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 new phosphinated acetoxybenzoic acid, 1-(4-acetoxyphenyl)-1-(4-carboxylphenyl)-1-(6-oxido-6H-dibenz<1,2> oxaphosphorin-6-yl)ethane (3), was prepared by a three-step procedure. Phosphinated copolyesters based on the acidolysis and polycondensation of (3) with poly(ethylene terephthalate) (PET) were prepared. The crystallinity of copolyesters decreased gradually with the content of (3), as shown in wideangle X-ray diffractograms and differential scanning calorimetry thermograms. Dynamic mechanical analysis and thermal mechanical analysis show T g increased with the content of (3). UL-94 flame retardant test shows that the flame resistance of PET was enhanced with the content of (3), and a copolyester with UL-94 V-0 grade can be achieved with a phosphorus content as low as 1.43 wt %.

We have developed a sequence‐dependent synthesis of the amino‐functionalized poly(ether sulfone) P2. The amino groups of P2 act as reactive sites toward epoxy resins. After curing P2 with diglycidyl ether of bisphenol A (DGEBA) and cresol novolac epoxy (CNE), we obtained the flexible, light‐yellow, transparent, epoxy thermosetting films P2/DGEBA, and P2/CNE, respectively, having glass transition temperatures (Tg) of 258 and 274°C, respectively. In addition, we also prepared a flexible film after condensation of the amino groups of P2 with the anhydride groups of 4,4′‐oxydiphthalic anhydride (ODPA); after imidization at 300°C for 1 h, the resulting P2/ODPA thermosetting film possessed a value of Tg of 340°C. These three thermosetting films also exhibited flame retardancy with a UL‐94 VTM‐0 grade. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40980.