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Molecular Dynamics (MD) Simulations and Large‐Angle X‐ray Scattering (LAXS) Studies of the Solid‐State Structure and Assembly of Isotactic ( R )‐Poly(2,2′‐dioxy‐1,1′‐binaphthyl‐)phosphazene in the Bulk State and in the Cast Film
Author(s) -
Carriedo Gabino A.,
Alonso Francisco J. García,
Alvarez José L. García,
Lombardo Giuseppe M.,
Pappalardo Giuseppe C.,
Punzo Francesco
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400051
Subject(s) - phosphazene , small angle x ray scattering , solid state , scattering , tacticity , dynamics (music) , materials science , crystallography , molecular dynamics , state (computer science) , physics , chemistry , computational chemistry , polymer , optics , polymerization , engineering physics , mathematics , composite material , algorithm , acoustics
The intrachain conformation, molecular structure and interchain assembly of isotactic ( R )‐poly(2,2′‐dioxy‐1,1′‐binaphthyl)phosphazene (P‐DBNP) both in the bulk state (I ) and in the cast film (II) were studied by molecular dynamics (MD) simulations of models, as implemented by a bias potential for the analysis of the radial distribution function (RDF) obtained from large‐angle X‐ray scattering (LAXS) data. The microscopic structure and order extension of the polymer changed from I to II, as qualitatively shown in the shapes of their experimentally measured RDF curves. With the use of a bias potential, the MD simulations provided a much more accurate analysis of the models, as seen in the reproduction of the RDFs. The chiral P‐DBNP chain was found to be consistent with helix conformations in both the I and the II samples. The predominant interchain clustering motif was best reproduced with a seven‐chain model. In the case of I, the maximum chain length was 18 monomeric R 2 NP units, while in the case of the cast film II the chain was more elongated, up to distances of approximately 100 Å, equivalent to over 48 monomeric R 2 NP units. The seven‐chain assembly was accounted for in terms of nonbonded interactions favouring the minimum voids area between the seven tubular structures of the material. The results validate our earlier finding that MD analysis with implementation of a biasing potential for the RDFs can provide quantitative information on the structural and conformational features of amorphous solids. The combined theoretical and experimental approach was found to be a useful tool to detect, locate and evaluate the intra‐ and intermolecular modifications of materials subsequent to their phase transformation and, as in the present case, changes in their microscopic structures or preparation methods.