Non-uniform spontaneous surface curvature gives limited shape control in simulated single-polymer micelles

Abstract

Polymeric micelles are used in a variety of applications, with the micelle’s shape often playing an important role. Consequently, it is desirable to identify a simple set of control parameters having an easily understood effect on micelle shape. In a previous study, we showed that a model two-dimensional linear multiblock copolymer may be designed to exhibit a dimpled shape. Extending this study, this paper characterizes in greater detail how such a dimpled micelle’s shape can be controlled by adjusting the copolymer block lengths. Using basic physical principles governing amphiphilic polymer, we identify a few aspects of the multiblock composition that are expected to have a well-behaved effect on micelle shape. Starting from a reference micelle composition, itself already exhibiting a nonstandard shape having a moderately sized concave dimple, we alter these aspects of the multiblock composition and observe the response of two features of the micelle shape: the size of the dimple and the magnitude of shape fluctuations. We find the response of the shape is smooth and regular for small excursions from a base composition, but larger excursions gave rise to nonmonotonic effects on the shape, suggesting that sophisticated techniques may be required to aid in micelle design.