Triphenylbenzene core based dendritic benzoxazines and their heat-resistant and photoluminescent polymers

Abstract

A facile and efficient synthetic route to connect 1,3,5-tri( p-hydroxyl-phenyl)benzene (TP) molecules into polymers was introduced. Specifically, a series of triphenylbenzene core based dendritic benzoxazines were synthesized via Mannich reaction using TP, paraformaldehyde, and amine derivatives including n-propylamine, cyclohexylamine, and aniline. The chemical structure of benzoxazines was characterized by nuclear magnetic resonance spectroscopy (proton and carbon nuclear magnetic resonance) and Fourier transform infrared spectroscopy. Thermally ring-opening polymerization of the dendritic benzoxazines yielded the cross-linked polymers. We found that N-substituents had the significant influence on polymerization temperature, glass transition temperature ( Tg), thermal stability, and char yield. Polybenzoxazine with the N-phenyl group exhibited the highest Tg of 276°C, char yield of 70%, and excellent thermal stability (5 and 10% weight loss temperatures at 356 and 411°C, respectively). Photoluminescent analysis indicated that the cross-linked structure did not quench the triphenylbenzene’s photoluminescence, while only the relative photoluminescent intensity of polybenzoxazines reduced compared with TP.