Wettability of Polymeric Solids by Aqueous Solutions of Anionic and Nonionic Surfactant Mixtures

Measurements of the surface tension (γ _LV) and advancing contact angle () on poly(tetrafluoroethylene) (PTFE) and poly(methyl methacrylate) (PMMA) were carried out for aqueous solutions of sodium decyl sulfate (SDS) and p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycol) (TX100) and their mixtures. The results obtained indicate that the values of the surface tension and contact angles of solutions of surfactants on PTFE and PMMA surfaces depend on the concentration and composition of the surfactant mixtures. Calculations based on the Lucassen-Reynders equation indicate that for single surfactants and their mixtures at a given concentration in the bulk phase the values of surface excess concentration of surfactants at water–air and PTFE–water interfaces are nearly the same, so the adsorption of the surfactants at water–air and PTFE–water interfaces should also be the same. However, the adsorption of TX100 and its mixtures with SDS at water–air interface is higher than that at PMMA–water interface, which is confirmed by the ratio of absolute values of molecular interaction parameters at these interfaces calculated on the basis of Rosen approach. If we take into account the hydration of the poly(ethylene oxide) chains of TX100 and acid and base parameters of the surface tension of water it appears that the PMMA surface is covered by the 'pure' water molecules from the solution or molecules connected with the chain of nonionic surfactant. On the other hand, the lack of SDS molecules at the PMMA–water interface may result from the formations of its micelles which are connected with the TX100 chain.     

Wetting and adsorption properties of cetyltrimethylammonium bromide and Triton X-100 mixture with short-chain alcohol in polymer–solution–air system

Measurements of the contact angle of the aqueous solutions of Triton X-100 (TX-100) and cetyltrimethylammonium bromide (CTAB) mixture with methanol or propanol on the polytetrafluoroethylene (PTFE) and nylon-6 surfaces were made. On the basis of the obtained results, the Gibbs surface excess concentration of alcohol and TX-100 + CTAB mixture at the polymer–solution and polymer–air interfaces was calculated and compared to that at the solution–air one. The standard Gibbs free energy of alcohol adsorption was determined by different methods. For TX-100 and CTAB mixture, this energy was calculated using the values of critical micelle concentration (CMC) of that mixture, the surface tension and contact angle of aqueous solution of alcohol as well as the surface tension and contact angle of the aqueous solution of TX-100 and CTAB mixture with alcohol at CMC. The polymer–solution interfacial tension, the adhesion tension, and the adhesion work of the studied solutions to the polymer surface were also determined. From the obtained data, it results that the studied solutions can wet completely only the nylon-6 surface and that below alcohol critical aggregation concentration the adsorption of surfactants and alcohols at the polymer–water and water–air interfaces is similar for PTFE and different for nylon-6.     

Wettability of polytetrafluoroethylene and polymethyl methacrylate by aqueous solutions of TX-100 and TX-165 mixture with propanol

The measurements of the contact angle of the aqueous solutions of TX-100 and TX-165 mixture with propanol on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) were carried out. On the basis of the obtained results, the dependence between the cosine of contact angle and surface tension as well as between the adhesion and surface tension of the solutions in the light of the work of adhesion of the solutions to the PTFE and PMMA surface was discussed. The dependence between the adhesion and surface tension for PMMA was correlated to the surface concentration of propanol as well as TX-100 and TX-165 mixture concentration determined from the Frumkin equation at the PMMA-air, PMMA-solution and solution–air interfaces. For this purpose, the surface tension of PMMA covered by a surface active agent film was determined using the Neumann et al. equation and next the PMMA–solution interface tension was evaluated from the Young equation. The values of the surface tension of PMMA covered by propanol and surfactants mixture layer were applied to describe the changes of the adhesion work of solutions to PMMA surface as a function of propanol and surfactants mixture concentration. The adhesion work of the aqueous solutions of TX-100 and TX-165 mixture with propanol to the PTFE and PMMA surfaces was discussed in the light of the adhesion work of particular components of the solutions. On the basis of the results obtained from the contact angle measurements, the standard Gibbs free energy of adsorption of particular components of solution was also considered.     

Adsorption of Binary Mixtures of Anionic Surfactants at Water–Air and Poly(Tetrafluoroethylene)–Water Interfaces

Measurements of the surface tension (γ _LV ) and the advancing contact angle (θ) on poly(tetrafluoroethylene) (PTFE) were carried out for aqueous solutions of sodium decyl sulfate (SDS) and sodium dodecyl sulfate (SDDS) and their mixtures. The results obtained indicate that the values of the surface tension and the contact angle of solutions of surfactants on PTFE surface depend on the concentration and composition of the surfactants mixture. On the curves presenting the relationship between the surface tension, contact angle and monomer mole fraction of SDDS (α) in the mixture of SDDS and SDS, there is a minimum at α equal to 0.8 which together with the negative values of the interaction parameters indicate that synergism occurs in surface tension and contact angle reduction almost in the range of concentration corresponding to the saturated monolayer of surfactants at the water–air interface. The results and calculations obtained also indicate that for single surfactants and their mixtures at a given concentration in the bulk phase, the values of surface excess concentration of the surfactants at water–air and PTFE–water interfaces are nearly the same, which suggests that the orientation of SDDS and SDS molecules at both interfaces in saturated monolayer should be vertical to the interfaces. Taking into account the values of the monomer mole fractions of the surfactants in a mixed monolayer at the water–air interface and values of the contact angle of a single surfactant on the PTFE surface, it is possible in a simple way to predict the values of the contact angle of a mixture at a given concentration and composition.     

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.     

Correlation between adhesion of aqueous solutions of nonionic and anionic surfactant mixture with short-chain alcohols to polymer surface and their adsorption at interfaces. I. Adhesion tension and adsorption

Contact angle measurements of aqueous solutions of a p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethylene glycol) (Triton X-100)/sodium dodecylsulfate (SDDS) mixture with a short-chain alcohol (methanol, ethanol or propanol) on polytetrafluoroethylene (PTFE) and nylon-6 surfaces were made. Complete spreading of the studied solutions was observed only in the case of nylon-6. Contact angle isotherms were considered with regard to alcohol activity as well as the adsorption of the surfactant mixture and alcohol at the polymer-solution interface. For this analysis solid-liquid interfacial tension and changes of adhesion tension as a function of the surface tension of the solution were taken into account. It appeared that in the range of alcohol concentration in which it is present in the monomeric form in the bulk phase, the Gibbs surface excess concentration of the surfactant mixture and alcohol at the PTFE-solution interface is close to that at the solution-air interface. However, alcohol activity at these interfaces differ from each other. The adsorption of the surface active agents at the nylon-6-solution interface is much lower than at the solution-air interface.     

Surface tension and contact angle of herbicide solutions affected by surfactants

Contact angle and surface tension were measured for distilled and hard water solutions of adjuvants, Ortho X-77, Span-20, Sterox-NJ. Surfactant-WK, Triton B-1956, Triton X-114, Tween-20, and Sun Oil 11E. The same parameters were measured for suspensions of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] and ametryne [2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine] with and without each adjuvant. All adjuvants reduced surface tension and contact angle of distilled water; Surfactant-WK was most effective and Tween-20 was least effective. Increasing concentration of surfactants from 0 to 0.1% (v/v) gave progressive reduction in surface tension and contact angle while higher concentrations, 0.1 to 2.0% (v/v), had no further effect. Surfactant-WK at 0.1% (v/v) in distilled water reduced the surfact tension from 72.8 dynes/cm to 27 dynes/cm and contact angle from 110° to 41°. An additional increase in Surfactant-WK concentration from 0.1% (v/v) to 2% (v/v) did not further reduce surface tension and contact angle. Sun Oil 11E was identical in behavior except that it was less effective than the surfactants. Water hardness up to 1,000 ppm as Ca ions did not affect surface tension and contact angle in surfactant solutions. An aqueous solution of atrazine had a higher surface tension and contact angle than ametryne in the absence of surfactants. However, these differences were not observed when surfactants were added to either herbicide.     

Electrochemical properties of supercapacitors operating in aqueous electrolyte with surfactants

Effect of surfactants present in alkaline and acidic solutions on the capacitance of carbon electrodes has been studied. Three various types of surfactants, i.e. sodium dodecyl sulphate (SDS), tetrapropylammonium bromide (TPAB) and non-ionic such as polymer of polyethylene glycol and p-t-octylophenol (Triton X-100) have been selected for this target. Concentration of these electrolyte additives was 0.005 mol L⁻¹. Decreasing the surface tension in the electrode/electrolyte interface allows better penetration of electrolyte into the pores. However, surfactants played a different role depending on the electrode polarity. Detailed analysis of capacitance versus current load, frequency dependence as well as self-discharge and cyclability proved especially a profitable effect of Triton X-100 on capacitor operating in alkaline solution.     

Adsorption of chlorinated solvents in nonionic surfactant solutions with activated carbon in a fixed bed

The adsorption characteristics of chlorinated solvents, trichloroethylene (TCE) and perchloroethylene (PCE), in surfactant solutions with granular activated carbon (GAC) were investigated with the goal of recovering the surfactant from the effluent in surfactant enhanced remediation (SER). Triton X-100 (TX100) and X-165 (TX165) were selected as model surfactants, and the GAC was Darco 20–40. The adsorption amounts for the TX100 and TX165 onto GAC was about 0.26–0.27 g/g GAC. On a GAC fixed bed, the adsorbed amounts of TCE (0.19 g/g) and PCE (0.35 g/g) in the TX165 (10 g/L) solution onto the GAC were higher than those for TCE (0.16 g/g) and PCE (0.24 g/g) in the TX100 (10 g/L) solution. Because the ratio of surfactants/chlorinated solvents in the ordinary effluent of SER is higher than 1, activated carbon adsorption could be used as an alternative of post-treatment method in SER.     

Some Surface Properties of Polysorbates and Cetyl Trimethyl Ammonium Bromine Mixed Systems

Mixed surfactant solutions consisting of cationic/nonionic surfactants were prepared in different compositions of the components in aqueous solution in order to determine the surface properties. The critical micelle concentration (CMC) of aqueous solutions of the individual surfactants cetyl trimethyl ammonium bromide (CTAB) and polysorbate nonionics, and their mixtures are determined at different proportions. The results show that there is synergistic behavior in mixtures at higher mole fraction of nonionic surfactant. The effect of the alkyl chain on the CMC is also determined.     

Adsorption of ethoxylated alkylphenol–formaldehyde polymeric surfactants at the aqueous solution–air interface

The adsorption behaviour of some ethoxylated alkylphenol–formaldehyde polymeric non-ionic surfactants, at the aqueous solution–air interface, was investigated by measuring the surface tension (γ) as a function of concentration (C) at four temperatures. By applying the Gibbs adsorption equation to the γ versus C data, the adsorption isotherms of these polymeric surfactants were obtained. Surface concentration (Λ) of the investigated polymeric non-ionics was found to increase with decreasing temperature and decreasing hydrophobic group (R) chain length, while varying the length of polyoxyethylene chain (%EO) appeared to have an insigificant effect. Effects of temperature, %EO and chain length R on the surface pressure (π) of the surfactant solutions were also investigated.     

Mixed Micellar and Interfacial Interactions of a Triblock Polymer (EO37PO56EO37) with a Series of Monomeric and Dimeric Surfactants

The mixed micellar and interfacial properties of mixtures of triblock polymer (TBP) with a series of monomeric (dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and cetyltrimethylammonium bromide, and dimeric (dimethylene bis[alkyldimethylammonium bromide], m-2-m, where m = 10, 12, and 14) cationic surfactants were investigated using surface tension and viscosity measurements in aqueous solutions at different temperatures. Various physicochemical properties such as critical micelle concentration, mixed micellar mole fraction, interaction parameter, interfacial, and thermodynamic parameters were evaluated. All the binary mixtures exhibit synergistic interactions which increase with temperature and pass through a minimum with the increase in hydrophobic chain length of the cationic surfactants. The contribution of TBP in mixed micelle formation also increases with the hydrophobic chain length of the surfactants. The interfacial and thermodynamic parameters reveal that the adsorption of the surfactant mixtures at the air–solution interface is more favorable than that of micelle formation and the unfavorable enthalpy changes are overwhelmed by favorable entropy changes. Further, the mixtures of TBP with smaller chain length surfactants show a sharp rise in relative viscosity at higher mole fractions of these surfactants.     

Surface tension,adsorption, and wetting behaviors of natural surfactants on a PTFE surface

The adsorption kinetics and wetting behaviors of three plant‐based natural surfactants (Reetha, Shikakai, and Acacia) on the polytetrafluoroethylene (PTFE) surface are reported in this study. Adsorption studies of these surfactants on PTFE surface show the equilibrium adsorption time is approximately 15 min, and Langmuir‐type isotherm fits well for all three surfactants. The contact angle measurements show that the value achieved by Reetha and Acacia solutions are close (～109°), but that is low in the case of Shikakai (98.13°). Although, comparing the adsorption densities of the surfactants at PTFE–water and air–water interfaces, it has been found that adsorption densities at the PTFE–water interface are low for all three surfactants than that of air–water interface. The alcohol–Shikakai mixed solutions show nonideal behavior of surface tension reduction through a strong interaction between alcohol and Shikakai molecules, which in turn, show lower surface tension and contact angle values than that of ideal. © 2014 American Institute of Chemical Engineers AIChE J, 61: 655–663, 2015     

Behavior of Anionic Surfactants and Short Chain Alcohols Mixtures in the Monolayer at the Water–Air Interface

Measurements of the surface tension of aqueous solution of mixtures of sodium dodecyl sulfate (SDDS) with methanol and ethanol in SDDS concentration range from 10⁻⁵ to 10⁻² M and mixtures of sodium hexadecyl sulfonate (SHS) with methanol and ethanol at SHS concentration from 10⁻⁵ to 8 × 10⁻⁴ M and for methanol and ethanol from 0 to 21.1 and, 11.97 M, respectively, were carried out at 293 K. Moreover, the surface tension of aqueous solution mixtures of SDDS with propanol in the concentration range from 0 to 6.67 M taken from the literature was also considered. The results obtained indicate that it is possible to describe the relationship between the surface tension and molar concentration or molar fraction of alcohol by Szyszkowski and Connors equations. However, the Fainerman and Miller equation allows us to predict the isotherm of the surfactant tension at constant anionic surfactants concentration at which their molecules are present in the solution in the monomeric form if the molar area of surfactants and alcohols can be determined. Based on the surface tension isotherms, the Gibbs surface excess of anionic surfactants and alcohols concentration at water–air interface was determined and then recalculated for Guggenheim-Adam surface excess concentration of these substrates, and next the molar fraction of alcohols and surfactants in the surface layer was determined. These molar fractions were discussed with regard to surfactant and alcohol standard free energy of adsorption at the water–air interface determined from Langmuir and Aronson and Rosen equations. The standard free energy of adsorption determined in these ways was compared to that deduced on the basis of pC₂₀ and Lifshitz van der Waals-components of the anionic surfactant and alcohol tails.     

Effect of hydrotropes on the aqueous solution behavior of surfactants

Aqueous solutions of surfactants—cationic: tetradecyltrimethylammonium bromide (C₁₄TABr); anionic: sodium dodecyl sulfate (SDS); and nonionic: polyoxyethylene t-octylphenol (trade name Triton X-102, also called OPE-8)— in the presence of three hydrotropes, viz., sodium xylene sulfonate, sodium p-toluene sulfonate, and sodium chlorobenzene sulfonate, were examined by measuring surface tension, viscosity, and cloud points for the nonionic surfactant. The results show a marked decrease in the critical micelle concentration with increase in hydrotrope concentration for C₁₄TABr, a marginal decrease for SDS, and very little change for OPE-8 up to 0.1 M hydrotrope. The viscosity of cationic surfactant solutions showed a remarkable increase in the presence of trace amounts of hydrotropes (up to 15 mM). In contrast, the SDS solution showed only a slight increase in viscosity at high hydrotrope concentration (150 mM), and the viscosity of the OPE-8 solution remained constant. The cloud point of OPE-8 increased in the presence of hydrotropes, unlike its behavior with the simple salt NaCl. The strong dependence of the solution behavior of cationic surfactants on the presence of hydrotropes is discussed in terms of electrostatic interaction.     

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.     

Behavior of Cetyltrimethylammonium Bromide, tert-Octylphenol (9.5 EO) Ethoxylate and Ethanol Mixtures at the Water–Air Interface

The surface tension measurements of aqueous solutions of p‐(1,1,3,3‐tetramethylbutyl)phenoxypoly(9.5)ethylene glycol or tert‐octylphenol ethoxylate (TOP10) and cetyltrimethylammonium bromide (CTAB) mixtures with ethanol were carried out in the range of the total concentration of CTAB and TOP10 mixtures from 1 × 10^?7 to 1 × 10^?2 M and ethanol from 0 to 17.13 M. In the CTAB and TOP10 mixtures, the mole fractions of TOP10 were equal to 0.2; 0.4; 0.6; and 0.8, respectively. The results obtained were compared to those calculated from the Fainerman and Miller equation developed for ideal mixtures of two homologous surfactants, as well as from the Connors equation derived for the concentrated organic solutions. The calculations of the surface tension from the Fainerman and Miller equation were carried out treating the solvent and solute in a few different ways. The differences between the measured and calculated values of the surface tension were discussed in the light of molecular interaction parameter and the composition of the surface layer. The composition of the mixed surface layer at the solution‐air interface was evaluated according to Rosen using the nonideal solution theory with the assumption that water with ethanol is a mixed solvent. Knowing the values of mole fractions of CTAB and TOP10 in the surface layer, the molecular interaction parameter was determined.     

Influence of Temperature on the Surface Tension of Triton Surfactant Solutions

The surface tension of different Triton surfactants (X-100, X-405, and X-705) with or without adding sodium chloride was measured in the temperature range between 20 and 40°C using the maximum bubble pressure method. Rising temperature reduced the surface tension of Triton surfactants via disrupting the H-bonds between the ethylene oxide (EO) group and water. Increasing the number of the EO groups created the steeper thermal gradient of the surface tension. The data indicated that EO-water bonds are easier to be broken by rising temperature than the water–water H-bonds, with an entropy change of −0.535 J deg⁻¹ per mole of EO. The presence of NaCl decreased the surface tension for all systems. However, NaCl produced a synergistic effect with surfactants on the surface tension.     

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.     

Effect of tartrazine dye on micellisation of cationic surfactants: conductometric,spectrophotometric, and tensiometric studies

The interactions between anionic dye (tartrazine) and cationic surfactants (dodecyltrimethylammonium bromide and cetyltrimethylammonium bromide) have been studied by conductometric, spectrophotometric, and tensiometric techniques. The conductance and surface tension of dodecyltrimethylammonium bromide and cetyltrimethylammonium bromide in pure water as well as in aqueous tartrazine when plotted with surfactant concentration gave values of the critical micelle concentration at different temperatures. As well as increasing the length of the carbon chain of surfactants, the presence of tartrazine reduces the critical micelle concentration. From specific conductivity data, the counterion dissociation constant, standard free energy, enthalpy, entropy of micellisation, surface excess concentration, surface tension at critical micelle concentration, minimum area per molecule, surface pressure at critical micelle concentration, and Gibbs energy of adsorption were evaluated. Spectroscopic studies reveal that the binding of dye to micelles brings a bathochromic shift in dye absorption spectra that indicates dye–surfactant interaction.