Stepwise copolymerization of polybenzimidazole for a low dielectric constant and ultrahigh heat resistance

• Published in: RSC advances Vol. 12; no. 19; pp. 11885 - 11895
• Main Authors: Zhong, Xianzhu, Nag, Aniruddha, Zhou, Jiabei, Takada, Kenji, Amat Yusof, Fitri Adila, Mitsumata, Tetsu, Oqmhula, Kenji, Hongo, Kenta, Maezono, Ryo, Kaneko, Tatsuo
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 13.04.2022; The Royal Society of Chemistry
• Subjects: Aramid fibers; Biopolymers; Chemistry; Copolymerization; Density functional theory; Depletion; Enthalpy; Heat resistance; Hydrogen bonding; Imidazole; Monomers; Permittivity; Polybenzimidazoles; Polymers; Terpolymers; Thermal degradation; Thermal resistance; Trimers
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d2ra01488b

Bio-based polymer materials having great potential due to the depletion of fossil-fuel resources have been applied as single-use and medicinal materials but their low thermomechanical resistance have limited wider applications. Here, ultrahigh thermoresistant bio-based terpolymers with a low dielectric constant, comprising polybenzimidazole and poly(benzoxazole- random -aramid), were prepared by a method involving stepwise polycondensation of three monomers, 3,4-diaminobenzoic acid for benzimidazoles, 3-amino-4-hydroxylbenzoic acid for benzoxazoles, and 4-aminobenzoic acid for aramids. For optimized monomer compositions, the obtained terpolymers exhibited dielectric constants lower than 3, and a 10% mass loss at approximately 760 °C which is a temperature higher than that for any other polymer material reported so far. The high thermal degradation temperatures of the prepared terpolymers were a result of the high interaction enthalpies of hydrogen bonding between imidazole rings in the polymer chains, which were obtained from density functional theory calculations using trimer models. Furthermore, the applicability of the prepared terpolymers as a wire-coating material for a simple motor insulation was demonstrated, indicating that it has significant potential to be used as a thermostable material with a low dielectric constant ( k ). A stepwise polymerization of polybenzimidazole is adopted to synthesize terpolymers with block structure, their films exhibit a low dielectric constant and ultrahigh thermal resistance.