Polymerization of w/o Microemulsions for the Preparation of Transparent SiO2/PMMA Nanocomposites

Reverse w/o microemulsions composed of methyl methacrylate (MMA) forming the oil phase, nonionic surfactants, and water are used for the synthesis of transparent SiO2/PMMA nanocomposites. An inorganic precursor, tetraethoxysilane (Si(OEt)4, TEOS), is hydrolyzed in the reverse micelles containing aqu...

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Bibliographic Details
Published in:Langmuir 2005-06, Vol.21 (13), p.6048-6053
Main Authors: Palkovits, R, Althues, H, Rumplecker, A, Tesche, B, Dreier, A, Holle, U, Fink, G, Cheng, C. H, Shantz, D. F, Kaskel, S
Format: Article
Language:English
Subjects:
Chemistry
Colloidal state and disperse state
Emulsions. Microemulsions. Foams
Exact sciences and technology
General and physical chemistry
Micelles. Thin films
Physical and chemical studies. Granulometry. Electrokinetic phenomena
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Summary:Reverse w/o microemulsions composed of methyl methacrylate (MMA) forming the oil phase, nonionic surfactants, and water are used for the synthesis of transparent SiO2/PMMA nanocomposites. An inorganic precursor, tetraethoxysilane (Si(OEt)4, TEOS), is hydrolyzed in the reverse micelles containing aqueous ammonia. During the hydrolysis of TEOS, polymerization of the continuous MMA phase is initiated using AIBN (azobisisobutyronitrile), and after thermal polymerization at 333 K for 12 h, solid blocks of PMMA are obtained in which nanometer-sized silica particles are trapped in the solid polymer matrix. According to small-angle X-ray and dynamic light scattering experiments, the water droplets in MMA microemulsions are 12 nm (R W = 13) in diameter, whereas after polymerization of the microemulsion, the SiO2 particles in the transparent SiO2/PMMA composites are 26 nm in diameter. Transmission electron micrographs demonstrate a low degree of agglomeration in the composites. In comparison with materials generated from micelle-free solutions, the particle size distribution is narrow. The reverse micelle-mediated approach produces composites of high transparency comparable with that of pure PMMA.
ISSN:0743-7463
1520-5827
DOI:10.1021/la050630k