4-Vinyl guaiacol acetate as a sustainable lignin-derivable alternative to styrene: Renewable monomer synthesis and its atom transfer radical polymerization

Abstract

4-Vinyl guaiacol acetate (4-VGA) is a renewable 4-vinylphenol-type monomer featuring a pendant protecting group suitable for post-functionalization. Herein, we report a more sustainable, telescoping synthesis route from vanillin, involving a Knoevenagel-Doebner condensation followed by acetylation, affording satisfactory yields through a single, straightforward purification step. The monomer was then tested in Atom Transfer Radical Polymerization (ATRP), achieving good control in the Supplementary Activator and Reducing Agent (SARA) variant. Optimization required evaluating reaction parameters and their effect on the polymerization system, leading to the optimal choice of solvent, catalytic system, and initiator. Notably, the use of highly active chloride-based initiators and CuCl2/TPMA catalytic system played a major role in establishing control over the polymerization. The polymers produced by SARA ATRP exhibit decent control over molecular weight and dispersity, and high initiation efficiency values. However, early termination due to dehydrohalogenation poses a severe limitation to the reaction system, allowing satisfactory monomer conversion values only at low target degrees of polymerization.