Selective and Quantitative Oxidation of Xanthate End-Groups of RAFT Poly(n-butyl acrylate) Latexes by Ozonolysis

Abstract

Although various successful strategies have been reported in the past for the postpolymerization modification of the reversible addition‐fragmentation chain transfer (RAFT) terminal group in homogeneous media, no solution is proposed for the tedious case of aqueous polymer dispersions where most of the thiocarbonylthio terminal group is buried into the core of the polymer particle. In this work, ozone is proposed to tackle this important academic and industrial challenge. After preliminary model ozonolysis reactions performed on a xanthate RAFT agent and a derived low molar mass poly(n‐butyl acrylate) (PBA) in dichloromethane solution, it is shown that the hydrophobic nature and strong oxidant properties of ozone are responsible for its efficient diffusion in aqueous PBA latex particles obtained by RAFT and selective and complete transformation of the xanthate terminal group into a thiocarbonate end‐group. In addition to the beneficial total discoloration of the final product, this chemical treatment does not generate any volatile organic compound and leaves the colloidal stability of the polymer particles unaffected, provided that a PBA latex with a sufficiently high Mn of 5000 g mol−1 is selected.

RAFT aqueous emulsion polymerization of methyl methacrylate: observation of unexpected constraints when employing a non-ionic steric stabilizer block

“…In 2015, Destarac and co-workers demonstrated that xanthate groups could be efficiently cleaved from aqueous poly(n-butyl acrylate) latexes using ozone at ambient temperature. 58…”

In Situ Spectroscopic Studies of Highly Transparent Nanoparticle Dispersions Enable Assessment of Trithiocarbonate Chain-End Fidelity during RAFT Dispersion Polymerization in Nonpolar Media

“… 45 , 46 Moreover, such CTAs are colored, malodorous, and potentially toxic, so their quantitative removal is often desired for potential applications. 47 , 48 Fortunately, RAFT chain-ends can be readily cleaved using reagents such as amines, 49 ozone, 47 H 2 O 2 , 50 or excess radical initiator. 51 …”

RAFT dispersion polymerisation of lauryl methacrylate in ethanol–water binary mixtures: synthesis of diblock copolymer vesicles with deformable membranes

“…Matioszek and co-workers used ozonolysis to remove xanthatebased RAFT end-groups buried within the cores of relatively low molecular weight poly(n-butyl acrylate) latex particles in aqueous media. 86 Complete removal of these RAFT end-groups was observed by UV GPC analysis within 1 h at room temperature. Colloidal stability was maintained provided that the Mn of the latex was above 5 000 g mol -1 .…”

“…[73][74][75][76] Moreover, the vast majority of work in this area has focused on the modification of soluble chains, [77][78][79][80][81][82][83][84][85] with only a few studies examining RAFT end-group removal from block copolymer nano-objects. 86,87 Mattson and co-workers used UV light (λ = 380nm) to remove terminal trithiocarbonate end-groups with a photoredox Intensity / a.u. Please do not adjust margins Please do not adjust margins catalyst in solution (acetonitrile or N,N-dimethylacetamide).…”