title: Periodic Formation/Breakdown of Lamellar Aggregates with Anionic Cyanobiphenyl Surfactants.
abstract: This study reports unusual behavior of aqueous-phase lamellar aggregates with a new class of hybrid surfactant, CB-B2ES, having mesogenic units {6-[4-(4-cyanophenyl)phenyloxy]hexyl} and temperature-sensitive oxyethylated (butoxyethoxyethyl) tails. These tails are poorly miscible and likely to microsegregate if the surfactant molecules assemble. Lamellar aggregates appear at CB-B2ES concentrations higher than 5 wt % and were found to undergo repeat formation/breakdown periodically at 30 °C, with an average domain lifetime of ∼10 s. To investigate effects of the temperature-sensitive oxyethylene units on the hydrophilic/lipophilic balance (HLB) of the CB-B2ES bilayers, a fluorescence probe 1-pyrene-carboxaldehide was solubilized in the mixtures to sense the micro-environmental polarities. Fluorimetric measurements suggested that the polarity of CB-B2ES bilayers is very similar to that of the non-ethoxylated CB-B2ES analogue at high temperatures (≥65 °C). However, for CB-B2ES, polarity increased with a decreasing temperature, in contrast with the small decrease in polarity observed for analogous non-ethoxylated bilayers. This is consistent with increased hydration of the oxyethylene units in CB-B2ES bilayers at low temperatures. The periodic formation/breakdown and cooling-induced hydrophilicity of the CB-B2ES lamellar aggregates did not appear in the non-hybrid and/or non-ethoxylated surfactant systems. Therefore, the combination of two unsymmetrical tails, one containing oxyethylene units and the other containing cyanobiphenyl terminal tips, must play an important role promoting this unusual behavior.
authors.affiliation: Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University , 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Sagisaka
authors.affiliation: Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University , 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Fujita
authors.affiliation: Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University , 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakanishi
authors.affiliation: Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University , 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University , 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
authors.forename: Narumi
authors.initials: N
authors.lastname: Tsuyoshi
authors.affiliation: Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University , 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
authors.forename: Craig
authors.initials: C
authors.lastname: James
authors.affiliation: Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University , 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yoshizawa
authors.forename: Azmi
authors.initials: A
authors.lastname: Mohamed
authors.affiliation: Equipe Surfaces et Interfaces, Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis , Parc Valrose, 06100 Nice, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Guittard
authors.affiliation: School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom.
authors.forename: Julian
authors.initials: J
authors.lastname: Eastoe
mesh_terms: D000838:Anions / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D000838:Anions; D013501:Surface-Active Agents