Effects of addition of short-chain alcohol solvents on micellization and thermodynamic properties of anionic surfactants sodium dodecyl sulfate and sodium dodecyl sulfonate in aqueous solutions

Micellar and thermodynamic properties of anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecyl sulfonate (SDSn) in aqueous solutions of 5 wt% short-chain alcohols methanol, ethanol, and 1-butanol were investigated by experimental electrical conductivities, densities and sound velocities at 298.15 K. It was found that methanol behaves like a cosolvent and increases the critical micelle concentration (CMC) of both surfactants in aqueous solutions. However, the other investigated alkanols act as a cosurfactant and decrease the CMC by their presence. The values of the degree of counterion association on the micelles of both surfactants in aqueous methanol solution are same as those in pure water, and they decrease with increasing the alkyl chain length of alcohol. Furthermore, the values of the apparent molar volume and isentropic compressibility of the monomeric and micellar forms of the investigated surfactants were obtained from the experimental density and sound velocity data. It was found that the values of the apparent molar properties of both micellar and monomeric forms of the studied surfactants increase by increasing the alkyl chain of the alcohols.     

Current perspective of sustainable surfactants based on renewable building blocks

Surfactants are active or essential ingredient of several industrial and consumer formulations. These amphiphilic organic molecules demonstrate unique ability to adsorb at the interface and self-aggregate or self-assemble into different phases in aqueous or nonaqueous solution. In recent years, environmental concerns coupled with increased consumer awareness have guided substantial growth of environmentally benign surfactant molecules often termed as ‘green surfactants’, oleochemical-based surfactants', ‘renewable surfactants’ ‘biosurfactants’, ‘natural surfactants’, and so on. These groups of new generation of eco-friendly surfactant molecules often directly or indirectly derived/developed from renewable building blocks can be broadly termed as ‘sustainable surfactants’ which are increasingly becoming popular in many application areas. The ever-increasing demand of surfactants in several application areas necessitates development of many new structural analogs of these molecules by sustainable approach. This review summarizes recent progress in the area of sustainable surfactants, their potential impact, and future perspective.     

Complexation of hydrophobically modified polyelectrolytes with surfactants: anionic poly(maleic acid/octyl vinyl ether)/anionic sodium dodecyl sulfate

Interactions of surfactants with hydrophobically modified polyelectrolytes in aqueous solutions are important in several applications such as detergents, cosmetics, foods, and paints. Fundamental questions arise on the mechanisms of complexation of the polyelectrolyte and surfactant that control their behavior. In this work, the complexation was studied by examining interactions in aqueous solutions of a hydrophobically modified polymer, poly(maleic acid/octyl vinyl ether) (PMAOVE), with sodium dodecyl sulfate (SDS) by monitoring viscosity, pyrene solubility, light scattering, and analytical ultracentrifugation. When the anionic surfactant SDS was added to aqueous solutions of the similarly charged polymer PMAOVE, the surfactant was incorporated into the hydrophobic nanodomains of PMAOVE even far below the cmc of the surfactant. On the basis of viscosity, pyrene solubility, and analytical ultracentrifugation data, it is proposed that PMAOVE undergoes structural unfolding and at higher SDS concentrations mixed micelles are formed.     

Synthesis and surface properties of anionic gemini surfactants with amide groups

Novel anionic gemini surfactants, 1,2-bis(N-beta-carboxypropanoyl-N-alkylamino)ethane (2CnenAm; n is hydrocarbon chain length of 6, 8, 10, 12, or 14), with two hydrocarbon chains, two carboxylate groups, and two amide groups, were synthesized by three-step reactions. Their solution properties were characterized by equilibrium and dynamic surface tension, steady-state fluorescence spectroscopy of pyrene, and dynamic light-scattering techniques. The surface tension measurements of 2CnenAm give low critical micelle concentrations (cmc), great efficiency in lowering the surface tension, and strong adsorption at air/water interface. Gemini surfactants behave normally with the logarithm of cmc decrease linearly with the chain length. In addition, adsorption and micellization behavior of 2CnenAm was estimated by parameter of pC20, cmc/C20, and standard free energy (DeltaG(0)mic and DeltaG(0)ads); they are significantly influenced by hydrocarbon chain length, and the adsorption is promoted more than the micellization as chain length becomes longer. The results of dynamic light-scattering and fluorescence quenching indicate that small micelles of 2CnenAm are observed at the concentrations above the cmc, and further large particles are also seen. Further, from the dynamic surface tension measurements, it is found that the shorter hydrocarbon chain length of 2CnenAm, the faster the rate of decrease of surface tension.     

Synthesis and properties of isosorbide based epoxy resin

Isosorbide based epoxy resin (IS-EPO) of epoxy number: 0.44 mol/100 g was synthesised in the one step reaction from 1,4:3,6-dianhydro-d-glucitol (isosorbide) and epichlorohydrin in the presence of concentrated aqueous NaOH. The product obtained was characterised by means of NMR, FT-IR and ESI MS spectroscopy. Compositions with typical hardeners were prepared and cured. The thermal and mechanical properties of the resulting materials were evaluated. Comparison with commercially available epoxy resin Epidian 5 shows relatively good mechanical performance of IS-EPO which makes isosorbide a promising candidate to replace bisphenol A (BPA).     

Synthesis and response of new microsensor coatings-II Acridinium betaines and anionic surfactants

Four acridinium betaines and two ionic surfactants were synthesized, and evaluated as chemical microsensor coatings by exposure to vapors of chloroethyl ethyl sulfide (CEES) and dimethyl methylphosphonate (DMMP). Two of the acridinium betaines showed selective and reversible responses (of 9.8 and 6.8 kHz) as SAW (surface acoustic wave) coatings in the detection of CEES vapor: there appears to be a connection between the long alkyl chain (C-12 and C-14) in the acridinium molecules and the response. Response times were generally less than 30 sec but desorption was significantly slower. The ionic surfactant coatings show small SAW changes (> 0.5 kHz) in response to DMMP vapor, and somewhat greater responses (20- and 68-fold), as chemiresistors, to CEES vapor. In each case the response occurred within 3 min, with return nearly to baseline levels within 6 min of cessation of exposure to the vapor. The responses were reproducible within +/- 5%.     

Effect of counterions on surface and foaming properties of dodecyl sulfate

The influence of counterions of surfactant on interfacial properties is studied by measuring foamability, foam stability, equilibrium and dynamic surface tension, and surface viscosity. The surfactant chosen is anionic dodecyl sulfate with various counterions, Li(+), Na(+), Cs(+), and Mg(++). Surface tension measurements show a decrease in the following order: LiDS > NaDS > CsDS > Mg(DS)(2). Foamability done using shaking method shows similar order as surface tension, i.e., LiDS > NaDS > CsDS > Mg(DS)(2). This has been explained in terms of the differences in micellar stability and diffusion of monomers. This is further confirmed by our dynamic surface tension results, which show the same order as equilibrium surface tension (i.e., LiDS > NaDS > CsDS > Mg(DS)(2)) at low bubble frequencies but the order is LiDS > NaDS = Mg(DS)(2) > CsDS at high bubble frequencies. Foam stability measurements were done at concentrations below and above cmc to elucidate the role of micelles. It was found that there is no significant change in foam stability when counterions are changed for surfactant concentration values below the cmc, but at concentration above cmc the foam stability of CsDS and Mg(DS)(2) are much greater than LiDS and NaDS indicating presence of stable micelles are essential to high foam stabilities. Surface viscosity measurements correlated well with the foam stability trends and gave the following order LiDS < NaDS < CsDS < Mg(DS)(2), indicating that the molecules of CsDS and Mg(DS)(2) are tightly packed at the air/water interface.     

Synthesis of a new conformationally constrained glycoamino acid building block

The synthesis of a suitably protected β-d-glucopyranosyl-(S)-α-methylserine derivative—a new conformationally constrained glycosylated quaternary amino acid analogue of β-d-glucopyranosyl-l-serine—is described. This compound can be used as an attractive building block for the synthesis of new, constrained glycopeptides.     

Synthesis and properties of new block copolymers based on polydimethylsiloxane and tetraphenylethylene-containing polyimide

New polydimethylsiloxane (PDMS)-polyimide block copolymers were synthesized by the solution polycondensation of aminopropyl-terminated polydimethylsiloxane, 1,1-bis(4-aminophenyl)-2,2-diphenylethylene, and 3,3′,4,4′-benzophenonetetracarboxylic dithioanhydride in pyridine. New 1,3-bis(3-aminopropyl)tetramethyldisiloxane (BADS)-based random copolyimides were also prepared. The inherent viscosities of all the random and block copolyimides were in the range of 0.13–0.90 dL/g in N-methyl-2-pyrrolidone. These copolymers were soluble in N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and m-cresol. All the BADS-based random copolymers and PDMS-containing copolymers with PDMS content above 42 wt % were soluble in tetrahydrofuran and chloroform. Transparent or somewhat cpaque films were prepared by casting from the reaction solutions. The BADS-based random copolyimides had one glass transition temperature (T_g) in the whole composition ranges, which showed single phase nature of the copolymers. On the other hand, the PDMS-polyimide block copolymers had double T_gS, indicating phase-separated morphology. The block copolymers containing PDMS content above 73 wt % behaved like a high temperature elastomer. © 1993 John Wiley & Sons, Inc.     

烷基酚阴离子表面活性剂的合成与应用进展

将本实验室最新研究成果与相关文献报导相结合,介绍了目前以烷基酚为原料合成阴-非离子表面活性剂、Extended表面活性剂和Gemini表面活性剂的最新动态,特别注重它们在三次采油等非直接环境排放型应用场合的高效合理利用。指出深入开发区域选择性硫酸化/磺化、硫酸酯盐转磺酸盐、羟基直接氧化合成羧酸盐以及烷基酚偶联合成Gemini骨架等技术对于合理和高效利用烷基酚具有重要意义。     

Mixed micellar properties of cationic trimeric-type quaternary ammonium salts and anionic sodium n-octyl sulfate surfactants

The properties of quaternary ammonium salt-type cationic trimeric surfactants (m-2-m-2-m, m represents the carbon atom number in alkyl chain lengths of 8, 10, and 12) and oppositely charged anionic monomeric surfactant, sodium n-octyl sulfate (SOS), were characterized by employing several techniques such as static surface tension, fluorescence spectroscopy, and dynamic light-scattering measurements. The critical micelle concentrations (cmc) of m-2-m-2-m were much lower than those of the corresponding dimeric and monomeric surfactants, and decreased with increasing chain length. The addition of SOS to m-2-m-2-m solutions resulted in a further decrease of the cmc. The mixed surfactants showed higher efficiencies in lowering the surface tension than the individual surfactants. The fluorescence measurements suggested the formation of mixed micelles with a hydrophobic environment in the solutions even at lower concentrations. The dynamic light-scattering study indicated the presence of two different kinds of aggregates with different hydrodynamic diameters. The larger one was attributed to the mixed micelle of m-2-m-2-m and SOS. These results indicated a decline of the electrostatic repulsion between cationic head groups through the incorporation of anionic surfactant into the mixed surfactants.     

Adsorption of mixtures of nonionic sugar-based surfactants with other surfactants at solid/liquid interfaces I. Adsorption of n-dodecyl-beta-D-maltoside with anionic sodium dodecyl sulfate on alumina

Sugar-based surfactants can be synthesized from renewable materials and are environmentally benign. They have some unique solution and interfacial properties and have potential applications in a wide variety of processes, and there is a need for corresponding information on their behavior at various interfaces. In this study, co-adsorption of nonionic sugar-based n-dodecyl-beta-D-maltoside (DM) and anionic sodium dodecyl sulfate (SDS) on alumina was studied as a function of mixing ratios and solution pHs. It is found that at solid-liquid interface, depending on the solid type and the solution conditions, there are various interactions that dictate synergy or antagonism. At pH 6 where alumina is positively charged, marked synergistic effects between DM and SDS were observed, while at pH 11 where alumina is negatively charged, SDS shows antagonistic adsorption effects with DM. The ratios of surfactant components on solids change as a function of surfactant structure and concentrations as well, indicating various interactions at solid/liquid interface under different conditions that can be utilized for many industrial processes.     

两性离子表面活性剂的合成及其表面性质

合成了一类含季铵基和磺酸基结构的非对称Gemini两性离子表面活性剂;利用红外光谱、质谱、离子定性试验验证了合成产物的分子结构,并测定了其表面性质.结果表明,目标产物的分子结构符合设计预期;五种非对称Gemini两性离子表面活性剂的表面张力在30mN/m左右,临界胶束浓度达到10-4~10-5数量级.此外,虽然非对称Gemini两性离子表面活性剂的起泡性能比相应单链型表面活性剂的稍差,但其稳泡性明显优于后者.     

糖苷基季铵盐与十二烷基硫酸钠复配性能的研究

研究了糖苷基季铵盐(CAPG)与十二烷基硫酸钠(K12)复配体系的稳定性、表面活性、泡沫性能和润湿性能.结果表明:CAPG与K12复配体系的稳定性好,并表现出很好的协同增效作用.当n(CAPG)∶ (K12)等于0.1∶ 1,0.3∶ 1,0.5∶ 1时,复配体系的临界胶束浓度(cmc)分别为0.081 mmol/L,0.065 mmol/L,0.054 mmol/L,大大低于单一组分的cmc,临界胶束浓度时的表面张力(γcmc)比单一组分略低,起泡力和泡沫稳定性均好于单一组分,润湿力比K12略低,但比CAPG好得多.     

Synthesis and solution properties of anionic linear–dendritic block amphiphiles

The design and synthesis of novel linear–dendritic diblock amphiphiles with linear poly(acrylic acid) (PAA) as the hydrophilic block and dendritic poly(benzyl ether) as the hydrophobic block are described. The synthetic process consisted of two steps: a poly(methyl acrylate) (PMA)–poly(benzyl ether) dendrimer series were synthesized with atom transfer radical polymerization, and through the hydrolysis of linear PMA block into PAA, amphiphilic block copolymers, the PAA–poly(benzyl ether) dendrimer series, were obtained. The copolymers were characterized by ¹H NMR, Fourier transform infrared, and size exclusion chromatography and exhibited well‐defined architectures and low polydispersities. When the generation number of the dendritic block (G_i) less or equal to 3 and the degree of polymerization of the linear chain (n) was greater than 10, the amphiphiles were water‐soluble. The solution intrinsic viscosity increased with both the length of linear chain and the generation number of the dendritic block. The results obtained demonstrate that dendritic blocks play an unusual role in aqueous solutions of amphiphiles. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4282–4288, 2000     

Synthesis and properties of new glucocationic surfactants: model structures for marking cationic surfactants with carbohydrates

[reaction: see text] In this work, we report the synthesis of a new series of glucocationic surfactants, a class of surfactants we introduced very recently. The preparation of the surfactants is based on the synthesis of the 2-bromoethyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside, whose preparation was studied in order to improve yields and stereoselectivity of this key intermediate. These glucocationic amphiphiles were prepared and studied as a model of cationic surfactants marked with a carbohydrate moiety. The use of carbohydrates as markers on cationic lipids was recently introduced to induce recognition by specific receptors, present on the surface of cell membranes. The chemicophysical characterization of these model structures can give more insight on the aggregation behavior. Conductivity and surface tension measurements were performed in order to characterize the compounds from the amphiphilic point of view. The results showed a different effect of the glucosidic moiety on the cmc value with respect to the glucopyridinium cationic surfactants. The surfactants also showed the tendency to form premicellar aggregates in solution when the hydrophobicity is raised.     

Effect of the nature of the counterion on the properties of anionic surfactants. 5. Self-association behavior and micellar properties of ammonium dodecyl sulfate

Micelles formed in water from ammonium dodecyl sulfate (AmDS) are characterized using time-resolved fluorescence quenching (TRFQ), electron paramagnetic resonance (EPR), conductivity, Krafft temperature, and density measurements. TRFQ was used to measure the aggregation number, N, and the quenching rate constant of pyrene by dodecylpyridinium chloride, k(Q). N depends only on the concentration (C(aq)) of ammonium ions in the aqueous phase whether these counterions are derived from the surfactant alone or from the surfactant plus added ammonium chloride as follows: N = N0(C(aq)/cmc0)(gamma), where N0 is the aggregation number at the critical micelle concentration in the absence of added salt, cmc0, and is equal to 77, 70, and 61 at 16, 25, and 35 degrees C, respectively. The exponent gamma = 0.22 is independent of temperature in the range 16 to 35 degrees C. The fact that N depends only on C(aq) permits the determination of the micelle ionization degree (alpha) by employing various experimental approaches to exploit a recent suggestion (J. Phys. Chem. B 2001, 105, 6798) that N depends only on C(aq). Utilizing various combinations of salt and surfactant, values of alpha were obtained by finding common curves as a function of C(aq) of the following experimental results: the Krafft temperature, N, k(Q), the microviscosity of the Stern layer determined from the rotational correlation time of a spin probe, 5-doxyl stearic acid methyl ester, and the spin-probe sensed hydration of the micelle surface. The values of alpha, determined from applying the aggregation number-based definition of alpha to all of these quantities, were within experimental uncertainty of the values alpha = 0.19, 0.20, and 0.21 derived from conductivity measurements at 16, 25, and 35 degrees C, respectively. The volume fraction of the Stern layer occupied by water decreases as N increases. For AmDS micelles, both the hydration and its decrease are predicted by a simple theory of micelle hydration by fixing the parameters of the theory for sodium dodecyl sulfate and employing no further adjustable parameters. For a given value of N, the hydration decreases as the temperature increases.     

Behavior of γ-ray-irradiated pullulan in aqueous solutions of cationic (cetyltrimethylammonium hydroxide) and anionic (sodium dodecyl sulfate) surfactants

 γ-ray-irradiated pullulan macromolecules acquire properties of an anionic polyelectrolyte and, upon aggregation with the oppositely charged surfactant cetyltrimethylammonium hydroxide, are found to precipitate according to their molecular weight. This provides a convenient means for obtaining polymer fractions with a narrower molecular-weight distribution than those of the original samples. The method can be employed to obtain fractions of radiation-modified pullulan required in the production of a blood-plasma substitute. Anionic properties of γ-ray-irradiated pullulan also manifest themselves in interactions with sodium dodecyl sulfate (SDS) in aqueous solution, which result in a significant change in the viscous behavior of the polysaccharide. Upon an increase in the concentration of γ-ray-irradiated pullulan in an SDS solution, the reduced viscosity of the polymer first increases and, upon reaching a certain concentration, C*, decreases. The C* values were found to be dependent on the molecular weight of the polymer. The phenomena observed are discussed in terms of the general theory of polymer solutions within which C* is treated as a critical concentration at which interpenetration of polymer molecules becomes important. Unperturbed dimensions of γ-ray-irradiated pullulan macromolecules were estimated on the basis of experimental viscosimetric data. Received: 29 March 2001 Accepted: 31 July 2001     

Nuclear magnetic resonance and small-angle neutron scattering studies of anionic surfactants with macrocounterions: tetramethylammonium dodecyl sulfate

Micellar solutions of tetramethylammonium dodecyl sulfate have been studied to determine the degree of counterion binding. Tetramethylammonium chloride was added over a wide range of surfactant concentrations such that the total concentration of tetramethylammonium ions in solution remained constant. Small angle neutron scattering experiments showed a constancy in aggregation number across this series, consistent with the constant C(aq) concept of Bales et al. (J. Phys. Chem. B 2001, 105, 6798). Pulsed-field gradient and electrophoretic NMR experiments were used to determine the degree of counterion dissociation, alpha, which was found to be 0.33. This value is in contrast to the value from conductivity measurements (alpha = 0.2), but supports the concept of an aggregation number based definition of alpha.     

Synthesis of 1,4-annulated cyclooctatetraenophanes based on a novel cubane building block approach

A general synthetic approach to strained 1,4-annulated cyclooctatetraene-based cyclophanes is described. A key feature in this approach is exploitation of the cubane core as a masked cyclooctatetraene synthon. Thus, 1,4-disubstituted cubanes 3 and 4 used as precursors to cyclooctatetraenophanes have been prepared in four steps from the readily available 1,4-cubanedicarboxaldehyde (5). The synthesis of 3 was effected by palladium/copper-mediated coupling of 1,4-bis[(Z,Z)-2-iodovinyl]cubane (6) and 1,4-bis[(Z,Z)-but-1-en-3-ynyl]cubane (8). For the synthesis of 4, on the other hand, modified Eglington-Glaser coupling was applied for the macrocyclization step. The general characteristic of Rh(I) to induce [2 + 2] cycloreversion of the cubane core to syn-tricyclo[4.2.0.0(2,5)]octa-3,7-diene followed by thermal rearrangement to cyclooctatetraene was applied as a key structural transformation toward targeted cyclooctatetraenophanes 1 and 2.