?-Lepton decay in an arbitrary plane-wave electromagnetic field

Павлова, О. С.; Klimenko, Yu. I.

doi:10.1007/bf00899086

Cited by 4 publications

(5 citation statements)

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“…C 14 E 7 :C 12 E 5 :C 12 E 7 ) 1.0:6.4:7.6) are about equal to those of the corresponding CMCs (Table 1). Tiberg 21 has also noted this for the adsorption of nonionics on silica. Our absolute values are lower by a factor of 5 than those of Tiberg, but this difference may be caused by stronger binding of aggregates at the cellulose surface compared to that onto silica.…”

Section: Modeling the Kinetics And Discussionmentioning

confidence: 72%

“…In addition to knowing the adsorbed amount at equilibrium, information about the kinetics is very useful to obtain further insight into the aggregation behavior of surfactants at solid interfaces. Klimenko et al focused on the adsorption of a poly(ethylene oxide) alkylphenolether, C 8 φ E 10 , and C 12 E 23 onto a silica gel and did not find any effect of micelles on the kinetics. More recent work on the adsorption kinetics of surfactants − and diblock copolymers − showed that monomers and micelles might both contribute to the initial rate.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption of Nonionic Surfactants on Cellulose Surfaces: Adsorbed Amounts and Kinetics

et al. 2005

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Kinetic and equilibrium aspects of three different poly(ethylene oxide) alkylethers (C12E5, C12E7, C14E7) near a flat cellulose surface are studied. The equilibrium adsorption isotherms look very similar for these surfactants, each showing three different regions with increasing surfactant concentration. At low surfactant content both the headgroup and the tail contribute to the adsorption. At higher surface concentrations, lateral attraction becomes prominent and leads to the formation of aggregates on the surface. The general shape of the isotherms and the magnitude of the adsorption resemble mostly those for hydrophilic surfaces, but both the ethylene oxide and the aliphatic segments determine affinity for the surface. The adsorption and desorption kinetics are strongly dependent on surfactant composition. At bulk concentrations below the CMC, the initial adsorption rate is attachment-controlled. Above the CMC, the micellar diffusion coefficient and the micellar dissociation rate play a crucial role. For the most hydrophilic surfactant, C12E7, both parameters are relatively large. In this case, the initial adsorption rate increases with increasing surfactant concentration, also above the CMC. For C12E5 and C14E7 there is no micellar contribution to the initial adsorption rate. The initial desorption kinetics are governed by monomer detachment from the surface aggregates. The desorption rate constants scale with the CMC, indicating an analogy between the surface aggregates and those formed in solution.

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Section: Modeling the Kinetics And Discussionmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Adsorption of Nonionic Surfactants on Cellulose Surfaces: Adsorbed Amounts and Kinetics

et al. 2005

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“…The rate increases abruptly at the cmc and continues to increase with the bulk concentration, indicating a distinct change in mechanism at the cmc. In a study of nonionic surfactant adsorption, Klimenko et al observed that the adsorption rate of poly(ethylene glycol) alkyl ethers on silica increased with concentration above the cmc.…”

Section: Resultsmentioning

confidence: 99%

Kinetics and Mechanism of Cationic Surfactant Adsorption and Coadsorption with Cationic Polyelectrolytes at the Silica−Water Interface

1998

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We used scanning angle reflectometry to measure the adsorption isotherm, adsorption kinetics, and desorption kinetics for cetyltrimethylammonium bromide (CTAB) surfactants on negatively charged silica surfaces. The initial adsorption rate increased with increasing CTAB concentrations between approximately 0.2 × cmc and 10 × cmc, displaying a discontinuous increase at the critical micelle concentration. The initial desorption rate was a monotonically increasing function of the bulk concentration of the surfactant solution from which the adsorbed layer was formed, both above and below the cmc. Combining equilibrium and kinetic information, we conclude that the adsorption mechanism and the structure of the adsorbed layer both change abruptly at the cmc. Below the cmc, monomeric surfactants adsorb to an extent that is consistent with a defective bilayer structure. Above the cmc, micelles adsorb directly to the surface, to an extent that is consistent with a close-packed monolayer of micelles. The adsorption rate was apparently limited by slow rearrangements within the adsorbed layer. CTAB adsorption was significantly hindered by coadsorption with polylysine, in terms of both the rate and extent of adsorption. The effect of polylysine on CTAB adsorption was very sensitive to the ionic strength and the order in which the surfactant and the polyelectrolyte were exposed to the surface. Different pathways to the same final bulk solution composition produced much different adsorption results. This demonstrates that coadsorption of CTAB and polylysine is inherently a nonequilibrium process dominated by kinetic traps. Although it had an overall hindering effect, coadsorption with polylysine did not alter the basic difference in CTAB adsorption mechanisms above and below the cmc.

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“…The aim of the present study was to examine the relationship between the structural properties of the adsorbed nonionic surfactant layers and the chemical nature of the solid surface. The interfacial behavior of nonionic surfactants has for quite some time attracted a large scientific interest. ,,,,− Adsorption is most commonly studied on natural oxides, such as silica, and at hydrophobic surfaces.…”

Section: Discussionmentioning

confidence: 99%

“…The interfacial behavior of nonionic surfactants has for quite some time attracted a large scientific interest. 1,2,4,6,[24][25][26][27][28] Adsorption is most commonly studied on natural oxides, such as silica, and at hydrophobic surfaces.…”

Section: Discussionmentioning

confidence: 99%

Influence of Surface Hydrophobicity on the Layer Properties of Adsorbed Nonionic Surfactants

2000

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The structure of adsorbed octa(oxyethlyene) n-dodecyl ether (C12E8) layers at a series of goldalkanethiolate surfaces was investigated by atomic force microscopy. The hydrophobicity of the surfaces was systematically varied by changing the relative amounts of chemisorbed thiohexadecane (CH3(CH2)15-SH) and thiohexadecanol (CH2OH(CH2)15SH) surface groups. This allowed complete control over the hydrophobicity of the surface. Adsorption was studied on five different thiol-modified gold surfaces prepared from solutions containing 0%, 25%, 50%, 75%, and 100% hexadecane thiol, respectively (henceforth referred to as 0% CH3, 25% CH3, 50% CH3, 75% CH3, and 100% CH3). The following general evolution of the adsorbed layer morphology with increasing surface hydrophobicity was observed: diffuse micellar coverage; dense micellar coverage; bilayer; and finally a monolayer structure at the most hydrophobic surface. The adsorbed layer structure observed at the different surfaces was interpreted in terms of the effective interaction between different parts of the surfactant and the solid surface. On the basis of our adsorption data, we also infer that hydrophobic interactions are the main driving force for adsorption of ethylene oxide segments at partially hydroxylated surfaces (such as silica) and that hydrogen bonding reduces the free energy penalty of displacing water.

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?-Lepton decay in an arbitrary plane-wave electromagnetic field

Cited by 4 publications

References 1 publication

Adsorption of Nonionic Surfactants on Cellulose Surfaces: Adsorbed Amounts and Kinetics

Adsorption of Nonionic Surfactants on Cellulose Surfaces: Adsorbed Amounts and Kinetics

Kinetics and Mechanism of Cationic Surfactant Adsorption and Coadsorption with Cationic Polyelectrolytes at the Silica−Water Interface

Influence of Surface Hydrophobicity on the Layer Properties of Adsorbed Nonionic Surfactants

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