title: Solvent-Dependent Properties and Higher-Order Structures of Aryl Alcohol + Surfactant Molecular Gels.
abstract: Molecular organogels, comprising small organic gelators in solvents, can be applied for dispersal of optical devices, such as emitters. Phenolic compounds and the surfactant bis(2-ethylhexyl) sulfosuccinate (AOT) are known examples of self-assembly organogels. However, conventional phenol + AOT gels in aromatic and acyclic alkane solvents are optically turbid, which is an obstacle for use as host materials in optical devices. In this study, a variety of aryl alcohol-AOT-solvent sets have been investigated systematically, and the correlation between the molecular architecture and optical transparency of the gels was considered. Accordingly, p-chlorophenol + AOT gels in cyclic alkane solvents were shown to form optically transparent gels. In contrast, aromatic and acyclic alkane solvents gave rise to turbid or opaque gels, even when utilizing the same gelators. AFM, NMR, SAXS, and FTIR were employed to determine the organogel structures. Consequently, we found that the gel transparency strongly depends on the size of the fibrous network of the gel, the structure of which is attributed to higher-order aggregates of the gelators. The average contour length and diameter of the fibrous network, lav and dav, respectively, were determined from AFM images. The transparent gels were shown to have lav = 4-9 μm and dav ≤ 0.3 μm, whereas the turbid gels had lav = 15 μm and dav = 0.4-0.6 μm. Such differences in the size of the fibrous network significantly affected the mechanical response of the gels, as shown by stress-strain measurements.
authors.affiliation: Faculty of Education, Shimane University , Matsue, Shimane 690-8504, Japan.
authors.forename: Shotaro
authors.initials: S
authors.lastname: Katsube
authors.affiliation: Faculty of Education, Shimane University , Matsue, Shimane 690-8504, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Kinoshita
authors.affiliation: Division of Chemistry and Materials, Faculty of Textile Science and Technology, Shinshu University , Ueda, Nagano 386-8567, Japan.
authors.forename: Kenshi
authors.initials: K
authors.lastname: Amano
authors.affiliation: Division of Chemistry and Materials, Faculty of Textile Science and Technology, Shinshu University , Ueda, Nagano 386-8567, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Chemistry, Faculty of Science, Fukuoka University , Fukuoka 814-0180, Japan.
authors.forename: Yukiteru
authors.initials: Y
authors.lastname: Katsumoto
authors.affiliation: Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University , Saga 840-8502, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Umecky
authors.affiliation: Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University , Saga 840-8502, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Takamuku
authors.affiliation: Department of Applied Physics, Tokyo University of Agriculture and Technology , Koganei, Tokyo 184-8588, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Kaji
authors.affiliation: Institute for Molecular Science , Okazaki, Aichi 444-8787, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hiramoto
authors.affiliation: Faculty of Education, Shimane University , Matsue, Shimane 690-8504, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Tsurunaga
authors.affiliation: Faculty of Education, Shimane University , Matsue, Shimane 690-8504, Japan.
authors.forename: Katsura
authors.initials: K
authors.lastname: Nishiyama