Spatiotemporal Vitrimerization of a Thermosetting Polymer using a Photo-Latent Catalyst

Globally rising environmental concerns have increased the demand for recyclable polymers and efficient recycling practices. The lack of melt-processability of thermosets significantly limits their recycling because the simplest and most economical way to recycle polymers with a minimum carbon footprint is repairing or re-melting them into new items. To this end, an approach to spatiotemporally converting a thermoset into a processable vitrimer is presented. This was achieved by incorporating a latent, heat-stable photo-active catalyst into an otherwise thermoset, activating associative network exchange reactions only after light exposure and subsequent heating. The thermoset film could be repaired and/or heat-processed by simply exposing the sample to light followed by annealing at elevated temperature and pressure, whereas the repairing/heat-processing failed in the absence of the light exposure step. This approach enables the polymer to initially behave as a thermoset at all temperatures until it requires repair or heat-processing.