Self-assembly of semiflexible homopolymers into helical bundles: a brownian dynamics simulation study

The controllable self-assembly of semiflexible homopolymers into regular bundles has received much attention because of its potential importance in various fields, such as the storage of elastic energy, the fabrication of nanostructures, and the formation of the cytoskeleton in living cells. In this article, using computer simulations, we investigate how semiflexible homopolymers anchored on a substrate self-organize into ordered structures, focusing on both the patterns formed and the dynamics of self-assembly. For the self-assembly pattern, four different patterns, including patterns with unclustered polymers, disordered semispherical clusters, highly ordered helical bundles, and parallel bundles, are observed from our simulations. The formation of stable bundles requires semiflexible homopolymers having a sufficient molecule length and intermediate bending stiffness, whereas the formation of the helical structures depends on the balance between the inter-homopolymer attraction and the bending stiffness of homopolymers. Furthermore, the bundle formation reinforces the bending stiffness, and the stiffness is further enhanced by the helical bundling. For the dynamic aspect, both hierarchical bundling and nonhierarchical bundling are observed from our simulations.