مقاله Nonionic reverse micelle formulation and their microstructure transformations in an aromatic solvent ethylbenzene : تی پی بین

خلاصه مقاله

Formation of reverse micelles at room temperature generally requires inclusion of water or other polar molecules in a mixture of long chain ionic surfactant and an organic solvent. In this paper, we report the formulation of nonionic reverse micelles at room temperature in an aromatic solvent, ethylbenzene using short-chain glycerol-based surfactants, and investigated the microstructure transformations induced by surfactant chain length, concentration, and temperature using SAXS and rheometry. We have also determined water solubility in reverse micelle and investigated water induced microstructure transitions. We found that a short chain nonionic surfactant, diglycerol monocaprate (C₁₀G₂), spontaneously self-assembles into an ellipsoidal prolate type micelle. Increasing surfactant chain induces a prolate-to-globular type transition forming globular micelles in diglycerol monomyristate (C₁₄G₂), which is expected to be caused by an increase in the lipophilicity of the surfactant. Increases in surfactant concentration favored one-dimensional micellar growth; the micellar size increases ca. 4.5–7.25 nm upon increase in the surfactant concentration from 3 to 20% while the cross-sectional radius maintained almost constant ca. 1.10 nm in the diglycerol monolaurate (C₁₂G₂) system. In contrast to the nonionic micelles in aqueous systems, reverse micelles get smaller with increasing temperature, which is similar to a rod-to-sphere type transition. Addition of trace water promotes a significant micellar growth; both the maximum dimension and radius of micelles increases and the size of the water-incorporated micelles was approximately three times greater than the micelles in the absence of water. Microstructure transitions revealed by SAXS are supported by rheological measurements; the relative zero-shear viscosity decreased with increase in the chain length of surfactant. On the other hand, relative viscosity increased nearly one order of magnitude upon increase in surfactant concentration from 3 to 20%.

نویسندگان

Lok Kumar Shrestha [ International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan ]

Rekha Goswami Shrestha [ Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan ]

Kenji Aramaki [ Graduate School of Environment and Information Sciences, Yokohama National University, Tokiwadai 79-7, Hodogaya, Yokohama 240-8501, Japan ]

Jonathan P. Hill [ International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan ]

Katsuhiko Ariga [ International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan ]

کلمات کلیدی

Nonionic surfactants Organic solvents Reverse micelles SAXS Rheometry

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Colloids and Surfaces A: Physicochemical and Engineering Aspects

Colloids and Surfaces A: Physicochemical and Engineering Aspects is an international journal devoted to the science underlying applications ofcolloids and interfacial phenomena. The journal aims at publishing high quality research papers featuring new materials or new insights into the role of colloid and interface science in (for example) food, energy, minerals processing, pharmaceuticals or the environment.Criteria for publication in Colloids and Surfaces A are novelty, quality and current interest. Manuscripts which only make routine use of or minor extensions to well established methodologies (e.g. fitting adsorption data to a Langmuir or Freundlich isotherm) are no appropriate for the journal.

حوزه های تحت پوشش : Physicochemical , food, energy, minerals processing, pharmaceuticals , environment