Three-in-one effect: Enhancement of processability, anti-aging and mechanical properties of phthalonitrile via modification with novel rare earth coordinated benzimidazole compound

To further improve the comprehensive performance of phthalonitrile (PN), a novel compound SiBPN-Ce was prepared using 2-benzimidazolinone (2-BI), diphenyldichlorosilane (DPDCS), 4-aminophthalonitrile (4-APN), and cerium chloride. The addition of SiBPN-Ce decreased the viscosity of PN exponentially and reduced the peak curing temperature by 29.4 °C. Through copolymerization modification, a highly efficient physical–chemical hybrid reinforcement mechanism was introduced into PN by SiBPN-Ce. The results indicated that SiBPN can effectively increase the temperature of 5 % mass loss (T_5%) and char yield of PN by 29 °C and 7.2 %, respectively. In the aging test at 350 °C, the formation of a SiO₂-Ce protective layer derived from SiBPN-Ce delayed the occurrence of microcracks on the PN matrix surface by 60 h. Meanwhile, PN modified with SiBPN-Ce (SiBPN15-Ce) retained most of its surface morphology after aging for 100 h. For the SiBPN-Ce composite, its flexural strength (FS) and interlaminar shear strength (ILSS) increased by 449.1 MPa and 17.2 MPa respectively compared to pure PN composite. Based on all the results, this physical–chemical hybrid reinforcement mechanism in SiBPN15-Ce was carefully analyzed.