Abstract.
Stability of dense globular structures formed by amphiphilic copolymers consisting of hydrophobic (insoluble) units and a small fraction of single polar (soluble) monomer units is considered in the mean-field approximation for different types of unit distributions along the chain. Polar (P) units are located in a relatively thin surface layer due to their strong repulsion from hydrophobic (H) monomer units. We compared globules formed by different copolymer sequences with the same gross numbers of P- and H-units: regular HP-sequences (P-units separated by equal H-blocks), random copolymers (uncorrelated positions of P-units, i.e. Flory distribution of H-block lengths), proteinlike (PL) sequences (designed sequences involving both long H-blocks dominating by total mass, and short blocks dominating by number). We showed that PL-globules are more stable (lower free energy) and are characterized by a higher temperature of the coil-to-globule transition when compared with the other sequences mentioned above. We also considered HP-H-copolymers consisting of one long and many short hydrophobic blocks; we showed that it is these sequences that yield the dense globules corresponding to the lowest free energy.
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Received: 3 July 2003, Published online: 11 November 2003
PACS:
61.25.Hq Macromolecular and polymer solutions; polymer melts; swelling
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Govorun, E.N., Khokhlov, A.R. & Semenov, A.N. Stability of dense hydrophobic-polar copolymer globules: Regular, random and designed sequences. Eur. Phys. J. E 12, 255–264 (2003). https://doi.org/10.1140/epje/i2003-10057-y
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DOI: https://doi.org/10.1140/epje/i2003-10057-y