Synthesis of transparent and thermally stable polycyanurates and their thermal rearrangement

Abstract

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)−6‐methoxy‐1,3,5‐triazine as a cyanurate is prepared and rearranged to an isocyanurate, 1,3‐bis(4‐methoxyphenyl)−5‐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‐transfer‐catalyzed 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 °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. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3950–3955

Synthesis and characterization of polycyanurates as dismantlable adhesives

“…The results are summarized in Table . A standard polycyanurate ( P1 ) was prepared by the phase‐transfer‐catalyzed polycondensation of DMT with M1 in the presence of quaternary ammonium salts following published procedures in previous articles . However, random copolymers, polycyanurates P2, P3, and P4 , were synthesized using M1 and a comonomer, M2 or M3 , respectively.…”

“…2,4‐Dichloro‐6‐methoxy‐1,3,5‐triazine ( DMT ) was kindly donated by Sankyo Chemical, and was recrystallized from n ‐hexane. P1 was prepared by the phase‐transfer‐catalyzed polycondensation of DMT with M1 in the presence of quaternary ammonium salts following procedures in previous articles …”

“…P1 was prepared by the phasetransfer-catalyzed polycondensation of DMT with M1 in the presence of quaternary ammonium salts following procedures in previous articles. 16…”

“…During the study of the synthesis of polycyanurates and their electric and optical applications, we found that the molecular weights of the polycyanurates rapidly decreased during the rearrangement to polyisocyanurates by a thermal treatment . For instance, the number‐average molecular weight ( M n ) value of a polycyanurate decreased from 104,000 to 23,000 after the thermal rearrangement at 180 °C for 5 min in air …”

“…During the study of the synthesis of polycyanurates and their electric and optical applications, we found that the molecular weights of the polycyanurates rapidly decreased during the rearrangement to polyisocyanurates by a thermal treatment. 16 For instance, the number-average molecular weight (M n ) value of a polycyanurate decreased from 104,000 to 23,000 after the thermal rearrangement at 180 8C for 5 min in air. 17 In a previous study, we carefully investigated the thermal rearrangement of 2,4-bis(4-methoxyphenyl)-6-methoxy-1,3,5triazine under various conditions, and found that the hydrolysis of aryl imidates in the presence of moisture occurred during the thermal rearrangement (Scheme 1).…”