Zaman A A, Singh P, Moudgil B M
Engineering Research Center for Particle Science and Technology and Department of Materials Science and Engineering, University of Florida, Gainesville, Florida, 32611, USA.
J Colloid Interface Sci. 2002 Jul 15;251(2):381-7. doi: 10.1006/jcis.2002.8442.
Rheological behavior of surfactant-stabilized colloidal dispersions of silica particles under extreme conditions (low pH, high ionic strength) has been investigated in relation to interparticle forces and stability of the dispersion. The surfactant used as the dispersing agent was C(12)TAB, a cationic surfactant. Stability analysis through turbidity measurements indicated that there is a sharp increase in the stability of the dispersion when the surfactant concentration is in the range of 8 to 10 mM in the system. The state of the dispersion changes from an unstable regime to a stable regime above a critical concentration of C(12)TAB in the system. In the case of interaction forces measured between the silica substrate and AFM tip, no repulsive force was observed up to a surfactant concentration of 8 mM and a transition from no repulsive forces to steric repulsive forces occurred between 8 and 10 mM. Rheological measurements as a function of C(12)TAB concentration indicated a significant decrease in the viscosity and linear viscoelastic functions of the dispersion over the same range of surfactant concentration (8 to 10 mM C(12)TAB), showing a strong correlation between the viscosity behavior, interparticle forces, and structure development in the dispersion.
研究了在极端条件（低pH值、高离子强度）下，二氧化硅颗粒的表面活性剂稳定胶体分散体的流变行为与颗粒间作用力及分散体稳定性之间的关系。用作分散剂的表面活性剂是阳离子表面活性剂十六烷基三甲基溴化铵（C(12)TAB）。通过浊度测量进行的稳定性分析表明，当体系中表面活性剂浓度在8至10 mM范围内时，分散体的稳定性急剧增加。在体系中，当C(12)TAB的浓度高于临界浓度时，分散体的状态从不稳定状态转变为稳定状态。在测量二氧化硅基底与原子力显微镜（AFM）探针之间的相互作用力时，在表面活性剂浓度达到8 mM之前未观察到排斥力，而在8至10 mM之间发生了从无排斥力到空间位阻排斥力的转变。作为C(12)TAB浓度函数的流变学测量表明，在相同的表面活性剂浓度范围（8至10 mM C(12)TAB）内，分散体的粘度和线性粘弹性函数显著降低，这表明分散体的粘度行为、颗粒间作用力和结构发展之间存在很强的相关性。
