Silicon-Containing Tri- and Tetra-Functional Cyanate Esters: Synthesis, Cure Kinetics, and Network Properties.

摘要

The synthesis and physical properties of new silicon-containing polyfunctional cyanate ester monomers tris(4-cyanatophenyl)methylsilane and tetrakis(4-cyanatophenyl)silane, as well as polycyanurate networks formed from these monomers are reported. The higher cross-linking functionality compared to di(cyanate ester) monomers enables much higher ultimate glass transition temperatures to be obtained as a result of thermal cyclotrimerization. The ability to reach complete conversion is greatly enhanced by cocure of the new monomers with di(cyanate ester) monomers such as 1,1-bis(4-cyanatophenyl)ethane (LECy). The presence of silicon in these polycyanurate networks imparts improved thermochemical stability in air compared to carbon-containing analogs in cases where the thermochemical performance in air is significantly worse than under nitrogen. The water uptake in the silicon-containing networks examined is 4 - 6 wt% after 96 hours of immersion at 85 degrees C, considerably higher than both carbon-containing and/or di(cyanate ester) analogs.