DOI:10.5488/CMP.20.13802 arXiv:1703.10401
Title:
Shape characteristics of the aggregates formed by amphiphilic stars in water: dissipative particle dynamics study
Author(s):
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O.Y. Kalyuzhnyi
(Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine; Doctoral College for the Statistical Physics of Complex Systems, Leipzig-Lorraine-Lviv-Coventry
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J.M. Ilnytskyi
(Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine; Doctoral College for the Statistical Physics of Complex Systems, Leipzig-Lorraine-Lviv-Coventry
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C. von Ferber
(Applied Mathematics Research Centre, Coventry University, Coventry, CV1 5FB, United Kingdom; Heinrich-Heine Universität Düsseldorf, D-40225 Düsseldorf, Germany;
Doctoral College for the Statistical Physics of Complex
Systems, Leipzig-Lorraine-Lviv-Coventry |
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 Na 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 Na. 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.
Key words:
star-like polymer, amphiphiles, micelle, vesicle, dissipative particle dynamics
PACS:
82.70.Uv, 78.67.Ve, 61.20.Ja
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