Understanding the self-polymerization mechanism of dopamine by molecular simulation and applying dopamine surface modification to improve the interfacial adhesion of polyimide fibers with epoxy resin matrix

The object of this paper is to interpret the self-polymerization mechanism of dopamine by molecular simulation and use dopamine polymerization to modify the surface properties of polyimide fibers for improving its interfacial adhesion strength with the epoxy resin matrix. Theoretically, the molecular simulation results of calculated energy band gaps and infrared spectrum of the intermediate products generated in the dopamine self-polymerization process confirmed that the spontaneity of self-polymerization of dopamine and the occurrence of intramolecular cyclization and intermolecular polymerization in the self-polymerization process of dopamine. Moreover, the interaction between polyimide and poly(dopamine) was simulated, and the calculated results showed that the interaction between them depended on hydrogen bonding and was verified by ultrasound treatment. Experimentally, the effect of dopamine treatment concentration on the surface properties of polyimide fibers was investigated. Obviously, after a relatively high dopamine concentration treatment, the surface roughness and surface energy of polyimide fibers were largely improved and the number of active groups on polyimide fibers surface were increased, which were altogether conducive to enhance the adhesion strength of polyimide fibers with the epoxy resin matrix.