title: Self-association of urea in aqueous solutions: a Voronoi polyhedron analysis study.
abstract: Molecular dynamics simulation of the aqueous solutions of urea of seven different concentrations (including neat water as a reference system) has been performed on the isothermal-isobaric (N,p,T) ensemble. The ability of the urea molecules of self-association is investigated by means of the method of Voronoi polyhedra. For this purpose, all the analyses are repeated by removing one of the two components from the sample configurations and considering only the other one. In this way, the analysis of self-aggregation is reduced to the analysis of voids, a problem that can routinely be addressed by means of Voronoi analysis. The obtained results show that the urea molecules exhibit self-association behavior, which is found to be the strongest at the urea mole fraction of 0.23. However, the size of these urea aggregates is found to be rather limited; on average, they are built up by 3-4 molecules, and never exceed the size of 20-25 molecules.
authors.affiliation: Laboratoire de Spectrochimie Infrarouge et Raman (UMR CNRS A8516), Centre d'Etudes et de Recherches Lasers et Applications, Universite des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France.
authors.forename: Abdenacer
authors.initials: A
authors.lastname: Idrissi
authors.forename: Pierre
authors.initials: P
authors.lastname: Damay
authors.forename: Kitamura
authors.initials: K
authors.lastname: Yukichi
authors.forename: Pal
authors.initials: P
authors.lastname: Jedlovszky
mesh_terms: D008958:Models, Molecular; D008968:Molecular Conformation; D012996:Solutions; D014508:Urea / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D012996:Solutions; D014867:Water; D014508:Urea