Understanding Depletion Forces beyond Entropy
نویسندگان
چکیده
The effective interaction energy of a colloidal sphere in a suspension containing small amounts of nonionic polymers and a flat glass surface has been measured and calculated using total internal reflection microscopy and a novel approach within density functional theory, respectively. Quantitative agreement between experiment and theory demonstrates that the resulting repulsive part of the depletion forces cannot be interpreted entirely in terms of entropic arguments but that particularly at small distances (&100 nm) attractive dispersion forces have to be taken into account.
منابع مشابه
Understanding shape entropy through local dense packing.
Entropy drives the phase behavior of colloids ranging from dense suspensions of hard spheres or rods to dilute suspensions of hard spheres and depletants. Entropic ordering of anisotropic shapes into complex crystals, liquid crystals, and even quasicrystals was demonstrated recently in computer simulations and experiments. The ordering of shapes appears to arise from the emergence of directiona...
متن کاملInfluence of inclined Lorentz forces on entropy generation analysis for viscoelastic fluid over a stretching sheet with nonlinear thermal radiation and heat source/sink
In the present study, an analytical investigation on the entropy generation examination for viscoelastic fluid flow involving inclined magnetic field and non-linear thermal radiation aspects with the heat source and sink over a stretching sheet has been done. The boundary layer governing partial differential equations were converted in terms of appropriate similarity transformations to non-line...
متن کاملFact-Checking Ziegler's Maximum Entropy Production Principle beyond the Linear Regime and towards Steady States
We challenge claims that the principle of maximum entropy production produces physical phenomenological relations between conjugate currents and forces, even beyond the linear regime, and that currents in networks arrange themselves to maximize entropy production as the system approaches the steady state. In particular: (1) we show that Ziegler’s principle of thermodynamic orthogonality leads t...
متن کاملEntropic Forces in Geophysical Fluid Dynamics
Theories and numerical models of atmospheres and oceans are based on classical mechanics with added parameterizations to represent subgrid variability. Reformulated in terms of derivatives of information entropy with respect to large scale configurations, we find systematic forces very different from those usually assumed. Two examples are given. We see that entropic forcing by ocean eddies sys...
متن کاملFundamental understanding of goaf gas displacement in longwall goaf
Fundamental understanding of the goaf gas distribution in a gassy coal mine is necessary for developing effective goaf gas drainage strategies in the longwall coal mine. The goaf gas was subjected to the surface and body forces that were classified depending upon whether they acted on the surface area or the volume of the gas element. Of these forces, the body forces were more predominant in di...
متن کامل