Effects of the Method of Preparation and Dispersion Media on the Optical Properties and Particle Sizes of Aqueous Dispersions of a Double-Chain Cationic Surfactant
Effects of the Method of Preparation and Dispersion Media on the Optical Properties and Particle Sizes of Aqueous Dispersions of a Double-Chain Cationic Surfactant
复制标题
制备方法和分散介质对双链阳离子表面活性剂水分散体光学性能和粒径的影响
DOI：
10.1021/acs.langmuir.1c01069
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发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
Corti, David S.
中科院分区：
文献类型：
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作者：
Hsieh, An-Hsuan;Franses, Elias I.;Corti, David S.
从目视观察和浊度测量推断，由阳离子双链表面活性剂双十二烷基二甲基溴化铵（DDAB）在水中形成的单层囊泡的平均半径随制备方法而变化，超声处理后（SS法）为24 nm，挤出/超滤后（SE法）为74 nm。当在10 mM NaBr中产生囊泡时，SS方法的半径为65 nm，SE方法的半径为280 nm。这些泡状分散体的比浊度或每单位路径长度的浊度除以表面活性剂的重量分数w随着w的减小而增加，直到达到恒定值atw*，这取决于制备方法和分散介质。恒定的比浊度是单一和独立的散射的指示，并被用来估计囊泡半径通过求解特定的瑞利-德拜-甘斯（RDG）制度推导出的浊度方程。使用了两个浊度方程，一个考虑了由于一些散射光到达检测器而引起的吸光度误差，另一个没有校正。的囊泡和它们相应的德拜长度之间的平均距离的估计，获得用于评估囊泡间静电相互作用的重要性，这可能会导致在更高的重量分数依赖散射。
As inferred from visual observations and turbidity measurements, the average radius of the unilamellar vesicles formed in water from the cationic double-chain surfactant didodecyldimethylammonium bromide (DDAB) varies with the method of preparation, being ∼24 nm after sonication (SS method) and ∼74 nm after extrusion/ultrafiltration (SE method). The radii were larger when the vesicles were produced in 10 mM NaBr, ∼65 nm for the SS method and ∼280 nm for the SE method. The specific turbidity, or turbidity per unit path length divided by the surfactant weight fraction,w, of these vesicular dispersions increased with decreasingwuntil a constant value was reached atw*, which depends on the preparation method and the dispersion medium. The constant specific turbidities are indicative of single and independent scattering and were used to estimate vesicle radii by solving the specific turbidity equations derived for the Rayleigh–Debye–Gans (RDG) regime. Two turbidity equations were used, one accounting for absorbance errors due to some scattered light reaching the detector and another with no correction. Estimates of the average distances between the vesicles and their corresponding Debye lengths were obtained for evaluating the importance of intervesicle electrostatic interactions, which could lead to dependent scattering at higher weight fractions.