Preparation Of Cotton Fabrics Finished With Silver And Zinc Oxide Nanoparticles For Their Antibacterial And Anti-ultraviolet Properties

Cotton is the most widely used natural fiber for textiles because of its softness,breathability,low price,regeneration performance,and its easy mass production.However,microorganisms can easily grow and propagate on the cotton fabrics because textiles are able to store humidity and have a high specific surface area.Meanwhile,cotton fabrics have other weakness such as high sensitivity to UV irradiation.Hence,cotton fibers with antimicrobial and UV-protective properties have attracted considerable attention due to their potential applications in various fields,such as health and medicine.There are various methods reported to combine antibacterial and UV-protective properties with textiles.However,in consideration of the ecological environment,effectiveness and durability,the most prominent method to prepare multifunctional hybrid textiles is the incorporation with metal or metal oxide nanoparticles(NPs)through finishing process.Herein,antibacterial finishing agent of Ag NPs,UV-protective finishing agent of Zn O NPs were prepared,respectively.They were incorporated into cotton fabrics through the crosslinking offered by citric acid(CA)or urea.The morphology and structure of the as-prepared hybrid fabrics were characterized by various techniques.Meanwhile,the antibacterial property against Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli)was assessed.The UV-protective activity and washing durability of the finished cotton fabrics were also tested.The main contents and conclusions of this dissertation are as follows.(1)A facile method to prepare size-tunable Ag NPs and its antibacterial mechanismThe antibacterial effect of Ag NPs is closely related to size.This could partly explain why size controllable synthesis of Ag NPs for bactericidal application is drawing much attention.Thus,we establish a facile and mild route to prepare size-tunable Ag NPs with highly uniform morphologies and narrow size distributions.The as-prepared Ag NPs with averaged sizes of 2,12 and 32 nm were characterized by transmission electron microscopy(TEM),ultraviolet-visible absorption spectroscopy(UV-vis),X-ray powder diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR).The antimicrobial effect of the as-prepared Ag NPs with different particles size was assessed by broth dilution and disk diffusion as well as measurement of optical density(OD600).Moreover,their antibacterial mechanism was discussed in relation to morphology observation of microorganism by scanning electron microscopy(SEM)and to concentration detection of Ag+ by stripping voltammetry.It was found that the parameters such as reactant molar ratio,reaction time,dropping speed,and most of all,p H of the reactant solutions,have significant influences on size-regulation of Ag NPs.The as-prepared Ag NPs exhibit excellent antibacterial properties and their antimicrobial activities increase with decreasing particles size.Besides,two kinds of mechanisms,i.e.,contact action and release of Ag+,are responsible for the antimicrobial effect of Ag NPs.(2)Fabrication of cotton fabrics with durable antibacterial activities finishing by Ag NPsIn this section,we choose the as-prepared Ag NPs with an average particles size of 2.3 nm to fabricate durable antibacterial cotton fabrics.Sodium citrate served as a stabilizing agent to prevent Ag NPs agglomeration in the synthesis process,and CA acted as a binder to fix Ag NPs on the cotton fabrics through chemical bonds in the finishing process.The results of FTIR,UV-vis,XRD,X-ray photoelectron spectroscopy(XPS),SEM,and energy-dispersive X-ray spectroscopy(EDX)demonstrate that Ag NPs have been fixed and well dispersed on cotton fabrics surface.Ag contents in the hybrid fabrics were measured by techniques of inductively coupled plasma atomic emission spectroscopy(ICP-AES)and UV-vis,and the antibacterial properties of hybrid fabrics were tested by shake flask and agar diffusion plate method.It’s found that the Ag NPs coated cotton fabrics exhibit excellent antimicrobial activities against both Gram-negative bacterium of E.coli and Gram-positive bacterium of S.aureus.The percentages of reduction bacteria remain at 91.8 and 98.7 % for S.aureus and E.coli;even after 50 cycles of consecutive laundering,which indicates that the antibiotic performance of the as-fabricated hybrid fabrics is also durable.(3)Enhanced antibacterial and UV-protective properties of hybrid cotton fabrics finishing by Ag and Zn O NPsIn advance,the high effective antibacterial finishing agent was obtained through carboxymethylated chitosan(CMCTS)capped Ag NPs,and UV-protective finishing agent was prepared by 3-aminopropyltriethoxysilane(APTES)modified Zn O NPs,respectively.The as-prepared Ag and Zn O NPs were characterized by TEM,UV-vis and XRD,to reveal its morphology,structure and particles size.Subsequently,functional cotton fabrics were fabricated by incorporation of NPs onto cotton fabrics in the assistant of crosslinking agent of CA,with the finishing process of pad-dry-cure techniques.The morphology and structure of functional fabrics were characterized through SEM,UV-vis,XRD and FTIR.The results show that Ag and Zn O NPs were uniformly and tightly loaded on cotton fabrics through chemical binding with CA.The antibacterial activity of the functional fabrics against S.aureus and E.coli were investigated by shake flask and agar diffusion plate method.It’s found that the NPs coated cotton fabrics exhibit excellent durable antimicrobial activities,due to the double synergistic effect form CMCTS and Zn O NPs with Ag NPs.In order to investigate the UV-protective activity,the UV transmittance was tested by UV-vis spectroscopy.The influence factors on UV-protective property such as finishing temperature and additive content of Zn O NPs were analyzed,and the optimum parameter was obtained at dipping temperature of 60°C and Zn O percentage of 0.3%.The fabrics fabricated at this condition show prominent UV-protective activity with an average UV transmittance of 2.5%.Cotton fabrics loaded with Ag and Zn O NPs also exhibit a remarkable washing durability even after 50 washing cycles.(4)One-pot in situ preparation of nano Ag-Zn O finished cotton fabrics for their durable multifunctionIn order to realize the one-pot in situ assembling of Ag NPs and Zn O NPs onto cotton fabric,the fabrics was reacted with urea to form carbamate groups on the surface.The abundant-NH2 groups can capture Ag+;and then,by adjusting of p H values,Ag and Zn O NPs were in situ grown on the cotton fabrics.This method is simple and direct,compared with step-by-step fabrication method for multifunctional fabrics.The morphology and structure of Ag-Zn O finishing cotton fabrics were analyzed by techniques of FTIR,UV-vis,XRD,SEM and EDX.It’s found that Ag NPs and Zn O NPs were successfully loaded on the cotton fabrics surface,with the chemical bonding reacted with carbamate groups.Furthermore,the antibacterial properties of Ag-Zn O finishing cotton fabrics,as well as its UV-protective activity,were insensitively investigated.The samples was prepared at dipping temperature of 60°C,p H value of 10 and Ag+? Zn2+ molar ratios of 1:4,and has an UV transmittance of 2.8%.However,it shows an extremely excellent antibacterial durability with bacterial reduction rate over 99.9% after 50 washing cycles.