title: Adsorption and Aggregation Properties of Homogeneous Polyoxypropylene-Polyoxyethylene Alkyl Ether Type Nonionic Surfactants.
abstract: Homogeneous polyoxypropylene (PO)-polyoxyethylene (EO) alkyl ether type nonionic surfactants comprising alkyl, EO, and PO chains with identical chain length distributions (CnEOxPOy; alkyl chain length n = 10, 12, 14, or 16; EO chain length x = 4, 6, or 8; and PO chain length y = 1, 2, or 3) were synthesized from homogeneous polyoxyethylene alkyl ether bromide and monosodium polyoxypropylene by Williamson ether synthesis. The adsorption and aggregation properties of these surfactants were characterized (cloud point, surface tension, dynamic light scattering, small-angle X-ray scattering, polarization microscopy, and cryogenic transmission electron microscopy) and compared to those of conventional homogeneous EO alkyl ether type nonionic surfactants (CnEOx). The introduction of a PO chain to the EO terminal group of the CnEOxspecies lowered the cloud points, especially for x = 6. Contrary to our expectations, the CnEOxPOysurfactants adsorbed efficiently at the air/water interface, despite their complex structure (hydrophobic alkyl chain/hydrophilic EO chain/hydrophobic PO chain). They also displayed excellent micelle-forming ability in solution. Furthermore, the CnEOxspecies formed small micelles in solution at low concentrations and the structures transformed to hexagonal liquid crystals as the surfactant concentration increased. Conversely, CnEOxPOymaintained a micellar structure even at high concentrations. Notably, the introduction of a PO chain into the CnEOxsurfactant controlled the formation of aggregates with a higher-order structure (hexagonal liquid crystals).
authors.affiliation: Department of Chemistry, Faculty of Science, Nara Women's University , Kitauoyanishi-machi, Nara 630-8506, Japan.
authors.forename: Shiho
authors.initials: S
authors.lastname: Yada
authors.affiliation: Nikkol Group Cosmos Technical Center Co., Ltd., 3-24-3 Hasune, Itabashi-ku, Tokyo 174-0046, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Nikkol Group Cosmos Technical Center Co., Ltd., 3-24-3 Hasune, Itabashi-ku, Tokyo 174-0046, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Hashimoto
authors.affiliation: Department of Chemistry, Faculty of Science, Nara Women's University , Kitauoyanishi-machi, Nara 630-8506, Japan.
authors.forename: Tomokazu
authors.identifier: 0000-0001-8283-1032
authors.initials: T
authors.lastname: Yoshimura