The wettability of polytetrafluoroethylene and polymethylmethacrylate by aqueous solutions of Triton X-100 and short chain alcohol mixtures

Measurements of advancing contact angles (θ) were carried out for aqueous solutions of Triton X-100 (TX-100) and methanol and ethanol mixtures at constant TX-100 concentration equal to 1 × 10⁻⁷, 1 × 10⁻⁶, 1 × 10⁻⁵, 1 × 10⁻⁴, 6 × 10⁻⁴ and 1 × 10⁻³ M, respectively, on polytetrafluoroethylene (PTFE) and polymethylmethacrylate (PMMA). Using measured contact angle values the relationships between cos θ, adhesion tension and surface tension of the solutions were determined, and on their basis the critical surface tension of PTFE and PMMA wetting was calculated. The obtained average value of the critical surface tension of PTFE wetting is lying in the range of the PTFE surface tension values which can be found in the literature, while for PMMA it is even lower than the Lifshitz-van der Waals component of its surface tension. From the relationship between the adhesion and surface tension and Lucassen-Reynders equation it results that in the case of PTFE the adsorption at the PTFE-solution and solution-air interfaces is the same, which was confirmed by a linear relationship between the cos θ and 1/γ_LV and intercept on cos θ axis equal to −1. However, for PMMA the adsorption of the surface active agents at solution-air interface is higher than at PMMA-solution. Using the values of the contact angle the values of the adhesion work of solution to the PTFE and PMMA surface were also determined, which are constant for PTFE, but for PMMA decrease with alcohol concentration increase. Next, using the contact angle values in the Young equation, the PTFE(PMMA)-solution interface tension was also calculated. The obtained values of PTFE-solution interface tension were compared with those evaluated from the Szyszkowski, Connors and Fainerman and Miller equations, and good agreement between these values was observed for all series of TX-100 and alcohol mixtures at a low alcohol concentration.     

The role of adsorption of dodecylethyldimethylammonium bromide and benzyldimethyldodecylammonium bromide surfactants in wetting of polytetrafluoroethylene and poly(methyl methacrylate) surfaces

The role of adsorption of dodecylethyldimethylammonium bromide (C₁₂(EDMAB)) and benzyldimethyldodecylammonium bromide (BDDAB) at water-air and polytetrafluoroethylene (PTFE)-water and poly(methyl methacrylate) (PMMA)-water interface, in wetting of PTFE and PMMA surface, was established from the measured values of the contact angle (θ) of aqueous C₁₂(EDMAB) and BDDAB solutions in PTFE (PMMA)-solution drop-air system, and from the measured values of the surface tension of aqueous C₁₂(EDMAB) and BDDAB solutions. Adsorption of C₁₂(EDMAB) and BDDAB at water-air interface was determined earlier from the Gibbs equation. Adsorption at solid-water interface was deduced from the Lucassen-Reynders equation based on the relationship between adhesion tension (γ_LV cos θ) and surface tension (γ_LV). The slope of the γ_LV cos θ-γ_LV curve was found to be constant and equal to −1, and about −0.3 for PTFE and PMMA surface, respectively (in the case of both surfactant studied: C₁₂(EDMAB) and BDDAB, and in the whole range of surfactants concentration in solution). It means that the amount of the surfactant adsorbed at the PTFE-water interface, Γ_SL, was essentially equal to its amount adsorbed at water-air interface, Γ_LV. However, Γ_SL at the PMMA-water interface was about three times smaller as compared to that at water-air interface. By extrapolating the linear dependence between γ_LV cos θ-γ_LV and dependence between cos θ-γ_LV and cos θ = 1 we determined the value of the critical surface tension of PTFE and PMMA surface wetting, γ_c. The obtained values of γ_c for PTFE surface were equal 23.4 and 23.8 mN/m, 23.1 and 23.2 mN/m for C₁₂(EDMAB) and BDDAB, respectively and they were higher than the surface tension of PTFE (20.24 mN/m). On the other hand, the obtained values of γ_c for PMMA surface were equal 31.4 and 30.9 mN/m, 31.7 and 31.3 mN/m for C₁₂(EDMAB) and BDDAB, respectively and they were smaller than the surface tension of PMMA (39.21 mN/m). Using the values of PTFE and PMMA surface tension and the measured values of the surface tension of aqueous C₁₂(EDMAB) and BDDAB solutions in the Young equation, the PTFE (PMMA)-solution interfacial tension, γ_SL, was also determined. Next, the work of adhesion (W_A) was deduced, and it occurred that the dependence between the W_A and the surface tension (γ_LV) for both studied solids was linear. However, the values of the W_A for PMMA change as a function of log C (C—surfactant concentration) changed from 91.7 to 68.5 mJ/m² and from 91.8 to 65.1 mJ/m² for C₁₂(EDMAB) and BDDAB, respectively. On the other hand, the work of adhesion of both studied surfactants solutions to the PTFE surface was practically constant (an average value was equal 45.8 and 45.4 mJ/m², respectively). These values were close to the value of the work of water adhesion to PTFE surface (45.5 mJ/m²).     

Adsorption of sodium bis(2-ethylhexyl) sulfosuccinate and wettability in polytetrafluoroethylene-solution-air system

The role of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) adsorption at water-air and polytetrafluoroethylene-water (PTFE) interfaces in wetting of low energy PTFE was established from measurements of the contact angle of aqueous AOT solutions in PTFE-solution drop-air systems and the aqueous AOT solution surface tension measurements. For calculations of the adsorption at these interfaces the relationship between adhesion tension (γ_LV cos θ) and surface tension (γ_LV), and the Gibbs and Young equations were taken into account. On the basis of the measurements and calculations the slope of the γ_LV cos θ-γ_LV curve was found to be constant and equal −1 over the whole range of surfactant concentration in solution. It means that the amount of surfactant adsorbed at the PTFE-water interface, Γ_SL, is essentially equal to its amount adsorbed at water-air interface, Γ_LV. By extrapolating the linear dependence between γ_LV cos θ and γ_LV to cos θ = 1 the determined value of critical surface tension of PTFE surface wetting, γ_C, was obtained (23.6 mN/m), and it was higher than the surface tension of PTFE (20.24 mN/m). Using the value of PTFE surface tension and the measured surface tension of aqueous AOT solution in Young equation, the PTFE-solution interface tension, γ_SL, was also determined. The shape of the γ_SL-log C curve occurred to be similar to the isotherm of AOT adsorption at water-air interface, and a linear dependence existed between the PTFE-solution interfacial tension and polar component of aqueous AOT solution. The dependence was found to be established by the fact that the work of adhesion of AOT solution to the PTFE surface was practically constant amounting 46.31 mJ/m² which was close to the work of water adhesion to PTFE surface.     

The role of adsorption of sodium bis(2-ethylhexyl) sulfosuccinate in wetting of glass and poly(methyl methacrylate) surface

Advancing contact angles, θ, for aqueous solutions of the anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) were measured on glass and poly(methyl methacrylate) (PMMA) surface. Using the obtained results we determined the properties of aqueous AOT solutions in wetting of these surfaces. It occurs that the wettability of glass and PMMA by these solutions depends on the concentration of AOT in solution. There is almost linear dependence between the contact angle (θ) and concentration of AOT (log C) in the range from 5 × 10⁻⁴ to 2.5 × 10⁻³ M/dm³ (value of the critical micelle concentration of AOT—CMC) both for glass and PMMA surface. For calculations of AOT adsorption at solid (glass, PMMA)-solution drop-air system interfaces the relationship between the adhesion tension (γ_LV cos θ) and surface tension (γ_LV) and the Gibbs and Young equations were taken into account. From the measurement and calculation results the slope of the γ_LV cos θ − γ_LV curve was found to be constant and equal 0.7 for glass and −0.1 for PMMA over the whole range of AOT concentration in solution. From this fact it can be concluded that if Γ_SV is equal zero then Γ_SL > 0 for the PMMA-solution and Γ_SL < 0 for glass-solution systems. It means that surfactant concentration excess at PMMA-solution interface is considerably lower than at solution-air interface, but this excess of AOT concentration at glass-solution interface is lower than in the bulk phase. By extrapolating the linear dependence between the adhesion and surface tension the value of the critical surface tension (γ_c) of wetting for glass and PMMA was also determined, that equaled 25.9 and 25.6 mN/m for glass and PMMA, respectively. Using the value of the glass and PMMA surface tension as well as the measured surface tension of aqueous AOT solutions in Young equation, the solid-liquid interface tension (γ_SL) was found. There was a linear dependence between the γ_SL and γ_LV both for glass and PMMA, but there were different slope values of the curves for glass and PMMA, i.e. −0.7 and 0.1, respectively. The dependence between the work of adhesion (W_A) and surface tension (γ_LV) was also linear of different slopes for glass and for PMMA surface.     

The wettability of poly(tetrafluoroethylene) by aqueous solutions of ternary surfactant mixtures

Contact angle measurements on poly(tetrafluoroethylene) (PTFE) surface were carried out for the systems containing ternary mixtures of cetyltrimethylammonium bromide (CTAB) and p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycols), Triton X-100 (TX100) and Triton X-165 (TX165). The aqueous solution of ternary surfactant mixtures were prepared by adding the third surfactant to the binary mixture of the surfactants where the synergetic effect in the reduction of the surface tension of water was determined, to compare the influence of the third surfactants on the values of surface tension of this binary mixture and the values of the contact angle on PTFE. The obtained results and calculations indicate that the ternary mixtures of CTAB + TX165 (αCTAB = 0.2, γ_LV = 60 and 50 mN/m) + TX100 (C = 10⁻⁸ to 10⁻² M) have the biggest efficiency of the reduction of contact angle of water on PTFE in comparison to aqueous solutions of the single surfactants and their binary and ternary mixtures. Also in the case of all studied ternary mixtures of surfactants at concentrations of the bulk phase corresponding to unsaturated monolayer at water-air interface the adsorption of surfactants at PTFE-water interface is different than that at water-air interface, but is the same at concentrations near the critical micelle concentration (CMC). Thus the linear dependences between γ_LV cos θ − γ_LV and cos θ − 1/γ_LV, in the range of concentration studied for all systems confirm the same adsorption at two interfaces only at C near the CMC.     

Effects of roughness on interfacial performances of silica glass and non-polar polyarylacetylene resin composites

The influence of roughness on interfacial performances of silica glass/polyarylacetylene resin composites was investigated. In order to obtain different roughness, silica glass surface was abraded by different grits of abrasives and its topography was observed by scanning electron microscopy and atomic force microscopy. At the same time, the failure mechanisms of composites were analyzed by fracture morphologies and the interfacial adhesion was evaluated by shear strength test. The results indicated that shear strength of silica glass/polyarylacetylene resin composites firstly increased and then decreased with the surface roughness of silica glass increased. The best surface roughness range of silica glass was 40-60 nm. The main mechanism for the improvement of the interfacial adhesion was physical interlocking at the interface.     

Light scattering and fluorescence probe studies on micellar properties of Triton X-100 in KCl solutions

The effect of KCl on micelle formation and structure of Triton X-100 (TX-100) was investigated by using combined static and dynamic light scattering measurements, together with the fluorescence probe technique. An analysis of the light scattering data, including hydrodynamic radius and micellar aggregation number, accounted for both micelle growth and hydration. Fluorescence studies using pyrene as a probe were carried out to determine the critical micelle concentration (CMC) as a function of solution composition. In addition, with the aim of gaining information on the possible changes in the micro-environmental properties of TX-100 micelles, fluorescence probe studies, including intermolecular pyrene excimer formation and fluorescence polarization of coumarin 6 associated with micelles, were carried out. It was found that the addition of electrolyte induces a decrease in the CMC and an increase in both aggregation number and hydration. However, complementary data of partial specific volume and cloud point of the surfactant suggested that the main contribution to micellar hydration is due to water mechanically trapped in the micelle. Fluorescence measurements do not indicate changes in the micellar micropolarity, probably due to modifications of the solubilization site of the probe caused by the micellar growth. Both pyrene excimer formation and fluorescence polarization of coumarin 6 revealed an increase in microviscosity with electrolyte addition, which is consistent with increased micellar hydration.     

曲通X-100的荧光光谱与荧光量子产率

报道了曲通X-100(TX)水溶液的荧光光谱与荧光量子产率。实验发现,在强酸性条件下,TX没有荧光,当pH ＞1时,TX有稳定的强荧光,荧光激发波长为229和275 nm,发射波长为302 nm。TX水溶液可产生共振荧光,共振荧光峰位于285 nm。在0.1～90 mg·L-1浓度范围内,TX荧光强度与浓度之间存在线性关系,检测限为0.1 mg·L-1。以L-色氨酸为参比,测得在激发波长280 nm处TX水溶液的荧光量子产率为0.121。     

Reaction products and oxide thickness formed by Ti out-diffusion and oxidization in poly-Pt/Ti/SiO2/Si with oxide films deposited

In the paper, we present experimental results to enhance the understanding of Ti out-diffusion and oxidization in commercial poly-Pt/Ti/SiO₂/Si wafers with perovskite oxide films deposited when heat-treated in flowing oxygen ambient. It indicates that when heat-treated at 550 and 600 °C, PtTi₃+PtTi and PtTi are the reaction products from interfacial interaction, respectively; while heat-treated at 650 °C and above, the products become three layers of titanium oxides instead of the alloys. Confirmed to be rutile TiO₂, the first two layers spaced by 65 nm encapsulate the Pt surface by the first layer with 60 nm thick forming at its surface and by the next layer with 35 nm thick inserting its original layer. In addition, the next layer is formed as a barrier to block up continuous diffusion paths of Ti, and thus results in the last layer of TiO_2−x formed by the residual Ti oxidizing.     

Tuning intermicellar potential of Triton X-100-anthranilic acid mixed micelles

Structural parameters of micelles formed by Triton X-100 in the presence of solubilized anthranilic acid at different pH values was investigated using light scattering and small angle neutron scattering. Analysis of the SANS data indicate that micelles are oblate ellipsoidal in nature with little variation in the dimensions, in the investigated pH range (from 0.5 to 6.0). The interaction potential of the micelles shows a minimum closer to the isoelectric point of anthranilic acid. A similar variation is observed in the cloud point of the micelles with pH. The observed variation in the interaction potential with pH of the micellar solution can be explained in terms of the reversal of charge on anthranilic acid due to shift in the acid-base equilibrium. The variation in interaction potential and cloud point with pH is modelled using Coulombic repulsion of charged molecules at the micelle interface.      

Two-photon and Three-photon Fluorescence of Triton X-100 in the Ultraviolet Region

Journal of Fluorescence - We report, to our best knowledge, the first observation of two-photon and three-photon fluorescence of Triton X-100 (TX-100) in water and cyclohexane. The observed...     

Triton X-100增敏催化动力学光度法测定痕量亚硝酸根

基于稀硫酸介质中,Triton X-100对亚硝酸根催化氯酸钾氧化甲基紫褪色反应的增敏作用,建立了测定痕量亚硝酸根的Triton X-100增敏催化动力学光度法.方法的线性范围为0.004-0.26μg·mL-1,检出限为9.24×10-10g·mL-1.测得反应表观活化能为75.33kJ·mol-1.方法简便、快速,选择性好.用于水样及蔬菜祥品中痕量亚硝酸根的测定,结果满意.     

Triton X-100增溶催化动力学光度法测定痕量银

报道了以TritonX-100为增溶剂,α,α′-联吡啶为活化剂,过硫酸钾氧化甲基绿催化动力学光度法测定痕量银的新体系。方法线性范围为2.0—60μg/L,检出限为7.5×10-10g/mL;相对标准偏差1.8%(n=11)。用于测定相纸中的银,结果满意。     

Triton X-100微乳液中铈与L-色氨酸荧光反应的研究与应用

研究了Triton X-100微乳液(Triton X-100-M)对荧光法测定L-色氨酸的增敏作用。在酸性条件中Ce4+可将色氨酸氧化为强荧光性物质,以此为基础建立了分析色氨酸的新方法。与Triton X-100胶束相比,Triton X-100微乳液对荧光法测定L-色氨酸具有更好的增敏作用,在该介质中测定灵敏度提高了225倍。实验中对影响荧光测定的各种因素进行了优化,同时考察了共存离子的干扰并做了回收试验,对荧光增敏机理也进行了初步探讨。试验结果表明：在优化条件下,色氨酸浓度在0.1～1.0 μg·mL-1范围内与荧光强度成线形关系,其线性方程为F=342.37+30.45c,r=0.998 4,检出限为0.09 μg·mL-1。在优化参数条件下,对实际样品进行分析,结果令人满意。     

Triton X-100胶束中双亲卟啉的光谱研究

光谱法研究了双亲卟啉 (P0 和 P1 )与非离子胶束 Triton X- 1 0 0间的相互作用 ,测定了卟啉在不同 p H值的 TX- 1 0 0胶束中的紫外 -可见吸收光谱。P0 和 P1 在碱性滴定中 ,可能经历了去质子化并由胶束内层至表面的转移 ;而在酸性滴定中 ,经历了质子化 ,但未完全移至胶束界面外 ,而是存在于胶束内相对极性较强且溶剂可到达的区域。分析了取代基对卟啉在去质子化和质子化过程的影响。     

Electrostatic forces in micromanipulations: Review of analytical models and simulations including roughness

Manipulations by contact of objects between 1 m and 1 mm are often disturbed by adhesion between the manipulated object and the gripper. Electrostatic forces are among the phenomena responsible for this adhesive effect. Analytical models have been developed in the literature to predict the electrostatic forces. Most models are developed within the framework of scanning probe microscopy, i.e. for a contact between a conducting tip and a metallic surface. Models are reviewed in this work and compared with our own simulations using finite elements modeling. The results show a good correlation. The main advantage of our simulations lies in the fact that they can integrate roughness parameters. For this purpose, a fractal representation of the surface topography was chosen through the use of the Weierstrass-Mandelbrot function. Comparisons with experimental benchmarks from the literature show very good correlation between experimental results and simulations. It demonstrates the importance of surface topography on electrostatic forces at very close separation distances.     

Microwave assisted one pot synthesis of biocompatible gold nanoparticles in Triton X-100 aqueous micellar medium using tryptophan as reducing agent

The present work reports an environmentally benign process for the synthesis of gold nanoparticles via microwave-assisted heating method, using a basic amino acid l-Tryptophan as reducing agent. The synthesis was carried out in the presence of a nonionic surfactant Triton X-100 (TX-100) aqueous micellar system. Influence of various reaction parameters such as microwave irradiation time and concentrations of precursor ion were analyzed. The effect of pH on the plasmonic properties and stability of synthesized AuNPs were studied in detail. The various size distributions of gold nanostructures obtained were characterized and analyzed by ultraviolet visible spectroscopy (UV-Vis), TEM and DLS analysis. Fourier transform infrared (FT-IR) measurements were carried out to identify the interaction sites responsible for capping and efficient stabilization by the amino acid as well as the surfactant. The synthesized gold nanoparticles were stable for more than 6 months at ambient conditions.     

光谱法研究3H-吲哚探针分子与Triton X-100胶束间的相互作用

用光谱法研究了荧光分子2－（对－己基胺基）苯基－3,3－二甲基－5－乙酯基－3H吲哚基－甲基二辛基磺化铵（A）与Triton X-100胶束间的相互作用,测定了A在不同浓度的Trtiton X-100溶液中的吸收光谱,荧光光谱和荧光寿命,实验得到了A与胶束的结合常数Ks,A在胶束中所处环境的极性及其在胶束中发生的pH效应,结果表明,A与胶束间存在较强的相互作用,A在胶束中所处环境的极性及其在胶束中发生的pH效应,结果表明：A与胶束间存在较强的相互作用;A在胶束中所处环境的极性接近于甲醇的极性,并推测出了A的不同基团在胶束中所处的不同位置,同时发现：在Triton X-100胶束中A可探测到两个位置,但当Triton X-100的浓度过大时,A只能探测到一个位置。     

A Study on the Permeability of the Triton X-100 Micelles by Fluorescence Decay Kinetics of Probe Molecules

Abstract

The third armonic (355 nm) of a pulsed Nd-YAG laser has been used to excite pyrene in micellar solutions of Triton X-100. Fluorescence quenching by nitromethane and triethylamine of the excited state of pyrene in Triton X-100 has been studied. Quenching rate constant values of 4.94 ± 0.13 × 10⁸M^?1s^?1 and 1.50 ± 0.04 × 10⁸M^?1s^?1 for deactivation by nitromethane and triethylamine, respectively, have been measured. The values obtained are discussed in terms of the interface permeability.     

The formation of subsurface oxygen on Pt(100)

PhotoEmission Electron Microscopy (PEEM) enables imaging a surface via its work function. If a CO covered Pt(100) surface is exposed to oxygen patches are formed which appear dark in the PEEM image due to their high work function. As the surface is heated to temperatures above 650 K we observe the conversion of these dark islands into very bright ones with work functions much lower than even that of the clean surface. These findings are attributed to a change in the dipole moment of the adsorbed oxygen induced by their migration beneath the surface. A total work-function decrease of up to 1.2 eV has been evaluated independently using a Scanning Photoemission Microscope (SPM). The properties of this new kind of oxygen were also further investigated with thermal desorption spectroscopy and with Auger-electron spectroscopy.