Kleimann Jörg, Lecoultre Guy, Papastavrou Georg, Jeanneret Stéphane, Galletto Paolo, Koper Ger J M, Borkovec Michal
Department of Inorganic, Analytical, and Applied Chemistry, University of Geneva, Science II, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland.
J Colloid Interface Sci. 2006 Nov 15;303(2):460-71. doi: 10.1016/j.jcis.2006.08.006. Epub 2006 Sep 15.
Deposition of positively charged nanosized latex particles onto planar silica and cellulose substrates was studied in monovalent electrolyte solutions at pH 9.5. The deposition was probed in situ with optical reflectometry in a stagnation point flow cell. The surface coverage can be estimated reliably with island film theory as well as with a homogeneous film model, as confirmed with atomic force microscopy (AFM). The deposition kinetics on the bare surface was of first order with respect to the particle concentration, whereby the deposition rate was close to the value expected for a perfect collector. The efficiency coefficient, which was defined as the ratio of the experimental and theoretical deposition rate constants, was in the range from 0.3 to 0.7. Subsequently, the surface saturated and a limiting maximum coverage was attained (i.e., blocking). These trends were in qualitative agreement with predictions of the random sequential absorption (RSA) model, where electrostatic interactions between the particles were included. It was observed, however, that the substrate strongly influenced the maximum coverage, which was substantially higher for silica than for cellulose. The major conclusion of this work was that the nature of the substrate played an important role in a saturated layer of deposited colloidal particles.
在pH值为9.5的单价电解质溶液中，研究了带正电的纳米级乳胶颗粒在平面二氧化硅和纤维素基底上的沉积情况。在驻点流动池中用光学反射法对沉积过程进行原位探测。通过原子力显微镜（AFM）证实，表面覆盖率可以用岛状膜理论以及均匀膜模型可靠地估计。裸表面上的沉积动力学相对于颗粒浓度为一级反应，沉积速率接近完美收集器预期的值。效率系数定义为实验和理论沉积速率常数之比，范围为0.3至0.7。随后，表面达到饱和并达到极限最大覆盖率（即阻塞）。这些趋势与包含颗粒间静电相互作用的随机顺序吸附（RSA）模型的预测在定性上一致。然而，观察到基底对最大覆盖率有很大影响，二氧化硅的最大覆盖率比纤维素的高得多。这项工作的主要结论是，基底的性质在沉积胶体颗粒的饱和层中起着重要作用。
