Prediction of optimum alkaline hydrolysis conditions for imparting superhydrophobicity to large-area fabrics using three-dimensional modeling

This study proposes a fabric-specific alkaline hydrolysis method to impart stable water repellency to large-area polyester fabrics, regardless of yarn type or weave pattern. The geometries of 120 virtual fabrics with varying yarn properties, weave patterns, and weave densities are modeled, and their surface-etching efficiency and superhydrophobicity are predicted. While the alkaline hydrolysis-derived nano-structuring efficiencies of fabrics are predicted based on the Kallay and Grancaric model (1990) with changes to reflect the fiber volume fraction F as a major variable for fabric structures. For predicting superhydrophobicity, the fabric meso-structure contact angle is calculated based on the Michielsen and Lee model (2007); the fixed yarn distance used in the original model is replaced by the simulated inter-yarn porosity P to exclude error caused by structural variability. The final virtual fabric contact angle is predicted reflecting the effect of nano-roughness, which is validated by comparing the predicted contact angle with a physical sample having identical geometries. The contact angle of any fabric can be predicted using structural simulation, given the alkaline treatment conditions are adjusted according to the unique geometry of each fabric to express superhydrophobicity. Moreover, even for samples with low predictive contact angles, superhydrophobicity can be achieved by maximizing the effect of the nanostructure through strong alkaline treatment. An ISO 5 water repellency is achieved for all large-area polyester fabrics.