Abstract
The kinetics of poly(ethylene oxide) (PEO) adsorption onto the surface of a trapped silica particle in a controlled flow and solution environment was studied using optical tweezers and microfluidics. The polymer layer thickness, δH, was monitored directly by exploiting the balance of the trapping force and the hydrodynamic drag force of the flowing solution past the particle. The effects of polymer concentration, volumetric flow rate, pH, particle size, and molecular weight were evaluated as parameters. In all conditions, the time-series evolution of the δH was observed to increase with time scale up to ≈ 50 s and approached a plateau due to the saturation of PEO on the surface. As for the PEO concentration dependence, the plateau of the δH was found to increase with PEO concentration, affected by the surface diffusion and reconformation of the preferentially adsorbed polymer at the interface, in agreement with the previous studies. The effect of pH was found to be influenced by the volumetric flow rate. At a low flow rate, the plateau of the δH was observed to be independent of pH. In contrast, at a high flow rate, the plateau of the δH was observed to decrease at high pH. This is attributed to the decrease in the attractive interaction between the silica surface and the polymer, in addition to the influence of fluid force. Furthermore, the plateau of the δH was found to increase with particle size, corresponding to the increase in the number of colliding polymers. Finally, this study presents a novel perspective in understanding polymer adsorption kinetics by directly evaluating the layer thickness on a single particle viewpoint that is not accessible to the bulk measurements.
Accepted Version (
Free)
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call