Structural Design And Multifunctional Application Of Nano-coating For Cotton Fabric

Compared with other synthetic fabrics,cotton fabric is one of the most suitable fabrics for clothes and textiles with breathability,hygroscopicity,high mechanical property,strong biocompatibility and biodegradability.However,some intrinsic obstacles of natural cellulosic fabrics such as ease of thermal degradation,ignition,and burning make them highly flammable and restrict greatly their application.With the improvement of people’s living standards and the rapid development of the textile industry,textile fabrics have gradually changed from economical and practical to diversified raw materials,varied styles,and diversified functions.Protective functional textiles such as flame retardant,antistatic and antibacterial textiles have become increasingly popular among people.Therefore,in order to expand the application fields of cotton fabrics,it is necessary to improve their functionality.Layer-by-layer（LBL）self-assembly technology is a finishing technology that can construct a multifunctional coating on the surface of cotton fabric.Thus,in this paper,we use this method to endow cotton fabrics with excellent functionality.The main results of this thesis were listed as follows:1.LBL self-assembly of composite nanocoating:To endow the cotton fabric with high efficiency flame retardant properties,a new cost–low and green approach is presented for constructing ternary composite coating on cotton fabric through spray-assisted LBL self-assembly of 3-aminopropyl triethoxysilane,sodium alginate and ammonium polyphosphate in aqueous solutions.The surface morphologies,flammability and thermal degradation properties of cotton fabrics before and after coating are investigated by scanning electron microscopy,thermogravimetric analysis,vertical flame tests and microscale combustion calorimetry.The results show that cotton fabrics treated with 15 composite layers self-extinguish immediately when the ignition source is removed and its limit oxygen index can reach 35.7%,moreover,it has good washing resistance.High structural stability and flame retardant property are attributed to external well-constructed flame retardant composite multilayers and phosphorus-nitrogen-silicon synergism on the degradation process and char yield.2.Constructing nanobrick wall structure in the composite nanocoating:Efficient construction of quaternary composite coating on cotton fabric is presented by spraying aqueous solutions of graphene oxide,3-aminopropyl triethoxysilane,sodium alginate and ammonium polyphosphate for providing the flame retardant,antimicrobial and antistatic properties.The results show that the graphene nanobrick wall structure can greatly boost the phosphorus-nitrogen-silicon synergism,and the assembly coating eliminates the afterglow during combustion and decreases the total heat release（THR）value.Particularly,（GO1）₁₀ cotton fabric has a significant self-extinguished effect with a THR value of about 7.0%of uncoated cotton,and the introduction of graphene oxide also makes coated cotton has excellent antistatic with a sheet resistance of 1.26×10~3kΩ/sq.Moreover,it can effectively inhibit the growth of E.coli and S.aureus according to AATCC 100-2004.Furthermore,it also keeps highly reliable flame retardant and antistatic ability during the washing test.3.Constructing hot-dog structure in the composite nanocoating:A novel hot-dog structured protective coating is successfully constructed on the surface of cotton fabrics by introducing polyaniline nanofibers into the above-mentioned graphene nanobrick wall structure.On the one hand,hot-dog structured coating can increase the load of the flame retardant and ensure that it is not easy to lose.The formed microenvironment can also give full play to the phosphorus-nitrogen-silicon synergistic effect.On the other hand,polyaniline can also play an excellent flame-retardant effect,and further enhance the synergistic effect of multi-element through organic acid doping.The results show that coated cotton fabrics with 5 composite layers can exhibit excellent self-extinguishing ability.Especially in the case of polyaniline nanofibers doped with phytic acid,the limited oxygen index of coated cotton is increased significantly from 18.1%for neat cotton to 35.1%.The peak heat release rate and the THR values are greatly declined by 78.3%and 49.0%,respectively.Furthermore,it has a low sheet resistance of 264.7 kΩ/sq,and can inhibit the growth of E.coli and S.aureus.In addition,the fabric can still self-extinguishing after 12 laundering,showing good washing durability.4.Constructing trap structure in the composite nanocoating:A novel trap structured nanocoating is successfully constructed on the surface of cotton fabric through in-situ polymerization of polyaniline（PANI）arrays on both cotton fibers and graphene oxide（GO）sheets.This ultra-thin coating with trap structure can well capture the flame retardant,provide efficient reaction micro-environment and ensure the stability of the coating structure.Moreover,excellent flame retardant,antistatic and antibacterial properties can be achieved,but the damage to the flexibility of cotton fabrics can be avoided.Particularly,（GO–PANI1.0）₃ coated cotton fabric with a weight gain of 12.7wt.%possesses the excellent self-extinguished ability,and its limited oxygen index can reach 36.0%as well as the THR value is greatly declined by 82.5%.In addition,the PANI and partially reduced GO can also provide a good conductive pathway,as a result,the coated fabric possessess significant antistatic property with a sheet resistance of207.1 kΩ/sq,meanwhile can remarkably inhibit the growth of E.coli and S.aureus.Therefore this novel facile and scalable strategy is believed to guide efficiently the construction of various kinds of cheap composite nanocoatings for multifunctional advanced textiles.