Shape characteristics of the aggregates formed by amphiphilic stars in water: dissipative particle dynamics study
arXiv:1703.10401 · doi:10.5488/CMP.20.13802
Abstract
We study the effect of the molecular architecture of amphiphilic star polymers on the shape of aggregates they form in water. Both solute and solvent are considered at a coarse-grained level by means of dissipative particle dynamics simulations. Four different molecular architectures are considered: the miktoarm star, two different diblock stars and a group of linear diblock copolymers, all of the same composition and molecular weight. Aggregation is started from a closely packed bunch of molecules immersed into water. In most cases, a single aggregate is observed as a result of equilibration, and its shape characteristics are studied depending on the aggregation number . Four types of aggregate shape are observed: spherical, rod-like and disc-like micelle and a spherical vesicle. We estimate "phase boundaries" between these shapes depending on the molecular architecture. Sharp transitions between aspherical micelle and a vesicle are found in most cases. The pretransition region shows large amplitude oscillations of the shape characteristics with the oscillation frequency strongly dependent on the molecular architecture.
10 pages, 7 figures