Surface dissimilarity affects critical distance of influence for confined water

Abstract

Water at interfaces and under nano-confinement is part of many natural processes. The behavior of this water is greatly influenced by the nature of the surfaces it is in contact with and the confinement distance. The objective of this study is to understand the behaviour of confined water between dissimilar (X–Y) surfaces under varying confinement spacing. The surfaces considered were hydrophilic in nature and the combinations were considered based on crystal structure and surface energy. The critical distance of influence of mineral substrates on the water molecules was determined by applying time-averaged static properties such as interfacial layer density and orientation and dynamic properties such as diffusion. It was observed that dynamic properties provide a higher value of critical distance compared to static properties for dissimilar surface combination. The reason for this disparity is probed in terms of mineral–water and water–water interactions. The disproportion of strong and weak H-bonds was observed to be significant in determining the dynamic behaviour of interfacial layer. We applied hydrophilic surface combinations of tricalcium silicate (C₃S) and dicalcium silicate (C₂S) for our investigations.