Synthesis of diallyl-containing polyimide and the effect of allyl groups on properties

A diallyl-containing bisphenol, 1,1-bis(3-allyl-4-hydroxyphenyl)-1-(6-oxido-6H -dibenzo [c,e][1,2] oxaphosphorin-6-yl) ethane (1), was prepared by a two-step procedure. Then, a diallyl-containing diamine, 1,1-bis(3-allyl-4-(4-aminophenoxy)-phenyl)-1-(6-oxido-6H-dibenzo [c,e][1,2] oxaphosphorin-6-yl)ethane (3), was prepared from the nucleophilic substitution of (1) with 4-fluoronitrobenzene, followed by the reduction by Fe/HCl. A flexible polyimide (4) with curable diallyl linkages was prepared from the condensation of (3) and 4,4′-oxydiphthalic anhydride in m-cresol in the presence of isoquinoline. Curing polyimide (4) at 300 °C leads to thermosetting polyimide (5). We discussed the amounts of allyl group on Tg, coefficient of thermal expansion, and thermal stability of thermosetting polyimides, and found that thermal properties and dimensional stability of thermosetting polyimides increase with the amounts of cured allyl moieties.