Polyimide organic-inorganic hybrid composites with formed in situ inorganic nanophase: influence of host polyimide chemical structure on molecular dynamic and permeability
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引用次数: 0
Abstract
To observe how changes in the structure of the host polymer affect the dynamic properties and permeability of polyimide matrices and nanocomposites the three series of hybrid organic-inorganic nanocomposites based on linear, branched or cardo polyimides and tetraethoxysilane (TEOS) were analyzed by EPR method using the stable nitroxyl radical 2,2,6,6,-tetramethylpiperidine-1-oxy (TEMPO) as a paramagnetic probe. The EPR data obtained were compared with the results of measuring the volume fraction of pores φ and dielectric permittivity ε as well as with X-ray structural analysis and optical microscopy. The introduction of an inorganic component in all cases led to a decrease in the segmental mobility of the linear and cardo polyimide-based composites as compared with the pure polyimide, due to partial immobilization of organic macrochains during the formation of inorganic microregions. For composites based on linear polyimide correlations are observed between the permeability values and the volume fraction of pores and the dielectric constant. EPR results agree with small angle X-ray scattering data that demonstrate formation of more heterogeneous structure of nanocomposites based on branched polyimide matrix as compared with linear one. According to optical microscopy the TEOS content, that allows obtaining most uniform distribution of inorganic inhomogeneities in the nanocomposites, depends on chemical structure of polyimide and is 40%, 50%, and 5% for linear, cardo and branched polyimides, respectively.
期刊介绍：
The primary objective of the Journal of Sol-Gel Science and Technology (JSST), the official journal of the International Sol-Gel Society, is to provide an international forum for the dissemination of scientific, technological, and general knowledge about materials processed by chemical nanotechnologies known as the "sol-gel" process. The materials of interest include gels, gel-derived glasses, ceramics in form of nano- and micro-powders, bulk, fibres, thin films and coatings as well as more recent materials such as hybrid organic-inorganic materials and composites. Such materials exhibit a wide range of optical, electronic, magnetic, chemical, environmental, and biomedical properties and functionalities. Methods for producing sol-gel-derived materials and the industrial uses of these materials are also of great interest.
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