The Trade-Off between Dechlorination and Polymerization for Facile Fabrication of Electronic Grade Epoxidized Cardol

The dechlorination of epoxidized Cardol (E-Cardol), which is a high-performance and sustainable adhesive and packaging material for electronics, remains challenging. The previous work proposed a new alcohol-sodium refining method to efficiently remove the chlorine of E-Cardol. However, this method is strongly limited by the trade-off between the dechlorination efficiency and its polymerization side effect, which leads to the viscosity as well as the epoxy equivalent increase of E-Cardol. Based on the detailed analysis of the refining process using fourier transform infrared spectroscopy (FTIR), simultaneous thermal analysis (STA), and nuclear magnetic resonance spectrometer (NMR) epoxidized Cardol (E-Cardol), this trade-off is studied. It is found that the dechlorination efficiency increases with the increase of the usage of the alcohol sodium. Meanwhile, when the residual alcohol-sodium content after refining exceeds 3000 ppm, the viscosity of the E-Cardol increases significantly due to the increased polymerization of E-Cardol by epoxy ring-opening reaction. It is demonstrated that the alcohol-sodium refining method can efficiently reduce the chlorine content of E-Cardol with the initial hydrolyzable chlorine content not higher than 3000 ppm to below 300 ppm without influencing their epoxy equivalent and viscosity. This paper thoroughly explores the mechanism and application range of the proposed alcohol-sodium refining method, which is crucial for the facile preparation of electronic-grade E-Cardol materials.