Solution Rheology of Polyelectrolyte-Grafted Nanoparticles
ORAL
Abstract
The variations in hydrodynamic sizes of a series of poly(acrylic acid) (PAA)-grafted silica (SiO2) nanoparticles indicated the compressed and fully extended grafted chain conformations as pH increased. At semi-dilute concentrations, interactions between grafted-chains were investigated by measuring the complex viscosity of the solutions. We found that the viscosity of grafted particle solution increased by an order of magnitude as a result of hydrogen bonding between inter-particles at neutral pH; and decreased by two orders of magnitude at the higher pH due to strong electrostatic repulsion between grafted chains. In particles with the higher graft density, the change in viscosity was reduced but followed the similar trend as pH was varied. The PAA-grafted particles were found to form hydrogen-bonded networks with the addition of short poly(vinyl pyrrolidone) (PVP) chains. The viscosity adjustment by the PVP concentration suggested that hydrogen bonding was possible within the grafted chains of individual particles at low graft density, whereas networking between inter-chains occurred with the high graft density.
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Presenters
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Chongfeng Zhang
Stevens Institute of Technology
Authors
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Chongfeng Zhang
Stevens Institute of Technology
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Pinar Akcora
Stevens Institute of Technology, Chemical Engineering and Materials Science, Stevens Institute of Technology