Adv Colloid Interface Sci. 2011 Oct 14;168(1-2):263-77. doi: 10.1016/j.cis.2011.05.003. Epub 2011 May 17.
The interparticle interactions in concentrated suspensions are described. Four main types of interactions can be distinguished: (i) "Hard-sphere" interactions whereby repulsive and attractive forces are screened. (ii) "Soft" or electrostatic interactions determined by double layer repulsion. (iii) Steric repulsion produced by interaction between adsorbed or grafted surfactant and polymer layers. (iv)and van der Waals attraction mainly due to London dispersion forces. Combination of these interaction energies results in three main energy-distance curves: (i) A DLVO type energy-distance curves produced by combination of double layer repulsion and van der Waals attraction. For a stable suspension the energy-distance curve shows a "barrier" (energy maximum) whose height must exceed 25kT (where k is the Boltzmann constant and T is the absolute temperature). (ii) An energy-distance curve characterized by a shallow attractive minimum at twice the adsorbed layer thickness 2δ and when the interparticle-distance h becomes smaller than 2δ the energy shows a sharp increase with further decrease of h and this is the origin of steric stabilization. (iii) an energy-distance curve characterized by a shallow attractive minimum, an energy maximum of the DLVO type and a sharp increase in energy with further decrease of h due to steric repulsion. This is referred to as electrosteric repulsion. The flocculation of electrostatically and sterically stabilized suspensions is briefly described. A section is devoted to charge neutralization by polyelectrolytes and bridging flocculation by polymers. A distinction could be made between "dilute", "concentrated" and "solid suspensions" in terms of the balance between the Brownian motion and interparticle interaction. The states of suspension on standing are described in terms of interaction forces and the effect of gravity. The bulk properties (rheology) of concentrated suspensions are described starting with the case of very dilute suspensions (the Einstein limit with volume fraction Φ≤0.01), moderately concentrated suspensions (0.2>Φ≥0.1) taking into account the hydrodynamic interaction and concentrated suspensions (Φ>0.2) where semi-empirical theories are available. The rheological behavior of the above four main types of interactions is described starting with "hard-sphere" systems where the relative viscosity-volume fraction relationship could be described. The rheology of electrostatically stabilized suspensions was described with particular reference to the effect of electrolyte that controls the double layer extension. The rheology of sterically stabilized systems is described using model polystyrene suspensions with grafter poly(ethylene oxide) layers. Finally the rheology of flocculated suspensions was described and a distinction could be made between weakly and strongly flocculated systems.
浓悬浮液中的颗粒间相互作用。可以区分出四种主要的相互作用：（i）“硬球”相互作用，其中排斥力和吸引力受到屏蔽。（ii）由双电层排斥决定的“软”或静电相互作用。（iii）由吸附或接枝的表面活性剂和聚合物层之间的相互作用产生的空间排斥。（iv）和主要由于伦敦色散力的范德华吸引力。这些相互作用能的组合导致了三种主要的能量-距离曲线：（i）由双电层排斥和范德华吸引力组合产生的 DLVO 型能量-距离曲线。对于稳定的悬浮液，能量-距离曲线显示出一个“势垒”（能量最大值），其高度必须超过 25kT（其中 k 是玻尔兹曼常数，T 是绝对温度）。（ii）能量-距离曲线的特征是在两倍吸附层厚度 2δ处有一个浅的吸引力最小值，并且当颗粒间距离 h 变得小于 2δ时，能量随着 h 的进一步减小而急剧增加，这就是空间稳定化的起源。（iii）能量-距离曲线的特征是一个浅的吸引力最小值，一个 DLVO 型的能量最大值和由于空间排斥而随着 h 的进一步减小能量的急剧增加。这被称为电动排斥。简要描述了静电和空间稳定悬浮液的絮凝。有一节专门讨论聚电解质的电荷中和和聚合物的桥接絮凝。可以根据布朗运动和颗粒间相互作用之间的平衡来区分“稀”、“浓”和“固”悬浮液。根据相互作用力和重力的影响，描述了悬浮液在静置时的状态。从非常稀的悬浮液（体积分数 Φ≤0.01 的爱因斯坦极限）开始，描述了浓悬浮液的体性质（流变学），中等浓度的悬浮液（0.2>Φ≥0.1）考虑到流体力学相互作用和浓悬浮液（Φ>0.2），其中有半经验理论可用。从“硬球”系统开始，描述了上述四种主要相互作用类型的流变学行为，其中可以描述相对粘度-体积分数关系。特别参考电解质对双电层扩展的控制作用，描述了静电稳定悬浮液的流变学。使用带有接枝聚（氧化乙烯）层的模型聚苯乙烯悬浮液来描述空间稳定体系的流变学。最后，描述了絮凝悬浮液的流变学，可以区分弱絮凝和强絮凝系统。
