ADSORPTION OF ETHOXYLATED NONIONIC SURFACTANTS FROM SILOXANE-BASED SOLVENT AND AQUEOUS SYSTEMS: USE OF QCM AND MODEL POLYMERIC SURFACES

Adsorption behavior was quantified with pure ethoxylated nonionic surfactants onto different polymeric surfaces (hydrophilic cotton and hydrophobic polyester) and model hydrophilic gold surface. The polymer materials used for the study were characterized using SEM. The role of ethylene oxide group variation in surfactant-polymer interaction was established using pure surfactant with the same alkyl chain length but varying ethoxylate chain lengths. It was observed that surfactant with more ethylene oxide groups per molecule, being more hydrophilic, interacts favorably with cotton in the hydrophobic siloxane solvent environment. The adsorption of the pure surfactants on model gold surface from hydrophobic solvent and water was also established using the quartz crystal microbalance with dissipation monitoring (QCM-D) system. Effect of ethylene oxide chain length and surfactant concentration on the extent of adsorption was quantified. At the gold-water interface, the plateau adsorption for C₁₂ E₃ (15.9 × 10^?6 mole/m²) is about four times higher than for C₁₂E₈. An opposite trend was observed for adsorption of the surfactants on gold in the hydrophobic D5 environment. Information about thickness, adsorption and desorption kinetics, and structure of adsorbed layer was obtained from the QCM-D frequency-dissipation data. The study is an important contribution towards fundamental understanding of applications involving the use of ethoxylated nonionic surfactants.     

Dispersing Carbon Nanotubes in Aqueous Solutions of Trisiloxane‐Based Surfactants Modified by Ethoxy and Propoxy Groups

Silicone surfactants favor spreading at interfaces and siloxane has strong interaction with carbon nanotubes (CNT), thus silicone surfactant may be a good dispersant of CNT. Here, four silicone surfactants (named S1E19, S2E38, S2E16 and S1E16P8) were used to disperse CNT in aqueous solutions. The effects of surfactant structure and concentration on the ability at dispersing CNT were considered. All of the four silicone surfactants can disperse CNT in aqueous solution and the sample with 1,000 mg L^?1 S1E16P8 was the best one. The hydrophilic group polyoxyethylene (PEO) and the hydrophobic groups siloxane and polypropylene (PPO) are crucial factors in the ability of dispersing CNT. S2E38 with more ethylene oxide (EO) groups has a stronger ability to disperse CNT than S2E16. The dispersion system provided by S1E19 which contains fewer siloxane and EO groups is relatively unstable and disperses less CNT. These experimental results are explained by molecular dynamics simulation. S2E38 compared with S1E19 and S2E16 has stronger interactions with CNT. The interaction energy of CNT with S1E16P8 which has a PPO moiety but fewer siloxane groups is close to that of S2E16. Furthermore, it can be concluded that these four surfactants are adsorbed on CNT mainly by van der Waals forces and the Si–O–Si chain of silicon surfactant was flexible due to the long Si–C bond and it could easily wrap onto the surface of CNT through hydrophobic and other intermolecular interactions. The hydrophilic part of PEO helped the CNT dispersed in the aqueous solution and prevented CNT from aggregating in water through steric stabilization.     

有机硅表面活性剂的研究进展及在纺织、染整等领域的应用

该文对有机硅表面活性剂的结构特征和性能做了简要的介绍,同时按照有机硅表面活性剂在水中电离情况分为阳离子、阴离子、非离子和两性有机硅表面活性剂,并对各自的研究进展和应用做了介绍。     

Experimental Study on Foam Properties of Mixed Systems of Silicone and Hydrocarbon Surfactants

Silicone surfactants are inevitably involved in industrial applications in combination with hydrocarbon surfactants, but properties of the mixtures of silicone and hydrocarbon surfactants have received little attention, especially foam properties of the mixtures. In this study, aqueous solutions of respective binary mixtures of a nonionic silicone surfactant with anionic, cationic, and nonionic hydrocarbon surfactants were prepared for evaluation of their foam properties. Surface tension of aqueous solutions of the mixtures were measured with the maximum bubble pressure method. Foaming ability and foam stability of the mixtures were then evaluated with the standard Ross–Miles method. The findings show that the addition of the silicone surfactant results in a decrease in surface tension for aqueous solutions of the hydrocarbon surfactants. The critical micelle concentration (CMC) of the hydrocarbon surfactants is also changed by the additive silicone surfactant. Additionally, clear foam synergistic effects were observed in the mixtures of silicone and hydrocarbon surfactants, regardless of the ionic types of the hydrocarbon surfactant. The foam stability of the hydrocarbon surfactant was shown to generally improve with the increasing concentration of the silicone surfactant. Even so, aqueous solutions of different ionic hydrocarbon surfactants in the presence of the silicone surfactant will give different foam stabilities. The results of the present study are meant to provide guidance for the practical application of foams generated by the mixtures of the silicone and hydrocarbon surfactants.     

聚醚改性硅油表面性质的研究

对实验室自制聚醚改性硅油(以下简称硅醚)的表面张力及浊点进行测定,并对其表面性质的特征及趋势进行了研究。结果表明,随硅醚质量浓度的增加,硅醚水溶液的表面张力值下降,硅醚质量浓度增至约0.01 g/L后,表面张力值降幅渐缓,其表面张力最低值为29~42 mN/m;随着硅醚侧链聚醚中环氧丙烷链段所占比例增加,其水溶液的浊点略有下降,质量浓度约为0.1 g/L的硅醚以侧链聚醚结构n(EO)∶n(PO)=1∶4的硅醚的浊点最小,为9.5℃;随体系温度上升,质量浓度约为0.01 g/L的硅醚水溶液的表面张力降幅小于同样质量浓度的甲基硅油加乳化剂A25(硬脂醇/脂肪醇醚-25)的水溶液,并求得质量浓度约为0.01 g/L不同环氧乙烷与环氧丙烷摩尔比的硅醚的表面张力随体系温度下降的系数及方程,根据实验建立的方程所得的某温度下表面张力的计算值与实测值之间的平均相对偏差为7%。     

Mixed Micelles of Trisiloxane Based Silicone and Hydrocarbon Surfactants Systems in Aqueous Media: Dilute Aqueous Solution Phase Diagrams, Surface Tension Isotherms, Dilute Solution Viscosities, Critical Micelle Concentrations and Application of Regular Solution Theory

Mixtures of trisiloxane type nonionic silicone surfactant (SS) with sodium dodecylsulfate, tetradecyltrimethylammonium bromide or tert-octylphenol ethoxylated with 9.5 ethylene oxide groups were studied in water at 30 °C by dilute aqueous solution phase diagrams, surface tension and dilute solution viscosity methods. The cloud points for the silicone surfactant aqueous solutions increased upon addition of hydrocarbon surfactants indicating the formation of hydrophilic complexes in mixture solutions. The scrutiny of the surface tension isotherms plotted as a function of SS concentration revealed that competitive adsorption effects are the characteristic features in these mixtures depending upon the SS concentration. Otherwise the isotherms exhibited two break points and the difference of concentration between the two break points increased with the increase in SS concentration indicating the cooperative nature of interactions. The micellar mole fractions of individual surfactants were determined by Rublingh's regular solution theory; interaction parameters and activity coefficients were evaluated and interpreted in terms of synergistic type interactions in these mixtures. The surface active parameters in mixture solutions were estimated and their analysis shows that the molecular species in the mixture solutions have a preferential tendency for adsorption at the air/water interface than in association form in the bulk solution. The effect of hydrocarbon surfactants on the intrinsic viscosity of SS micelles was monitored and related to the enhanced hydration in mixed micelles.     

Mechanistic Studies of Particulate Soil Detergency: I. Hydrophobic Soil Removal

The mechanism of particulate soil detergency using aqueous surfactant systems is not well understood. In this research, carbon black (model hydrophobic soil) removal from a hydrophilic (cotton) and hydrophobic (polyester) fabric is studied using anionic, nonionic, and cationic surfactants. The zeta potential, solid/liquid spreading pressure, contact angle and surfactant adsorption of both soil and fabric are correlated to detergency over a range of surfactant concentrations and pH levels. Electrostatic repulsion between fabric and soil is generally found to be the dominant mechanism responsible for soil removal for all surfactants and fabrics. Steric effects due to surfactant adsorption are also important for nonionic surfactants for soil detachment and antiredeposition. Solid/liquid interfacial tension reduction due to surfactant adsorption also aids in detergency in cationic surfactant systems. Wettability is not seen as being an important factor and SEM photos show that entrapment of soil in the fabric weave is not significant; the particles are only attached to the fabric surface. Anionic surfactants perform best, then nonionic surfactants. Cationic surfactants exhibit poor detergency which is attributed to low surfactant rinseability.     

非离子系高分子表面活性剂的研究进展

综述了聚乙烯醇类、聚酯类、纤维素基类和糖基类非离子系高分子表面活性剂的进展过程以及这些非离子表面活性剂的制备反应和一些用途；介绍了非离子系高分子表面活性剂不同于低分子表面活性剂的优良表面活性性能和特有性能，讨论了影响这些性能的内在因素和外在因素以及性能和各种内在因素的关系。     

Adhesion of latex films. Part II. Loci of failure

In order to continue our work on surfactant effects on the adhesion properties of latex films, we investigated a new system based on an acrylic copolymer, synthesized in the presence of a hydrophilic polyester. The surfactants were either sodium dodecyl sulfate (SDS) or an ethoxylated nonyl phenol containing 30 ethoxy groups (NP30). As substrates, either glass plates or poly(ethylene terephthalate) (PET) films were used. This article describes the analysis of the loci of failure after peeling of the films. The analytical techniques used were X-ray photoelectron spectroscopy (XPS) (or ESCA), static secondary ion mass spectrometry (SSIMS), and contact angle measurements. It was shown that the loci of failure were independent of the peel rate and of the nature of the substrate. The failure occurs in a thick surfactant layer for SDS, and in a thin one for NP30. The thickness of the layer increases with the concentration of surfactant in the latex film. The surfactant is located near the surface of the substrate, on top of a layer of hydrophilic polyester. The consequences of the structure of the film-substrate interface on the adhesion properties is presented in Part III in this series.     

Surfactant properties of low molecular weight phospholipids

Surface tensions, critical micelle concentrations (CMCs), contact angles on hydrophobic polyethylene, and foaming characteristics of phosphatidic acids, phosphatidylcholines, phosphatidylethanolamines, and phosphatidylglycerols were measured to determine their suitability as substitutes for traditional surfactants. These phospholipids have fatty acid chains of 5 to 12 carbon atoms, a range over which they are soluble at room temperature. Their surface tensions decrease with increasing concentrations until their CMCs are reached, above which their plateau surface tensions are as low as 21 mN/m, indicating excellent surface activities. In general, plateau surface tensions decrease with increasing chain length within each phospholipid type. The classical relationship for In CMC vs. chain length is followed with slopes typical of anionic surfactants for phosphatidic acids and phosphatidylglycerols and resembling zwitterionic surfactants for phosphatidylcholines and phosphatidylethanolamines, consistent with the charge on the hydrophilic group. The wetting capabilities of aqueous solutions on polyethylene are good and foam heights and stabilities are high, the latter two properties being comparable to traditional anionic (sodium dodecylsulfate) and nonionic (octylphenol polyethoxylate) surfactants. Some anomalies are observed regarding the effect of chain length on wetting and foaming, probably due to the depletion effect. Many phospholipids slowly degrade in aqueous solution. We conclude that short-chain phospholipids exhibit excellent surfactant properties and may be useful in many applications.     

有机硅表面活性剂在日化及纺织行业的应用

概述了有机硅表面活性剂的种类及其在日化，纺织行业的应用状况，阳离子型有机硅表面活性剂具有抗菌，抗静电，柔软，滑爽等特点，可广泛用作织物抗菌整理剂，柔软整理剂及头发调理剂，阴离子型有机硅表面活性剂具有超低的表面张力，广泛用作湿润剂，亲水剂，乳化剂，流平剂，消泡剂等。     

Surface adsorption in the mixtures of sodium dodecylsulphate and oxyethylenated nonylphenol with different oxyethylenation degrees

The effectiveness of surface adsorption in an aqueous solution of mixtures of surfactants composed of an anionic surfactant, sodium dodecylsulphate, mixed with a nonionic one, polyoxyethylenated nonylphenol, was studied. Their behavior was compared separately. This surface adsorption was characterized by the values of the surface tension at 25°C of the total concentrations below, but near to the critical micelle concentration (CMC) in the mixtures mentioned. These were obtained as a function of different proportions of surfactants in the mixture and different chain lengths of nonionic polyoxyethylenated surfactant. The total surface excess concentrations of the surfactant mixtures and the average of molecular area per surfactant species at the aqueous solution/air interface were calculated. Finally, the values were analyzed vs the above parameters. Presented at the XDCth Meetings of CED/AID, Granada, Spain, March, 1988.     

Surfactant effect on production of monodispersed microspheres by microchannel emulsification method

Super-monodispersed oil-in-water (O/W) microspheres (MS) were produced using a microchannel (MC) emulsification technique. To investigate the effect of the surfactant on the behavior of the O/W-MS formation, the MS size and its distribution, various surfactants were used for the MC emulsification process. An MC plate with 8.9 μm equivalent diameter was employed. It was found that the super-monodispersed O/W-MS production depends on the type of surfactant used. When nonionic and anionic surfactants were used, supermonodispersed O/W-MS were produced, and the average droplet diameter was about 30 μm with a standard deviation less than 1 μm. For cationic surfactants, the super-monodispersed O/W-MS production was not successful, especially for the case where hydrophobic surfactant was dissolved in the oil phase. The results indicated that it is very important to maintain the hydrophilicity of the MC surface during the MC emulsification process. It is considered that the hydrophilic group of the anionic and nonionic surfactant was repulsed from the negatively charged MC surface so that the hydrophilicity of the MC surface was maintained. Otherwise, adsorption of the positively charged group of the cationic surfactant occurred on the MC surface which improved wetting of the MC surface and deteriorated the MC emulsification process. The analysis was supported by contact angle measurement.     

磺酸盐型双基表面活性剂的合成与表面性能

以壬基酚和甲醛为原料,合成了一种新型的磺酸盐型双基表面活性剂(Gemini-A)。利用元素分析、红外光谱确定了Gemini-A的结构。研究了Gemini-A水溶液的润湿性,比较了Gemini-A与传统表面活性剂的增溶能力。试验结果表明,Gemini-A水溶液具有较低的表面张力(33.51 mN/m)和临界胶束浓度(0.141 mmol/L)及良好的润湿性,显示出了较好的表面性能,具有很强的增溶能力,是符合3次采油要求的表面活性剂。     

非离子型Gemini表面活性剂的性质

Gemini表面活性剂具有的优良表面活性,使之有望作为三次采油用的表面活性剂。用界面张力仪及HAAKERS600流变仪研究了非离子型Gemini表面活性剂的表面活性及流变特性。结果表明,25℃下,氧乙基数(EO数)分别为8,10,12的3种非离子型Gemini表面活性剂8-NP-8、10-NP-10及12-NP-12的临界胶束浓度(cmc)值分别为:0.99,0.15和0.032 mmol/L;非离子型Gemini表面活性剂的表面活性及cmc值受电解质的影响较小;氧乙基数为12的非离子型Gemini表面活性剂可以使亲水及亲油固体表面的接触角明显降低,水润湿性增强;非离子型Gemini表面活性剂溶液的粘度随剪切速率增加基本保持不变,呈现出牛顿流体的特性。     

Surface Properties and Solubility Enhancement of Anionic/Nonionic Surfactant Mixtures Based on Sulfonate Gemini Surfactants

As a class of novel surfactants, Gemini surfactants usually exhibit fairly excellent interfacial properties in aqueous solutions on account of the unique structure. They have significant application and development potential for industrial production. However, the mixing properties of Gemini surfactants with conventional surfactants are the key to their application. The equilibrium surface tension curves of anionic/nonionic surfactant mixtures based on the sulfonate Gemini surfactant (SGS-12) were measured using the Wilhelmy Plate method. The parameters of surface adsorption, the interaction parameters between anionic and nonionic surfactants, and the thermodynamic parameters of micelle formation were calculated from the corresponding equations. In addition, the dynamic surface tension (DST) curves of anionic/nonionic surfactant mixtures were examined through bubble profile analysis, and the diffusion performance parameters were acquired from empirical formulas. The solubilization of pyrene in micelle solutions was studied using UV–vis absorption spectroscopy. The results show that the interaction parameters of all anionic/nonionic surfactants are negative, indicating that there is a synergistic effect on reducing the surface tension. For the SGS-12/OP-10, SGS-12/Tween 80, SGS-12/AEO9, and SGS-12/APG0810 mixtures, the optimum mixing ratios are 6:4, 7:3, 7:3, and 8:2, respectively. The thermodynamic data of micelles show that the formation of mixed micelles for SGS-12/APG0810 mixtures is an enthalpy-driven process. The tendency of DST curves of the SGS-12/APG0810 mixture is similar to that of SGS-12. In comparison with single-surfactant solutions, the anionic/nonionic surfactant mixtures show stronger solubilization capacity toward pyrene.     

Poly(oxyethylene)diamine‐derived hydrophilic copolymers for emulsifying diglycidylether of bisphenol‐A

A series of reactive surfactants were synthesized by the reaction of hydrophilic poly(oxyethylene)diamines of 2000–6000 g/mol molecular weight and diglycidylether of bisphenol‐A resin. The synthesized surfactants consisted of multiple functionalities including tertiary amines, hydrophobic alkylphenoxys, and reactive oxirane groups. After treatment with hydrochloric acid, the surfactants consisted of two different hydrophilic groups: cationic quaternary ammonium salts and nonionic oxyethylene segments. By prudent selection of the proper hydrophile–lipophile balance, the surfactant can be highly effective for solubilizing the epoxy resin in water to form a stable emulsion at a fine particle size of 350 nm. Another advantage is that the surfactant may participate in a curing process through the built‐in oxirane reaction and become a nonextractable component in polymer matrix. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1797–1802, 2004     

室温硫化硅橡胶乳液的制备与性能

通过乳液转相点法,制备了稳定性好的嵌段甲基硅橡胶纳米乳液。研究了表面活性剂的化学结构、亲水亲油平衡值对硅橡胶乳液稳定性的影响;确定了非离子乳化剂和阴离子乳化剂的复配体系;研究了复合乳化剂的复配比例和添加量对硅橡胶乳液稳定性的影响;分析了乳液转相点法的相转变机理。对硅橡胶乳液交联固化得到的弹性体的性能进行了表征。结果表明:当非离子乳化剂聚氧乙烯月桂醚和阴离子乳化剂十二烷基苯磺酸钠以物质的量比1∶1进行复配,复合乳化剂添加量10%时,硅橡胶乳液的粒径为57 nm,以3 000 r/min的速度离心30 min仍能保持稳定;固化得到的弹性体密度0.98 g/cm ³,邵A硬度43,拉伸强度1.69 MPa,断裂伸长率178.68%,各项指标均与溶剂型硅橡胶弹性体较为接近。     

Solubilisation of dyes by surfactant micelles. Part 1; Molecular interactions of azo dyes with nonionic and anionic surfactants

An ultraviolet-visible spectroscopic investigation has been made of the interactions of a specially synthesised series of substituted, model arylazonaphthol dyes with nonionic and anionic surfactants. Changes in spectral features were recorded above the critical micelle concentrations, suggesting specific interactions of dyes with micelles of the respective surfactants. The affinity of the dye for the surfactant micelles increased when various p -substituent were incorporated in to the dyes. Similarly, there was a shift in azo–hydrazone tautomeric equilibria and an increase in measured dye p K _a values. Models are proposed for the location of dyes in nonionic or anionic micelles. Unlike earlier studies, it is concluded that the solubilised dye experiences only one environment in nonionic micelles but the specific location, i.e. whether preferentially incorporated in the hydrophobic micellar interior or in the more hydrophilic, outer polyoxyethylene layer, depends upon the nature of the substituent.     

温度及无机盐对LMEE和SDS混合溶液表面张力的影响

通过表面张力的测定,研究了温度和不同无机盐对月桂酸甲酯乙氧基化物(laurylmethylesterethoxylate,简称LMEE)与十二烷基硫酸钠(SDS)复配物表面张力及临界胶束浓度(CMC)的影响。研究表明:混合体系的CMC在很宽的复配比例内出现最低值,25℃、未加无机盐时可使CMC最低降至3 8×10-5mol/L;温度对复配体系表面张力的影响较小,温度上升复配物的CMC略有降低。3种价态无机盐的加入均可使复配物的CMC有所降低,但与单一表面活性剂相比,温度和无机盐对复配物的CMC影响均不大,说明复配体系的抗温变及抗盐能力均有增强。