High-Tg and low-dielectric epoxy thermosets based on a propargyl ether-containing phosphinated benzoxazine

ABSTRACT 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 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. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1359–1367 A propargyl ether‐containing benzoxazine was prepared and used as an epoxy curing agent. Epoxy thermosets cured by benzoxazine possess half the amount of highly polar hydroxyl groups than those based on a phenolic OH‐containing benzoxazine derivative, leading to low dielectric characteristic. The double‐strand structure in the benzoxazine‐cured epoxy thermosets lead to high‐Tg characteristic.