Stretching Response of a Polymer Chain with Deformable Bonds

The stretching response of polymer chains fundamentally determines the mechanical properties of polymer networks. In this Letter, we develop a statistical mechanics model that incorporates both bond stretching and bond angle deformation, enabling accurate predictions of chain behavior up to large forces. We further propose a semianalytical deformable freely rotating chain (dFRC) model, which represents the chain as a freely rotating chain with effective bond stretch and bond angle that depend on the chain stretch. Using physical parameters without fitting, both the statistical and dFRC models achieve excellent agreement with experimental data for carbon chains across all force regimes. Additionally, the dFRC model provides a direct estimate of the bond force, which is important to predict chain scission. By capturing key bond deformations while remaining computationally efficient, our work lays the foundation for future modeling of polymer network elasticity and failure. Published by the American Physical Society 2025