A theoretical framework for investigating the role of stiffness heterogeneity in structure and dynamics of flexible polymer

Abstract

Heteropolymers are ubiquitous in both synthetic systems, such as block copolymers, and biological macromolecules, including proteins and nucleic acids. Beyond their chemical composition, these polymers often exhibit spatial variations in physical properties. For instance, in biopolymers such as chromatin, stiffness heterogeneity arises from inherent molecular features as well as extensile or contractile active forces. In this letter, we develop a theoretical framework that extends the physics of flexible polymers, a widely used tool to describe biopolymer dynamics, to incorporate spatially varying stiffness. Using this approach, we specifically analyze the structure and dynamics of flexible heteropolymers with periodic stepwise stiffness profiles. We find that stiffness heterogeneity leads to qualitative deviations in dynamical observables such as mean squared displacement while also increasing structural anisotropy. Altogether, this framework provides a platform to interpret stiffness heterogeneity from experimental data especially for biopolymers as well as to design heteropolymers with tailored structural and dynamic properties.