Photoactive Rose Bengal-based Latex via RAFT Emulsion Polymerization-Induced Self-Assembly

Charlène Boussiron (1) , Mickael Le Béchec (1) , Julia Sabalot (1) , Sylvie Lacombe-Lhoste (1) , Maud Save (1)

1 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux

Copolymerization of acrylic acid (AA) with a photosensitizer-based comonomer by reversible addition fragmentation transfer (RAFT) polymerization produces reactive stabilizer for emulsion polymerization induced self-assembly (PISA). This polymerization in aqueous dispersed medium is a surfactant-free and solvent-free environmentally friendly process efficient to design dye-supported polymer colloids dispersed in water. Rose Bengal (RB) was selected as photosensitizer for the synthesis of two types of comonomers (MRB), vinyl benzyl Rose Bengal (VBRB) and ethyl acrylate Rose Bengal (EARB). The effect of the structure of MRB and solvent of RAFT copolymerization with AA was investigated. While VBRB induced strong retardation in 1-4-dioxane, to a larger extent compared to EARB, such retardation was overcome in polar dimethyl sulfoxide. The high level of chain end fidelity of PAA-based macromolecular chain transfer agent, as highlighted by UV-visible spectroscopy and proton NMR, allowed for efficient chain extension. Self-assembled amphiphilic block copolymers synthesized by RAFT-mediated emulsion polymerization are stable monodisperse core-shell particles of 90 - 100 nm diameter. The shell is a hydrophilic poly(ammonium acrylate-co-MRB) statistical copolymer and the core is a film-forming poly(alkyl acrylate), either poly(n-butyl acrylate), or poly(ethyl acrylate) or poly(n-butyl acrylate-co-ethyl acrylate). A second synthetic route is proposed to label the particle core with photosensitizer. The interfacial singlet oxygen production was monitored by the degradation of furfuryl alcohol quencher under visible light irradiation. The average quantum yield of supported Rose Bengal in a close range with free Rose Bengal in water proves the photoactivity of photosensitizer-grafted waterborne latexes

Domaines: Polymères

Charlène Boussiron, Mickael Le Béchec, Julia Sabalot, Sylvie Lacombe-Lhoste, Maud Save. Photoactive Rose Bengal-based Latex via RAFT Emulsion Polymerization-Induced Self-Assembly. Polymer Chemistry, 2021, 12, pp.134-147. ⟨10.1039/D0PY01128B⟩. ⟨hal-02979190⟩