Growth process for fractal polymer aggregates formed by perfluorooctyltrimethoxysilane. Time-resolved small-angle X-ray scattering study |
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| Authors: | T Ogasawara K Izawa N Hattori H Okabayashi C J O'Connor |
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| Institution: | (1) Department of Applied Chemistry Nagoya Institute of Technology Gokiso-cho, Showa-ku, Nagoya 466-855 Japan, JP;(2) Department of Chemistry The University of Auckland Private Bag 92019, Auckland, New Zealand, NZ |
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| Abstract: | The acid-catalyzed condensation reaction of perfluorooctyltrimethoxysilane (PFOS) and n-octyltrimethoxysilane (OTMS) in ethanol has been followed by time-resolved synchrotron radiation small-angle X-ray scattering
(SAXS) on a short time scale. SAXS curves for PFOS and OTMS have been interpreted as arising from mass fractals with D
f=2 (PFOS) and D
f=1.7 (OTMS). The time dependence of the apparent radius of gyration, obtained from the Guinier plots, showed that the growth
of fractal precursors occurs in a two-step process within 2 h for PFOS and within 1.5 h for OTMS, in which small clusters
involving monomers, dimers and trimers are formed in the initial step and formation of larger clusters occurs in the second
step. Furthermore, it has been suggested that the hydrophobicity and lipophobicity of the bulky alkyl groups may also contribute
to the formation of these giant aggregates.
Received: 13 July 1999/Accepted in revised form: 6 October 1999 |
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| Keywords: | Perfluorooctyl-trimethoxysilane Mass fractal Small-angle X-ray scattering |
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