Basavaraj Madivala G, McFarlane Naa Larteokor, Lynch Matthew L, Wagner Norman J
Center for Neutron Science, Department of Chemical & Biomolecular Engineering, University of Delaware, Colburn Laboratory, Newark, DE 19716, United States.
Corporate Research Division, Procter and Gamble Company, Beckett Ridge Technical Center, West Chester, OH 45069, United States.
J Colloid Interface Sci. 2014 Sep 1;429:17-24. doi: 10.1016/j.jcis.2014.04.064. Epub 2014 May 10.
Surfactant vesicles composed of ditallowethylesterdimethylammonium chloride (DEEDMAC), a cationic double tail surfactant, are commonly present in personal care industrial formulations such as fabric softeners. There is significant interest in formulating vesicle dispersions, investigation of stability, characterization of their structure and flow properties due to the biodegradable nature of DEEDMAC.
We investigate the formation and structure of unilamellar nanovesicles having a shell made of DEEDMAC and a core containing water. We use bright field optical microscopy to elucidate the formation mechanism, and a combination of small angle neutron scattering (SANS), cryogenic transmission electron microscopy (cryo-TEM), viscometry, densitometry, dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and zeta potential measurements to determine the nanostructure of well-defined surfactant nanovesicles (∼15 nm diameter).
We report methods for the determination of volume fraction of nanovesicles and vesicle density, which are crucial for quantitative estimation of nanovesicle performance in practical applications and for predicting vesicle stability. The nanovesicle volume fraction can be obtained directly from the intrinsic viscosity and density. The robust method presented here is simple and effective as confirmed by quantitative agreement of the results with independent SANS measurements.
由阳离子双尾表面活性剂二牛脂基二甲基氯化铵（DEEDMAC）组成的表面活性剂囊泡普遍存在于织物柔软剂等个人护理工业配方中。由于DEEDMAC的可生物降解性，人们对配制囊泡分散体、研究其稳定性、表征其结构和流动性质有着浓厚兴趣。
我们研究了具有由DEEDMAC制成的外壳和含水核心的单层纳米囊泡的形成和结构。我们使用明场光学显微镜来阐明形成机制，并结合小角中子散射（SANS）、低温透射电子显微镜（cryo-TEM）、粘度测定、密度测定、动态光散射（DLS）、小角X射线散射（SAXS）和zeta电位测量来确定明确的表面活性剂纳米囊泡（直径约15纳米）的纳米结构。
我们报告了测定纳米囊泡体积分数和囊泡密度的方法，这对于在实际应用中定量评估纳米囊泡性能以及预测囊泡稳定性至关重要。纳米囊泡体积分数可直接从特性粘度和密度获得。这里提出的稳健方法简单有效，结果与独立的SANS测量的定量一致性证实了这一点。
