frag,0,b ) that can re-initiate the polymerization ( k re-in ).…”

Preparation of a Mini-Library of Thermo-Responsive Star (NVCL/NVP-VAc) Polymers with Tailored Properties Using a Hexafunctional Xanthate RAFT Agent

“…Initially, the reaction was explored at 30 • C using V70 as initiator, and at 60 and 70 • C using ACVA as initiator, but no copolymer was obtained. This reaction was only successful at 80 • C using ACVA for 24 h. The initial polymerization conditions chosen were based on the reactivity of PNVCL macro-radicals (reinitiating Z-group) and low reactivity of VAc monomer [25,38]. When star PNVCL with initial M n = 82,600 g/mol was used as macro-CTA (sample (PNVCL 99 ) 6 ), under favorable polymerization conditions (80 • C), diblock copolymers with increased M n of 94,500, 94,300 and 93,700 g/mol were obtained.…”

“…Polymers 2018, 10, 20 11 of 25 the reactivity of PNVCL macro-radicals (reinitiating Z-group) and low reactivity of VAc monomer [25,38]. When star PNVCL with initial Mn = 82,600 g/mol was used as macro-CTA (sample (PNVCL99)6), under favorable polymerization conditions (80 °C), diblock copolymers with increased Mn of 94,500, 94,300 and 93,700 g/mol were obtained.…”