Effect of Electrostatics on the Structural and Dynamic Properties of Polyzwitterions

Polyzwitterions (PZs) are a unique class of polyampholytes with each repeating unit carrying a pair of covalently bonded positively and negatively charged group. The dipole–dipole interactions and the chain connectivity and architecture are considered to govern the local structure and segmental relaxation dynamics in polyzwitterion melts and glasses. In this work, we use coarse-grained molecular dynamics (CGMD) simulations to model PZs with explicit charges and investigate how electrostatic interactions and chain architecture affect the static partial structure factor, glass transition temperature, segmental relaxation, fragility, and frequency-dependent dielectric response. By comparing PZs to linear chains and flexible polymers with uncharged side groups, we demonstrate that chain architecture primarily determines the local packing, whereas electrostatic interactions dominate the dynamics, which manifest in the elevated glass transition temperature values, slower segmental and dipolar relaxation, and reduced fragility. In addition, our analysis also connects the underlying molecular characteristics to the macroscopic dielectric response, thus establishing a direct connection between microscopic features and experimentally measurable properties. The results offer guidance for interpreting broadband dielectric spectroscopy data and for designing next-generation ion-containing polymers with tailored dynamic properties.