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Structure of weakly bonded PPG‐silica nanocomposites
Author(s) -
Chaker J.A.,
Dahmouche K.,
Craievich A.F.,
Santilli C.V.,
Pulcinelli S.H.
Publication year - 2000
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/s0021889899013254
Subject(s) - small angle x ray scattering , nanocomposite , materials science , fractal dimension , chemical engineering , scattering , phase (matter) , crystallography , fractal , composite material , chemistry , organic chemistry , optics , mathematical analysis , physics , mathematics , engineering
The structure of silica‐polypropyleneglycol (PPG) nanocomposites with weak physical bonds between the organic (PPG) and inorganic (silica) phase, prepared by the sol‐gel process, was investigated by small angle X‐ray scattering (SAXS). These nanocomposite materials are transparent, flexible, have good chemical stability and exhibit high ionic conductivity when doped with lithium salt. Their structure was studied as a function of silica weight fraction x (0.06 ≤ x ≤ 0.29) and [O]/[Li] ratio (oxygens being of ether‐type). The shape of the experimental SAXS curves agrees with that expected for scattering intensity produced by fractal aggregates sized between 30 and 90Å. This result suggests that the structure of the studied hybrids consists of silica fractal aggregates embedded in a matrix of PPG. The correlation length of the fractal aggregates decreases and the fractal dimension increases for increasing silica content. The variations in structural parameters for increasing Li + doping indicate that lithium ions favor the growth of fractal silica aggregates without modifying their internal structure and promote the densification of the oligomeric PPG matrix.