Engineers developed a new method to pattern solid surfaces and enhance water interaction with them, according to a study published on August 20, 2018.
This study was conducted by the chemical engineers at the University of California – Santa Barbara. One well-known method to influence the dynamics of water was to modify the surface hydrophobicity or the extent to which the surface repels water.
A new perspective on the factors that control these dynamics has been provided by the engineers through this study. The researchers identified a more nuanced way in which surface hydrophobicity influences water dynamics at an interface by using computer simulations to design the surfaces.
Engineers observed that by arranging all of the hydrophobic groups together and making the surface very patchy, the water moves faster and if they spread them all apart, the water slows down. Hydrophobic and hydrophilic groups often are present at some density in many types of materials, and while the rate at which water moves near a surface is not the only factor that impacts how a membrane performs, understanding the dynamics is also important to design more efficient membranes. This in turn relates to the energy cost of filtration and to how easily contaminants can stick to the membrane walls and, thus, be removed from the water.
The researchers have not yet used the information about surface patterning to design materials for specific applications, though they plan to. But their finding about patterning holds immediate relevance for interpreting experiments, because it means that assessing the surface density of hydrophobic groups alone is not enough to characterize the material.
The simulations of molecular dynamics was combined with a genetic algorithm optimization, which led to the discovery of the distribution effect. According to Jacob Monroe, lead author, this method of sub-nanoscale surface patterning is an important design parameter for engineering solid-water interfaces for multiple applications, and that it can provide a broad strategy for engineering materials having designed hydration-water dynamics.