Effect of Confinement Geometry on Semiflexible Linear Polymer Conformations: A Computational and Simulation Study

ABSTRACT Based on a coarse‐grained model, we simulated semiflexible linear polymer chain melts confined within a fixed rigid ellipsoidal cavity using molecular dynamics. Results show a distinct chain centroid number density peak near the wall. Using the distance from this peak to the wall, we defined a wall‐adjacent layer and found that its relative thickness increases with increasing flattening factor of the ellipsoid. Properties in this layer depend on polar angle, driven by competition between variations in surface curvature, chain bending energy penalty, and orientational ordering of chains. Specifically: (i) At the equatorial plane, monomer number density is elevated, and the bending energy penalty is substantial. Meanwhile, the entropy increase dominates the maximization of parallel packing to avoid the occurrence of unacceptable bending energy penalties, leading to a higher‐ordered parallel alignment of chains. (ii) Near the poles, chains demonstrate lower monomer number density, reduced bending energy penalty, and lower orientational order. The greater the oblateness of the ellipsoid, the more pronounced the polar effects. In the design of nanoreactors, this feature can be utilized to place stimuli‐responsive polymers (e.g., pH‐sensitive PAA) at the poles, which provides deformation space for conformational collapse and extension of polymer chains, thereby enabling rapid channel switching.