Growth of Preformed 3D Nuclei in Langmuir Monolayers below Critical Supersaturation

Vollhardt, D.; Retter, U.

doi:10.1021/la980408y

Cited by 23 publications

(25 citation statements)

References 22 publications

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“…Besides monolayer fracture, also a thermodynamically driven expulsion of the interfacial molecules can take place. Examples hereof are the formation of a 3D solid phase [13], [14] or the (compression- 50 induced) dissolution of interfacial species into the sub-phase [13,15,16]. The occurrence of these processes makes the resistance of the layer against loss of its constituents an important aspect of its mechanical stability.…”

Section: Introductionmentioning

confidence: 99%

“…The mechanism in which 3D crystals nucleate and grow in a direction perpendicular to the interface [17] has been proposed by Xu et al [18] and Carry and Rideal [19], demonstrated by Lee and Liu [13] and modeled by Vollhardt et al [20]. Nucleation can only occur if the 55 surface pressure exceeds the equilibrium spreading pressure (ESP) [14,18]. Similar to the situation in bulk liquids, it involves an activation energy which diminishes upon increasing the surface pressure [21].…”

Section: Introductionmentioning

confidence: 99%

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Stability of stearic acid monolayers on Artificial Sea Water

Brzozowska

Duits

Mugele

2012

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Please cite this article as: A.M. Brzozowska, M.H.G. Duits, F. Mugele, Stability of stearic acid monolayers on artificial sea water, Colloids and Surfaces A: Physicochemical and Engineering Aspects (2010), Abstract We studied the formation and stability of Stearic Acid (SA) based films on aqueous sub-phases via Langmuir trough and imaging ellipsometry experiments. The aqueous phase was based on Artificial Sea Water (ASW), a multicomponent salt solution with a total molarity of 0.53. The composition of this 10 solution was varied via dilution (1, 10 and 100 times) and adjustment of the pH (3, 7, 10). Also water sub-phases without the ASW salts were studied. Pressure-area isotherms of the SA monolayers show an enhanced stability of the film against fracture when the pH and/or the salt concentration of the subphase are increased. Isobars of SA measured below the pressure needed for film fracture, indicate distinct mechanisms for loss of material: 1) at low pH and salt concentration, three dimensional (3D) 15 structures are formed at the air/water interface via nucleation and growth, and 2) at high pH and salt concentration, diffusion-controlled dissolution of molecules in the sub-phase occurs. The formation of multilayer structures was corroborated with ellipsometry images of the films after Langmuir-Blodgett transfer. 20 Highlights 615  Langmuir films of stearic acid can be stabilized by increasing salt concentration and/or pH of the sub-phase. 3D solid phase is formed under acidic conditions.  Dissolution of molecules into sub-phase occurs only at high pH and low salt concentration. The influence of multicomponent salt is a combination of ionic strength and specific ion effects.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stability of stearic acid monolayers on Artificial Sea Water

Brzozowska

Duits

Mugele

2012

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…Vollhardt et al [58,[71][72][73] proposed the most widely used kinetic models of the collapse. These models were based on the kinetic dependences of the area of a monolayer relaxing to the stable state upon the collapse at a constant value of Π > Π lim .…”

Section: Metastability and Nonequilibrium Structures In Langmuir Monomentioning

confidence: 99%

Self-assembly of metastable langmuir monolayers on planar solid surfaces

Kalinina

2015

Colloid J

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For several decades, the method of Langmuir monolayers and the Langmuir-Blodgett technique have been unique instruments for the formation and study of ordered ultrathin films, the structure of which can be controlled at the molecular level. In spite of the wide variety of problems relevant to the study of such systems and the diversity of their functional characteristics, the methodological approach to their preparation has remained unchanged for almost a hundred years. When assembling Langmuir-Blodgett films, most of researchers try to achieve a perfect mono or multilayer system on a solid substrate, with exactly reproduced and preserved structural characteristics of a Langmuir monolayer organized on a liquid surface. Nevertheless, in addition to the traditional approach to the preparation of molecularly ordered Langmuir-Blodgett films, a new field of research associated with the self organization of Langmuir monolayers under the action of a moving solid substrate has been developed. The self assembly of this type is based on the use of nonequilib rium structural and phase transitions in metastable Langmuir monolayers brought in contact with a solid sur face. These transitions are accompanied by the spontaneous formation of periodically ordered structures ("patterns") with sizes of elements varying from a few tens of nanometers to several hundreds of microns. This review offers an opportunity for the readers to gain insight into different types of the solid modified self orga nization of Langmuir monolayers using the currently known examples of systems based on lipids, fatty acids, bases, and mixtures thereof. In this review, contemporary ideas are discussed concerning the metastability of Langmuir monolayers, formation mechanisms of periodic patterns in monolayers on solid surfaces, possible practical applications of such systems, and the perspectives of this new and interesting field of the physical chemistry of thin films.

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“…13 One reason for the appearance of the overshoot is because the nucleation process is, in any case, slower than the monolayer compression rate. 13 One reason for the appearance of the overshoot is because the nucleation process is, in any case, slower than the monolayer compression rate.…”

Section: Surface Pressurearea Isothermmentioning

confidence: 99%

Aggregation and structural study of the monolayers formed by an amphiphilic thiapentacarbocyanine

et al. 2015

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Exotic assemblies with unique photophysical features can be built based on organic dyes at the air-liquid interface. Langmuir monolayers of N,N 0 -dioctadecylthiapentacarbocyanine (OTCC) at air-water and airsolid interfaces have been studied. A single type of domain and presumably of one single aggregate type has been found by Brewster angle microscopy. Peanut-shaped domains with internal anisotropy have been observed. However, this structure leads to a complex absorption spectrum which shows 4 bands, two red-shifted (822 nm and 757 nm), and two blue-shifted (600 nm and 530 nm) with respect to the monomer band (665 nm). Our results confirm that all the absorption components are polarized in approximately the same direction. The absence of an emission spectrum indicates that this interfacial aggregate cannot be classified as a simple J-aggregate. Moreover, these bands cannot relate to Davydov splitting, given that all of them have the same polarization direction. We propose possible explanations based on a strong exciton-phonon interaction, and/or the formation of aggregates with different coherent lengths within the domain. The basic exciton model cannot explain this behavior. The coherent aggregate described in this study is proposed as a unique dye supramolecular structure obtained by assembly at the air-liquid interface.

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Growth of Preformed 3D Nuclei in Langmuir Monolayers below Critical Supersaturation

Cited by 23 publications

References 22 publications

Stability of stearic acid monolayers on Artificial Sea Water

Stability of stearic acid monolayers on Artificial Sea Water

Self-assembly of metastable langmuir monolayers on planar solid surfaces

Aggregation and structural study of the monolayers formed by an amphiphilic thiapentacarbocyanine

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