Gel shrinking resulting from uneven distribution of ionic micelles between the inside and the outside of the polymer gel network

The volume change of crosslinked nonionic poly (N‐isopropylacrylamide) (NIPA) polymer gel immersed in tetradecyldimethylaminoxide (C14DMAO) surfactant solutions at 0.1M NaCl, were investigated to distinguish between binding and nonbinding polymer gel/C14DMAO surfactants. Also, the aggregation behavior of C14DMAO surfactants the inside and the outside the polymer hydrogels has been studied through solubilization of Sudan III dye. For the C14DMAO surfactants at the degrees of ionization (α) of 0.5 and 1, they bind to the NIPA gel at low surfactant concentration (C_D) that enhance the gel swelling due mainly to the osmotic pressure contribution from the counter ions (regime I, C_D<10mM). However, the deswelling behavior was observed as the surfactant concentration increases above 10 mM (regime II). The solubilization experiments indicated that the surfactant concentration inside the gel is lower than that outside the gel in the regime II, which may be due to the large micelle size that cannot accommodate the mesh size of the gel. It was suggested that the uneven distribution of the ionic micelles leads to the reduction of the net swelling osmotic pressure of the gel (i.e., the decrease of the gel volume). In the case of the nonionic C14DMAO at α = 0, on the other hand, the deswelling behavior was not clearly observed and the surfactant concentration inside the gel and outside the gel was almost identical even at 30 mM. For the nonionic surfactant, it was also found that the gel volume increases with the surfactant concentration at low surfactant concentration less than 1mM. This may be attribute to the dipole‐dipole repulsion of N‐O headgroups. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2001–2006, 2004     

Gel filtration of surfactants

A simulation technique was developed for analyzing the gel filtration chromatography of surfactants. Theoretical elution curves obtained by this technique were compared with the experimental curves for the following five systems: an ionic or a nonionic surfactant of a single component, an ionic surfactant in the presence of an electrolyte, a mixture of two nonionic surfactants, a mixture of two ionic surfactants, and a mixture of an ionic and a nonionic surfactant. In the first four systems, good agreement was found between the theoretical and experimental elution curves. A possible explanation for the disagreement in the last system is presented.     

Characterization and In Vitro Evaluation of Freeze-Dried Nasal Insert Composed of Chlorpheniramine Maleate with Ionic and Nonionic Polymer for Intranasal Delivery

In this study, the authors report the fabrication of nasal delivery system, termed nasal insert, and was carried out with ionic and nonionic polymer(s). The data revealed that nonionic polymer has less water uptake and low mucoadhesion time in comparison to the ionic polymers. With ionic polymers, relaxation of entangled polymer from the gel was toward lesser extent, thereby providing sustained release during in vitro release. The SEM images show more compact nature of ionic polymer when compared with nonionic polymer. Histopathology and in vitro permeation study conducted using sheep nasal mucosa showed significantly higher drug permeation from nonionic polymer.     

添加剂对非离子表面活性剂浊点的影响

研究了醇类、聚合物、离子型表面活性剂、有机复配物等添加剂对非离子表面活性剂浊点的影响,总结出几类添加剂对非离子表面活性剂浊点的影响规律。结果表明,有机醇对浊点的影响比较复杂,聚合物随着分子链的长短对浊点的影响而不同,离子型表面活性剂的加入会有效提高非离子表面活性剂的浊点。     

Gels of carbon nanotubes and a nonionic surfactant prepared by mechanical grinding

Mixtures of carbon nanotubes (CNTs), including multi-wall CNTs and single-wall CNTs, and polyoxyethylene(12) tridecyl ether (POETE), a nonionic surfactant and a fluid at room temperature, became gels after mechanical grinding. The heavily entangled multi-wall or single-wall CNTs debundled during the grinding and dispersed with fewer bundles in POETE. The mechanism for the gel formation was studied by the dynamic mechanical measurements and scanning electron microscopy. The results suggest that the formation of the CNT/POETE gel is the result of the physical-crosslinking CNT networks, mediated by the van der Waals interaction between CNTs and the nonionic surfactant. The gels were stable from room temperature up to 200 °C and did not shrivel even in vacuum. The CNT/POETE gels were electrically conductive and could be processed into conductive CNT films by coating the CNT/POETE gels on a substrate by a doctor blade and subsequent heating. POETE was removed during the heating, while the heating did not degrade the CNTs. The CNT films had a conductivity of about 13 S cm⁻¹ and had good adhesion to the substrate.     

Comparative Study of Effect of Surfactant-Polymer Interactions on Properties of Alkyl Polyglucosides and Alpha Olefin Sulphonate

The properties of Alpha Olefin Sulphonate (AOS) and Alkyl polyglucosides (APG) were studied in the presence and absence of nonionic polymers such as polyethylene glycol, poly vinyl pyrrolidone and methyl cellulose and hydroxy propyl cellulose. Properties like surface tension, foaming, viscosity and emulsification were studied at a constant concentration of polymer (0.1%) and varying concentrations of surfactant. It was found that at low surfactant concentrations there is an association between surfactant and polymer at the liquid/air surface in the case of an anionic surfactant and a nonionic polymer, which is not seen in the case of nonionic surfactants and nonionic polymers. A nonionic polymer reduces the surface tension of AOS by forming a surfactant-polymer complex which in turn increases the foamability, emulsifying property and viscosity of solution. APG does not show any effect on its surface tension in the presence of nonionic polymers but its foamability and emulsifying properties are improved. Reduction in surface tension is not the only reason behind increased foamability in the presence of the polymer. Higher molecular weight polymers give a rich, creamy foam because of increased viscosity in the surfactant solution as compared to lower molecular weight polymers.     

Effect of Hydrophobic Modification on the Properties of Polymer‐Blended Microemulsion Gels

Phase behavior of sodium oleate (NaOl)/isoamyl alcohol‐based lamellar gel phase in cedar oil/water medium in the presence of the nonionic polymer hydroxyethyl cellulose (HEC) and its hydrophobic modified product (HMHEC) is investigated for the development of polymer‐embedded surfactant gels. HMHEC is more soluble in oil‐in‐water (o/w) microemulsions, but nonionic HEC shows limited solubility in the lamellar microemulsion (o/w type). Quantitative estimation of rate of adsorption of the polymer on lamellae bilayers can be easily done by Sudan solubilization and methylene blue complexation methods. Addition of HMHEC to the lamellar gel phase increases the polymer solubilization limit of lamellar gels as well as the viscoelasticity and thermal stability. The polymer‐embedded microemulsion gel acts as a “clean gel” since it exhibits good solubilization in different hydrocarbon media at ambient conditions. Elastic modulus of the polymer‐embedded gel influences directly the suspension performance of gels at high temperature and yields a reasonable sand‐settling velocity acceptable according to fracturing standards. The thermal characteristics and viscoelastic properties of polymer‐embedded gel were found to be suitable for moderate‐temperature reservoir stimulation where the bottom hole temperature is in the range 70–75 °C. Already a large amount of experimental data on pure microemulsions (without polymer) exists. Our studies indicate that the developed polymer‐embedded microemulsion gel has great potential as a model system for the study of polymer–microemulsion interactions.     

Aqueous Emulsion Acrylic Binders for Low-Foaming Ceramic Slips

Experiments are reported to fundamentally understand foaming in ceramic slips. Adsorption of two different types of surfactants, one anionic and another nonionic, onto alumina powders was studied. The most significant observation was that while the anionic surfactant strongly adsorbed onto alumina powders, the nonionic surfactant had essentially no adsorption. A model polymer based on the anionic surfactant was synthesized and compared with a similar polymer prepared with the nonionic surfactant. The comparison demonstrated that while the model polymer foamed severely in its neat form, it produced a very low-foaming ceramic slip when formulated with alumina powder because the surface-active agents in the binder strongly adsorbed onto the powder. Based on these fundamental understandings, a series of aqueous emulsion acrylic Duramax binders were developed. The influence of these binders on foaming in alumina slips is reported.     

Influence of surfactant properties on thermal behavior and sol–gel transitions in surfactant‐HPMC mixtures

Four surfactants, namely, sodium n‐decyl sulfate (SDeS), sodium n‐hexadecyl sulfate (SHS), sodium n‐dodecyl sulfate (SDS), and Triton X‐100, were used as additives to study thermal behavior and sol–gel transformations in dilute aqueous hydroxypropyl methyl cellulose (HPMC)/surfactant mixtures using micro‐differential scanning calorimetry. The influence of anionic surfactant, SDS on the gelation varied with SDS concentration where the sol–gel transition started at a higher temperature. Shape of the thermograms changed from single mode to dual mode at the SDS concentration of 6 mM and higher. SDeS and SHS, however, resulted in “salt‐in” effect of a different magnitude during gelation. Triton X‐100, being a non‐ionic surfactant, showed a minor “salt‐out” effect on the thermo‐gelation process. On the basis of different thermal behavior of anionic and non‐ionic surfactant/HPMC systems, a mechanism is proposed explaining how the chemical structure and electro‐charge of the surfactants affect the polymer/surfactant binding and polymer/polymer aggregation because of hydrophobic interaction during the sol–gel transition. © 2009 Wiley Periodicals, Inc. Journal of Applied Polymer Science, 2009     

Novel Structural Increments for Estimating the Krafft Temperature of Ionic Surfactants in Aqueous Solutions

In this work, we report results of our investigation on the relationship between the Krafft temperature of ionic surfactants in aqueous solutions and their chemical structure. We tested empirical values of the Krafft temperature available in literature for aqueous solutions of 234 ionic surfactants and correlated them to the surfactant chemical structure. In this work, we propose a novel set of 67 group contributions for calculation of the Krafft temperature of ionic surfactants in aqueous solutions. Using them, the Krafft temperature values in aqueous solutions for 174 anionic, 43 cationic, and 17 zwitterionic surfactants were calculated and the estimated values obtained in this way were compared with experimental values. We have demonstrated that the newly developed set of numerical values structural group contributions of the surfactants allows correct estimation of the Krafft temperature value for the tested set of data with the maximum error 7.6°C and the mean square error 3.7°C for various types of ionic surfactants in aqueous solutions.     

Adsorption of dyes to cotton and inhibition by polymers

This paper addresses some key factors that control the transfer of dyes between garments during detergency. It is shown that adsorption of a series of substituted arylazo-2-naphthol dyes to cotton under simulated detergency conditions is influenced by the log P fragment value of the dye substituent; this suggests that hydrophobic interactions make an important contribution to the binding free energy. The comparative effectiveness of nonionic, zwitterionic and cationic polymers in inhibiting adsorption of dye to cotton was also investigated. Increase in polymer concentration reduces dye adsorption to cotton; increase in polymer molecular weight at constant polymer concentration also inhibits dye adsorption up to a molecular weight of ca. 20000, above which there is no further change. Anionic surfactants reduce the efficacy of polymers by displacing dyes from polymers. Surprisingly, certain dyes become relocated in polymer/surfactant complexes; binding is much more effective than in corresponding surfactant micelles.     

Review: Implementing the hydrophilic–lipophilic deviation model when formulating detergents and other surfactant-related applications

When designing surfactant formulations using ionic and nonionic surfactants, the hydrophile lipophile balance (HLB) is a generalized surfactant characterization parameter that has shown to be useful when designing surfactant formulations, in the case of both ionic and nonionic surfactants (Davies' and Griffin's methods). Microemulsion phase behavior studies have been extensively used to optimize surfactant formulations, but these studies can cover a very wide phase space and can often encounter troublesome non-equilibrium issues such as coacervation. Detailed phase behavior studies can be time-consuming and difficult to apply beyond the specific surfactant-oil system studied. The hydrophilic–lipophilic deviation (HLD) provides a method to help expedite surfactant formulation research by reducing the number of phase behavior studies required to optimize a given formulation. Detergency experiments have indicated that there is an optimal range of HLD for a given fabric surface. This appears to apply to other applications, as well, for example, surfactant formulations used in enhanced oil recovery have been optimized using the HLD method. These studies found that the HLD can reflect total oil recovery, even if the surfactants were derived from different alcohol feedstocks (e.g., HLD of 0 would describe optimum conditions regardless the type of surfactant). Also with additional parameterization, the HLD method can also be applied to non-ideal surfactant mixtures, specifically ionic/nonionic blends. Overall, the HLD framework has shown to be an effective screening tool for a wide range of surfactant-related applications when appropriate experiments, assumptions, and understanding of surfactant and oil interactions are used to generate the HLD parameters.     

The determination of polyoxyethylene nonionic surfactants in water at the parts per million level

A method has been developed to determine the concn of polyoxyethylene nonionic surfactant (PNS) in the parts/million concn range in a water-bacteria medium. The method has successfully determined the concn of PNS during the course of biodegradation studies using either activated sludge or river water as the bacterial source. The nonionic surfactant was removed from the water solution by continuous ether extraction. Detection and measurement of the PNS was accomplished using cobalt thiocyanate and measuring the absorbance of the blue cobalt-PNS complex at 620 m.03 in a five-cm absorption cell. Optimum extraction conditions required a neutral pH and a low ionic strength. The colorimetric step required that each molecule of PNS contain at least six ethylene oxide units for color development, and since the absorbance varies with the length of the polyoxyethylene chain, the method must be standardized using the particular compound under investigation.     

Solubilisation of dyes by surfactant micelles. Part 2; Molecular interactions of azo dyes with cationic and zwitterionic surfactants

A UV–vis spectroscopic investigation has been made of the interactions of a specially synthesised series of o - and p -substituted, model arylazonaphthol dyes with the cationic and zwitterionic surfactants above and below their critical micelle concentrations at pH 10. Spectra of dyes incorporated in micelles of zwitterionic surfactant or cationic surfactant at pHs < 8 are similar to those found in nonionic micelles, i.e. dye substituents control its location similarly for all the micelle types. However, the common anion is selectively favoured in cationic micelle solutions at pH 10, due to electrostatic interactions within the micellar surface. Introduction of polar groups at either end of the molecule confines the dyes to the surface of either zwitterionic or cationic micelles and are characterised by atypical p K _A shifts. Electrostatic complexes between dyes and cationic or zwitterionic surfactants were formed in sub-micellar regions, those with cationic surfactant being sparingly soluble.     

Morphology,structure, and conductivity of polypyrrole prepared in the presence of mixed surfactants in aqueous solutions

Polypyrrole (PPy) was prepared from different mixed‐surfactant solutions with ammonium persulfate as an oxidant. Three types of combinations were selected, including cationic/anionic, cationic/nonionic, and anionic/nonionic mixed‐surfactant solutions. The surfactants used in the experiments included cetyltrimethylammonium bromide (cationic surfactant), sodium dodecyl sulfate (anionic surfactant), sodium dodecyl sulfonic acid salt (anionic surfactant), poly(vinyl pyrrolidone) (nonionic surfactant), and poly(ethylene glycol) (nonionic surfactant). The morphology, structure, and conductivity of the resulting PPy were investigated in detail with scanning electron microscopy, Fourier transform infrared spectra, and the typical four‐probe method, respectively. The results showed that the interaction between the different surfactants and the interaction between the surfactants and the polymer influenced the morphology, structure, and conductivity of the resulting polymer to different degrees. The cationic surfactant favored the formation of nanofibers, the addition of anionic surfactants produced agglomeration but enhanced the doping level and conductivity, and the presence of a nonionic surfactant weakened the interaction between the other surfactant and the polymer in the system. In comparison with the results for monosurfactant solutions, the polymerization of pyrrole in mixed‐surfactant solutions could modulate the morphologies of PPy, which ranged from nanofibers of different lengths to nanoparticles showing various states of aggregation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1987–1996, 2007     

非离子表面活性剂溶液的雾点现象

非离子表面活性剂溶液的雾点现象顾惕人（北京航空航天大学应用数理系，邮编１０００８３）较全面地评述了非离子表面活性剂的雾点现象。特别是多方面地讨论了各种添加物（包括无机盐、有机物和离子型表面活性剂）对非离子表面活性剂溶液雾点的影响。一、引言非离子表面活...     

Synergistic Effect of Mixed Surfactant Systems on Foam Behavior and Surface Tension

Foam and surface tension behaviors of different ionic/nonionic surfactant solutions along with their different combinations have been investigated. Among different surfactants, sodium dodecyl sulfate showed the highest foamability over other surfactants. Mixed surfactant systems were always found to have higher foamability than the individual surfactant. It was also noticeable that nonionic surfactants show good foamability when they combine with anionic and cationic surfactants. In the case of mixed surfactant systems, nonionic/cationic surfactant mixtures showed lower surface tension than nonionic/anionic surfactant mixture due to a synergistic effect.     

Extraction of anionic dyes with ionic liquid–nonionic surfactant aqueous two-phase system

The cloud point of nonionic surfactant (Triton X-114) in ionic liquid ([Bmim]Cl) aqueous solution exhibits as increase and then decrease and increase again with the increase of ionic liquid (IL) content, which is the origin of an IL–nonionic surfactant aqueous two-phase system. The nonionic surfactant-rich phase coexists with a high content of IL aqueous solution phase in the IL–nonionic surfactant aqueous two-phase system. The partitioning of various ionic dyes indicates that anionic species exhibit a high partitioning coefficient between the IL-rich phase and the nonionic surfactant-rich phase.     

Drag reduction in turbulent pipeline flow of mixed nonionic polymer and cationic surfactant systems

Turbulent drag reduction behaviour of a mixed nonionic polymer/cationic surfactant system was studied in a pipeline flow loop to explore the synergistic effects of polymeric and surfactant drag reducing additives. The nonionic polymer used was polyethylene oxide (PEO) at three different concentrations (500, 1000, and 2000 ppm). The surfactant used was cationic octadecyltrimethylammonium chloride (OTAC) at concentration levels of 1000 and 2500 ppm. Sodium salicylate (NaSal) was used as a counter‐ion for the surfactant at a molar ratio of 2 (MR = Salt/OTAC = 2). Relative viscosity and surface tension were measured for different combinations of PEO and OTAC. While the relative viscosities demonstrated a week interaction between the polymer and the surfactant, the surface tension measurements exhibited negligible interaction. The pipeline results show a considerable synergistic effect, that is, the mixed polymer–surfactant system gives a significantly higher drag reduction (lower friction factors) as compared with pure polymer or pure surfactant. The addition of surfactant to the polymer always enhances drag reduction. However, the synergistic effect in mixed system is stronger at low polymer concentrations and high surfactant concentrations. © 2011 Canadian Society for Chemical Engineering     

Zero flash ultrasonic micro embossing on foamed polymer substrates: A proof of concept

This article reviews a novel method to produce microembossed features with an aspect ratio of three and negligible flash on polymer surfaces. An embossing technique that utilizes localized heating (ultrasonic energy) was used with polystyrene and polypropylene substrates. It was demonstrated that when foamed substrates were used, the amount of flash produced was negligible compared to nonfoamed substrates, which has been a significant unresolved problem with embossing using localized heating. The depth of microembossed features as a function of heating times and amplitudes of ultrasonic embossing is detailed in this article, along with a characterization of complex embossed geometries. It was seen that embossing depth was generally proportional to heating time and amplitude until the maximum feature depth was achieved. Although this article deals with embossing of microfeatures for lab‐on‐a‐CD applications, it is envisioned that it is also suitable for lab‐on‐a‐chip applications. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers