Synthesis and properties of a novel autocatalytic phthalonitrile monomer and its copolymerization with multi‐functional fluorene‐based benzoxazine monomers

Abstract

A novel autocatalytic phthalonitrile monomer [4,4 0 -(((((oxy-bis [4,1-phenylene]) bis (azanediyl)) bis (methylene)) bis (2-methoxy-4,1-phenylene)) bis (oxy)) diphthalonitrile, OPD] is obtained by nucleophilic substitution of 4-nitrophthalonitrile and bisphenol compound [4,4 0 -(((oxy bis [4,1-phenylene]) bis (azanylylidene)) bis (methanylylidene)) bis (2-methoxyphenol)]. Bisphenol compound is a reductant with secondary amine groups of Schiff base derived from the reaction of vanillin and 4,4 0 -diaminodiphenylether. The OPD monomer has a self-catalytic polymerizing reaction. OPD monomer has good processability, and the processing window was 130 C. Moreover, OPD polymer [poly(OPD)] shows higher glass-transition temperature (345 C). The 5% and 10% thermal decomposition temperatures of poly(OPD) and char yield at 800 C are 407, 451 C, and 69%, respectively. To further improve the properties of poly(OPD), the OPD monomer was modified by multi-functional fluorene-based benzoxazine monomers (MFFB) due to their excellent reaction activities. The results showed that OPD/MFFB systems had high reaction activities. The similar thermal stabilities between OPD and MFFB can give stable and excellent thermal stability to the poly(OPD/MFFB). Compared with poly(OPD), the T g values of poly(OPD/MFFB) were significantly increased, and their stiffness values were reduced. The tensile, flexural, and impact properties for poly(OPD/MFFB) were improved significantly.

Preparation of phthalonitrile resins containing siloxane linkages with improved processability

“…Considering the excellent mechanical properties and thermal stability of phthalonitrile, it is usually blended or copolymerized with epoxy resin, benzoxazine resin, or cyanate ester resin to prepare a series of resins with high performance and excellent thermal stability. [28][29][30][31][32] Additionally, widening the processing window of phthalonitrile resin by blending different types of phthalonitrile monomers to prepare phthalonitrile alloy resins has been demonstrated to be feasible. Domingez and Keller blended a low melting point phthalonitrile monomer containing ether bonds (40°C) with high melting point biphenyl monomers (4,4'-bis(3,4-dicyanophenoxy) biphenyl (BPh)) for the first time, 33 which widened the processing window of BPh by 30°C and the prepared resin showed excellent thermal stability.…”