Synthesis, cure kinetics, and physical properties of a new tricyanate ester with enhanced molecular flexibility

1,2,3-Tris(4-cyanatophenyl)propane, a new tricyanate ester monomer that was designed to incorporate more flexible chemical linkages at junction points in the cured macromolecular network, was synthesized in nine steps with an overall yield of 26%. The highly purified monomer exhibited an activation energy of 110 kJ/mol for auto-catalytic cure at temperatures of 210 °C-290 °C, modestly lower than the comparably measured activation energy of a commercial cyanated novolac. The overall extent of cure achievable at these temperatures was also higher for the new monomer. Many physical properties of the cured monomer, including density, thermochemical stability, moisture uptake, and the impact of hydrolytic degradation on glass transition temperature were similar to those of commercial tricyanates, with a dry glass transition temperature at full conversion of at least 340 °C. These results illustrate how careful control of the local chemical structure in the vicinity of network junction points may be utilized to improve the properties of thermosetting polymer networks.