Study on the kinetics of adsorption of poly(ethylene oxide) onto a silica particle using optical tweezers and microfluidics
Study on the kinetics of adsorption of poly(ethylene oxide) onto a silica particle using optical tweezers and microfluidics
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DOI：
10.1016/j.colsurfa.2022.128691
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发表时间：
2022-03-04
影响因子：
5.2
通讯作者：
Adachi, Yasuhisa
中科院分区：
文献类型：
--
作者：
Geonzon, Lester C.;Kobayashi, Motoyoshi;Adachi, Yasuhisa
利用光镊和微流控技术研究了聚氧化乙烯（PEO）在受控流动和溶液环境中吸附到被捕获的二氧化硅颗粒表面的动力学。通过利用捕获力和流过颗粒的流动溶液的流体动力拖曳力的平衡，直接监测聚合物层厚度Δ（H）。聚合物浓度、体积流速、Δ（H）、粒度和分子量的影响作为参数进行评价。在所有条件下，观察到δ（H）的时间序列演变随着时间尺度增加至约50 s，并且由于表面上的PEO饱和而接近平台。对于PEO浓度依赖性，发现Δ（H）的平台随着PEO浓度的增加而增加，受界面处优先吸附的聚合物的表面扩散和重构的影响，与先前的研究一致。pH值的影响被认为是由体积流量的影响。在低流速下，观察到Δ（H）的平台与pH无关。相反，在高流速下，观察到Δ（H）的平台在高pH下降低。这归因于二氧化硅表面与聚合物之间的吸引相互作用的降低，以及流体力的影响。此外，发现Δ（H）的平台随着颗粒尺寸增加而增加，对应于碰撞聚合物数量的增加。最后，这项研究提出了一个新的角度来理解聚合物吸附动力学直接评估层厚度上的一个单一的颗粒的观点，是无法访问的散装测量。
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, delta(H), 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, delta(H), particle size, and molecular weight were evaluated as parameters. In all conditions, the time-series evolution of the delta(H) was observed to increase with time scale up to approximate 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 delta(H) 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 delta(H) was observed to be independent of pH. In contrast, at a high flow rate, the plateau of the delta(H) 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 delta(H) 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.