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71.
Pseudo-first-order rate constants, kobs, for the alkaline hydrolysis of N-hydroxyphthalimide, 1, at 0.02 M NaOH and 30°C remain essentially independent of the total concentration of C12E23, [C12E23]T, at ≤0.005 M C12E23. The increase in [C12 E23]T from 0.005 to 0.015 M causes a nonlinear decrease in kobs. The rate of hydrolysis becomes either too slow or the change in absorbance values becomes significantly small to allow a reliable observed data fit to a first-order kinetic equation at ≥0.020 M C12E23 in the absence and presence of total concentration of cetyltrimethylammonium bromide, [CTABr]T ranging from 0.003 to 0.020 M. The values of fraction of nonionized 1, FSH, obtained at reaction time t = 0 and 0.02 M NaOH, remain ~0 at ≤0.010 M C12E23 while they increase from 0.39 to 0.89 with the increase of [C12E23]T from 0.015 to 0.10 M. The values of kobs show a nonlinear decrease of ~5-fold with the increase of [C12E23]T from 0.0 to 0.010 M in the presence of 0.02 M NaOH and [CTABr]T range of 0.003 to 0.020 M. The values of FSH remain ≤~0.10 at ≤0.015 M C12E23 while they vary between 0.40 and 0.90 within a [C12E23]T range 0.02 to 0.05 M in the presence of 0.02 M NaOH and [CTABr]T ranging from 0.003 to 0.020 M. The values of FSH represent the fraction of nonionized 1 trapped almost irreversibly by pure C12E23, and mixed C12E23–CTABr micelles. 相似文献
72.
Malek Bendjaballah Rabah Oumeddour 《Journal of Dispersion Science and Technology》2013,34(9):1260-1272
To find an optimal formulation of oil-in-water (O/W) emulsions (φo = 0.05), the effect of emulsifier nature and concentration, agitation speed, emulsifying time, storage temperature and their mutual interactions on the properties and behavior of these dispersions is evaluated by means of an experimental design (Nemrodw software). Long-term emulsion stability is monitored by multiple light scattering (Turbiscan ags) and acoustic attenuation spectroscopy (Ultrasizer). After matching surfactant HLB and oil required HLB, a model giving the Sauter diameter as a function of emulsifier concentration, agitation speed and emulsification time is proposed. The highest stability of C12E4-stabilized O/W emulsions is observed with 1% emulsifier. 相似文献
73.
Yassin A. Aggour Ikuyoshi Tomita Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1994,32(10):1991-1995
Cationic crosslinking reactions of poly(allenyl ether)s having oligo(oxyethylene) moieties prepared by the radical polymerization of the corresponding allenyl ethers were carried out under some varied reaction conditions. For instance, a crosslinked polymer was obtained in 82% yield by the treatment of poly(ethylene glycol methyl allenyl ether) ( 1a ) with 1.2 mol% of BF3·OEt2 ( 2 ) under high concentration in dichloromethane (46 wt %). The gels obtained showed good swelling properties in water, alcohols, and polar organic solvents such as dichloromethane. In particular, the degrees of swelling of these gels in aqueous sodium chloride (1M) were quite similar to those in ion-free water, indicating that these gels served as nonionic hydrogels. © 1994 John Wiley & Sons, Inc. 相似文献
74.
Ryzhkina I. S. Enikeev K. M. Timosheva A. P. Pashirova T. N. Lukashenko S. S. Kudryavtseva L. A. Konovalov A. I. 《Russian Chemical Bulletin》2004,53(7):1528-1535
Aggregation and intermolecular interactions of amphiphilic calix[4]resorcinarene (1), aminomethylated calix[4]resorcinarenes (AMC 2—7) with different structures of the upper rim (including the oxazine structure in 6 and 7) and hydrophobic substituents on the lower (2—5), upper (6), or both rims (7) in the absence and in the presence of the nonionic surfactant Triton-X-100 (8) and p-nitrophenol (9) in chloroform and 1,4-dioxane were studied by permittivity measurements and 2D ROESY 1H NMR technique. The tendency of amphiphilic derivatives 1—7 toward self-aggregation and mixed aggregation with surfactant 8 primarily depends on the nature of both the solvent and the polar groups on the upper rim of calixarenes. In chloroform, AMC—8 aggregates show interactions of the methyl and methylene groups of the hydrophobic substituents of AMC with the ethyleneoxy fragments of surfactant 8, while in stable intermolecular complexes of 5 and 6 with compound 9, the methylene groups of the long-chain radicals of the AMC strongly interact with the aromatic protons ortho to the hydroxy group of 9. In 1,4-dioxane, calix[4]resorcinarenes 1 and 5 are bound in stable solvates, which prevents them from forming aggregates and mixed micelles. 相似文献
75.
IntroductionCriticalmicelleconcentration (cmc)ofsurfactantsinaqueoussolutionisoneofthemostusefulparametersforcharacterizingthepropertiesofsurfactants.Overaverynarrowconcentrationrangearoundthecmctransitionsoftheexistenceofsurfactantsoccurfrommonomer ,premicel lartomicellar .Andcompanyingthesetransitions ,manyotherimportantpropertiesofsurfactantsolution ,suchassurfacetension ,interfacialtension ,conductivity ,osmoticpressure ,detergency ,emulsification ,foamingandsoon ,alsochangesharplyatthepoi… 相似文献
76.
The dynamic surface tension (γt) and apparent diffusion coefficient (D) of nonionic surfactant Tween‐20 in the presence and absence of bovine serum albumin (BSA) have been investigated via the measurements of surface pressure (π) at different time (t). The curves of γt~t are obtained from π~t isotherms. Results show that the γt~t relationships of Tween‐20 solution with or without BSA accord with the Ward‐Tordai equation in the region of initial adsorption. D value obtained from the γt~t1/2 curves shows that the diffusion of Tween‐20 slows down with the increase of the concentration of Tween‐20 (c Tween‐20). And D value of Tween‐20 in the presence of BSA is almost the same as that of the system without BSA when c Tween‐20 is constant, suggesting that the interaction between Tween‐20 and BSA is weak. 相似文献
77.
Tingting Zhou Xiaohui Xu Xiangying Wang Guojun Dong 《Journal of Dispersion Science and Technology》2013,34(9):1189-1194
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. 相似文献
78.
研究Au(111)和Au(100)表面非离子型氟表面活性剂FSN自组装膜的电化学行为.电化学扫描隧道显微术和循环伏安法测试表明,在0~0.8 V电位区间,FSN自组装膜未发生氧化还原,均一性好,可稳定地存在于电极表面,并显著抑制硫酸根离子在电极表面的吸附和Au单晶表面的重构.在FSN自组装膜Au单晶电极的初始氧化阶段,Au(111)表面有少量突起,而Au(100)表面呈现台阶剧烈变化,但FSN自组装膜的吸附结构没有改变.与Au(100)表面相比,Au(111)表面形成的FSN自组装膜可更有效地抑制Au表面的氧化. 相似文献
79.
Micellar solution of nonionic surfactantn-dodecyloligo ethyleneoxide surfactant, decaoxyethylene monododecyl ether [CH3(CH2)11(OCH2CH2)10OH], C12E10 in D2O solution have been analysed by small-angle neutron scattering (SANS) at different temperatures (30, 45 and 60° C) both in
the presence and absence of sugars. The structural parameters like micelle shape and size, aggregation number and micellar
density have been determined. It is found that the micellar structure significantly depends on the temperature and concentration
of sugars. The micelles are found to be prolate ellipsoids at 30° C and the axial ratio of the micelle increases with the
increase in temperature. The presence of lower concentration of sugar reduces the size of micelles and it grows at higher
concentration of sugar. The structure of micelles is almost independent of the different types of sugars used. 相似文献
80.