Structure–Performance Relationship of Low-k Polybenzoxazine Based on Molecular Simulation

Low dielectric constant (low-k) polymers play a crucial role in electronic communications by improving the signal transmission speed and reducing the signal loss. In this study, five siloxane-containing benzoxazines were designed and synthesized. The effect of different substituents on the benzene ring on the ring-opening curing of benzoxazine monomers was studied by nonisothermal differential scanning calorimetry and density functional theory. The corresponding polybenzoxazine models constructed using molecular simulation were employed to calculate the glass transition temperature and dielectric constant. Among them, PP-aptmds with tert-butyl substituted group on the benzene ring exhibited the best dielectric properties, with a dielectric constant of 2.44 and a dielectric loss of 0.0053 at 10 GHz. In addition, the relationship between the structure and dielectric properties of polybenzoxazines was analyzed based on dipole moment, polarizability, number density, and the highest occupied molecular orbital–lowest unoccupied molecular orbital gap. This method is expected to provide theoretical guidance for the design and development of low-k polybenzoxazines.