Thermal-mechanical fluctuations of fluid membranes in confined geometries: The case of soft confinement

Journal Article · Sat Feb 01 00:00:00 EST 1992 · Langmuir; (United States)

DOI:https://doi.org/10.1021/la00038a041· OSTI ID:5624742

Podgornik, R; Parsegian, V A ^[1]

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1. National Inst. of Health, Bethesda, MD (United States)

By definition, membrane or macromolecular assembly is an event of molecular confinement against the configurational entropy of a disordered state. Bilayer membranes under progressive confinement experience a continual damping of undulatory fluctuations, first interpreted as a steric force (Helfrich. Z. Naturforsch. 1978). This paper uses a new, diffusion-equation formalism based on the Feynman-type variational principle to describe how direct interbilayer forces - of hydration, electrostatic double layers, and van der Waals attraction - confine membrane fluctuations. We recover theoretical results to examine measured forces in multilamellar arrays showing that [open quotes]soft[close quotes] collisions, through long-range forces, create a mutual enhancement of both the direct forces and the undulatory steric interactions. Thus, there is yet another way to resolve the old, but false, dilemma to choose between steric and direct forces driving membrane assembly. One may develop a systematic connection between bilayer charge, hydration, and flexibility and the action of configurational entropic forces. The results make clear that one should measure forces between membranes or macromolecules in a way that allows them to express their native mechanical freedom. 15 refs., 3 figs.

• OSTI ID: 5624742
• Journal Information: Langmuir; (United States), Vol. 8:2; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
MEMBRANES
HYDRATION
MATHEMATICAL MODELS
DIFFUSION
ENTROPY
FREE ENERGY
POLYMERS
ENERGY
PHYSICAL PROPERTIES
SOLVATION
THERMODYNAMIC PROPERTIES
360606* - Other Materials- Physical Properties- (1992-)
400201 - Chemical & Physicochemical Properties
990200 - Mathematics & Computers