Morphological and Mechanical Evaluation of Hybrid Organic/Inorganic Thermoset Copolymers of Dicyclopentadiene and Polyhedral Oligomeric Silsesquioxanes

摘要

A new class of organic/inorganic hybrid thermoset copolymers have been by prepared by ring opening metathesis polymerization (ROMP) catalyzed with bis(tricyclohexylphosphine)ruthenium dichloride. Dicyclopentadiene (DCPD) and norborylene-substituted polyhedral oligomeric silsesquioxane (POSS) with isobutyl pendent groups have been copolymerized at 60℃ over a range of POSS concentrations. The X-ray structure of the copolymers shows small aggregates of POSS at higher concentrations with uniform dispersion below 10 wt% POSS. These copolymers exhibit a decrease in T_g from128℃ for PDCPD to 114℃ with the addition of 20% wt POSS. The stiffness, in tension and compression, is decreases with increasing POSS concentration. Additionally, the incorporation of POSS changes the fracture mechanism from shear banding or ductile to brittle failure and is accompanied by a decrease in the fracture toughness of the copolymers.