A propargyl ether-containing benzoxazine (4) was prepared from a potassium carbonate-catalyzed nucleophilic substitution of propargyl bromide and a phenolic OH-containing benzoxazine (3), which was prepared from 1-(4-hydroxyphenyl)-1-(4-aminophenyl)-1-(6-oxido-6H -dibenz <1,2> oxaphosphorin-6-yl)ethane (1) by a three-step procedure. The curing reactions of (4) were monitored by IR and DSC. A reaction mechanism was proposed based on the observation. Benzoxazines (3) and (4) were applied as epoxy curing agents. The microstructure and the structure-property relationship of the resulting thermosets are discussed. The double-strand structure in (4)-cured epoxy thermosets afforded higher crosslinking density, and led to higher thermal properties. In addition, the (4)-cured epoxy thermosets possess half the amount of highly polar hydroxyl groups than those of the (3)-cured epoxy thermosets, resulting in a lower dielectric constant, dissipation factor, and water absorption.

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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 diallylcontaining diamine, 1,1-bis(3-allyl-4-(4-aminophenoxy)-phenyl)-1- (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 0 -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 T g , 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.