Hydrodynamic influence on the fractal morphology of the linoleic acid adsorbed layer at the mercury/electrolyte interface

Risović, Dubravko; Gašparović, Blaženka; Ćosović, Božena

doi:10.1016/s0927-7757(03)00150-x

Cited by 18 publications

(4 citation statements)

References 48 publications

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“…41,42 On the other hand, the monolayer structures are often fractal: characterized with fractal dimension D lower than the corresponding Euclidean dimension d of the embedding space, i.e., D ≤ 2. 49 Also, fractal concepts proved to be an indispensable tool in the description of continuous stochastic processes and modeling of complex phenomena. [43][44][45] Moreover, fractal dimension is related to basic material properties.…”

Section: Theorymentioning

confidence: 99%

Application of Brewster angle microscopy and fractal analysis in investigations of compressibility of Langmuir monolayers

Risović

Frka²,

Kozarac³

2011

The Journal of Chemical Physics

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The aim of this study was to investigate the connection between the lipid/amphiphile monolayer structure at the interface and its macroscopic/rheological properties, in particular, to establish the link between the fractality of the monolayer structure and its compressibility modulus. To that purpose we have used fractal analysis of images obtained by Brewster angle microscopy to infer the fractal dimension of the monolayer structure and relate its change to the corresponding changes in compressibility derived from a simultaneously measured π-A isotherm. The results of the study confirmed the starting assumption based on theoretical considerations that the fractal dimension of an amphiphilic monolayer and its compressibility should be correlated. We have shown that there exists a strong correlation between the fractal dimension and the corresponding compressibility modulus of different amphiphilic materials. Thus, confirming the link between the short ordered structure on the molecular level and the macroscopic property-compressibility of the monolayer. The established correlation between the fractal dynamics and compressibility modulus of the monolayer enabled identification of onset of percolation-a second-order phase transition that is otherwise not easy and unambiguously detectable. We have found that the signature of percolation in a monolayer, regardless of its composition, is the occurrence of a sharp increase (a jump) of compressibility modulus (at macroscopic level) at the characteristic value of the corresponding fractal dimension D = 1.89. This is the result of the abrupt establishment of a connected structure on the molecular level, consequently involving a change in the elastic properties of the monolayer on a macroscopic scale. The results of this investigation provide means for unambiguous identification of the onset of percolation in the Langmuir layer and should facilitate a more efficient application of the percolation theory in further study of processes and structures at the interface during the monolayer compression.

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Section: Theorymentioning

confidence: 99%

Application of Brewster angle microscopy and fractal analysis in investigations of compressibility of Langmuir monolayers

Risović

Frka²,

Kozarac³

2011

The Journal of Chemical Physics

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“…Different experimental conditions were included in this study because it has been found that morphology of fractal adsorbed layer is a result of growth mechanism which is influenced by hydrodynamics (stirring or diffusion) and by the structure of the solution (monomers, dimers). 33 The fractal dimension (D) was determined from the size scaling of the hanging mercury drop electrode. 16 In this method D is related to the capacitive current, that is proportional to the electrode surface area (A = 4r 2 ), described by the electrode radius r, through relation ic A r D .…”

Section: Methodsmentioning

confidence: 99%

Impact of Fractal Geometry on Permittivity and Related Quantities

2002

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A new physical model of relative permittivity and derived quantities of fractal structures, contrary to the current concept, predicts their dependence on the fractal dimension (D) and on the extent (R) of the considered structure. The scaling of considered quantities predicted by our theory is  R D-d , where d is dimension of Euclidean space. Hence, fractality, a feature often found in physical, chemical and biological systems, influences also basic properties of such systems that, so far, were believed to be material and not structure related. The theory has been experimentally verified by electrochemical measurements of capacitance of adsorbed layers of nonionic surfactant Triton-X-100 and linoleic acid that have fractal structure. The experimental results, substantiating theoretical predictions, are presented and the influence of relevant parameters is discussed. IntroductionThe dielectric features of material, relative permittivity, susceptibility, polarizibility and related properties such as capacitance play a significant role in various chemical, physical and biological systems, and on scales ranging from microscopic to macroscopic. Among other things capacitance is link to the knowledge of the fluctuations of several physical quantities, e.g. voltage and electromagnetic field fluctuations, 1-6 dipole moment, 5-7 pH and charge, 8 and also to polarizibility and dielectric dispersion of colloidal and polyelectrolite systems [5][6][7] . Hence, it is crucial for understanding of biological systems that include ionic channels and cell membranes, [9][10][11] but also other systems such as adsorbed and spread films [12][13][14] . On the other hand it has been shown that many of these systems are fractal structures or exhibit fractal behavior, 15 and can be described with effective fractal dimension D. Therefore it was worthwhile to examine the possible influence of fractal geometry on fundamental and derived electric properties. In that context we examine the relative permittivity and specific capacitance of fractal structures and their dependence on geometrical features.The notion of these quantities in classical (non-fractal) system implies that they are constant and characteristics of the material of the considered system be it physical, chemical or biological.Starting from considerations of fundamental material properties we have developed a general theoretical model that predicts dependence of relative permittivity and consequently Cs of fractal structures (e.g. adsorbed layer, molecular or particle aggregates, porous material etc.) on structure size and fractal dimension. These theoretical predictions have been experimentally verified by electrochemical measurements of capacitance of adsorbed layers possessing fractal structure, in 3 conjunction with recently introduced method for determination of fractal dimension of such layers 16 . This specific testbed was chosen because structural and dynamic properties of adsorbed molecular films are of both fundamental and applied interest in diverse areas. These ...

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“…In particular it has been shown that adsorbed lipid layers are fractal structures 35 whose fractal dimension is related to the dominant mechanism responsible for their growth. 36 Furthermore, fractal dimension provides insight into the lattice structure and in plane molecular organization of Langmuir monolayer of amphiphilic material. 37 Thus, in this context, we have conducted fractal analysis of gray-scale and binarized (black and white) AFM images of supported lipid layers.…”

Section: Fractal and Lacunarity Analysismentioning

confidence: 99%