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ABSTRACT Four cyclotriphosphazene-based benzoxazine monomers (I, II, III, and IV) with relatively high molecular weight were synthesized by a nucleophilic substitution reaction, and their chemical structures were confirmed by 1H-NMR and 31P-NMR. A new term, oxazine value (OV, similar to epoxy value), was first proposed to explain the structure-property relationship of the cured polymers. The polymerization behaviors of the four monomers were studied by differential scanning calorimetry and Fourier transform infrared spectroscopy. The maximum exothermic peaks of the four monomers are in the range 244-248 °C. All monomers possess a wide processing window despite their high molecular weight. The thermal stability, glass-transition temperature ( T g), and mechanical properties of each cured polymer were studied by thermogravimetric analysis and dynamic mechanical thermal analysis. The char yield at 850 °C, T g, and storage moduli of PIV (polybenzoxazine obtained from monomer IV) are 60.0%, 218 °C, and 9.0 GPa, respectively. The surface property and humidity absorption character of the cured polybenzoxazines were also studied. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44453. [ABSTRACT FROM AUTHOR]

To improve the performance of traditional polybenzoxazines, copolymerized 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (Pa) and bisphenol-A benzoxazine (Ba) with three kinds of cyclotriphosphazene (CP)-based benzoxazine monomers, respectively. The ring-opening copolymerization behaviors of the benzoxazines mixtures are investigated by differential scanning calorimetry (DSC), the results imply that the CP-based benzoxazines could decrease the polymerization temperature of common benzoxazines. Due to the different structures of the CP-based benzoxazines that possess different numbers of organic benzoxazine moieties tether onto the inorganic CP ring, they produce the different dimensional crosslinking structures of the CP-based benzoxazines under ring-opening polymerization, the TGA and DMA results display the CP-based benzoxazines exhibit different degrees of improvement on the thermal stability and mechanic properties to the co-polybenzoxazines. [ABSTRACT FROM AUTHOR]

A linear oligobenzoxazine precursor with cyclotriphosphazene ring was prepared through the Schiff base route. The resulting polymers showed higher molecular weight and better thermal stability than those from the traditional Mannich polycondensation method. The oligomeric benzoxazine precursor can form a high-quality transparent yellow film; however, it was fragile after being cured. In order to identify the effect of end groups on the cured polymer, an aniline-capped polymer was prepared by the same Schiff base method and then was changed into a benzoxazine end group. The results indicated that the uncapped polymer exhibited higher stability than the capped polymer. This can be ascribed to different chemical structures resulting from different end groups. [ABSTRACT FROM AUTHOR]

The synthesis and mesomorphic properties of a class of cyclotriphosphazenes containing cyanostilbene groups with different terminal substituents (-H, -CH3, -OCH3, -CN) are described. All the resulting compounds are characterized by 1H, 13C, and 31P NMR, matrix-assisted laser desorption/ionization time of flight, and elemental analysis. The thermal behaviors of cyclotriphosphazene derivatives are studied by the means of differential scanning calorimetry and polarizing optical microscopy. Nematic phases are observed in cyclotriphosphazenes with terminal substituents (-CH3, -OCH3, -CN). [ABSTRACT FROM AUTHOR]