Colloids and Surfaces最新文献

{"title":"Physical characterization of E-glass fibres treated with alkylphenylpoly(oxyethylene)alcohol","authors":"H.M. Fagerholm ,&nbsp;C. Lindsjö ,&nbsp;J.B. Rosenholm ,&nbsp;K. Rökman","doi":"10.1016/0166-6622(92)80218-Q","DOIUrl":"10.1016/0166-6622(92)80218-Q","url":null,"abstract":"<div><p>The adsorption of a non-ionic surfactant, alkylphenylpoly(oxyelhylene)alcohol from aqueous solutions onte industrial E-glass fibres has been followed by measurements of their surface properties (electron spectroscopy for chemical analysis (ESCA) technique), streaming/zeta potential and wetting characteristics. All three techniques indicate substantial changes in the interaction between glass fibres and water as a consequence of surfactant adsorption, although it seems that only a fraction of the total surface is covered by the surfactant. The streaming/zeta potential has been found to reflect the processability of the fibres in a realistic way, whereas the wettability of the fibres provides indirect information concerning the surface coverage and polarity of the fibres. Although the ESCA measurements are performed in ultra-high vacuum, the results are shown to give semi-quantitative information about the amount adsorbed on the surface, and correlate well with the wetting properties. All methods indicate, as expected, an enhanced absorption with increased surfactant concentration.</p></div>","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 2","pages":"Pages 79-86"},"PeriodicalIF":0.0,"publicationDate":"1992-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80218-Q","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89420165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phase and dispersion stability effects in the synthesis of silica nanoparticles in a non-ionic reverse microemulsion","authors":"F.J. Arriagada,&nbsp;K. Osseo-Asare","doi":"10.1016/0166-6622(92)80221-M","DOIUrl":"10.1016/0166-6622(92)80221-M","url":null,"abstract":"<div><p>Silica nanoparticles synthesized by the controlled, base-catalyzed hydrolysis of tetraethoxysilane (TEOS) in cyclohexane-polyoxyethylene(5) nonylphenyl ether—water reverse microemulsions exhibit a bimodal size distribution when a relatively high water/surfactant molar ratio (<em>R</em>) is utilized. During the particle formation process there is a partial expulsion of water from the microemulsion phase and this creates a second phase of bulk water which apparently induces the formation of new silica nuclei. This reaction-promoted phase instability is attributable to the ability of ethanol, a product of TEOS hydrolysis, to shift the water solubility limit of the phase diagram to higher temperatures. At relatively low water/TEOS ratios, the resulting silica dispersions become unstable with the passage of time and eventually large flocs form. This behavior is rationalized in terms of a water-shell model according to which the presence of a water film around the silica particles facilitates the ionization of the surface silanol groups, which in turn permits the development of the necessary electrostatic stabilization. Investigation of the solubilization locale of ethanol with fluorescence techniques indicates that at low <em>R</em> there is a preferential partitioning of the alcohol to the continuous cyclohexane phase. Thus, under these conditions, ethanol molecules (which can also support silica ionization) are not available to substitute for water in the water shell.</p></div>","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 2","pages":"Pages 105-115"},"PeriodicalIF":0.0,"publicationDate":"1992-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80221-M","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85993280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modified Langmuir—Hinselwood kinetics for dynamic adsorption of surfactants at the air/water interface","authors":"C.H. Chang,&nbsp;E.I. Franses","doi":"10.1016/0166-6622(92)80230-Y","DOIUrl":"10.1016/0166-6622(92)80230-Y","url":null,"abstract":"<div><p>The Langmuir—Hinselwood (L-H) equation is the simplest kinetic equation which is consistent with Langmuir's equilibrium isotherm. This kinetic equation cannot describe well the dynamic surface tension data for octanol, sodium dodecyl sulfate (SDS), and other surfactants. A new kinetic equation for the rate of adsorption from the subsurface (d<em>l</em>/d<em>t</em> = <em>k</em>^a_L<em>c</em>(θ,<em>t</em>)(1−θ) exp(−<em>B</em>θ)−<em>k</em>^d_L Γ exp(−<em>B</em>θ). where θ is the fractional surface coverage Γ/Γ_m, <em>c</em>(θ,<em>t</em>) is the subsurface concentration, and <em>k</em>^a_L, <em>k</em>^d_L, and <em>B</em> are constants) includes modification of the kinetics but not of the equilibrium isotherm. The new equation describes better the capture efficiency of the interfacial monolayer for additional surfactant, and can describe activation barriers for adsorption and desorption, or cooperative adsorption caused by primarily attractive interactions between the monolayer and the dissolved surfactant. This equation was used in a new model of mixed kinetics for one-dimensional diffusion/adsorption/desorption. For octanol and heptanol, the initial adsorption rate is controlled by intrinsic adsorption/desorption kinetics (slow adsorption/desorption). With increasing surface coverage, dynamic adsorption gets closer to the diffusion-controlled limit (fast adsorption/desorption relative to diffusion). This indicates attractive and cooperative interactions of alcohol molecules in the monolayer. For sodium di-2-ethylhexylsulfosuccinate (DESS or AOT) and SDS, adsorption is much slower than predicted by diffusion-controlled models. The modified L-H equation in a mixed-kinetics model can fit the data well. The capture efficiency factor, <em>k</em>^a_L exp(−<em>b</em>θ), increases with increasing SDS concentration <em>c</em>_SDS or NaCl concentration <em>c</em>_s, indicating that adsorption is strongly affected by electrostatic barriers. For <em>c</em>_s = 0 and <em>c</em>_SDS = 1.7 to 5.9 m<em>M</em> (for θ_c&lt;0.4), the estimated surface electrical potential is in the range 150–230 mV, and is consistent with classical double-layer theory. For θ_c &gt; 0.4 and a high salt concentration, the parameter <em>B</em> may involve substantial steric or other interactions.</p></div>","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 2","pages":"Pages 189-201"},"PeriodicalIF":0.0,"publicationDate":"1992-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80230-Y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76936566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of a comb-like amphiphilic polymer on the stability of alumina dispersions","authors":"Chin Li,&nbsp;Xiang Yu,&nbsp;P. Somasundaran","doi":"10.1016/0166-6622(92)80226-R","DOIUrl":"10.1016/0166-6622(92)80226-R","url":null,"abstract":"<div><p>The effect of a hydrophobically modified anionic polymer (a maleic anhydride α-olefin copolymer. DAPRAL), which has a comb-like structure, on the stability of alumina suspensions was studied. In the absence of the polymer the suspension stability is controlled by the electrostatic repulsion between particles. Addition of DAPRAL was found to have a significant effect only when the electrostatic repulsion was not sufficient to maintain a stable suspension. The zeta potential of alumina particles and the adsorption density of DAPRAL on alumina were also measured in order to develop the underlying mechanisms for the stability changes. The results suggest that interactions between hydrocarbon chains on the dangling loops and tails do reduce the effect of electrostatic repulsion between alumina particles at low polymer concentrations. At higher polymer concentrations, the hydrocarbon chains on such loops and tails form micellar aggregates; the stability of the suspension is drastically enhanced under such conditions by both steric and electrostatic repulsion.</p></div>","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 2","pages":"Pages 155-158"},"PeriodicalIF":0.0,"publicationDate":"1992-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80226-R","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72667661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of homogeneous liposomes with high trapping efficiency by the surface chemical method","authors":"Teruhisa Kaneko,&nbsp;Hiromichi Sagitani","doi":"10.1016/0166-6622(92)80223-O","DOIUrl":"10.1016/0166-6622(92)80223-O","url":null,"abstract":"<div><p>A new physicochemical method for preparing homogeneous liposomes with high trapping efficiency has been developed. A lamellar liquid crystalline (LLC) phase formed in the egg yolk lecithin (EPC)/propylene glycol/glycerol/water four-component system is utilized in this method. The ratio of propylene glycol to glycerol is important for the preparation of fine liposomes. The roles of propylene glycol and glycerol in the preparation process were studied using phase diagrams, small angle X-ray diffraction and video-enhanced microscopy. It has been shown that propylene glycol and glycerol control the hydrophile-lipophile balance (HLB) of lecithin and that the liposome size changes according to the HLB. The lamellar liquid crystalline phase with a 1:1 propylene glycol:glycerol weight ratio expands for a low concentration of lecithin, and liposomes with minimum size (116 nm) are prepared by adding water to the LLC phase. It was found that the trapping efficiency of the liposomes prepared by this new method was 19.5%, while the trapping efficiency was 0.2% for the sonication method and 2.1% for the extrusion method.</p></div>","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 2","pages":"Pages 125-133"},"PeriodicalIF":0.0,"publicationDate":"1992-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80223-O","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79126112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The relative solution and interfacial hydrophobicity of ethylene oxide—propylene oxide—ethylene oxide block copolymers","authors":"Patrick W. Houlihan,&nbsp;Daniel Fornasiero ,&nbsp;Franz Grieser,&nbsp;Thomas W. Healy","doi":"10.1016/0166-6622(92)80225-Q","DOIUrl":"10.1016/0166-6622(92)80225-Q","url":null,"abstract":"<div><p>By varying the ratio of the ethylene oxide (EO) to propylene oxide (PO) units in a series of poly(ethylene oxide—propylene oxide—ethylene oxide) (EPE) non-ionic copolymers we have been able to quantify the relative hydrophobic energy contribution of the EO and PO units in bulk solution and interfacial processes. These polymers are known to form aggregates in solution which consist of a hydrophobic PO core surrounded by a hydrophilic EO shell. In order to determine the hydrophobic character of the respective EPE polymers the partitioning of pyrene, a strongly hydrophobic probe, between the aqueous environment and the hydrophobic polymer environment was monitored as a function of polymer concentration. Aggregate hydrophobicity was found to be dependent on both the EO and PO chain lengths such that the hydrophobic contribution per PO unit is ten times the hydrophilic contribution per EO unit. The ability of EPE to stabilise an aqueous colloidal dispersion of hydrophobic particles (carbon black) was measured as a function of EPE concentration. The critical stabilisation concentration, which represents the onset of colloidal stability, was round to be inversely related to the hydrophobicity of the polymer aggregates in the bulk solution. The information gathered in this study allows the optimum EO:PO:EO ratio for stabilisation of a hydrophobic colloidal dispersion to be predicted.</p></div>","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 2","pages":"Pages 147-153"},"PeriodicalIF":0.0,"publicationDate":"1992-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80225-Q","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75476399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anionic surfactant adsorption on to asphalt-covered clays","authors":"B. Siffert,&nbsp;A. Jada,&nbsp;E. Wersinger","doi":"10.1016/0166-6622(92)80237-V","DOIUrl":"10.1016/0166-6622(92)80237-V","url":null,"abstract":"<div><p>Asphalt adsorption from from water-saturated tolene on Na⁻ kaolinite, Ca²⁻ kaolinite, Na⁻ illite and Ca²⁻ illite clays was investigated. It was found that the kaolinite surface adsorbed more asphalt than illite for both the Na⁻ -and the Ca²⁻ exchanged forms. Adsorption from aqueous solutions of sodium dodecylbenzenesulphonate (SDBS) and sodium dodecyl sulphate (SDS) on various asphalt-covered clays was also studied. The shape of the isotherms depended on the asphalt-clay substrate and showed a much lower adsorption of SDBS beyond the CMC. Desorption of asphalt from various clays with SDBS and SDS surfactants was measured spectrophotometrically. The percentage weight of asphalt desorbed with SDBS was twofold higher than that desorbed with SDS surfactant.</p></div>","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 1","pages":"Pages 45-51"},"PeriodicalIF":0.0,"publicationDate":"1992-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80237-V","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73914148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Static and quasi-elastic light scattering of an aggregating colloidal suspension","authors":"Stephen D.T. Axford,&nbsp;Thelma M. Herrington,&nbsp;B.R. Midmore","doi":"10.1016/0166-6622(92)80240-3","DOIUrl":"10.1016/0166-6622(92)80240-3","url":null,"abstract":"","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 1","pages":"Pages 73-77"},"PeriodicalIF":0.0,"publicationDate":"1992-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80240-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82899160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Competitive solubilization of Sudan IV and anthracene in micellar systems","authors":"Sangeeta Kumar,&nbsp;H.N. Singh","doi":"10.1016/0166-6622(92)80231-P","DOIUrl":"10.1016/0166-6622(92)80231-P","url":null,"abstract":"<div><p>Single solubilization of Sudan IV and anthracene has been studied in aqueous surfactant systems of sodium dodecyl sulphate, cetyltrimethylammonium bromide and Triton X-100 at 30°C by a spectrophotometric technique. Sudan IV was found to be more highly solubilized in micellar solutions than anthracene. Solubilization of Sudan IV and anthracene in the presence of each other was also studied in the surfactant systems. It was found that Sudan IV is preferentially solubilized over anthracene when solubilized jointly. This is reflected in the calculated values of the number of moles of surfactant solubilizing 1 mol of dye, the free energy change and the number of molecules of dye solubilized in a micelle. From the successive solubilization studies of Sudan IV and anthracene it has been found that the absorbance of one solubilizate does not change after the addition of the second solubilizate. The solubilization behaviour of dyes was discussed with respect to the aggregation number, occupancy of different solubilization sites and the chemical nature of the two dyes.</p></div>","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 1","pages":"Pages 1-4"},"PeriodicalIF":0.0,"publicationDate":"1992-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80231-P","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90194611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface chemistry of silicon nitride powders: Adsorption from non-aqueous solutions","authors":"Lennart Bergström","doi":"10.1016/0166-6622(92)80238-W","DOIUrl":"10.1016/0166-6622(92)80238-W","url":null,"abstract":"<div><p>The adsorption behaviour of different silicon nitride powders in cyclohexane has been studied. Adsorption isotherms of organic probe molecules covering a wide spectrum of Lewis acidity/basicity showed large variations in adsorption behaviour between the different probes. Mathematical analysis showed that the adsorption data could be described by a Langmuir-Freundlich type of isotherm.</p><p>Using a previously presented model of the silicon nitride surface, it was possible to relate the variation of the isoclectric point in water between the three powders, to a difference in the relative site density or silanol and amino groups on the surface. It was found that the maximum concentration (<em>T</em>_M) of benzoic acid increased linearly while of pyridine decreased with an increase in the relative amount of amino groups on the surface.</p></div>","PeriodicalId":10488,"journal":{"name":"Colloids and Surfaces","volume":"69 1","pages":"Pages 53-64"},"PeriodicalIF":0.0,"publicationDate":"1992-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0166-6622(92)80238-W","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72930743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}