Structural design and synthesis of naphthalene-containing phthalonitrile polymer with excellent processability and high temperature properties

Currently, there is limited literature on the introduction of naphthalene ring into phthalonitrile. In this study, we have successfully synthesized a novel phthalonitrile monomer (CPND) by incorporating a symmetrical rigid naphthalene ring structure, long flexible chains, and high-density cyano groups into the resin. The monomer is being cured with two different agents and procedures to investigate the impact of curing agent structure and ramp-up procedure on polymer properties. The structure of the monomer is being verified using nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR), and wide-angle X-ray diffraction (WAXD). Differential scanning calorimetry (DSC) results reveal that the monomer has a low melting point of 111°C, making it easily processable. After mixing with the curing agent in the appropriate proportion, it has a calculated processing window of 129–135°C. Thermogravimetric analysis (TGA) reveals that the polymers exhibit remarkable thermal stability, with all T_5% above 470°C under a nitrogen atmosphere. Additionally, the results obtained from dynamic mechanical analysis (DMA) indicate that the polymer, which is cured using APPH as a curing agent, displays favorable thermo-mechanical properties. The storage modulus of the polymers at room temperature is all higher than 3330 MPa, respectively. Moreover, the glass transition temperature is found to be higher than 400°C, signifying the excellent thermo-mechanical properties of the polymer.