Nanostructured coatings for super hydrophobic textiles

The promising aspects of nanocomposite coatings to mimic the nano roughened self cleaning surface of lotus leaf is explored in this paper. A detailed study on nanosilica and clay based nanocomposite coatings using dip coating and layer by layer self assembly (L-b-L) is being described where lotus leaf effect has been mimicked on the cotton fabric surface using these particles as they develop nanosized surface roughness which helps to produce a super-hydrophobic surface. Nanosilica performs better in creating nano roughness on cotton fabric wherein the contact angle is 150. The water contact angle of 2 wt% fluoro emulsion (Nuva HPU) treated cotton fabric increases from 115 to 155 when the fabric is pretreated with 05 wt% nanosilica emulsion. The water repellency rating of fabric treated with 016 wt% nanosilica along with 2 wt% Nuva HPU is comparable to that of 4 wt% Nuva HPU treated cotton fabric. On the other hand, 40 bilayers of nanosilica need to be applied on cotton fabric surface through L-b-L technique to create uniform nano roughening and gives a water repellency rating of 4. The air permeability of L-b-L nanocoated cotton fabric is not adversely affected by the super-hydrophobic nanostructured coating.