Steric repulsion between grafted side chains inhibits interpenetration of bottlebrushes, transforming them into flexible filaments.

We study the impact of arm architecture of polymers with a single branch point on their structure in solvents. Many physical properties of polymer liquids strongly dependent on the size and shape measures of individual macromolecules, which in turn are determined by their topology. Here, we use combination of analytical theory, based on path integration method, and molecular dynamics simulations to study structural properties of complex Gaussian polymers containing $$f^c$$f c linear branches and $$f^r$$f r closed loops grafted to the central core. We determine size measures such as the gyration radius $$R_g$$R g and the hydrodynamic radii $$R_H$$R H , and obtain the estimates for the size ratio $$R_g /R_H$$R g / R H with its dependence on the functionality $$f=f^c+f^r$$f = f c + f r of grafted polymers. In particular, we obtain the quantitative estimate of the degree of compactification of these polymers with increasing number of closed loops $$f^r$$f r as compared to linear or star-shape molecules of the same total molecular weight. Numerical simulations corroborate theoretical prediction that $$R_g /R_H$$R g / R H decreases towards unity with increasing f. These findings provide qualitative description of polymers with complex architecture in $$\theta $$θ solvents.

Friction between ring polymer brush bilayers sliding past each other is studied using extensive coarse-grained molecular dynamics simulations and scaling arguments, and the results are compared to the friction between bilayers of linear polymer brushes.

Concentration-dependent properties of bottlebrush polymers in solutions demonstrate a sequence of decays facilitated by their hierarchical structure.

Abnormal cell nuclear shapes are hallmarks of diseases, including progeria, muscular dystrophy, and many cancers. Experiments have shown that disruption of heterochromatin and increases in euchromatin lead to nuclear deformations, such as blebs and ruptures. However, the physical mechanisms through which chromatin governs nuclear shape are poorly understood. To investigate how heterochromatin and euchromatin might govern nuclear morphology, we studied chromatin microphase separation in a composite coarse-grained polymer and elastic shell simulation model. By varying chromatin density, heterochromatin composition, and heterochromatin-lamina interactions, we show how the chromatin phase organization may perturb nuclear shape. Increasing chromatin density stabilizes the lamina against large fluctuations. However, increasing heterochromatin levels or heterochromatin-lamina interactions enhances nuclear shape fluctuations by a "wetting"-like interaction. In contrast, fluctuations are insensitive to heterochromatin's internal structure. Our simulations suggest that peripheral heterochromatin accumulation could perturb nuclear morphology, while nuclear shape stabilization likely occurs through mechanisms other than chromatin microphase organization.