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Projects / Programmes source: ARIS

Dielectric Spectroscopy of Electroactive Polymer Composites

Research activity

Code Science Field Subfield
1.02.00  Natural sciences and mathematics  Physics   

Code Science Field
P190  Natural sciences and mathematics  Mathematical and general theoretical physics, classical mechanics, quantum mechanics, relativity, gravitation, statistical physics, thermodynamics 
P250  Natural sciences and mathematics  Condensed matter: structure, thermal and mechanical properties, crystallography, phase equilibria 
P260  Natural sciences and mathematics  Condensed matter: electronic structure, electrical, magnetic and optical properties, supraconductors, magnetic resonance, relaxation, spectroscopy 
Keywords
dielectric spectroscopy, polymer, composite, relaxor, ferroelectric
Evaluation (rules)
source: COBISS
Researchers (3)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  15644  PhD Vid Bobnar  Physics  Head  2004 - 2007  363 
2.  04347  PhD Cene Filipič  Physics  Researcher  2004 - 2007  289 
3.  00199  PhD Adrijan Levstik  Physics  Researcher  2004 - 2007  372 
Organisations (1)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  91,855 
Abstract
Dielectric spectroscopy is one of the basic experimental methods for studying the static and dynamic properties of relaxors, which exhibit large values of piezoelectric and dielectric constants in a broad temperature range. The fact that, contrary to inorganic systems, P(VDF-TrFE) copolymer-based organic relaxors can be easily prepared in a variety of shapes, makes them a very promising material for numerous applications. Although electromechanical response of organic relaxors is much larger than that of inorganic, the dielectric constant of polymers is typically much smaller. As the input electric energy that can be converted into strain energy is proportional to the dielectric constant, high electric fields are required for the electromechanical operation of polymers. Therefore a big effort is put into the synthesis of new polymer-based materials with large dielectric constant. We will investigate the linear and nonlinear dielectric response in polymer composites, where materials with high dielectric constant (relaxor ceramics, large organic molecules such as copper-phthalocyanine (CuPc)) or conductive particles (polyaniline, metals), which also enlarge the net dielectric constant, are embedded into the polymer matrix. As there is no chemical reaction between the admixture and the matrix, composites retain the electromechanical response of the polymer. Experimental results will reveal whether dielectric dynamics in composites is similar to those in relaxors and dipolar glasses, as well as how constituents contribute to the net properties of composites. Relaxor-like polymer composites are the first materials with large simultaneous electromechanical and dielectric response. Dielectric investigations therefore seem to be very interesting as from the experimental as well as from the theoretical point of view. For the basic research, CuPc-polymer composite is particularly interesting. Here, completely delocalized electrons can move over large CuPc molecules, thus acting very much like dipoles, while hopping between separated localized states governs very interesting conductive properties. Experimental results should reveal the microscopic origin of large electromechanical and dielectric response of these systems, which should result in their optimization and synthesis of new polymer-based composites.
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