Denton AR
Department of Physics, Acadia University, Wolfville, Nova Scotia, Canada B0P 1X0.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Sep;62(3 Pt B):3855-64. doi: 10.1103/physreve.62.3855.
Interparticle interactions in charge-stabilized colloidal suspensions, of arbitrary salt concentration, are described at the level of effective interactions in an equivalent one-component system. Integrating out the degrees of freedom of all microions from the partition function, and assuming a linear response to the macroion charges, general expressions are obtained for both an effective electrostatic pair interaction and an associated microion volume energy. For macroions with hard-sphere cores, the effective interaction is of the Derjaguin-Landau-Verwey-Overbeek screened-Coulomb form, but with a modified screening constant that incorporates excluded volume effects. The volume energy-a natural consequence of the one-component reduction-contributes to the total free energy, and can significantly influence thermodynamic properties in the limit of low-salt concentration. As illustrations, the osmotic pressure and bulk modulus are computed and compared with recent experimental measurements for deionized suspensions. For macroions of sufficient charge and concentration, it is shown that the counterions can act to soften or destabilize colloidal crystals.
在任意盐浓度下，电荷稳定的胶体悬浮液中的粒子间相互作用，在等效单组分系统的有效相互作用层面进行了描述。从配分函数中积分掉所有微离子的自由度，并假设对大离子电荷呈线性响应，得到了有效静电对相互作用和相关微离子体积能的一般表达式。对于具有硬球核心的大离子，有效相互作用具有德亚金 - 朗道 - 韦弗 - 奥弗贝克屏蔽库仑形式，但具有一个纳入了排除体积效应的修正屏蔽常数。体积能是单组分简化的自然结果，它对总自由能有贡献，并且在低盐浓度极限下会显著影响热力学性质。作为示例，计算了渗透压和体积模量，并与近期去离子悬浮液的实验测量结果进行了比较。对于具有足够电荷和浓度的大离子，结果表明反离子可起到使胶体晶体软化或使其不稳定的作用。
