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Anisotropy in the dimensional and elastic parameters of confined macromolecules
Author(s) -
Cifra Peter,
Bleha Tomáš
Publication year - 1999
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/(sici)1521-3919(19991101)8:6<603::aid-mats603>3.0.co;2-k
Subject(s) - perpendicular , anisotropy , materials science , condensed matter physics , displacement (psychology) , ellipsoid , elastic energy , orientation (vector space) , macromolecule , molecular physics , geometry , physics , chemistry , optics , thermodynamics , mathematics , psychology , biochemistry , astronomy , psychotherapist
Using lattice simulations the effect of confinement on the size, orientation and elastic properties of athermal chains was investigated. For chains confined in a slit or in a “cylinder” with square profile a minimum was observed in the dependence of the mean‐square end‐to‐end distance 〈 R 2 〉 on the plate distance D . However, the components of the mean chain dimensions perpendicular and parallel to the walls, 〈 R 2 ⟂ 〉 and 〈 R 2 ∥ 〉, steadily diverge with reduction of the pore size. In a slit the distribution functions of the chain vector perpendicular and parallel to the plates, W 〈 R 2 ⟂ 〉 and W 〈 R 2 ∥ 〉, respectively, were computed. The marked difference between these distribution functions is interpreted as a sign of enhanced alignment of chains of the shape of elongated ellipsoids along the pore walls. A major part of the free energy of confinement Δ A cf stems from this mechanism of pore‐induced macromolecular orientation. A striking anisotropy was observed in the elastic free energies A el ⟂ and A el ∥ of chains deformed in the direction perpendicular and parallel to the walls and in the corresponding force‐displacement functions. Finally, the relation between the elastic free energy A el and the free energy of confinement Δ A cf and between the forces f and f solv derived thereof is analysed.