Effect of Nanoparticle Functionalization on the Performance of Polycyanurate/Silica Nanocomposites

The impact of silica functionalization in determining the performance of polycyanurate networks polymerized from 1,1-bis(4-cyanatophenyl)ethane, known commercially as Primaset LECy, reinforced with modified fumed silica, was elucidated through systematic comparison of the properties of nanocomposite networks in which the silica surface treatment was altered. Three types of surfaces were investigated: moderately acidic (unmodified silanol), neutral (alkylsilane modified), and slightly basic (3-aminopropylsilane modified). In terms of cyanate ester cure, the acidic surface proved to be moderately catalytic, the neutral surface mildly catalytic due to slight residual silanol content, and the basic amino-functional surface mildly inhibitory. In terms of network performance, the amino-functional surface led to significant degradation of the network at elevated temperatures, while the silanol-functional surface outperformed the alkyl-functional surface in terms of protection against hydrolytic degradation. In a...