Catalyst-Free Vitrimers from Vinyl Polymers

Abstract

Cross-linked networks feature exceptional chemical and mechanical resilience but consequently lack recyclability. Vitrimers have emerged as a class of materials that feature the robustness of thermosets and the recyclability of thermoplastics without compromising network integrity. Most examples of vitrimers have involved new polymers with exchangeable bonds within their backbones. In pursuit of a more universal, commercially viable route, we propose a method utilizing commercially available and inexpensive reagents to prepare vitrimers from vinyl monomer-derived prepolymers that contain cross-linkable βketoester functional groups. Controlled radical copolymerization of methyl methracrylate and (2-acetoacetoxy)ethyl methacrylate afforded linear prepolymers that were converted into vitrimers in a single step by treatment with a trifunctional amine. These materials displayed the characteristic features and reprocessability of vitrimers over as many as six (re)processing cycles. Critically, the networks prepared through this process largely retain the chemical and thermal properties of their linear counterparts, suggesting this method holds significant utility as a user-friendly and commercially relevant approach to the rational design of vitrimers with diverse properties.

Vitrimers: directing chemical reactivity to control material properties

“…Compared to real vitrimers, such weakly cross-linked thermoplasts show very limited resistance to dissolution by solvents. [66][67][68] In spite of such drawbacks, these 'vitrimerised thermoplasts' have attracted considerable attention, [66][67][68][69][70][71][72][73][74] considering the fact that they can be processed using usual thermoplastic processing techniques, while their properties can be improved in comparison to the bulk thermoplastic counterparts.…”

Conformational Entropy as a Means to Control the Behavior of Poly(diketoenamine) Vitrimers In and Out of Equilibrium

“…[1][2][3] Thec ross-linking density of av itrimer influences its thermal and mechanical properties:f or example,h igher network density increases the probability that cross-links will interact and be involved in bond-exchange reactions,w hich impact the dynamics of vitrimer reconfigurability across multiple length scales and therefore its rheology. Theenergetics of bond-exchange reactions have been studied for vitrimers undergoing uncatalyzed or catalyzed transesterification, [4][5][6] transcarbamoylation, [7][8][9][10] olefin metathesis, [11] boronic ester exchange, [12][13][14] siloxane exchange, [15,16] triazo-lium transalkylation, [17] imine bond exchange, [18,19] ketoenamine exchange, [20][21][22] and diketoenamine exchange. [23] However,there is alack of understanding of how conformational degrees of freedom available to the network influence av itrimerst hermal and rheological behavior in and out of equilibrium.…”

Conformational Entropy as a Means to Control the Behavior of Poly(diketoenamine) Vitrimers In and Out of Equilibrium

“…The cross‐linking density of a vitrimer influences its thermal and mechanical properties: for example, higher network density increases the probability that cross‐links will interact and be involved in bond‐exchange reactions, which impact the dynamics of vitrimer reconfigurability across multiple length scales and therefore its rheology. The energetics of bond‐exchange reactions have been studied for vitrimers undergoing uncatalyzed or catalyzed transesterification, transcarbamoylation, olefin metathesis, boronic ester exchange, siloxane exchange, triazolium transalkylation, imine bond exchange, ketoenamine exchange, and diketoenamine exchange . However, there is a lack of understanding of how conformational degrees of freedom available to the network influence a vitrimer's thermal and rheological behavior in and out of equilibrium.…”