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

A novel autocatalytic phthalonitrile monomer [4,4 '-(((((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-nitro-phthalonitrile and bisphenol compound [4,4 '-(((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 '-diaminodiphenylether. The OPD monomer has a self-catalytic polymerizing reaction. OPD monomer has good processability, and the processing window was 130 degrees C. Moreover, OPD polymer [poly(OPD)] shows higher glass-transition temperature (345 degrees C). The 5% and 10% thermal decomposition temperatures of poly(OPD) and char yield at 800 degrees C are 407, 451 degrees 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.

Automated summary

A novel autocatalytic monomer, OPD, was obtained through nucleophilic substitution, which has good processability and high glass-transition temperature. By modifying OPD monomer with multi-functional fluorene-based benzoxazine monomers (MFFB), the properties of the polymer were further improved.