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Anomalous rheology of polypyrrole nanoparticle/alginate suspensions: effect of solids volume fraction, particle size, and electronic state |
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| Authors: | Tuspon Thanpitcha Zheng Li Ratana Rujiravanit Anuvat Sirivat Alexander M. Jamieson |
| Affiliation: | 1. Conductive and Electroactive Polymers Research Unit, The Petroleum and Petrochemical College, Chulalongkorn University, Bangkok, 10330, Thailand 3. Department of Macromolecular Science, Case Western Reserve University, Cleveland, OH, USA 2. Center for Petroleum, Petrochemicals, and Advanced Materials, Chulalongkorn University, Bangkok, 10330, Thailand |
| Abstract: | The rheology of dispersions of polypyrrole (PPY) nanoparticles (nPPY) is compared to that of micron-sized PPY particles (CPPY), each suspended in aqueous sodium alginate. With increasing PPY volume fraction, the Newtonian viscosity of the CPPY/alginate suspensions exhibits a ??normal?? increase, whereas that of the nPPY/alginate suspensions decreases to a minimum and then increases again. Enhanced elasticity, indicative of agglomerate formation via bridging interactions with the alginate, is observed only in the CPPY rheology. By comparing doped versus dedoped nPPY particles, and investigating the effect of nPPY particle size, we conclude that the negative viscosity change of the nPPY dispersions is due to adsorption of a dense layer of alginate, resulting in a decrease in bulk alginate concentration. The viscosity upturn at higher nPPY volume fractions indicates the onset of particle agglomeration via bridging interactions with alginate. The results demonstrate improved dispersability of both doped and dedoped nPPY over CPPY particles. |
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