Department of Inorganic and Analytical Chemistry , University of Geneva , Sciences II, 30 Quai Ernest-Ansermet , 1205 Geneva , Switzerland.
Langmuir. 2018 Nov 27;34(47):14368-14377. doi: 10.1021/acs.langmuir.8b03191. Epub 2018 Nov 15.
Aqueous suspensions of amidine latex (AL) and sulfate latex (SL) particles containing sodium tetraphenylborate and NaCl are studied with electrokinetic and time-resolved light-scattering techniques. In monovalent salt solutions, AL is positively charged, whereas SL is negatively charged. Electrophoretic mobility measurements demonstrate that adsorption of tetraphenylborate anions leads to a charge reversal of AL particles. At higher concentrations, both types of particles accumulate negative charge. For AL particles, the charge reversal leads to a narrow fast aggregation region and an intermediate regime of slow aggregation. For SL particles, the intermediate slow regime is also observed. These aspects can be explained with classical theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO). Another regime of fast aggregation is observed at intermediate concentrations, and the existence of this regime can be rationalized by an additional attractive non-DLVO force. We suspect that this additional force is caused by surface charge heterogeneities.
采用动电和时间分辨光散射技术研究了含有四苯硼酸钠和 NaCl 的脒乳胶（AL）和硫酸盐乳胶（SL）颗粒的水悬浮液。在单价盐溶液中，AL 带正电荷，而 SL 带负电荷。电泳迁移率测量表明，四苯硼酸盐阴离子的吸附导致 AL 颗粒的电荷反转。在较高浓度下，两种类型的颗粒都积累负电荷。对于 AL 颗粒，电荷反转导致快速聚集区变窄和缓慢聚集的中间区。对于 SL 颗粒，也观察到中间缓慢区。这些方面可以用德加古因、朗道、维韦和奥弗贝克（DLVO）的经典理论来解释。在中间浓度下还观察到另一个快速聚集区，这个区的存在可以通过附加的吸引力非 DLVO 力来合理化。我们怀疑这种额外的力是由表面电荷不均匀引起的。
