Polyacrylamide Based Breathable Coating for Cotton Fabric

Breathable coatings based on polyacrylamide on cotton fabrics have been developed. The coatings show high water vapor permeability, while providing desirable protection against air and liquid water-penetration. These polyacrylamide based coatings were obtained by coating the fabric with polyacrylamide solution (4%), containing citric acid as a crosslinker (5–50 mol%), and sodium hypophosphite (0.3%) as a catalyst, followed by drying at 90 C and curing at 150 C. The curing reaction leads to formation of crosslinks among the polymer chains as well as between the polymer and the cotton fabric. The integrity of the crosslinked polyacrylamide coating was observed to be good. The resistance, to hydrostatic head for double and triple-coated samples, with cross-linker concentration of 50 and 20 mol% was found to be in the range of 800–1280 mm, while the air-permeability values reduced drastically by two orders of magnitude, compared to the control fabric. The water vapor transmission rate (WVTR) values for these samples were found to be excellent with only 5–23% reduction compared to the values shown by control cotton fabric. The mechanism of the reaction leading to the formation of crosslinks has been evaluated using FTIR and NMR spectroscopy.