Acrylamide-assisted Photografting of Bisacrylamide Dyes onto Cotton

Dibromopropionamide groups of C.I. Reactive Red 136 were dehydrobrominated to obtain bisbromoacrylamide groups. Photografting yield of the modified dyes onto cotton increased with the addition of acrylamide comonomer, presumably reducing the steric hindrance between the dyes with bulky chromophores. The acrylamide-assisted grafting was more prominent with increasing degree of the functionality. The optimum grafting was obtained with 2.5 molar ratio AAm and 7 % photoinitiator with respect to 0.03 mol/l dye under a UV energy of 25 J/cm 2 . The grafting yield and K/S of the grafted cotton with C.I. Reactive Red 83 was lower than that with the modified Red 136 at the same degree of functionality 2.0, probably because the relatively larger chromophore of the Red 83. In addition, the washing, rubbing and light fastness of the grafted cotton fabrics with the modified Red 136 were higher than the adsorption-based conventional dyeing, which was more pronounced as the degree of functionality increased.