The modification of cotton substrate using chitosan for improving its dyeability towards anionic microencapsulated nano-pigment particles

The cotton samples were treated by chitosan solution at acidic condition to modify their dyeing properties to anionic coloring materials. By fluorescence spectrum together with FTIR, XRD and TGA analysis, it was concluded that the chitosan molecules could spontaneous transfer from solution onto cotton surface yet would not influence its internal structure. In order to color the chitosan-treated cotton, an anionic polystyrene-encapsulated copper phthalocyanine (CuPc) pigment was prepared in a miniemulsion process. The full encapsulation of nano-pigment could be directly observed by TEM. The encapsulation would not alter the crystal structure and color properties of CuPc while could make the nano-pigment more stable against centrifuge and temperature variation. Finally, the dyeing properties of this encapsulated nano-pigment on chitosan-treated cotton samples were studied. It was indicated the chitosan molecules on cotton had great capability to improve the uptake of encapsulated nano-pigment mainly due to the accessible amino groups introduced.