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

Abstract

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.