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排序方式: 共有266条查询结果,搜索用时 214 毫秒
101.
采用丁二酮室温光猝灭法研究了胶束介质中丁二酮的增溶位点,通过研究4种不同荷电和不同亲水亲脂性的光猝灭剂以及盐效应等对Stern-Volmer常数的影响,表明了二酮在SDS、CTAB的胶束中是增溶在胶团的栏栅并靠近离子头基一侧和头基/水界面附近,而在CTAB胶束中更加趋向于胶团外部头基附近. 相似文献
102.
We synthesized the GSH/pH responsive amphiphilic random polycarbonate poly(MN-co-MSS) with the disulfide and tertiary amine groups situated on the backbone. The poly(MN-co-MSS) was therefore a promising candidate for GSH/pH-sensitive drug carriers. 相似文献
103.
Marcela?A.?Morini Paula?V.?Messina Pablo?C.?SchulzEmail author 《Colloid and polymer science》2005,283(11):1206-1218
The effect of NaCl and HCl on two non-ionic surfactant micelles was studied using several techniques, including conductivity
and ion-selective electrodes. Both surfactants exhibit opposite behaviour. When Tween 20 is titrated with HCl the conductivity
notably increases in comparison with water, whereas that of Triton X-100 solutions do not change with respect to water until
a certain HCl concentration is reached, when it increases. The hydrogen ion activity is lower in Triton X-100 solutions and
higher in Tween 20 solutions than in pure water. Chloride ion activity is higher in Tween 20 solutions than in water, whereas
in Triton X-100 the activity does not significantly differ from that in water. The activity of sodium ion is lower in Tween
20 solutions than in water, whereas that in Triton X-100 solutions does not differ from the titration of water. These phenomena
are explained by the changes in conformation of the non-ionic headgroups, which capture water, and in some cases ions, modifying
the activity of ions in the intermicellar solution. 相似文献
104.
The anionic dye 8-anilino-1-napthalensulfonic acid ammonium salt, or ANS, was used as a fluorescent probe to investigate the behaviour of dye-surfactant interactions in aqueous solutions of Triton X-100 and the Brij and polyoxyethylene tridecyl ether (POE TDE) series of polyoxyethylene non-ionic surfactants. The fluorescence behaviour of the dye with the non-ionic surfactants was examined in micellar media. The concentration of surfactant was kept well above the cmc to investigate the interaction of the dye with surfactant micelles. In this investigation, the relative fluorescence enhancements, binding constants of the dye to the surfactant micelles and aggregation numbers of the micelles were determined, from the analysis of spectroscopic data. 相似文献
105.
Hydrophobic interaction chromatography (HIC) of proteins using a phenyl column has been performed in the presence of various surfactants with micellar and submicellar concentration ranges. Most surfactants were effective for a decrease in the retention of proteins in both concentration ranges. However, the use of anionic cholate derivatives increased the retention of the proteins with high isoelectric point, such as lysozyme, cytochrome c, and trypsin, in submicellar concentration range, and then decreased it above the critical micellar concentration, while the retention of the other proteins was monotonously decreased. The results of frontal chromatographic analysis of the surfactant and capillary electrophoresis for the proteins in the presence of surfactant show that in the submicellar concentration range, cholate derivatives allowed to be adsorbed on the stationary phase, while they exhibited no interactions with the proteins. Thus, it appeared that the increase in the retention of basic proteins was due to the electrostatic attraction between the proteins and cholate-modified stationary phase. We have applied the unique property of cholate to the separation of ovalbumin and lysozyme in egg white sample using hydrophobic chromatography. 相似文献
106.
This paper reports the synthesis and characterization of polystyrene nanorods in hemicylindrical hemimicelles of a nonionic polyoxyethylene surfactant, C
12
E
5, on graphite. The surface structure is characterized by atomic force microscopy (AFM), Fourier transform infrared spectroscopy, and contact angle goniometry. Uniformly aligned polystyrene nanorods are captured by AFM. The nanorod dimensions are studied as a function of the reaction time and styrene monomer concentration. The template synthesis using self-assembled surfactant surface aggregates promises to create functional and stable nanostructures for optoelectronics and surface engineering. 相似文献
107.
A. Suárez Varela M. I. Sández Macho A. Gil González 《Colloid and polymer science》1995,273(9):876-880
The steady-state fluorescence quenching technique was used to investigate the effect of the presence of a series of alcohol homologues of mid-sized straight chain on the size of mixed micelles of sodium dodecyl sulfate (SDS). We used pyrene at concentration of ca. 10–6M, where only its monomer exhibits any fluorescence, as fluorescent probe, and cetylpiridinium chloride at concentrations in the range (1–9)×10–5 M as quencher. This technique allows one to determine the micellar aggregation number. The number of alcohol molecules per micelle was calculated from reported values for the micelle-water partition coefficient. On the assumption of spherical micelles, their hydrophobic radii was then calculated. The hypothesis that micelle size is determined by the available surface area per charged headgroup is discussed in the light of the results obtained. 相似文献
108.
The self-association of n-hexyltrimethylammonium bromide (C6TAB) in aqueous solution has been studied by static and dynamic light scattering and NMR spectroscopy at 25 °C in the presence
of added electrolyte, and critical aggregation concentrations, aggregation numbers and the degree of ionization have been
calculated. Aggregation numbers determined from light scattering and from the application of mass-action theory to the concentration
dependence of 1H NMR chemical shifts of four protons along the alkyl chain of C6TAB, were between three and four over the range of electrolyte concentration studied (0.2–0.7 molkg−1 NaBr). A structure for the small aggregates has been proposed from the NMR chemical shift data.
Received: 4 June 2001 Accepted: 17 September 2001 相似文献
109.
The micelle formation of a poly(vinylphenol)-block-polystyrene diblock copolymer was studied in ethyl acetate, a nonselective solvent using α,ω-diamine. The copolymer formed
micelles in ethyl acetate in the presence of a small amount of the α,ω-diamine. Light scattering studies demonstrated that
the micellization was dependent on the grade, the bulkiness, and the conformation of the diamines. The copolymer needed more
diamine with the increasing grade of the diamine, due to a decrease in the basicity of the diamine. The bulkiness of the diamines
also reduced the efficiency of the micellization by hindering the formation of the hydrogen bond cross-linking. Similarly,
the conformation of the diamine affected the micellization, since the conformation determined the intramolecular spatial distance
between the animo groups. Trans-1,2-cyclohexanediamine was more effective than the cis-isomer to produce the micelles. Furthermore,
(1S,2S)-(+)-1,2-cyclohexanediamine, one of the mirror image isomers composing the trans-isomer, was more effective in producing
the micelles than the trans-isomer. The interaction between the mirror image isomers also obstructed the micellization. The
micellization, coupled with the thermoresponsivity of the micelles, were influenced by the solvent quality. The dissociation
of the micelles into unimers was suppressed in ethyl acetate, while the reconstruction was promoted, in comparison with those
in 1,4-dioxane and THF. 相似文献
110.
We found the novel photolysis-induced micellization of the poly(tert-butoxystyrene)-block-polystyrene diblock copolymer (PBSt-b-PSt). PBSt-b-PSt with a molecular weight of Mn(PBSt-b-PSt) = 15,000-b-97,000 showed no self-assembly in dichloromethane and existed as isolated copolymers with a hydrodynamic diameter of 16.6 nm.
Dynamic light scattering demonstrated that the copolymer produced micelles with a 63.0 nm hydrodynamic diameter when the copolymer
solution was irradiated with a high-pressure mercury lamp at room temperature in the presence of bis(alkylphenyl) iodonium
hexafluorophosphate, a photoacid generator. The 1H NMR analysis revealed that the micellization resulted from the photolysis of the PBSt blocks into insoluble poly(vinyl phenol)
blocks based on the fact that the signal intensity of the tert-butyl protons decreased over time during the irradiation. It was found that the micellization rapidly proceeded as the degree
of the photolysis reached over 50% and was completed at 90%. 相似文献