Cationic surfactant/bile salt interaction studied by fluorescence quenching

Fluorescence quenching measurements were performed on aqueous solutions of the cationic surfactant cetyltrimethylammonium halide (CTAX) and two bile salts, sodium cholate (NaC) and sodium deoxycholate (NaDC), to study the state of aggregation in the mixtures. Pyrene was used as a photoluminiscence probe in the study, and dimethylbenzophenone (DMBP) as the quencher. Analysis of time-resolved decay data with and without quencher using a simple kinetic model gave information of the different aggregation characteristics in the above two cases. Mixed micelles of CTAX/NaC were small and spherical at all compositions, while those of CTAX/NaDC tended to grow from spherical micelles to larger rod-like mixed aggregates at equimolar and close-to-equimolar concentrations. In the latter case more complex kinetics ensues and the fluorescence decays were treated using a generatized model for diffusion-controlled quenching along one dimension for infinitely long rod-like micelles. The mutual diffusion coefficient for the probe-quencherpair was determined.     

Analysis of polyethoxylated surfactants in microemulsion-oil-water systems: Part II

Commercial ethoxylated surfactants are always a mixture of oligomers with different ethylene oxide number (EON). The different oligomers were separated by high performance liquid chromatography (HPLC) on an amino column using a mixture of polar and nonpolar mobile phases. Surfactant oil-water-systems were studied according to the unidimensional scan technique. The surfactant content in the oil, microemulsion and water phases was determined by UV spectroscopy and HPLC. The partitioning of the surfactant oligomers in the oil and water phases of a Winsor III system was determined. The effect of different salts on the surfactant partitioning is discussed.     

透明超微粒子氧化铝的制备

以三氯化铝为原料，制备水合氧化铝水溶胶，加阴离子表面活性剂（ＤＢＳ）将其转变成疏水性胶粒，用有机溶剂萃取使其成为有机溶胶，除去有机溶剂，经热处理生成覆盖有表面活性剂的氧化铝超微粒子，这种超微粒子在许多有机溶剂及合成树脂中易分散呈透明状态．     

Characteristics of proflavine solubilized in complexes of anionic polymers with a cationic surfactant

Absorption and emission spectra of 3,6-diaminoacridine (proflavine) are reported in mixed solutions of dodecyltrimethylammonium bromide (DTAB) with various polyelectrolytes including the sodium salts of poly(acrylic acid) (PAA). poly(methacrylic acid) (PMA), poly(styrenesulfonic acid) (PSS), poly(garacturonic acid) (pectate), and the alternating copolymers of maleic acid with ethylene (PMA-E) and styrene (PMA-S). The spectral change indicates the association of the dye (blue-shift) on these polyions except on PSS, the easy dissociation of the aggregated form into the monomeric form and the solubilization into the hydrophobic PMA-S/DTAB complex (red-shift), the little dissociation in the PAA/DTAB, PMA/DTAB and PMA-E/DTAB complexes, and the liberation of the bound dye in the case of pectate/DTAB complexes. In the PSS system, the strong interaction of the dye with the styrene groups induces the completely different spectral behavior. These results are discussed with the cooperative binding of the dye and the surfactant ion.     

Emulsion copolymerization of styrene with a nonionic styrenic polymerizable surfactant

Among the variety of possible structures for polymerizable surfactants, it seems clear that the most interesting should be those with the reactive group located in the hydrophobic part of the molecule. We report here a study based on such a surfactant. Its general formula is A set of surfactants has been produced with m varying from 23 to 48 and n = 6 or 12. The compounds have been characterised by ¹H-NMR (nuclear magnetic resonance), size exclusion chromatography, surface tension measurements and turbidimetry. These surfactants have been copolymerized with styrene in emulsion polymerization. The coagulum is rather important, except if m is large enough. Although the incorporation of the surfactant in the latex is rather high. Most of the anchored surfactant remains at the surface and is not too buried inside. The particle size decreases with both the amount of surfactant and the length of its hydrophilic part. The use of these polymerizable surfactants leads to an excellent stability of the latex against the addition of electrolytes, and also against freeze-thawing constraints.     

Rapid and sensitive determination of proteins by enhanced resonance light scattering spectroscopy of sodium lauroyl glutamate

A rapid and sensitive method for the determination of proteins is proposed based on the measurements of the enhanced resonance light scattering (RLS) spectroscopy of sodium lauroyl glutamate (SLG). Under the optimum conditions, the interaction between SLG and proteins occurred rapidly, resulting in greatly enhanced RLS intensity with the maximum peak located at 394 nm. It was found that the enhanced RLS intensities were in proportion to the concentrations of proteins in the range of 0.01-3.1 μg ml⁻¹ depending on the kind of proteins. The detection limits were below 6 ng ml⁻¹. Compared with some other methods for the determination of proteins, this method shows high sensitivity, low detection limit and simplicity. This is an inexpensive, simple and fast one-step procedure which requires only measuring the RLS intensities. Human serum samples were determined with satisfactory results.     

Synthesis of phosphate-type fluorocarbon-hydrocarbon hybrid surfactants and their adsorption onto calcium hydroxyapatite

Five novel phosphate-type hybrid surfactants, C_mF_2m+1C₆H₄CH[OPO₂(OC₆H₅)Na]C_nH_2n+1 (FmPHnPPhNa: m = 4, 6, 8; n = 3, 5), have been synthesized. When compared with sulfate-type hybrid surfactants, C_mF_2m+1C₆H₄CH(OSO₃Na)C_nH_2n+1 (C₆H₄ = p-phenylene), the new hybrid surfactants were found to have comparable abilities to lower the surface tension of water. The critical micelle concentrations of FmPHnPPhNa followed Klevens’ rule and their occupied areas per molecule increased with increasing m and n. Calcium hydroxyapatite (CaHAp) pellets modified with FmPH3PPhNa gave high hydro and lipophobic surfaces. The hybrid surfactants are expected to be useful as new dental reagents for oral hygiene.     

环境因素对正负表面活性剂体系相行为的影响

在1:1正负离子表面活性剂混合体系(十二烷基硫酸钠/辛基三甲基溴化铵 SDS-C8NM3Br; 十二烷基硫酸钠/十二烷基三甲基溴化铵,SDS-C12NM3Br)中加入短链脂肪醇 (乙醇,正丙醇,正丁醇),正负离子表面活性剂沉淀溶解,出现表面活性剂双水相.上相有液晶存在,下相有囊泡自发形成.折光率数据和电镜结果表明:上相为表面活性剂富集相,下相表面活性剂浓度较低.混合体系中,出现表面活性剂双水相所需短链脂肪醇的体积百分数,随短链脂肪醇的链长增加而降低.温度升高,出现表面活性剂双水相所需短链脂肪醇的体积百分数降低.对SDS/C8NM3Br/H2O体系的研究结果表明:超声处理,可使混合体系中沉淀向囊泡转化,与短链脂肪醇的加入后的作用类似.     

活性氧化铝孔结构的控制

研究了pH值交替变动、水热处理以及表面活性剂对活性氧化铝孔结构的影响。实验结果表明：pH值交替变动可以制备出结晶度高，晶粒大且均匀的拟薄水铝石；水热处理有利于氧化铝结构内铝原子迁移，促进晶粒进一步增长；而表面活性剂能够插入拟薄水铝石层间，减少焙烧过程中层间坍塌和毛细孔收缩，从而有效调控氧化铝孔结构。其中pH值交替变动和水热处理使氧化铝微孔分布向大孔方向迁移，比表面降低；加入表面活性剂使氧化铝微孔分布向小孔方向迁移，比表面增加，制备出了低比表面(≤150 m²·g^-1)和高比表面(≥250 m²·g^-1)的大孔容氧化铝载体。同时对铝原子的配位情况进行考察，发现铝原子主要以四配位和六配位状态存在，加入表面活性剂和水热处理能显著改变四配位铝和六配位铝的比值。