ISSN:
0887-6266
Keywords:
organic-inorganic composites
;
sol-gel
;
TEOS
;
TMOS
;
SAXS
;
morphology
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Two morphological models have been proposed to describe small-angle x-ray scattering from organic-inorganic composite (OIC) materials. The first model invokes the idea of a liquid-like arrangement among noninterpenetrating fractal clusters, and the second employs an empirical correlation function that would be expected for a bicontinuous two-phase (B2P) picture with the inorganic portion exhibiting fractal characteristics. Simulated scattering profiles have been generated for direct comparison with experimental data. The samples studied were a triethoxysilane-endcapped bisphenol A epoxide resin (EAS) reacted in the presence of tetraethoxysilane (TEOS) under slightly basic conditions, and a random trimethoxysilane-functionalized copolymer of poly(methyl methacrylate) (MMA-TMS) with added tetramethoxysilane (TMOS), reacted in an acidic medium. Each morphology model qualitatively simulates the broad scattering maximum and limiting high-angle slope commonly seen in SAXS profiles. It is concluded that the inorganic phase in the EAS hybrid exhibits particle-like characteristics at length scales less than approximately 250 Å, and the organic and inorganic components are bicontinuous at larger distances. The MMATMS composite is better described by bicontinuous organic and inorganic phases with a periodic fluctuation of about 40 Å. The scattering maximum arises either from the mean separation of particles or a dominant wavelength in a concentration fluctuation, similar to that observed for spinodal decomposition. In either case, the SAXS peak position is related to the distance between junction points of the crosslinked organic polymer. © 1995 John Wiley & Sons, Inc.
Additional Material:
16 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/polb.1995.090330414
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