Praparation Of Citral/MCT-β-CD Inclusion Complex And Its Finishing Application

The β-Cyclodextrin has a special truncated cone structure with hydrophobic inner surface and hydrophilic outer surface, The exterior side of CDs is hydrophilic due to the outward hydroxyl groups, while the interior cavity is hydrophobic, which can be a host to include many guest molecules of appropriate dimensions and properties, such as fragrances, to form inclusion complexes selectively. Simultaneously, it could reach an endurable effect by controlled release of the guest molecules and protect these active substance and core materials from reactive, corrosive, and hostile environment Thus, CDs are usually used to increase the solubility, stability, and bioavailability of volatile oil.Monochlorotriazine-β-cyclodextrin (MCT-β-CD) is an active derivative of β-CD. Each β-cyclodextrin molecule contains approximately two to three monochlorotriazinyl groups, which are able to form covalent bonds with nucleophilic groups, such as-OH in textile. MCT-β-CD offers the possibility to immobilize flavors or any hydrophobic includable components at the surface of fabrics, and offers the ability to capture the unpleasant smells induced by perspiration. With the two properties above, in this paper, citral was chosen as the core material, MCT-β-CD as the wall materical to prepare the citral/MCT-β-CD inclusion complex and the effect of wall material concentration, mass ratio between citral and MCT-β-CD, reaction time, reaction temperature and magnetic stirring speed on the loading capacity of inclusion complex were discussed. Through a series of single factor experiments, the optimal conditions of the preparation of the citral/MCT-β-CD inclusion complex were confirmed:the wall material concentration was 5%, the mass ratio between citral and MCT-β-CD was 1:10 reaction time was 10 h, reaction temperature was 45℃, magnetic stirring speed was 1000 rpm. And we got the loading capacity of inclusion complex is about 8.96% under this optimum conditions. The result of Ultraviolet spectrometer shows that the molar ratio of citral with MCT-β-CD is 1:1 by the method of molar ratio. Infrared spectroscopy, thermal analysis, and surface morphology analysis were also used to turn out the formation of citral/MCT-β-CD inclusion complex.The MCT-β-CD was used to graft on the surface of cotton fabric through the active electrophilic groups on MCT-P-CD by the method of impregnation. After the finishing, the cotton fabric has a lasting lemon flavor. The research discussed the effect of finishing bath ratio, concentrations of citral/MCT-β-CD, impregnation time, concentrations of urea, and three base catalyst of NaHCO3, Na2CO3 and NaOH and their concentrations on the grafting rate of cotton fabric. Through a series of single factor experiments, the optimal conditions of the citral/MCT-β-CD inclusion complex graft on the surface of cotton fabric were confirmed: finishing bath ratio was 125, concentrations of citral/MCT-β-CD was 80 g/L, impregnation time was 80 min, concentrations of urea was 20 g/L, chosen the Na2CO3 as the base catalyst and its concentrations was 20 g/L. SEM was used to study the structure and appearance of the finished fabric. The result shows that the unfinished fabric present smooth surface. At the same time, the finished fabrics were distributed with irregular protuberances in surface and had wrinkled surfaces because the inclusion complexes were adsorbed onto the fibers and produced covalent bonds between monochlorotriazine groups and hydroxyl groups of the fabric. The release property of finished cotton fabric was tested. The release rate of unfinished fabric is obviously faster than that of finished fabric. This phenomenon demonstrates that core materials were encapsulated in the MCT-β-CD, which made the release property of citral improved and has a good durability.