Detection of free volumes in polyaniline complexes with various acids by using positron lifetime spectroscopy |
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| Institution: | 1. Institute of Polymers, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria;2. Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784, Bulgaria;1. Department of Bioengineering, Rice University, Houston, TX, USA;2. Department of Chemistry, Rice University, Houston, TX, USA;3. Menninger Department of Psychiatry & Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA;4. Department of Pharmacology, Baylor College of Medicine, Houston, TX, USA;5. Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA;6. Department of Veterans Affairs Medical Center, Houston, TX, USA;7. Center for Human Toxicology, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA;8. Department Biomaterials, Bioengineering Institute, New York University, 433 First Avenue, Room 820, New York, NY 10010-4086, USA;1. Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan;2. Institute of Polymer Science and Engineering, National Taiwan University, Taipei 10617, Taiwan;1. Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang, 330013, PR China;2. Department of Physics, Jiangxi Science and Technology Normal University, Nanchang 330013, PR China |
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| Abstract: | The positron lifetime spectroscopy (PLS), a non-destructive characterization method, utilizes positronium (Ps; an electron–positron bound state) as a probe and measures its lifetime in polymer free volumes. For the first time the free volumes have been estimated by PLS in polyaniline (PANI) complexes with various inorganic and organic acids. It was found that the o-Ps lifetime increases and the intensity decreases with increasing ionic radius of the counter-ions in PANI complexes. Obviously, larger counter anions result in enhanced mean size of the voids corresponding to the free volume in the bulk polymer.Electrical conductivity has been measured by conventional four-probe technique. The glass transition temperature and temperature of removal of the absorbed water have been determined by using differential scanning calorimetry. It was established fairly well correlation of the mentioned polymer parameters with the o-Ps lifetime and the free volume of PANI complexes, respectively. The greater free-volume results in a decrease of conductivity, glass transition temperature and temperature of removal of the absorbed water. |
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