A Novel Organophosphorus Hybrid with Excellent Thermal Stability: Core–Shell Structure, Hybridization Mechanism, and Application in Flame Retarding Semi-Aromatic Polyamide

An organophosphorous hybrid (BM@Al-PPi) with unique core–shell structure was prepared through hybridization reaction between boehmite (BM) as the inorganic substrate and phenylphosphinic acid (PPiA) as the organic modifier. Fourier transform infrared spectra (FTIR), solid state 31P and 27Al magic angle spinning nuclear magnetic resonance, X–ray diffraction, and element analysis were used to investigate the chemical structure of the hybrids, where the microrod–like core was confirmed as Al-PPi aggregates generated from the reaction between BM and PPiA, and those irregular nanoparticles in the shell belonged to residual BM. Compared with the traditional dissolution–precipitation process, a novel analogous suspension reaction mode was proposed to explain the hybridization process and the resulting product. Scanning electronic microscopy further proved the core–shell structure of the hybrids. BM exhibited much higher initial decomposition temperature than that of Al-PPi; therefore, the hybrid showed better th...