Anomalous effects of concentrated salts on the equimolarly mixed   cationic-anionic surfactant mixtures

doi:10.1039/c1sm05115f

CORC > 北京大学 > 化学与分子工程学院

	Anomalous effects of concentrated salts on the equimolarly mixed cationic-anionic surfactant mixtures
	Chen, Li ; Xing, Hang ; Yan, Peng ; Ma, Ji-Ming ; Xiao, Jin-Xin
刊名	软性材料
	2011
关键词	FREE CATANIONIC SURFACTANT SODIUM DODECYL-SULFATE REVERSIBLE PHASE-TRANSITION LIQUID EXPANDED MONOLAYERS NEUTRON-SCATTERING SANS AQUEOUS 2-PHASE SYSTEMS TO-MICELLE TRANSITION HOFMEISTER SERIES MODEL SYSTEMS VESICLE AGGREGATION
DOI	10.1039/c1sm05115f
英文摘要	Effects of alkali metal halides (NaX, X = F(-), Cl(-), Br(-), I(-); KX, X = Cl(-), Br(-), I(-); and CsCl) on the morphology of the aggregates of decyltriethylammonium bromide and sodium decylsulfonate (C(10)NE-C(10)SO(3)) mixtures with equimolar ratios were studied by static/dynamic light scattering and viscosity measurements. The average hydrodynamic radii of the aggregates, the apparent aggregation number, and the relative viscosity as functions of both the concentrations of surfactants and added salts were investigated, respectively. It showed that the addition of a small amount of NaX (e. g., 0.1 M) had only small effects on the C(10)NE-C(10)SO(3) vesicles. However, striking anion specificity, which differed anomalously with the anions of salts varying from F(-) to I(-), was observed when large amounts of NaX (e. g., 1 M) were added. The size of the C(10)NE-C(10)SO(3) aggregates was normally increased and then a liquid-liquid phase separation occurred with the addition of NaF; meanwhile, the addition of NaCl had little effect on the C(10)NE-C(10)SO(3) aggregates under experimental conditions; however, the size of the C(10)NE-C(10)SO(3) aggregates was abnormally decreased when high concentrations of NaBr or NaI (up to 2 M) were added, implying a vesicle-to-micelle transition which might be due to a decrease in the intramicellar attraction between oppositely charged headgroups by electrical shielding, and the mixtures still remained homogeneous. A cation specificity of added salts was also observed with the increase of the ionic radii from Na(+) to Cs(+). However, it was noted that the influence of increasing the ionic radii of cations on the aggregate size was not as pronounced as that of anions in the presence of high concentrations of salts. The aggregates of C(10)NE-C(10)SO(3) became a little smaller when concentrated alkali metal halides with bigger cations were added into this homogeneous equimolar cationic-anionic surfactant mixture. Both the observed cation and anion specificities were consistent with the Hofmeister series.; Chemistry, Physical; Materials Science, Multidisciplinary; Physics, Multidisciplinary; Polymer Science; SCI(E); 4; ARTICLE; 11; 5365-5372; 7
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/151066]
专题	化学与分子工程学院
推荐引用方式 GB/T 7714	Chen, Li,Xing, Hang,Yan, Peng,et al. Anomalous effects of concentrated salts on the equimolarly mixed cationic-anionic surfactant mixtures[J]. 软性材料,2011.
APA	Chen, Li,Xing, Hang,Yan, Peng,Ma, Ji-Ming,&Xiao, Jin-Xin.(2011).Anomalous effects of concentrated salts on the equimolarly mixed cationic-anionic surfactant mixtures.软性材料.
MLA	Chen, Li,et al."Anomalous effects of concentrated salts on the equimolarly mixed cationic-anionic surfactant mixtures".软性材料 (2011).