Simulations of Lock and Key Colloids

Abstract

We introduce the concept of self-assembly and describe how it can explored with a system of colloids. We introduce the lock and key colloid, and describe how it can be useful probe for exploring a specific, geometry-centric, type of colloidal self-assembly called the depletion interaction.We illustrate some of the problems with simulating the lock and key colloid, and intro duce a novel simulation method to side-step many of these problems.Using this simulation technique, and derived theoretical thermodynamic apparatus, we show a methodology for parametrising the depletion drive self-assembly of colloids. This parametrisation allows us to avoid explicitly modelling the nanoparticles that mediate depletion-driven self-assembly and thereby speeds up any subsequent simulations by an order of magnitude compared to the novel simulation technique. Using our parametrisation, we repeat some measurements of explicitly modelled lock and key simulations and find good agreement.As a small aside, we also simulate a sedimenting, lock-only system in the same spirit as a published work. In this work, the authors find an interesting decrystallisation over time from a solid to liquid-like phase. We do not observe this in our experiment but instead note that we can induce a liquid-solid phase transition by varying the depth of the lock mouth.To end, we discuss the quality of our findings and what future avenues of work they may lead to.

Date of Award	5 Mar 2015
Original language	English
Awarding Institution	University of Bath
Supervisor	Robert Jack (Supervisor) & Nigel Wilding (Supervisor)