Dynamic self-assembly of block copolymers regulated by time-varying building block composition via reversible chemical reaction

Abstract

Dynamic self-assembly processes occurring out of thermodynamic equilibrium underlie many forms of adaptive and intelligent behaviors in natural systems. Because of the continuous input of energy, the dynamic self-assembly provides the opportunity for creating structures that are unattainable in equilibrium state. In this paper, we propose a strategy in the dynamic self-assembly of amphiphilic block copolymers regulated by reversible chemical reaction. By time-dependently tuning the reaction direction in the simulations, the amphiphilicity of building block keeps changing periodically. Relying on this dynamic process, we can obtain exotic self-assembled vesicle with surface pores which is otherwise metastable in an equilibrium state. The effects induced by the type of chemical reaction and the reaction period are discussed. Only at short reaction period in suitable reversible reaction, novel self-assembly structure emerges. It is attributed to the competition of reaction and diffusion in the dynamic process, by which the local component of building blocks alters a lot, leading to large local surface tension resulting in the formation of perforated vesicle. In order to predict the assembled structure in a dynamic process, we build up the relationship between component ratio P, the diffusion effect parameter P_diff and assembled structures. The dynamic self-assembly regulated by chemical reaction holds great promise as a rational strategy to realize exotic functional materials that are not easily obtained in equilibrium.