Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States.
Department of Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States.
J Phys Chem B. 2023 Feb 23;127(7):1664-1673. doi: 10.1021/acs.jpcb.2c07858. Epub 2023 Feb 13.
While the interaction between two uniformly charged spheres─viz colloids─is well-known, the interaction between nonuniformly charged spheres such as Janus particles is not. Specifically, the Derjaguin approximation relates the potential energy between two spherical particles with the interaction energy per unit area between two planar surfaces. The formalism has been extended to obtain a quadrature expression for the screened electrostatic interaction between Janus colloids with variable relative orientations. The interaction is decomposed into three zones in the parametric space, distinguished by their azimuthal symmetry. Different specific situations are examined to estimate the contributions of these zones to the total energy. The effective potential is renormalized such that the resulting potential energy is identical with the actual one for the most preferable relative orientations between the Janus particles. The potential energy as a function of the separation distance and the mutual orientation of a pair of particles compares favorably between the analytical (but approximate) form and the rigorous point-wise computational model used earlier. Coarse-grained models of Janus particles can thus implement this potential model efficiently without loss of generality.
虽然两个均匀带电球体（即胶体）之间的相互作用是众所周知的，但非均匀带电球体（如 Janus 粒子）之间的相互作用却不是。具体来说，Derjaguin 近似将两个球形粒子之间的势能与两个平面之间的单位面积相互作用能量相关联。该形式已扩展到获得具有可变相对取向的 Janus 胶体之间屏蔽静电相互作用的求积表达式。在参数空间中，相互作用分解为三个区域，它们的角向对称性不同。研究了不同的具体情况来估计这些区域对总能量的贡献。有效势能进行了正则化，使得得到的势能与 Janus 粒子之间最优选的相对取向的实际势能相同。作为分离距离和粒子对相互取向的函数的势能，在分析（但近似）形式和之前使用的严格逐点计算模型之间进行了很好的比较。Janus 粒子的粗粒化模型可以有效地实现这种势能模型，而不会失去一般性。
