Polystyrene Hybrid-Vitrimer Based On The Hemiacetal Ester Exchange Reaction

Vitrimer materials, which are permanently crosslinked but reshapable polymers, are a class of materials of growing interest due to their potential in recycling and sustainable development. More precisely, vitrimers derived from commodity polymers could have a drastic impact on plastic consumption in the upcoming years. Here, the development of a polystyrene-based vitrimer harnessing the recently discovered hemiacetal ester exchange reaction of carboxylic acid is presented. 1,4-Cyclo-hexanedimethanol divinyl ether was reacted with 4-vinylbenzoic acid (VBA) to form a divinyl species containing two hemiacetal ester functions. This dimer was then copolymerized with styrene, butyl acrylate, and VBA to form a cross-linked material presenting pendent acid groups. This material exhibited three distinct behaviors at different temperature regimes: below 80 degrees C, despite the exchange reactions able to occur at this temperature, the crosslinked material behaved as a frozen material due to the hydrogen bonding formed by the carboxylic acid pendent groups. Between 80 and 130 degrees C, the vitrimer behavior was demonstrated by rheological creep experiments. At higher temperatures, the dissociation of the hemiacetal ester groups led to the loss of the covalent cross-linking.