Researchers from University of California – Santa Barbara study interactions of water with solid surfaces by altering the surface density of hydrophobic chemical groups on the interface.
Water filtration and purification, chromatography and catalysis are determined by the dynamics of water near solid surfaces. The wetting effect of water influences these processes. Change in the water dynamics can be achieved by modifying the surface hydrophobicity, which is the extent to which the surface repels water. Altering the average coverage or surface density of hydrophobic chemical groups on the interface facilitates these modifications in the dynamics of water. Now, a research led by Jacob Monroe, a fifth-year Ph.D. student and M. Scott Shell, chemical engineer in the lab of UC Santa Barbara, provides a new perspective on the factors that control these dynamics. The researchers were able to identify a more nuanced way in which surface hydrophobicity influences water dynamics at an interface with the help of computer simulations to design the surfaces.
The researchers found that water moves faster when all of the hydrophobic groups are arranged together, which in turn make the surface very patchy. Moreover, the water slows down when the hydrophobic groups are spread all apart. Many types of materials contain hydrophobic and hydrophilic groups at some density. The researchers stated that understanding the dynamics of these groups is necessary to design more efficient membranes, which in turn can reduce the energy cost of filtration and facilitate easy removal of contaminants that stick to the membrane walls. The researchers further focus on understanding surface patterning of water to design materials for specific applications. The findings published in the Proceedings of the National Academy of Sciences on August 7, 2018, could have important ramifications for membranes, especially those used in water filtration.