Reproduction of super-multicomponent self-assembled structures and their functionality using coarse-grained molecular simulation – the example of cleansing agents

Self-assembly of multi-component systems can provide a large variety of functions, which is impossible for a single-component system, and those multi-component derived functional materials attract attention in various fields such as biomedical, engineering, and materials science. This gives multi-component systems importance, but molecular elucidation of such systems is a major challenge, since this type of complex system has large degrees of freedom. In this study, we focused on cleansing agents as multi-component systems, which are cosmetics products mainly used to remove oily compounds such as makeup, and are multi-component aqueous solutions consisting of many surfactants, moisturizers, and pH regulators. Our aim is to link the macroscopic properties of multi-component systems with the mesoscale structures to elucidate the molecular evidence of functions. We have studied the self-assembled morphologies of cleansing agents using coarse-grained molecular simulations as mesoscale structures and compared them to cleansing performance as a macroscopic property. From the simulation results of morphologies and the experimental results of performance, the key features which explain their functionalities were examined. As a result, it was quantitatively shown that the distribution of specific particles or molecules such as hydrophobic particles both in the bulk state and when they are applied on dirty surfaces is one of the clues to explain the performance. Through molecular designing based on this result, it will be much easier to reach the desired property or performance in the field of multi-component functional materials. Thus, this molecular simulation method will push the field of materials science and materials informatics forward.