Curing behaviors and properties of epoxy resins with para-hexatomic ring blocks: Excellent comprehensive performances of tetrafluorophenyl

Abstract

It is a longstanding bottleneck for epoxies applied in high-tech fields to obtain integrated performances, including excellent thermal mechanical and stability properties, hydrophobicity, low permittivity and curing activation energy. A novel epoxy monomer with stiff tetrafluorophenyl backbone and robust intramolecular/intermolecular forces is expected to fundamentally break through this challenge. Herein, three model epoxy monomers with different symmetrical para-hexatomic ring blocks were synthesized, including tetrafluorophenyl-based (FEP), phenyl-based (TEREP) and cyclohexyl-based (CEP), followed by curing with methylhexahydrophthalic anhydride (MeHHPA) and polyetheramine (D230), respectively. As expected, TEREP showed better thermal mechanical properties than CEP due to closer stacking density and electronic effect. Noticeably, FEP self-consistently showed the best comprehensive properties among three resins, which mainly benefited from the introduced C–F bonds and the unique electronic effect caused by tetrafluorophenyl. Moreover, the exhilarating results of tetrafluorophenyl para-hexatomic ring provide an efficient guideline for building epoxy-based material genomes to better design future-oriented engineering materials.