Synthesis of transparent and thermally stable polycyanurates and their thermal rearrangement

Transparent and thermally stable polycyanurates, whose solubility can be changed by thermal rearrangement, have been synthesized as functional films used in the multilayer coating process. Before the synthesis of polycyanurates, the model compound, 2,6-bis(4-methoxyphenyl) 26-methoxy-1,3,5-triazine as a cyanurate is prepared and rearranged to an isocyanurate, 1,3-bis(4-methoxyphenyl) 25-methyl-1,3,5-triazinane-2,4, 6-trione in an excellent yield by thermal treatment. Based on this result, polycyanurates are prepared by the phase-transfercatalyzed polycondensation of 2,4-dichloro-6-methoxy-1,3,5-triazine with bisphenol monomers in the presence of quaternary ammonium salts. The polycyanurate obtained from 9,9-bis(hydroxyphenyl) fluorene exhibits a high glass transition temperature at 251 degrees C. The solubility of polycyanurate films containing 1 wt % of tetrabutylammonium bromide can be changed by thermal rearrangement. The partially rearranged films keep high transparency and low birefringence. (C) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3950-3955