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Titolo:
Interfacial properties of model colloid-polymer mixtures
Autore:
Evans, R; Brader, JM; Roth, R; Dijkstra, M; Schmidt, M; Lowen, H;
Indirizzi:
Univ Bristol, HH Wills Phys Lab, Bristol BS8 1TL, Avon, England Univ Bristol Bristol Avon England BS8 1TL Bristol BS8 1TL, Avon, England Univ Utrecht, Debye Inst, NL-3584 CC Utrecht, Netherlands Univ Utrecht Utrecht Netherlands NL-3584 CC 3584 CC Utrecht, Netherlands Univ Dusseldorf, Inst Theoret Phys 2, D-40225 Dusseldorf, Germany Univ Dusseldorf Dusseldorf Germany D-40225 , D-40225 Dusseldorf, Germany
Titolo Testata:
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
fascicolo: 1782, volume: 359, anno: 2001,
pagine: 961 - 975
SICI:
1364-503X(20010515)359:1782<961:IPOMCM>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
HARD-SPHERE MIXTURES; PHASE-BEHAVIOR; ASYMPTOTIC DECAY; TRANSITIONS; SUSPENSIONS; LATEX;
Keywords:
colloid-polymer mixtures; depletion forces; effective Hamiltonians; wetting and layering transitions; surface tension; adsorption;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
23
Recensione:
Indirizzi per estratti:
Indirizzo: Evans, R Univ Bristol, HH Wills Phys Lab, Tyndall Ave, Bristol BS8 1TL, Avon, England Univ Bristol Tyndall Ave Bristol Avon England BS8 1TL on, England
Citazione:
R. Evans et al., "Interfacial properties of model colloid-polymer mixtures", PHI T ROY A, 359(1782), 2001, pp. 961-975

Abstract

We summarize the main results of our recent investigations of the interfacial properties of the simplest model of a colloid-polymer mixture, namely that introduced by Asakura & Oosawa and by Vrij, in which colloid-colloid and colloid-polymer interactions are treated as hard sphere-like, while the polymer-polymer interaction is ideal (perfectly interpenetrating coils). In spite of its simplicity, we find that the model exhibits rich interfacial behaviour which depends on the size ratio q equivalent to sigma (p)/sigma (c), where sigma (p) and sigma (c) denote the diameters of polymer and colloid, respectively. For highly asymmetric mixtures, q < 0.1547, an explicit and exact mapping of the binary mixture to an effective one-component Hamiltonian for the colloids allows one to perform computer simulations for inhomogeneous mixtures. We investigate a mixture with q = 0.1 and find that smallamounts of polymer give rise to strong depletion effects at a hard wall. The colloid density at contact with the wall is several times greater than that for pure hard spheres at a hard wall. However, for states removed from the bulk fluid-solid coexistence curve we find no evidence of wall-induced crystallization. In order to treat less asymmetric cases, where stable fluid-fluid demixing occurs in bulk, we have designed a density functional theory specifically for this model mixture. For q = 0.6 we find a first order wetting transition from partial to complete wetting by the colloid-rich phase at the hard-wall-colloid-poor interface as the packing fraction eta (r)(p) of polymer in the reservoir is decreased. At a slightly higher value of eta (r)(p), there is a novel single layering transition, characterized by a jump in the densities in the first two adsorbed layers, as the bulk colloidpacking fraction eta (c) is increased. The same density functional has been used to investigate the surface tension and colloid and polymer density profiles at the free interface between the demixed fluid phases.

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Documento generato il 25/11/20 alle ore 01:28:59