Cooperative Adsorption of Polymer Chains on Solid Surfaces

The adsorption of polymer chains in different phases onto the surfaces is a ubiquitous phenomenon in natural systems, composite materials, and thin-film devices. It is the key to triggering bioreactions, improving the storability of materials, improving the material's mechanical properties, and so on. Polymer chains generally form interfacial layers where their aggregation states and thermal molecular motions differ from the bulk. In this study, we visualize well-defined double-stranded DNAs (dsDNAs) with three lengths using atomic force microscopy and molecular dynamics simulations to clarify the adsorption mechanism of polymer chains onto solid surfaces. Initially, short and long dsDNAs show individual and cooperative adsorption, respectively. Cooperative adsorption involves the intertwining of multiple chains. The dependence of adsorption on the chain affects the formation of the interfacial layer, realizing different mechanical properties of DNA/filler bulk composites. These findings will contribute to developing light and durable polymer composites and films for various industrial, biomedical, and environmental applications.