Polystyrene Hybrid-Vitrimer Based on the Hemiacetal Ester Exchange Reaction

Abstract

Vitrimer materials, which are permanently cross-linked 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-Cyclohexanedimethanol 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 °C, despite the exchange reactions able to occur at this temperature, the cross-linked material behaved as a frozen material due to the hydrogen bonding formed by the carboxylic acid pendent groups. Between 80 and 130 °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.

Taking advantage of β-hydroxy amine enhanced reactivity and functionality for the synthesis of dual covalent adaptable networks

“…Other CANs have also been based on disulfide exchange, 27,28 alkoxyamine bond dissociation, 29 transalkylation, 30 transacetalation, 31 transamidation 32 or acid exchange. 33,34…”

Fully biomass-derived vitrimeric material with water-mediated recyclability and monomer recovery

“…1e), which is in the range of other reported acetal-based networks. 44,47,48,50,51 Various mechanisms have been identified for acetal exchanges, ranging from transacetalisation/metathesis of spiroacetals, 50 to dissociative mechanisms via a vinyl ether 44,47 or carbocation intermediates. 48 Here, we observe the presence of furfural, indicating that the dynamic exchanges for furfuralacetal with sorbitol proceeds via an initial dissociation into the aldehyde furfural, followed by sorbitol attack to rapidly reach an equilibrium mixture of acetal and furfural.…”

“…The acid-labile cyclic acetal bonds present was identified as a key factor influencing material rigidity as well as reprocessibility. 44,47,48,50,51 The obtained polymer demonstrated both mechanical and chemical reprocessability, with closed-loop monomer-to-polymer-to-monomer recycling by facile aqueous hydrolysis and simple monomer separation by extraction with green solvents. From cradle to cradle, this circular material fulfils 11 out of the 12 principles of green chemistry, 34,35 as presented in Table 1.…”

Catalyst-Free Epoxy Vitrimers Based on Transesterification Internally Activated by an α–CF3 Group

“…Vitrimers, introduced by L. Leibler in 2011, are a class of CANs in which the exchange reaction proceeds via an associative mechanism, keeping the cross-link content in the material constant at any reprocessing temperatures. A fastly expanding range of exchange reactions such as transesterification, transamination, , transcarbamoylation, transimination, transalkylation, transacetalation, boronate metathesis, transamidation, or acid exchange , have been used in vitrimer chemistry.…”