Ion redistribution and meniscus stability at Langmuir monolayer deposition

Kovalchuk, V. I.; Vollhardt, D.

doi:10.1016/j.cis.2004.08.008

Cited by 10 publications

(11 citation statements)

References 75 publications

(173 reference statements)

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“…The domains form stripes that are either parallel or perpendicular to the water-substrate contact line [3]. The phase transition distinguishes these patterns from similar patterns formed in the Langmuir-Blodgett transfer of fatty acids that does not involve any phase transition [8][9][10][11]. Remarkably, before the transfer the floating monolayer is in the pure LE phase.…”

Section: Introductionmentioning

confidence: 81%

Substrate-mediated pattern formation in monolayer transfer: a reduced model

et al. 2012

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The formation of regular stripe patterns during the transfer of surfactant monolayers from water surfaces onto moving solid substrates can be understood as a phase decomposition process under the influence of the effective molecular interaction between the substrate and the monolayer, also called substrate-mediated condensation (SMC). To describe this phenomenon, we propose a reduced model based on an amended Cahn-Hilliard equation. A combination of numerical simulations and continuation methods is employed to investigate stationary and time-periodic solutions of the model and to determine the resulting bifurcation diagram. The onset of spatiotemporal pattern formation is found to result from a homoclinic and a Hopf bifurcation at small and large substrate speeds, respectively. The critical velocity corresponding to the Hopf bifurcation can be calculated by means of the marginal stability criterion for pattern formation behind propagating fronts. In the regime of low transfer velocities, the stationary solutions exhibit snaking behavior.

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Section: Introductionmentioning

confidence: 81%

Substrate-mediated pattern formation in monolayer transfer: a reduced model

et al. 2012

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“…The dependence of the structure period on the transfer velocity is inverse to that observed for substrate induced condensation of lipids; i.e., the dis tance between the structural elements increases with V t . Patterns of this type are formed via an electroki netic mechanism and a complex set of dynamic inter actions between a monolayer on a moving meniscus and a solid surface already coated with the first mono layer of the same substance [100][101][102]. It is known that, due to the condition of charge neutrality on TPCL, the transfer of a charged mono layer of a salt or an acid is always accompanied by con centration polarization, which, as a rule, does not change the composition of a monolayer but deter mines the maximum amount of a substance trans ferred onto a solid surface [100,103].…”

Section: Substrate Mediated Self Assembly Of Langmuir Monolayers Intomentioning

confidence: 99%

“…Patterns of this type are formed via an electroki netic mechanism and a complex set of dynamic inter actions between a monolayer on a moving meniscus and a solid surface already coated with the first mono layer of the same substance [100][101][102]. It is known that, due to the condition of charge neutrality on TPCL, the transfer of a charged mono layer of a salt or an acid is always accompanied by con centration polarization, which, as a rule, does not change the composition of a monolayer but deter mines the maximum amount of a substance trans ferred onto a solid surface [100,103]. Usually, the higher the transfer velocity, the lower this amount, because the work of adhesion tends to zero with increasing transfer velocity [102].…”

Section: Substrate Mediated Self Assembly Of Langmuir Monolayers Intomentioning

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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“…However, in the case there are charged impurity molecules in the system, they can get adsorbed at these gaseous layers, making them charged (such charging of gaseous layers by adsorption of surfactant molecules is well known; see Ref. [73]), which induces electric double layers in the presence of added salt, so that the resulting electrostatic wetting tension can still affect the surface nanobubbles. However, for relatively clean experimental set ups it is likely that the impurities exist only in small concentration, which will lead to relatively weak charging of these interfaces so that the effect of added salt on surface nanobubbles, as proposed in the present theory, will get substantially reduced.…”

Section: A Scope and Limitation Of The Proposed Theorymentioning

confidence: 99%

Effect of added salt on preformed surface nanobubbles: A scaling estimate

Das

2011

Phys. Rev. E

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In this paper we propose a scaling argument to quantify the role of added electrolyte salt in affecting the stability and the morphology of preformed surface nanobubbles on hydrophobic substrates like the water-OTS-silicon or the water-HOPG interfaces. The added salt controls the electric double layer formation as well as affects the zeta (ζ) potential at the air-water and solid-water interfaces. The resulting electrostatic wetting tension acts in conjunction with the air-water surface tension (analogous to electrowetting scenarios), thereby affecting the nanobubble morphologies. Weak ζ potential of the water-HOPG interface or the water-OTS-silicon interface at acidic pH ensures that the added salt will have imperceptible effect on the corresponding preformed surface nanobubbles, validating the experimental observations. However, at alkaline buffer pH for the OTS-silicon substrate, under certain system conditions, salt-induced ζ potential can be substantially high so that the properties of preformed surface nanobubbles will be affected. This paper will thus readdress the long-held universal notion that added salt, no matter in what concentration, will not influence the properties of preformed surface nanobubbles.

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Ion redistribution and meniscus stability at Langmuir monolayer deposition

Cited by 10 publications

References 75 publications

Substrate-mediated pattern formation in monolayer transfer: a reduced model

Substrate-mediated pattern formation in monolayer transfer: a reduced model

Self-assembly of metastable langmuir monolayers on planar solid surfaces

Effect of added salt on preformed surface nanobubbles: A scaling estimate

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