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Effect of Induced Self-Organization in Mixtures of Amphiphilic Macromolecules with Different Stiffness

Glagolev, Mikhail K., Vasilevskaya, Valentina V., Khokhlov, Alexei R.
Macromolecules 2015 v.48 no.11 pp. 3767-3774
hydrophilicity, hydrophobicity, molecular dynamics, polymers, solvents
Effect of induced self-organization and liquid-crystal ordering of disordered globules of flexible amphiphilic macromolecules was observed in 1:1 mixtures of flexible and stiff helical macromolecules of similar composition. Mixtures of fully flexible macromolecules and helical macromolecules with various stiffness of backbone were studied by means of molecular dynamics simulation. It was found that if the local helical structure of the backbone is stiff enough to induce formation of aggregates with helical packing of backbone in poor solvent, the helical and flexible macromolecules segregate upon worsening of solvent quality. In dilute solution the flexible macromolecules are compacted into single globules with hydrophobic core and hydrophilic shell. The macromolecules with stiff local helical structure form aggregates of few helical chains. The aggregates have a core composed by intertwined backbones which is surrounded by a hydrophilic outer shell consisting of side groups. Increase of volume fraction of polymer results in formation of long wire-like aggregates of helical macromolecules. The aggregates exhibit liquid-crystalline ordering and facilitate formation of elongated aggregates from disordered globules of flexible macromolecules with about the same cross-section as aggregates of helical macromolecules.