Cell-sized confinements alter molecular diffusion in concentrated polymer solutions due to length-dependent wetting of polymers

• Published in: arXiv.org 2023-03
• Main Authors: Kanakubo, Yuki, Watanabe, Chiho, Yamamoto, Johtaro, Yanagisawa, Naoya, Nikoubashman, Arash, Yanagisawa, Miho
• Format: Article
• Language: English
• Subjects: Confinement; Droplets; Heterogeneity; Macromolecules; Molecular diffusion; Phase separation; Polymer blends; Polymers; Wettability; Wetting
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2303.02818

Living cells are characterized by the micrometric confinement of various macromolecules at high concentrations. Using droplets containing binary polymer blends as artificial cells, we previously showed that cell-sized confinement causes phase separation of the binary polymer solutions because of the length-dependent wetting of the polymers. Here we demonstrate that the wetting-induced heterogeneity of polymers also emerges in single-component polymer solutions. The resulting heterogeneity leads to a slower transport of small molecules at the center of cell-sized droplets than that in bulk solutions. This heterogeneous distribution is observed when longer polymers with lower wettability are localized at the droplet center. Molecular simulations support this wetting-induced heterogeneous distribution by polymer length. Our results suggest that cell-sized confinement functions as a structural regulator for polydisperse polymer solutions that specifically manipulate the diffusion of molecules, particularly those with sizes close to the correlation length of the polymer chains.