Norbornenyl-Modified Nanosilica for Reinforced Polydicyclopentadiene Composites

Polydicyclopentadiene (PDCPD) is a type of rigid thermosetting engineering plastic that is polymerized from dicyclopentadiene (DCPD). In industry, it is often combined with various organic or inorganic fillers to produce composites. However, because DCPD is nonpolar, surface modification of the fillers is necessary to enhance composite performance. This study designed and synthesized four readily available norbornenyl-based silane coupling agents based on nadic anhydride and isocyanate siloxane to modify nanosilica. The modified nanosilicas were then stably dispersed in DCPD to prepare a series of norbornenyl-based nanosilica/PDCPD composites. The results showed that the nanosilica modified with additional phenyl groups can lead to better composite performance. The impact toughness of the composites can be increased by 100%, and the tensile and flexural strengths can be improved by approximately 10%. Moreover, these norbornenyl-based nanosilica/PDCPD composites demonstrated good thermal stability, with higher glass transition temperature (T_g) and maximum decomposition temperature (T_dmax) values.