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A novel polyarylene ether nitrile terminated with phthalonitrile (PEN-t-Ph) was synthesized by a simple solution polycondensation of biphenyl and hydroquinone with 2,6-dichlorobenzonitrile, followed by termination with 4-nitrophthalonitrile. The PENt-Ph/1,3,5-Tri-(3,4-dicyanophenoxy) benzene (TPh) system was prepared by cure treatment. The phthalonitrile on PEN-t-Ph were thermally crosslinked with TPh in the presence of diamino diphenyl sulfone through cure treatment up to 280-340 C, which led to the transformation from thermoplastic polymers to thermosetting polymers. This is because the phthalonitrile on the PEN-t-Ph can react with TPh by forming phthalocyanine ring. The glass transition temperatures of the PEN-t-Ph/TPh system increased from 152.4 C to 194.7 C, and the initial decomposition temperature (ranging from 475.3 C to 544.0 C) increased by 68 C after thermal curing. Therefore, their thermal properties can be greatly enhanced by crosslinking.

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Abstract:In this report, flexible cross-linked polyarylene ether nitrile/functionalized barium titanate(CPEN/F-BaTiO 3 ) dielectrics films with high permittivitywere prepared and characterized. The effects of both the F-BaTiO 3 and matrix curing on the mechanical, thermal and dielectric properties of the CPEN/F-BaTiO 3 dielectric films were investigated in detail. Compared to pristine BaTiO 3 , the surface modified BaTiO 3 particles effectively improved their dispersibility and interfacial adhesion in the polymer matrix. Moreover, the introduction of F-BaTiO 3 particles enhanced dielectric properties of the composites, with a relatively high permittivity of 15.2 and a quite low loss tangent of 0.022 (1 kHz) when particle contents of 40 wt % were utilized. In addition, the cyano (-CN) groups of functional layer also can serve as potential sites for cross-linking with polyarylene ether nitrile terminated phthalonitrile (PEN-Ph) matrix and make it transform from thermoplastic to thermosetting. Comparing with the pure PEN-ph film, the latter results indicated that the formation of cross-linked network in the polymer-based system resulted in increased tensile strength by~67%, improved glass transition temperature (T g ) by~190 • C. More importantly, the CPEN/F-BaTiO 3 composite films filled with 30 wt % F-BaTiO 3 particles showed greater energy density by nearly 190% when compared to pure CPEN film. These findings enable broader applications of PEN-based composites in high-performance electronics and energy storage devices materials used at high temperature.