Unraveling the thermal stability of aromatic disulfide epoxy vitrimers: a comprehensive study using principal component analysis (PCA)†

Abstract

Polymer networks possessing reversible covalent crosslinks have emerged as an interesting type of material that combine the excellent performance of thermoset materials with the processability of thermoplastic materials. Several studies have focused on different reversible bonds. However, little or no attention has been paid to degradation events occurring during reprocessing. In this study, we utilize ¹H NMR spectra coupled with chemometric methods to define the best processing conditions for aromatic disulfide-based vitrimers. By using a principal component analysis (PCA) tool, we show it is possible to gauge which variable has a greater impact on the degradation of aromatic disulfides. Analyzing 80 different spectra simultaneously, the PCA reveals that from the analyzed variables, the processing time is the most influential variable, followed by temperature. Using Multivariate Curve Resolution (MCR) models we show that it is possible to estimate the extent of degradation as a function of the different experimental conditions. The data obtained with model compounds using chemometrics has been validated by analyzing the impact of reprocessing conditions in vitrimer networks. Our study suggests that NMR analysis combined with chemometric tools can provide highly valuable information to define processing conditions for covalent adaptable networks with minimal degradation.