title: Polyethylene glycol aggregates in water formed through hydrophobic helical structures.
abstract: The present study was aimed at elucidating the mechanism of aggregation in water of hydroxyl-terminated polyethylene glycol (PEG) of low molecular weight (600 g/mol). The results from fluorescence spectroscopy at different temperatures were consistent with surface tension measurements, suggesting aggregate formation. Indeed, the process of aggregation is accompanied by an increase in the fluorescence emission of a hydrophobic probe. So, PEG aggregates in the form of internal hydrated helices covered with CH(2) groups are shown to yield hydrophobic regions. These regions created upon PEG aggregation in water and at a temperature close to 35°C result from a balance between H bonding and entropic effects. By providing the first experimental evidence for hydrophobic mediation of aggregation with OH-terminated oxy-ethylene chains of low molecular weight, this study highlights their surfactant-like behaviour.
authors.affiliation: UMR CNRS 6521, Département de Chimie, Université de Bretagne Occidentale, Brest, France.
authors.forename: Aziz
authors.initials: A
authors.lastname: Azri
authors.forename: Philippe
authors.initials: P
authors.lastname: Giamarchi
authors.forename: Yves
authors.initials: Y
authors.lastname: Grohens
authors.forename: René
authors.initials: R
authors.lastname: Olier
authors.forename: Mireille
authors.initials: M
authors.lastname: Privat
mesh_terms: D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry*; D013500:Surface Tension; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D011092:Polyethylene Glycols