Premium
Exploring the structure of inter‐platelet galleries in organically modified montmorillonite using the small‐angle X‐ray scattering interface distribution function approach
Author(s) -
Rosenthal Martin,
Anokhin Denis V.,
Defaux Matthieu,
Portale Giuseppe,
Ivanov Dimitri A.
Publication year - 2011
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889811019121
Subject(s) - montmorillonite , small angle x ray scattering , scattering , alkyl , chemistry , ammonium bromide , phase (matter) , melting point , adsorption , bromide , phase transition , crystallography , thermodynamics , inorganic chemistry , organic chemistry , optics , physics , pulmonary surfactant , biochemistry
Small‐angle X‐ray scattering interface distribution function (IDF) analysis is successfully applied to evaluate the two‐ and three‐phase inter‐platelet gallery structure in synthetic montmorillonite (MMT) modified with a mixture of chemically grafted and physically adsorbed chains of a typical organic modifier, octadecyl trimethyl ammonium bromide. Two distinctly different states of adsorbed chains in the inter‐platelet galleries are identified. The first one corresponds to a fully cation‐exchanged structure with an inter‐platelet distance of about 21 Å. In this case the organic modifier is in a liquid‐like state, and the system does not exhibit any structural or thermal transitions between ambient temperature and 433 K. When the number of adsorbed chains exceeds the cation‐exchange capacity of the MMT platelets the inter‐platelet spacing is increased to 43 Å. In this case, the variable‐temperature IDFs reveal partially crystalline order in the inter‐platelet galleries, which vanishes at the melting point of the alkyl tails confined in the galleries.