Diagram of State of Stiff Amphiphilic Macromolecules

Abstract

Summary: We studied coil‐globule transitions in stiff‐chain amphiphilic macromolecules via computer modeling and constructed phase diagrams for such molecules in terms of solvent quality and persistence length. We showed that the shape of the phase diagram essentially depends on the macromolecule degree of polymerization. Relatively short amphiphilic molecules always form a spherical globule in a poor solvent, and the coil‐globule transition includes one or two intermediate conformations, depending on the chain's stiffness. These are a disk‐like globule in case of high enough Kuhn segment length, and a pearl necklace‐like structure of spherical micelles and a disk‐like globule in case of relatively flexible chains. The phase diagram of a long stiff amphiphilic chain was found to be more complex still. Thus three specific regions can be distinguished in the poor solvent region, depending on the chain stiffness. These correspond to a cylindrical globule without any specific backbone ordering, a cylindrical globule containing blobs with collagen‐like ordering of the chain, and co‐existence of collagen‐like and toroidal globules. In the intermediate transition region in this case, apart from the pearl necklace‐like conformations with spherical micelles, necklace conformations can be also observed where the polymeric chain has collagen‐like ordering within each bead.

Self-Organization in Solutions of Stiff-Chain Amphiphilic Macromolecules

“…To decrease these losses, homopolymer stiff-chain macromolecules form not spherical globules but globules of complex toroidal or rod-like form. − The amphiphilic stiff-chain macromolecules while collapsing are obliged form structures which have both minimal bend energy and “core-shell” organization. Our calculations show that depending on stiffness parameters amphiphilic macromolecules form cylindrical globules with a blob-like chain organization, collagen-like, and toroidal structures. − Hydrophobic groups in such structures occupy the inner parts, and hydrophilic ones are arranged at the surface. The total bending stress of the chain in this case is rather high because of the high stiffness of the macromolecule.…”

“…Our calculations show that depending on stiffness parameters amphiphilic macromolecules form cylindrical globules with a blob-like chain organization, collagen-like, and toroidal structures. [18][19][20] Hydrophobic groups in such structures occupy the inner parts, and hydrophilic ones are arranged at the surface. The total bending stress of the chain in this case is rather high because of the high stiffness of the macromolecule.…”

“…The conformational properties of macromolecules − and properties of their concentrated solutions , depend essentially on the polymeric chain stiffness. The collapse of stiff macromolecules is accompanied not only by a great reduction of the entropy of the monomeric units, but also by essential energy losses due to the bends in the polymeric chain.…”

Self-organization of amphiphilic polymers

“…One of the possible extensions of the HP model is the model introduced in Refs. [15][16][17][18][19][20] (cf. Fig.…”

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

“…Self-organization in concentrated solutions of macromolecules with hydrophobic backbone and hydrophilic side groups was investigated by means of molecular dynamics simulation. − The papers − study macromolecules with amphiphilic monomer units containing both hydrophobic and hydrophilic groups. The duality of the monomer units results in their simultaneous affinity and incompatibility with both polar and organic solvents.…”