Reaction-Induced Liquid Crystalline Polybenzoxazine Bearing Aromatic Amide Side Branches

In this study, a nematic phase structure is incorporated into polybenzoxazine to increase its thermal conductivity. A simple route for the synthesis of a thermally conductive polybenzoxazine containing liquid crystalline (LC) structure by grafting oligomeric p-sulfophenylene-terephthalamide (PSTA) is offered. Benzoxazine monomer of pHBA-da is synthesized via Mannich reaction of p-hydroxy benzoic acid, p-formaldehyde, and dodecyl amine. After ring-opening polymerization, the oligomer benzoxazine of OBZCOOH is obtained. The OBZCOOH/PSTA mixture is prepared by mixing PSTA with OBZCOOH. Afterward, the grafted copolymer is named OBZPSTA copolymer. The liquid crystalline behavior of OBZCOOH/PSTA is studied by polarized optical microscopy and small angle X-ray scattering analysis. The results show that the OBZPSTA forms the LC structure during isothermal and non-isothermal curing. The LC structure displays a floral textured nematic phase. The phase formation is induced by an amidation reaction. Due to the grafts of LC PSTA, the thermal conductivity of OBZPSTA is 0.296 W m-1 K-1, which is 26% greater than OBZCOOH. The glass transition temperature (Tg) of OBZPSTA is 241 degrees C. The 5% (Td5) and 10% weight loss temperatures (Td10) of OBZPSTA are 346 and 362 degrees C, respectively. In this study, we enhance polybenzoxazine's thermal conductivity by introducing a nematic phase structure. We synthesize thermally conductive polybenzoxazine with liquid crystalline properties through the grafting of oligomeric p-sulfophenylene-terephthalamide (PSTA). This involves the synthesis of pHBA-da benzoxazine monomers, leading to OBZCOOH oligomers. Mixing PSTA with OBZCOOH synthesizes OBZPSTA copolymer. Polarized optical microscopy and small-angle X-ray scattering confirm the formation of a floral textured nematic phase through amidation reactions. OBZPSTA exhibits a remarkable thermal conductivity of 0.296 W m-1 K-1, 26% higher than OBZCOOH. Its Tg is 241 degrees C, with Td5 and Td10 at 346 and 362 degrees C, respectively.image