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Structure of the Hexadecane Rotator Phase: Combination of X-ray Spectra and Molecular Dynamics Simulation.
Burrows, Stephen A; Lin, E Emily; Cholakova, Diana; Richardson, Sam; Smoukov, Stoyan K.
Afiliação
  • Burrows SA; Centre for Sustainable Engineering, School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K.
  • Lin EE; Centre for Sustainable Engineering, School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K.
  • Cholakova D; Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria.
  • Richardson S; Centre for Sustainable Engineering, School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K.
  • Smoukov SK; Centre for Sustainable Engineering, School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K.
J Phys Chem B ; 127(36): 7772-7784, 2023 Sep 14.
Article em En | MEDLINE | ID: mdl-37647602
ABSTRACT
Rotator phases are rotationally disordered plastic crystals, some of which can form upon freezing of alkane at alkane-water interfaces. Existing X-ray diffraction studies show only partial unit cell information for rotator phases of some alkanes. This includes the rotator phase of n-hexadecane, which is a transient metastable phase in pure alkane systems, but shows remarkable stability at interfaces when mediated by a surfactant. Here, we combine synchrotron X-ray diffraction data and molecular dynamics (MD) simulations, reporting clear evidence of the face-centered orthorhombic RI rotator phase from spectra for two hexadecane emulsions, one stabilized by Brij C10 and another by Tween 40 surfactants. MD simulations of pure hexadecane use the recently developed Williams 7B force field, which is capable of reproducing crystal-to-rotator phase transitions, and it also predicts the crystal structure of the RI phase. Full unit cell information is obtained by combining unit cell dimensions from synchrotron data and molecular orientations from MD simulations. A unit cell model of the RI phase is produced in the crystallographic information file (CIF) format, with each molecule represented by a superposition of four rotational positions, each with 25% occupancy. Powder diffraction spectra computed using this model are in good agreement with the experimental spectra.

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Tipo de estudo: Prognostic_studies Idioma: En Revista: J Phys Chem B Assunto da revista: QUIMICA Ano de publicação: 2023 Tipo de documento: Article País de afiliação: Reino Unido

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Tipo de estudo: Prognostic_studies Idioma: En Revista: J Phys Chem B Assunto da revista: QUIMICA Ano de publicação: 2023 Tipo de documento: Article País de afiliação: Reino Unido