Department of Chemical Engineering, University of Massachusetts, 686 North Pleasant Street, Amherst, MA 01003, USA.
J Colloid Interface Sci. 2011 Jan 1;353(1):87-97. doi: 10.1016/j.jcis.2010.09.058. Epub 2010 Sep 26.
The DLVO force and potential energy of interaction between microspheres and topographically and chemically heterogeneous surfaces in aqueous solution are computed using a modification of the surface element integration approach. The heterogeneous surface has an array of cylindrical pillars of varying height, diameter, and arrangement to model different nano-topographies. In agreement with previous studies, the nano-topography decreases the size of the potential energy barrier for unfavorable surfaces because the pillars limit the minimum separation distance. The influence of topography is significant even for pillars several nanometers high and is more pronounced if the surface potential of the pillar tops differs from that of the underlying surface. A new force- and energy-averaging model is introduced as a simple method to compute the mean interaction energy or force between the particle and a heterogeneous surface, which differs significantly from a mean-field approach based on the average or nominal surface potential. Small variations in topography are found to remove large energy barriers to colloidal deposition. These results help explain the increased attraction of patchy surfaces towards particles relative to expectations based on typical DLVO calculations, which is particularly significant for surfaces with adsorbed polyelectrolytes.
使用表面元积分方法的改进版，计算了微球与水相中的具有形貌和化学异质性表面之间的 DLVO 力和相互作用势能。具有不同高度、直径和排列的圆柱状立柱阵列的非均匀表面用于模拟不同的纳米形貌。与先前的研究一致，纳米形貌减小了不利表面的势能势垒的大小，因为立柱限制了最小分离距离。即使是几纳米高的立柱，形貌的影响也很显著，如果立柱顶部的表面电位与下面的表面不同，则影响更为明显。引入了一种新的力和能量平均模型，作为计算颗粒与非均匀表面之间的平均相互作用能或力的简单方法，该方法与基于平均或名义表面电位的平均场方法有很大不同。研究发现，微小的形貌变化可以消除胶体沉积的大能量势垒。这些结果有助于解释与基于典型 DLVO 计算的预期相比，有斑点的表面对颗粒的吸引力增加，这对于吸附有聚电解质的表面尤其重要。
