Tato diplomová práce je zaměřena na přípravu kompozitních částic polypyrol-stříbro (PPy-Ag) a srovnání jejich chemických vlastností a elektroreologických (ER) a dielektrických vlastností v suspenzích v silikonovém oleji se samotnými PPy částicemi. Kompozitní částice PPy-Ag byly připraveny pomocí oxidace pyrolu směsí persíranu amonného a dusičnanu stříbrného. Experimenty ukázaly, že ačkoliv přítomnost Ag zvýšila vodivost o jeden řád, ER účinnost těchto částic nebyla ve srovnání s čistým PPy výrazně ovlivněna při nižších intenzitách elektrického pole. Přítomnost Ag v částicích navíc zvýšila jejich vzájemnou kompatibilitu se silikonovým olejem a urychlila mezifázovou polarizaci kompozitních částic PPy-Ag.
Annotation in English
This Master Thesis is aimed on the synthesis of polypyrrole-silver (PPy-Ag) composite particles and comparing their chemical, electrorheological (ER) and dielectric properties of their suspensions in silicone oil with those of pure PPy particles. Polypyrrole-silver composite particles were synthesized by oxidation of Pyrrole with mixture of Ammonium persulfate and Silver nitrate. Although the presence of Ag in the composite particles increased their conductivity in one order of magnitude, Experiments revealed that the ER performance did not change significantly at low electric field strengths compared to that of pure PPy. Moreover, it appeared that Ag improved the compatibility of dispersed particles with silicone oil used as a carrier liquid in ER suspensions and caused faster interfacial polarization of PPy-Ag composite particles.
Tato diplomová práce je zaměřena na přípravu kompozitních částic polypyrol-stříbro (PPy-Ag) a srovnání jejich chemických vlastností a elektroreologických (ER) a dielektrických vlastností v suspenzích v silikonovém oleji se samotnými PPy částicemi. Kompozitní částice PPy-Ag byly připraveny pomocí oxidace pyrolu směsí persíranu amonného a dusičnanu stříbrného. Experimenty ukázaly, že ačkoliv přítomnost Ag zvýšila vodivost o jeden řád, ER účinnost těchto částic nebyla ve srovnání s čistým PPy výrazně ovlivněna při nižších intenzitách elektrického pole. Přítomnost Ag v částicích navíc zvýšila jejich vzájemnou kompatibilitu se silikonovým olejem a urychlila mezifázovou polarizaci kompozitních částic PPy-Ag.
Annotation in English
This Master Thesis is aimed on the synthesis of polypyrrole-silver (PPy-Ag) composite particles and comparing their chemical, electrorheological (ER) and dielectric properties of their suspensions in silicone oil with those of pure PPy particles. Polypyrrole-silver composite particles were synthesized by oxidation of Pyrrole with mixture of Ammonium persulfate and Silver nitrate. Although the presence of Ag in the composite particles increased their conductivity in one order of magnitude, Experiments revealed that the ER performance did not change significantly at low electric field strengths compared to that of pure PPy. Moreover, it appeared that Ag improved the compatibility of dispersed particles with silicone oil used as a carrier liquid in ER suspensions and caused faster interfacial polarization of PPy-Ag composite particles.
Composites of conducting polymers and noble metals attract a large interest due to the variety of nanostructures displayed by both components. The combination of metallic and semiconductor types of conduction may provide materials having a reduced dependence of conductivity on temperature and this feature can be promising in the use of such particles as a disperse phase in electrorheological fluids, i.e. systems which are able to reversibly change their rheological properties according to the external electric field strength. The diploma thesis will deal with oxidation of pyrrole with mixture of two oxidants, ammonium peroxydisulfate and silver nitrate, to give polypyrrole?silver composites with variable content of silver in the composite and thus variable conductivity of prepared particles. Furthermore, the electrorheological characteristics of suspensions based on composite particles with optimum conductivity will be investigated. 1. Make a literature review on the given topic 2. Prepare polypyrrole particles of different conductivities depending on the content of silver 3. Measure dielectric, electric and rheological properties of suspensions based on particles of suitable conductivities 4. Evaluate and interpret obtained results
Research Plan
Composites of conducting polymers and noble metals attract a large interest due to the variety of nanostructures displayed by both components. The combination of metallic and semiconductor types of conduction may provide materials having a reduced dependence of conductivity on temperature and this feature can be promising in the use of such particles as a disperse phase in electrorheological fluids, i.e. systems which are able to reversibly change their rheological properties according to the external electric field strength. The diploma thesis will deal with oxidation of pyrrole with mixture of two oxidants, ammonium peroxydisulfate and silver nitrate, to give polypyrrole?silver composites with variable content of silver in the composite and thus variable conductivity of prepared particles. Furthermore, the electrorheological characteristics of suspensions based on composite particles with optimum conductivity will be investigated. 1. Make a literature review on the given topic 2. Prepare polypyrrole particles of different conductivities depending on the content of silver 3. Measure dielectric, electric and rheological properties of suspensions based on particles of suitable conductivities 4. Evaluate and interpret obtained results
Recommended resources
1. T. Hao, Electrorheological fluids: The non aqueous suspensions, 1st ed., Cambridge, Massachusetts, 2005, ISBN-13: 978-0-444-52180-4 2. Online databases accessible from TBU in Zlín
Recommended resources
1. T. Hao, Electrorheological fluids: The non aqueous suspensions, 1st ed., Cambridge, Massachusetts, 2005, ISBN-13: 978-0-444-52180-4 2. Online databases accessible from TBU in Zlín
