Synthesis And Application Of Macromolecular UV Absorbers For Cotton

In this thesis, macromolecular UV absorbers for cotton fabrics were synthesized by the reaction of polyvinylamine and UV absorbers. As polyvinylamine contains multiple reactive sites, UV absorbers with reactive groups could be grafted onto it. Due to the cationic amino groups within polyvinylamine, the synthesized macromolecular UV absorbers showed high affinity to cotton fibers and good solubility in water. The performances of the macromolecular UV absorbers were enhanced by optimization of structure design and application research.Two UV absorbers of benzotriazol type were synthesized and modified to be reactive to polyvinylamine. The bromination of benzyl group of 2-(2'-hydroxy-5'-methylphenyl)-2H-benzotriazole (UV-P) was systematically studied. Effects of reaction conditions including solvent, initiator, temperature, reaction time, ratio of the reactants and concentration of acetylated UV-P on the yield of the target product and reaction efficiency were analyzed. The results showed that optimum conditions were as follows:under N2 atmosphere, CCl4 was used as solvent and azobisisbutyronitrile (AIBN) as initiator, the ratio of N-Bromosuccinimide (NBS) to 2-(2'-acetoxy-5'-methylphenyl)-2H-benzotriazole was 1:1(mol:mol) and bromination was carried out under reflux for 1 hour. Under above conditions, the yield reached 60%. The phenomena of decarboxylation in the synthesis of 2-(2'-hydroxy-5'-carboxyl-phenyl)-2H-benzotriazole was studied and the target molecule was synthesized by the protection of carboxyl group. The structures of both products were confirmed by UV-Vis, IR,1H-NMR and MS spectra.The grafting reaction of UV-P onto polyvinylamine was carried out under reflux in THF and water mixed solvent for 1 hr, pH was controlled at 10, the yield was above 90%. The water-solublity of the product (UV-P-g-PVAm) decreased when the amount of grafting UV-P enhanced.In order to enhance the water-solubility of macromolecular UV absorbers, benzophenone type UV absorber-2,4-dihydroxybenzophenone was used and modified to synthesize 2-hydroxy-4(2,3-epoxypropoxy)benzophenone. The grafting reaction of UV-0 onto polyvinylamine was carried out under reflux in THF and water mixed solvent for 3 hr, pH was controlled at 10, the yield was above 80%. The water-solublity of the products (UV-0-g-PVAm) was better than that of UV-P-g-PVAm. The structures of UV-P-g-PVAm and UV-0-g-PVAm were charaterized by TLC, IR and UV-Vis spectra. Additionally, complex grafting of benzotriazole and benzophenone type UV absorbers onto polyvinylamine was tried in this paper for adjusting the water-solubility of the UV absorbers and optimizing the UV absorption spectra of the product. The macromolecular UV absorbers were used to finish cotton fabics through dip-pad-bake process. The effect of addition of crosslinker on fastness of UV absorbers to the fabrics was studied, and the results showed that the washing fastness with treatment of crosslinker was better than that without treatment of crosslinker. Macromolecular UV absorbers with different grafting ratio were used on cotton, the results showed that the anti-UV performance did not enhance by the increase of grafting ratio and finishing agent concentration, which may relate with the adsorption amount of the absorber on cotton.