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M Napiórkowski

Publications and source records attributed to M Napiórkowski.

14 recordsLinked to original sources
PubMed2006

Point tension in adsorption at a chemically inhomogeneous substrate in two dimensions.

We study adsorption of liquid at a one-dimensional substrate composed of a single chemical inhomogeneity of width 2L placed on an otherwise homogeneous, planar, solid surface. The excess point free energy eta(L,T) associated with the adsorbed layer's inhomogeneity induced by the substrate's chemical structure is calculated within exact continuum transfer-matrix approach. It is shown that the way eta(L,T) varies with L depends sensitively on the temperature regime. It exhibits logarithmic divergence as a function of L in the limit L-->infinity for temperatures such that the chemical inhomogeneity is completely wetted by the liquid. In the opposite case eta(L,T) converges for large L to 2eta0, where eta0 is the corresponding point tension, and the dominant L-dependent correction to 2eta0 decays exponentially. The interaction between the liquid layer inhomogeneities at -L and L for the two temperature regimes is discussed and compared to earlier mean-field theory predictions.

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PubMed2005

Influence of inhomogeneous substrate curvature on line tension.

Line tension accompanying equilibrium liquidlike films adsorbed at cylinder-shaped substrates equipped with chemical heterogeneities is studied within an effective interfacial Hamiltonian approach. The heterogeneity has the form of a stripe of width 2L. The leading corrections to the line tension coefficient due to nonzero substrate curvature R(-1) are derived. Their character is shown to be sensitively dependent on the system's temperature regime. For temperatures low enough that both the homogeneous components of the heterogeneous substrate remain nonwetted, the leading curvature correction is found to be proportional to R(-1). For temperatures such that one of the solid surface components is wetted by the fluid, one obtains corrections to the line tension of the order of either (L/R) ln R or R(-1/2) depending on the relative values of R and the heterogeneity width 2L . For temperatures exceeding wetting temperatures of both the substrate components, the line tension is shown to decay to 0 in the limit R --> infinity according to the power law eta approximately R(-1/2).

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PubMed2002

Adsorption in a nonsymmetric wedge.

We study adsorption in a nonsymmetric wedge consisting of two chemically different, homogeneous planes. First, we macroscopically analyze configurations of nonvolatile liquid drop placed in such a two-dimensional wedge and construct phase diagrams describing transitions between various interfacial shapes. Then adsorption is discussed within MFT based on the effective interfacial Hamiltonian. Two regimes for the system parameters--the wedge opening angle (2phi) and the critical wetting temperatures of each of the planar walls (T(W1) and T(W2), T(W2)<T(W1))--are identified. In one of them we find the critical filling transition at T(F)<T(W2) and the corresponding critical indices which are equal to those found for a symmetric wedge. In the other regime (T(W2)<T(F)<T(W1)) interfacial configurations are similar to those exhibited in the case of a planar substrate consisting of two chemically different parts. In the borderline case (T(F)=T(W2)), the interface profile above the wall with the lower wetting temperature becomes parallel to it. The line tensions corresponding to T(F)<T(W2) and T(F)=T(W2) cases are evaluated and the critical exponents - different in each case - are identified. An effective one-dimensional Hamiltonian describing fluctuations along the wedge is constructed for the T(F)<T(W2) case.

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PubMed2001

Interfacial fluctuations near the critical filling transition.

We advance a method to describe the short-distance fluctuations of an interface spanning a wedge-shaped substrate near the critical filling transition. Two different length scales determined by the average distance of the interface from the substrate at the wedge center can be identified. On one length scale, the one-dimensional approximation of A. O. Parry, C. Rascon, and A. J. Wood [Phys. Rev. Lett. 85, 345 (2000)], which allows one to determine the interfacial critical exponents, is extracted from the full description. On the other scale, the short-distance fluctuations are analyzed by mean-field theory.

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PubMed1999

Filling transition for a wedge.

We study the formation and the shape of a liquid meniscus in a wedge with opening angle 2phi which is exposed to a vapor phase. By applying a suitable effective interface model, at liquid-vapor coexistence and at a temperature Tphi we find a filling transition at which the height of the meniscus becomes macroscopically large while the planar walls of the wedge far away from its center remain nonwet up to the wetting transition occurring at Tw>Tphi. Depending on the fluid and the substrate potential the filling transition can be either continuous or discontinuous. In the latter case it is accompanied by a prefilling line extending into the vapor phase of the bulk phase diagram and describing a transition from a small to a large, but finite, meniscus height. The filling and the prefilling transitions correspond to nonanalyticities in the surface and line contributions to the free energy of the fluid, respectively.

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