Controlled Synthesis, Dye-fixing Performance and Dye-fixing Mechanisms on Cotton Fabric of Novel Reactive Cationic Copolymers of N,N-Diallyl-3-hydroxy-azetidinium Chloride and Dimethyldiallylammonium Chloride (P(DHAC-DMDAAC)s)

First, a series of novel reactive cationic copolymers (P(DHAC-DMDAAC)s) of N,N-diallyl-3-hydroxy-azetidinium chloride (DHAC) and dimethyldiallylammonium chloride (DMDAAC) with controlled structures and controlled molecular weights characterized by intrinsic viscosities of 0.11–0.89 dL g–1 were successfully synthesized by varying the molar ratios of raw materials DHAC to DMDAAC from 1 : 99 to 20 : 80 and increasing initial monomer concentrations from 35 to 55 % with a decrease of initiator amount from 7 to 3 % during polymerization. Second, it was found that the dye-fixing performance of P(DHAC-DMDAAC)s could be further increased by incorporation of 7 % molar content of DHAC units into the main chains of controlled-molecular-weight poly(dimethyldiallylammonium chloride) (PDMDAAC) dye fixatives, and their best dye-fixing performance was better than all the widely used commercial polycationic dye fixatives, indicating that the obtained P(DHAC-DMDAAC)s could be novel useful reactive polycationic dye fixatives for cotton fabric. Last, it was found from studies on dye-fixing mechanisms on cotton fabric by modern analysis techniques that the reactive units (DHAC) of the obtained P(DHAC-DMDAAC)s could form covalent bonds with the hydroxyl groups of cotton (cellulose) to give an ether linkage, resulting in strong interactions of P(DHAC-DMDAAC)s with the cotton fabric as well as the electrostatic forces between the anionic dyes and the basic cationic groups in the polymers to produce water-insoluble colour lakes, for the development of the dye fastness on cotton fabric.