Vitrimers represent an interesting class of materials that exhibit many of the desirable properties of conventionally crosslinked materials, while also being able to be reprocessed through the utilization of dynamic exchangeable crosslinks. Recently, the thiourethane moiety has been explored as a potential dynamic crosslink in vitrimeric materials, as it exhibits both associative and dissociative exchange pathways in response to an external stimulus – i.e. heat. Herein, we aim to utilize the selectivity of various thiol-X reactions to achieve rapidly forming vitrimeric systems. In the present study, a sequential “one pot – two step” process was utilized to develop a series of ternary thiol-ene/thiourethane networks from commercially available building blocks. Each network studied exhibited rapid curing under UV irradiation, consistent with photocured thiol-ene network fabrication, and excellent network reprocessibility imparted by the dynamic exchange of the thiourethane linkages. Through dynamic mechanical analysis, the rate of stress relaxation was shown to be directly dependent on the macromolecular architecture imparted by the diisocyanate monomer selection. Furthermore, we found that these materials exhibited excellent retention of mechanical properties upon reprocessing.

Ternary thiol-ene/thiourethane covalent adapatable networks: a rapid and versatile route to vitrimeric materials

ACS Fall 2021

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