Orientation-dependent electrostatic interaction between inverse patchy colloids

ABSTRACT

An inverse patchy colloid (IPC) refers to a particle having patches that are mutually repulsive while the bare particle–patch interactions are attractive. We model a system of charged IPCs with a single patch using Debye-Hückel theory. We derive the full analytical expression for the effective interaction energy for a pair of IPCs as a function of inter-particle separation and particle orientations. The model is applicable for various patch coverage, ionic strengths and dielectric permittivity of the medium. Approximate solutions are derived under high screening limit and the results are compared with the full solution. The model can be used in molecular simulations such as Monte Carlo simulations to accurately describe the interaction between a pair of IPCs for a given experimental conditions.

KEYWORDS:

• Janus colloids
• Poisson-Boltzmann equation
• Yukawa potential
• double-layer
• effective-charge

Acknowledgments

The authors thank Emanuela Bianchi for valuable discussions. The authors acknowledge the Aqua High-Performance Computing Facility (HPC) at IIT-Madras for the computational resources.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

E. M. acknowledges the Department of Science and Technology, India, for the funding through Indo-Norway research grant (INT/NOR/RCN/NS/P-07/2019).