Appllications Research Of Sol-gel Methods In Functional Finishing Textiles

Sol-gel method is an important way to prepare nano-powder, nano-film, nano-block,etc and play an significant role in soft chemistry. The main process are to make the hydrolysis product of metallic compound reacting with water in organic solvent,which could further condense and form sol and gel. After drying and sintering the gel, nano materials could produce. Sol-gel method has been widely used in finishing the textile, such as improving the fastness of dyeing fabric, improving water and oil repellence, changing the light absorption of textiles and producing the conductive and magnetic films for textiles. In this paper, threee applications of this simple method for finishing textiles was developed: preparation of halochromic textiles, preparation of ZnO-loaded textiles and the improvement of washing fastness, controlling the release of drug by sol-gel film.The halochromic textiles was prepared by adding the pH indicators into sol solution. Results indicated the continuous film was formed in the surface of fiber and replaced the original groove structure. Indicators could affect the condensation of sol and damage the film. The halochromism of indicators in water was not changed by adding sol. Indicators seriously leached in the case of dyeing fabric after washing and could not detect the pH value. BTB and BCG indicators could retain in gel film and the color could be recognized. The tensile strength of dyeing fabric dramatically reduced after finishing, which could regain in regard with sol finished fabric.The halochromic mechanism of MR was the isomerization between azo and hydrazone structure. The vibration of C=N could be distinguished in dyeing fabric and the vibration of N=N could not. In gel film, only one characteristic peak of N=N could be observed and the vibration of C=N became weak. BCG molecule presented tautomerism between lactone and quinone, which also showed in the dyeing fabric. The tautomerism was inhibited in gel film due to the bigger molecular volume of BCG and two isomers appeared in acid.Temperature could influence the condensation of gel. Results indicated the condensation of inorganic part of sol could complete in 60℃, while the epoxy group of GPTMS accomplished in 120℃. MI could catalyze the two condensation process. GPTMS/TEOS component had a higher inorganic cross-linking degree than the Ph-TriEOS /TEOS one owing to the bigger volume of Ph-TriEOS.The research in the interaction between gel film and indicators suggested the-Si-O-C possibly formed between MR and silica sol. Positively charged MR molecules could bridge the negatively charged silanol molecules and then improve the condensation of sol. The molecular volume of BCG was twice bigger than MR and the condensation decreased because the motion of sol was impeded.The best fixing effect was produced by GPTMS/TEOS/MI component, however the finished cotton could not change color due to the dense film coving the fabric. BCG and BTB indicators could discolor and did not leach out, while MR and PR could not be well fixed in all kinds of sol system due to their small molecular volume.The ZnO-loaded fabric was prepared by sol-gel method and the photocatalytic performance was tested. Results suggested the finished fabric presented the typical hexagonal ZnO diffraction peak and the size of nanoparticles was 12 nm calculated by Scherrer formula. The thermal decomposition of cotton involved three stages: dehydration, decomposition of organic compound and carbonization and the amount of ZnO in cotton was 12 wt.%. The ZnO-loaded fabric could effectively decompose the methylene blue. The ability of photocatalytic degradation trended down over three circulation test, which significantly reduced after washing due to the weak affinity between ZnO and cotton. Washing process could elute ZnO nanoparticles from fabric.The durable ZnO-loaded fabric against washing was prepared by MTEOS sol. Results indicated lots of particles aggregate existed in the surface of fabric finished by pure ZnO particles. After adding MTEOS, ZnO particles could evenly distribute in the gel film due to the coordination between ZnO and MTEOS. The amount of ZnO were 3.04 wt.% and 8.74 wt.% analyzed by TG and the fabric finished by MTEOS/ZnO had a higher amount. The MTEOS/ZnO finished fabric presented high antibacterial property against E.coil and S. aureus and the inhibition zone was 13 mm. S. aureus was more sensitive to the ZnO finished cotton. The sol treated cotton possessed good antimicrobial activity and UV resistance and the two properties continuously decreased for the cotton finished by pure ZnO particles after washing.Adsorption kinetics and thermodynamics of sodium copper chlorophyllin and berberine hydrochloride onto cotton fabric was investigated. Results suggested second-order kinetic equation had the highest degree of fitting. Ionic diffusion model indicated there are two stages in the process of absorption. The first was guest molecules quickly diffusing to the surface of fiber and the second one was guest molecules slowly diffusing into the interior of fiber, which is the control step. The absorption of berberine hydrochloride onto cotton was a spontaneous exothermic process and the adsorption enthalpy and entropy were negative. Sodium copper chlorophyllin could make the water ordered arrange to form ice class structure and this structure would be broke after absorption, which increased the disorder of whole system. Thus the adsorption entropy was positive.The absorption of berberine hydrochloride fitted the Freundlich model and had a high degree of fitting to Langmuir model, which suggested this process were mainly physical multilayer absorption, together with some chemical absorption. The absorption of sodium copper chlorophyllin onto cationic cotton completely fitted the Langmuir model and this was because there exist strong electrostatic attraction between them and the saturation value of adsorption and Langmuir coefficient was also calculated.The release profile of berberine hydrochloride depended on the sol component, which fitted the Higuchi model for the pure cotton and TEOS treated cotton. The control step was diffusing rate of drug. After treated by TEOS/BTCA, the release profile change to liquid level movement control mechanism, which fitted the zero-order kinetics model. Because of the electrostatic attraction the release of sodium copper chlorophyllin also fitted the zero-order kinetics model and the release rate was reduced after treated by sol.The pure cotton had the best environment for the growth of cells, followed by the blank group containing nutrient solution. Cationic cotton displayed some inhibiting effect against the proliferation of cells. The cell viability of two kinds of sol treated fabric was inferior to the pure cotton due to the gel film.