Monolayer studies

Sheppard, Erwin; Tcheurekdjian, Noubar

doi:10.1007/bf02086191

Cited by 13 publications

(14 citation statements)

References 3 publications

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“…[39,76] and was taken up by Fulda and Tieke in the 1990s for the examination of nanoscopic polystyrene colloids. [77][78] The surface-pressure area isotherms of colloid films are extremely steep as is expected in a incompressible, crystalline and stiff film at the interface.…”

Section: Crystallization On a Langmuir Troughmentioning

confidence: 99%

Surface Patterning with Colloidal Monolayers

Vogel

2012

Springer Theses

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This thesis focuses on the controlled assembly of monodisperse polymer colloids into ordered two-dimensional arrangements. These assemblies, commonly referred to as colloidal monolayers, are subsequently used as masks for the generation of arrays of complex metal nanostructures on solid substrates.The motivation of the research presented here is twofold. First, monolayer crystallization methods were developed to simplify the assembly of colloids and to produce more complex arrangements of colloids in a precise way. Second, various approaches to colloidal lithography are designed with the aim to include novel features or functions to arrays of metal nanostructures.The air/water interface was exploited for the crystallization of colloidal monolayer architectures as it combines a two-dimensional confinement with a high lateral mobility of the colloids that is beneficial for the creation of high long range order. A direct assembly of colloids is presented that provides a cheap, fast and conceptually simple methodology for the preparation of ordered colloidal monolayers. The produced two-dimensional crystals can be transformed into nonclose-packed architectures by a plasma-induced size reduction step, thus providing valuable masks for more sophisticated lithographic processes. Finally, the controlled co-assembly of binary colloidal crystals with defined stoichiometries on a Langmuir trough is introduced and characterized with respect to accessible configurations and size ratios.Several approaches to lithography are presented that aim at introducing different features to colloidal lithography. First, using metal-complex containing latex particles, the synthesis of which is described as well, symmetric arrays of metal nanoparticles can be created by controlled combustion of the organic material of the colloids. The process does not feature an inherent limit in nanoparticle size and is able to produce complex materials as will be demonstrated for FePt alloy particles. Precise control over both size and spacing of the particle array is presented.Second, two lithographic processes are introduced to create sophisticated nanoparticle dimer units consisting of two crescent shaped nanostructures in close proximity; essentially by using a single colloid as mask to generate two structures simultaneously. Strong coupling processes of the parental plasmon resonances of the two objects are observed that are accompanied by high near-field enhancements. A plasmon hybridization model is elaborated to explain all polarization dependent shifts of the resonance positions. Last, a technique to produce laterally patterned, ultra-flat substrates without surface topographies by embedding gold nanoparticles in a silicon dioxide matrix is applied to construct robust and re-usable sensing architectures and to introduce an approach for the nanoscale patterning of solid supported lipid bilayer membranes.

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Section: Crystallization On a Langmuir Troughmentioning

confidence: 99%

Surface Patterning with Colloidal Monolayers

Vogel

2012

Springer Theses

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“…Determination of surface pressure (Π) vs surface area ( A ) isotherms of noncohesive monoparticulate layers on aqueous solutions has contributed fruitful information on particle sizes, particle−particle repulsive interactions, and wettabilities. − Information on particle wettability can only be obtained by assuming the identity of E r and W r where Π c is the collapse pressure and A c is the surface area of a particle at the collapse pressure.…”

Section: Introductionmentioning

confidence: 99%

“…Equation 3 was successfully adapted for the determination of contact angles for solid nanometer- and micrometer-sized particles which were floating at aqueous surfactant−air interfaces . In spite of these studies, − the effect of particle hydrophobicity on the particle−particle and particle−subphase interaction is incompletely understood.…”

Section: Introductionmentioning

confidence: 99%

Monoparticulate Layers of Silanized Glass Spheres at the Water−Air Interface: Particle−Particle and Particle−Subphase Interactions

1996

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Silanization has rendered spherical (75 ± 5 μm diameter) glass particles to be weakly (sample A, ϑ = 55°), moderately (sample B, ϑ = 72°), and highly (sample C, ϑ = 90°) hydrophobic. Nonequilibrium surface pressure (Π) vs surface area (A) isotherms have been determined for monoparticulate layers which were prepared from samples A, B, and C at water−air interfaces in a Langmuir film balance. The effect of hydrophobicity on the particle−particle interaction and on the energy (E r) which is necessary for the removal of a particle from the water−air interface (particle−subphase interaction) has been elucidated. Contact cross-sectional areas (CCSA), surface coverages (SC), and collapse energies (E c), evaluated from Π vs A isotherms, provided semiquantitative information on the structural strength. Monoparticulate layers which were formed from the most hydrophobic glass spheres (sample C) had a structural strength which was almost 5 times greater than that of those which were formed from the least hydrophobic sample (sample A), as revealed by the E c values which were elucidated for these systems. Long-term stability, determined by time-dependent surface-pressure measurements, was only found for sample C. The energy of a particle−particle contact was calculated, for the strongly cohesive layer of sample C, to be (1.2−1.4) × 10-10 J. The weakly cohesive layer, prepared from sample A, had a 490-nm interparticle distance at the secondary energy minimum and a total repulsive interaction energy in the range of (0.5−1.3) × 10-13 J between two beads at an interparticle distance of 1−200 nm. Values for adhesion work (W r) were calculated from in situ contact-angle measurements and compared to corresponding E r values which were obtained experimentally by the isotherms. The significant discrepancies between the W r and E r values which were found for sample A or sample B were rationalized in terms of contact-angle hysteresis, dynamic wetting, and distortion of the electric double layer around the interfacial beads.

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“…they can be studied though the surface pressure/area isotherms. Early studies of this kind were performed in the sixties and seventies of the last century with spherical monodisperse polystyrene particles and allowed to obtain information on particle sizes and particle-particle repulsive interactions [57][58][59][60][61]. In particular, it was shown in [57] that the collapse pressure is greatest if the particles are monodisperse.…”

Section: Surface Pressure/area Isothermsmentioning

confidence: 98%