Synthesis and Aqueous Solution Properties of Polyoxyethylene Surfactants with Ultra-Long Unsaturated Hydrophobic Chains

Methoxypolyethylene glycols (M _n = 750, 1000, 2000, and 5000 g/mol) were hydrophobically modified by transestification with mono-unsaturated alkyl chains (UC18, UC22, and UC24), and the obtained ultra-long-chain nonionic surfactants were characterized by ¹H NMR, FTIR and gel permeation chromatographic, respectively. Aqueous solution properties of all these surfactants, including cloud point, surface activities, viscosifying ability, and phase diagrams were examined. It was found that all these ultra-long-chain polyoxyethylene surfactants exhibit good water solubility and typical Newtonian rheological behavior. For the surfactants with the same hydrophobic length, the CP, equilibrium surface tension (γ_cmc), as well as zero-shear viscosity (η₀) increase with increasing their hydrophilic length; for those with same hydrophilic head group, the critical micellar concentration and η₀ increase while the γ_CMC decreases with increasing hydrophobic tail length. Moreover, a decrease in the critical overlap concentration and an increase in the critical temperature were observed in phase diagrams of all these ultra-long-chain polyoxyethylene surfactants. (Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Dispersion Science and Technology to view the free supplemental file.)     

Spectrophotometric and Thermodynamic Studies of Micellar Interaction of Surfactants with p-Nitrophenol

Interaction of p-nitrophenol (NPH) with various surfactants, viz., cetylpyridinium chloride (cationic), sodium dodecylsulphate (anionic) and Triton X-100 (nonionic) are studied spectrophotometrically, in aqueous-micellar medium. The interactions are of electrostatic as well as hydrophobic nature. The strength of interaction is represented in terms of the equilibrium constants and other thermodynamic quantities of formation of the p-nitrophenol-micelle donor-acceptor complexes in addition to a shift in the acid-base equilibrium of NPH. The interaction between NPH and CPC is much stronger that with Triton X-100 whereas the interaction with SDS is very weak. Formation of 1:1 charge transfer (or electron donor-acceptor) complex is evidenced from the results. The interaction of NPH is enthalpy driven with CPC and entropy driven with Triton X-100.     

Density and viscosity studies of poly(ethylene-oxide) alkyl alcohols

Density and viscosity of binary systems water-nonionic surfactants poly(ethylen-oxide) alkyl alcohols type, [C_nH_2n+1(OCH₂CH₂)_mOH, C_nE_m], have been studied. The partial molar volumes in the dilute solution range and the viscosity B-coefficients were calculated. The nonionic surfactants partial molar volumes were compared with those of ethylene glycol and poly(ethylenglycol) (PEG). The comparison shows that the ethoxy unit volume, (OCH₂CH₂), seems to be independent of the particular system. The consequences of this are discussed. A model for interpreting the experimental B values has been proposed. The model treats the macroscopic viscosity as the superimposition of different local effects. The following surfactants have been considered: C₅E₁, C₅E₂, C₆E₁, C₆E₂, C₆E₃, C₆E₄.     

聚合物对非离子十二烷基聚氧乙烯聚氧丙烯醚浊点的影响

测定了水溶性高分子聚乙二醇(PEC1000、PEG2000、PEG6000)和聚乙烯吡咯烷酮(PVP-K30、PVP-K90)对三种非离子表面活性剂十二烷基聚氧乙烯聚氧丙烯醚C12H25O(EO)m(PO)nH(LS36,m=3,n=6;LS5,m=4,n=5;LS54,m=5,n=4)浊点的影响.结果表明,聚乙二醇(PEG)可使三种表面活性剂水溶液浊点降低;而聚乙烯吡咯烷酮(PVP)随其浓度增加,表面活性剂溶液浊点先升高然后又下降;浊点下降程度与聚合物浓度和分子量有关.     

两亲无规聚合物的聚集行为及其与非离子表面活性剂的相互作用

以2-丙烯酰胺基-十二烷基磺酸(AMC12S)与2-丙烯酰胺基-2-甲基丙磺酸(AMPS)进行无规共聚,合成了含AMC12S摩尔分数(X)较高(X=0.1,0.3,0.5)的一系列两亲聚合物.采用稳态荧光及动态光散射技术对聚合物在水溶液中的聚集行为及其与三种非离子表面活性剂(HO(CH2CH2O)10C12H25(C12E10)、HO(CH2CH2O)20C12H25(C12E20)和HO(CH2CH2O)40C12H25(C12E40))的相互作用进行了研究,并考察了X对聚集行为的影响以及表面活性剂亲水基团长度对相互作用的影响.随着X的增大,聚合物的临界聚集浓度(CAC)明显减小,X=0.5时聚合物的CAC低达0.0039g·L-1.聚集体的流体力学半径(Rh)都大于26nm,并随着聚合物浓度的升高而增大,说明聚合物分子主要以分子间的聚集方式聚集,形成多分子聚集体.随X的增大,聚集体Rh减小,同时Rh随聚合物浓度升高而增大的幅度减小,说明聚集体结构变得更加紧实.表面活性剂与聚合物之间存在很强的相互作用,在混合溶液中表面活性剂浓度达到临界胶束浓度(CMC)左右时聚合物聚集体开始解离,形成混合聚集体.亲水基团长度增长,表面活性剂对聚合物聚集体的解离能力随之增强.C12E40与X=0.5的聚合物形成的混合聚集体Rh为6.8nm,与C12E40自身形成的聚集体尺寸相当.     

Synthesis,Micellar and Surface Properties of Cationic Trisiloxane Surfactants with Different Siloxane Hydrophobic Groups

Three cationic trisiloxane surfactants, 1-methyl-1-[bis(trimethylsiloxy)methyl]silyl-propylpyrrolidinium chloride (Si₃pyCl), 1-methyl-1-[bis(triethylsiloxy)methyl]silyl-propylpyrrolidinium chloride (Et-Si₃pyCl), and 1-methyl-1-[bis(vinyldimethylsiloxy)methyl]silylpropylpyrrolidinium chloride (Vi-Si₃pyCl) were synthesized. The aggregation behavior of the trisiloxane surfactants with different siloxane hydrophobic groups in aqueous solution was investigated by surface tension and electrical conductivity measurements. The structures of hydrophobic groups of the trisiloxane surfactants can obviously influence their surface activities and thermodynamics. All the three cationic trisiloxane surfactants have excellent surface activity. Owing to the steric hindrance of hydrophobic groups, the CMC values increase following the order Et-Si₃PyCl?<?Vi-Si₃PyCl?<?Si₃PyCl. The \(\Delta G_{\text{m}}^{\text{o}}\) values increase in the order Et-Si₃PyCl?>?Vi-Si₃PyCl?>?Si₃PyCl, attributed to the decrease in the hydrophobic effect. The micellization processes of these surfactants are entropy-driven.     

非离子表面活性剂的吸附机理和表面胶团化对二氧化硅悬浮液稳定性的影响

测定了CAB-O-SIL在290.7K和304.2K时自水和1mol/LNaCl溶液中吸附非离子表面活性剂TritonX-100(TX100)的吸附等温线。结果表明,吸附量随温度升高而增加。NaCl的存在也使吸附量增加。运用生成表面胶团的吸附理论处理了实验结果,求得了表面胶团化的平衡常数、表面胶团的平均聚集数、临界表面胶团浓度和表面胶团化的标准热力学函数。实验表明,随TX100浓度的增大,CAB-O-SIL悬浮液稳定性出现不规则的变化。加入NaCl的效应是使悬浮液的稳定性下降和促进表面胶团的形成。结合吸附研究结果,提出了一个涉及表面胶团的颗粒相互作用模型,合理地解释了悬浮液稳定性的实验结果。     

壬基酚聚氧乙烯醚二聚和三聚表面活性剂的合成及表面性质

合成了系列壬基酚聚氧乙烯醚二聚表面活性剂(DNP)和三聚表面活性剂(TNP), 用核磁共振、红外光谱和元素分析等手段对其结构进行了表征, 并用表面张力法和稳态荧光法对DNP和TNP的表面性能进行了研究. 结果表明, 随着氧乙烯(EO)单元数的增长, DNP和TNP的临界胶束浓度(cmc)值逐渐增大; DNP和TNP的cmc值较相应的单体壬基酚聚氧乙烯醚表面活性剂(NP)明显降低, 显示了较高的表面活性、吸附能力和润湿能力.     

Salt Effect,Surface, and Aggregation Properties of Binary Surfactant Mixtures of a Nonionic Gemini Surfactant (HBA(EO)80) with Anionic Surfactants

Nonionic gemini surfactants HBA(EO)₈₀ were synthesized and characterized by means of surface tension measurements. CMCs of two mixed system, nonionic gemini mixed with anionic gemini (HBA(EO)₈₀/C11pPHCNa) and nonionic gemini mixed with anionic monomeric (HBA(EO)₈₀/SL) and the effect of salt on the two mixed system were investigated. Freeze-fracture transmission electron microscopy and scanning electron microscopy were used to investigate the mixed aggregates' morphologies. The results show that large spherical aggregates were formed in the mixed solution, which trend to transfer into micelles with the increases of the salt concentration.     

Surface and Thermodynamic Properties of Nonionic Surfactants Based on Rosin-Maleic Anhydride and Acrylic Acid Adducts

Ester-adduct derivatives of rosin were synthesized by reacting rosin maleic anhydride (RMA) or rosin acrylic acid (RAA) adducts with polyethylene glycol 600 (PEG600), 1000 (PEG1000) or 2000 (PEG2000) and at elevated temperature. These derivatives were evaluated for acid number, FTIR spectroscopy, molecular weight (Mw) and polydispersity. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The surface tension, critical micelle concentration, and surface activities were determined at different temperatures. Surface parameters such as surface excess concentration (Γmax), the area per molecule at interface (Amin) and the effectiveness of surface tension reduction (πCMC) were determined from the adsorption isotherms of the prepared surfactants. Some thermodynamic data for the adsorption process were calculated and are discussed.     

Temperature-driven Precipitation of poly(N-isopropylacrylamide-co-methacrylic acid) in Cationic,Anionic and Nonionic Surfactant Solutions

The temperature-driven precipitation of poly(N-isopropylacrylamide-co-methacrylic acid) (P(NIPAM-co-MAA)) in anionic, cationic, and non-ionic surfactants solutions was investigated under an acidic (e.g. pH 3.0) and an alkali condition (pH 9.0). Under the acidic condition, sodium dodecyl sulfate (SDS, anionic) and cetyltrimethylammonium chloride (CTAC, cationic) increased the cloud point of the copolymer and they suppressed the temperature-sensitivity. Under the alkali condition, SDS suppressed the temperature sensitivity as under the acidic condition, but CTAC boosted the temperature sensitivity and it decreased the cloud point of the copolymer. The effect of CTAC on the phase transition under the alkali condition was opposite to the effect observed under the acidic condition. Tween 20 (non-ionic) had little effect on the cloud point and the temperature-sensitivity under both the acidic and the alkali conditions.     

Effect of Surfactant Chain Length on the Rheological Properties of Cationic Surfactants and a Hydrophobic Counterion

The rheological behavior of alkyimethylammonium 2-hydroxy-1-carboxy-naphthoate, C_xTA-2.1-HCN (x = 16, 14, 12, 10, and 8) is presented. With increasing 2.1 HNC/C_xTAOH (x = 16, 14, 12) ratio, the viscoelasticity of the solutions changes due to a transition in the micellar shape from small micelles to rodlike micelles and finally to multilamellar vesicles (MLV). On the other hand, a transition from small micelles to multilamellar vesicles (MLV) was observed for solution with C_xTA-2.1-HCN (x = 10 and 8). The MLV phases behave like a weak gel and have a yield stress value. Rheological measurements were performed for these viscoelastic systems in order to find out the dependency of the viscoelastic behavior on the surfactant chain length and hydrophobic counterion concentration. Some theoretical models as reptation mechanism was also applied in order to get some structural details and to illustrate the rheological behavior of these viscoelastic systems. Some models that correlate MLV-modulus on the surfactant morphology are also presented and discussed.     

The Determination of Thermodynamic Properties of Polymer Solutions by Finite-Concentration Gas Chromatography

Although the technique of gas chromatography has been widely used to study polymer properties and to obtain information on polymer solution thermodynamics, few workers have extended their results beyond infinite dilution of solvent, Finite-concentration gas chromatography has been used to study several poly(dimethylsiloxane)-solvent systems at 25°C. The results are in good agreement with those obtained by traditional vapor sorption methods. A comparison of the various available techniques has been made, and the advantages and disadvantages of each are discussed.     

Mutual Influence of Some Flavonoids and Classical Nonionic Surfactants on Their Adsorption and Volumetric Properties at Different Temperatures

Due to the increasing practical use of mixtures of flavonoids with nonionic surfactants the presented studies were based on the measurements of surface tension and conductivity of aqueous solution of the quercetin (Q) and rutin (Ru) in the mixtures with Triton X-114 (TX114) and Tween 80 (T80) as well as the contact angle of model liquids on the PTFE surface covered by the quercetin and rutin layers. Based on the obtained results components and parameters of the quercetin and rutin surface tension were determined and the mutual influence of Q and Ru in the mixtures with TX114 and T80 on their adsorption and volumetric properties were considered. It was found, among others, that based on the surface tension isotherms of the aqueous solution of the single flavonoid and nonionic surfactant, the surface tension isotherms of the aqueous solution of their mixture, the composition of the mixed monolayer at the water-air interface as well as the CMC of flavonoid + nonionic surfactant mixture can be predicted. The standard Gibbs energy, enthalpy and entropy of the adsorption and aggregation of the studied mixtures were also found, showing the mechanism of the adsorption and aggregation processes of the flavonoid + nonionic surfactant mixture.     

Structural Behavior of Aggregate Assemblies of Cationic Surfactants and Their Mixtures with Triblock Polymers

Small angle neutron scattering (SANS) technique has been employed to study the structural aspects of micellar system of cationic surfactants viz. alkyltriphenylphosphonium bromide (C₁₂-, C₁₄-, C₁₆TPB) and hexadecylpyridinium chloride (C₁₆PyCl) with triblock polymers (L64, F68, and F127). SANS data analysis reveals the prolate ellipsoidal shape of mixed micelles and increase in the micellar size upon addition of triblock polymers (L64, F68, and F127). The influence of effective size of the head group segment on the growth of micelles of HTPB (larger head group) has also been compared with that of HPyCl (smaller head group). A proportionate micellar growth of cationic surfactants has been found with increase in the length of tail segment of cationic surfactants. The observed mixed micellar growth in mixed systems is also accounted on the basis of simultaneous increase in the hydrophobicity of both the components in the mixed system. Results from the present study enlightened the effect of variation in head group segment and hydrophobicity on the structural aspects of mixed micellar system.     

Evaluation of Surface Active Properties and Voltammetric Characterizations of Some New Anionic Copolymer Surfactants

The onset of micelles formations critical micelle concentration, diffusion coefficients as well as particle sizes for some new synthesized anionic copolymer surfactants PSA_4a, PSA_4b, and PSA_4c, were determined and discussed. Three different electrochemical techniques such as cyclic voltammetry (CV), rotating disk voltammetry (RDV), and chronocoulometry (CC) were used in this investigation. The voltammetry of electroactive hydrophobic probe ferrocene solubilized surfactants was investigated in aqueous buffer carbonate solutions of pH 10. The CMC for each PSA_4a, PSA_4b, and PSA_4c, was found to be 3.20 × 10^?4, 4.60 × 10^?4 and 6.30 × 10^?4 M, respectively, using both CV and RDV techniques. The amount of adsorption contribution of ferrocene solubilized surfactants at the glassy carbon electrode was determined from chronocoulometric measurements and it was found in the range from (1.4 to 2.7) × 10^?15 M. The apparent diffusion coefficients were estimated from RDV measurements and the real micelles diffusion coefficients were obtained. Re-quilibrium considerations of ferrocene probe kinetics at the electrode surface were treated according to two different modes of slow- and fast-kinetics. The corrected diffusion coefficient values showed constancy at (5.3 ± 0.1) × 10^?7, (4.8 ± 0.1) × 10^?7, and (3.6 ± 0.4) × 10^?7 cm²/sec for PSA_4a, PSA_4b, and PSA_4c, respectively in the concentration range from 20 to 200 mM. The morphological features of anionic copolymeric surfactants PSA_4a, PSA_4b, and PSA_4c, micelles showed globular self-assembled structure.     

PVC膜修饰电极直接测定痕量聚氧乙烯类非离子表面活性剂

研究了一种新的PVC膜修饰电极微分脉冲伏安法直接测定痕量聚氧乙烯类非离子表面活性剂(PENS)的方法。由硫酸铜和四苯硼钠制得的配合物为活性物制成的PVC膜修饰电极在0.1mol/L NaOH溶液中对PENS有良好的选择性,-0.436V处出现1个灵敏的氧化峰。在最佳实验条件下,峰电流的降低与AEO9、AEO6、AEO3、TX-10分别在1.11×10-2~0.21nmol/L、4.34×10-2~64nmol/L、20.8nmol/L~4.1μmol/L、6.77×10-2~0.21nmol/L范围内有很好的线性关系,检出限分别为5.54×10-3、4.38×10-3、2.12、4.42×10-2nmol/L。该电极性能稳定,在AEO9浓度分别为0.16nmol/L和0.21nmol/L时,进行DPV测量(n=9),相对标准偏差分别为2.03%和1.97%。考察了环境水样中常见的共存离子对PENS测定的影响,结果表明大多数共存离子都有较高的允许量。PVC膜修饰电极的灵敏度高、选择性好、线性范围宽,不需预先分离,可直接用于环境水样中PENS含量的测定。