Document Detail


On the Unexpected Cation Exchange Behavior, Caused by Covalent Bond Formation Between PEDOT and Cl- Ions: Extending the Conception for the Polymer - Dopant Interactions.
MedLine Citation:
PMID:  22486557     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The ionic motion in connection with the redox transformation of poly(3,4-ethylenedioxythiophene) (PEDOT) conjugated polymer have been studied by both experimental: electrochemical (electrochemical quartz crystal nanobalance - EQCN), spectroscopic (Infrared spectroscopy - IR-ATR); and theoretical methods. The observations have been completed by direct, semiquantitative analytical data, provided by energy dispersive X-ray (EDX) microanalysis. The EQCN results suggested an anomalous behavior, since only cationic movements have been observed for films deposited from chloride solutions. Chloride ions were proved to be immobile also when bulky tetrabutylammonium (Bu4N+) cations were substituted with even larger (hexadecyl-trimethylammonium) cations. Since PEDOT films synthesized in the presence of other spherical, not too large anions - such as perchlorate and tetrafluoroborate - endowed mixed ion exchange behavior together with the Bu4N+ cation, the possibility of a special interaction between chloride and the polymeric chain has been assumed. Semi-empirical and DFT calculations indicated that chloride ions interact with the alpha carbon atoms of the thiophene rings of the oxidized EDOT oligomers, creating sp3 type perturbations in the polymer chain. FTIR-ATR spectra evidenced the appearance of C-Cl bonds. Elementary analysis, performed by EDX spectroscopy with 8 polymer samples at different doping levels clearly showed the permanent presence of constant amount of chlorine, independently of the oxidation state of the PEDOT layer. Finally, the presented observations call attention to the fact that unique dopant-polymer interactions during the electrochemical polymerization are of prime importance, being able to rule over conventions for the charge compensation of conjugated polymers, often solely based on steric parameters.
Authors:
Péter S Tóth; Csaba Janáky; Ottó Berkesi; Tarmo Tamm; Csaba Visy
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-4-10
Journal Detail:
Title:  The journal of physical chemistry. B     Volume:  -     ISSN:  1520-5207     ISO Abbreviation:  -     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-4-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101157530     Medline TA:  J Phys Chem B     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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