title: Neutron reflectivity study of alkylated azacrown ether at the air-liquid and the liquid-liquid interfaces.
abstract: We report the neutron reflectometry study of partially deuterated di-hexadecyl-diaza-18-crown-6 ether (d-ACE-16) at the air-water and the oil-water interfaces. At the air-water interface, the thickness of the monolayer is smaller than that for a fully stretched d-ACE-16 molecule, suggesting a tilt of the alkyl chains with respect to the normal. At the oil-water interface, the same molecules were found to form a more diffuse layer distribution stretching across both sides of the interface. On the oil side, the molecules are densely packed within a thickness of 17 A, the hydrophilic part of the molecule with the azacrown ether ring being immersed in the adjacent aqueous side of the interface. The latter consists of a thick 38 A layer comprising staggered, loosely adsorbed d-ACE-16 molecules. With increasing spread amount, the adsorbed layer density increases at the oil side until saturation at ca. 2.25 x 10(-6) mol m(-2), above which the layer collapses.
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary, University of London, Walter Basent Building, Mile End Road, London E1 4NS, UK. a.zarbakhsh@qmul.ac.uk
authors.forename: A
authors.initials: A
authors.lastname: Zarbakhsh
authors.forename: J R P
authors.initials: JR
authors.lastname: Webster
authors.forename: K
authors.initials: K
authors.lastname: Wojciechowski
mesh_terms: D000327:Adsorption; D000388:Air; D000478:Alkylation; D043844:Crown Ethers / Q000737:chemistry*; D003903:Deuterium / Q000737:chemistry; D033363:Neutron Diffraction; D009821:Oils / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D043844:Crown Ethers; D009821:Oils; C545169:di-hexadecyl-diaza-18-crown-6 ether; D014867:Water; D003903:Deuterium