Quantification of residual liquid on repellent cotton fabrics after liquid roll off

A method to detect and quantify any residual liquid left on coated cotton fabrics after liquid roll off was developed. Repellent cotton fabrics were prepared by grafting the diblock copolymer poly[3-(triisopropyloxysilyl)propyl methacrylate]- block -poly[2-(perfluorooctyl)ethyl methacrylate] (PIPSMA- b -PFOEMA) under acidic conditions. The PIPSMA block undergoes a sol–gel grafting reaction with the cotton, while the PFOEMA block imparts repellent properties to the cotton's surface. Liquid droplets loaded with quantum dots were placed on top of tilted coated cotton fabrics and allowed to roll off the surface. Fluorescence microscopy was then used to observe the path of the liquid droplets. The amount of quantum dots detected along this path was measured. The effects of varying the amount of polymer grafted to the cotton and the surface tension of the probe liquid on the residual liquid along the path of the rolling droplet was investigated.