Functionalization Of Textiles By Submicron/Nano Level Surface Modification For Gas Filtration, Dyeing And UV Protection

With the awareness of the health and safety of human being,the functionalization of textiles has acknowledged diversified applications due to its countless advantages.The effects of the functionalization of textile materials include not only the betterment of existing properties,but also the creation of new properties and functionalities.There are several ways to provide the functionalities onto textile surface.One of the outstanding methods is the surface modification of textiles.Successful surface modification techniques not only overcome fundamental shortcomings of the substrates,but also improve their end-use performances.By redesigning the textile surface at submicron/nano levels,many new possibilities emerge for textiles that can be used in environmental protection or protective clothing.In this sense the goal of this dissertation is the surface modification of textiles for gas filtration,dyeing and UV protective applications.In terms of coating level and applications,different surface modification techniques have been selected including nano and submicron levels coating covering physical and chemical attachments.Firstly,the surface of basalt fabrics was coated by submicron size electrospun ultrafine fiber for gas filtration.Secondly,cotton fabrics were modified via polyelectrolytes multilayer nano thin films through layer-by-layer assembly with hydrogen bond,?-? interaction and aside with strong electrostatic interaction for textile dyeing and dye aggregation behavior.Finally,nylon fabrics were modified by polydopamine(PDA)deposition and titanium dioxide(TiO2)nanoparticle immobilization to improve the UV protection property even after washing due to the strong covalent bonding.Gas filtration is important to separate the gas from solid particles of the air.However,fabrication of filter with high filtration efficiency,robust air permeability and better service life is very challenging.Current gas filter fabricated from electrospun ultrafine fiber are successful for the high filtration efficiency but suffers to obtain low pressure drop and cannot filtrate very small size particles.Present research highlights the functionalization of basalt fabric by fabricating polyacrylonitrile(PAN)incorporated multiwall carbon nanotubes(MWCNT-fs)ultrafine fiber with the supplied high voltage(HV)for submicron particles while maintaining a lower pressure drop.The effects of HV on the filtration properties of the functionalized basalt fabric were investigated by varying the applied voltage,MWCNT-fs concentrations,basis weight of the ultrafine fibers,air flow rate,duration of filtration time and different particle sizes.The filtration performance tests showed that the filtration efficiency was increased with the increase of the basis weight of ultrafine fibers,MWCNT-fs concentrations and supplied voltage.The maximum filtration efficiency was reached to 99.57% for PM 2.5,maintaining the pressure drops of 44.5 Pa under 15.85 L/min air flow rate.As the air flow rate was increased from 10-40L/min,the filtration efficiency was reduced slightly from 99.57% to 99.46 %.It was also observed that the pressure drops were always showing much lower side than the required pulse-jet cleaning pressure(1000 Pa).SEM micrograph upon filtration test showed the successfully captured of small and large particles by the ultrafine membranes and the basalt fabric itself,respectively.This study proved the successful surface functionalized basalt fabrics to develop room temperature gas filters.In order to investigate the dye aggregation behaviors,cotton fabrics were functionalized by fluorescein isothiocyanate labeled poly(allylamine hydrochloride)(PAH-FITC)and with poly-(acrylic acid)(PAA)/ PAH-FITC through LbL assembly technique.The obtained(PAA/PAHFITC)*n and(PAH-FITC)*n films demonstrated that the LbL-assembly technique is suitable for homogenously dyeing the complex fabrics.Importantly,different aggregation behaviors of dye FITC were exhibited in the two matrixes of(PAA/PAH-FITC)*n and(PAH-FITC)*n,showing the significant role of LbL-assembly in textile dyeing.Moreover,for the deposition of PAHFITC,the LbL assembly of PAH-FITC is superior to the continuous immersion of cotton fabrics in PAH-FITC solution in terms of the deposition amount,presenting the unique advantage of LbL-assembly on the textile dyeing.In this work,layer-by-layer(LbL)assembled films were prepared by fluorescein isothicyanate labeled poly(allylamine hydrochloride)(PAH-FITC)and poly(acrylic acid)(PAA)on cotton fabrics,and researched the influence of the PAH-FITC concentration on the FTIC aggregation.With the LbL assembly,the ratio of FITC dimers to monomers in films approached a constant that was decided by the deposition situation of PAH-FITC on cotton.The concentration increase of the PAH-FITC solution induced more FTIC dyes to deposit on fabrics,thus generating a higher degree of H-aggregation.Interestingly,as the PAH-FITC concentration decreased,a high content of FITC dimers was obtained in LbL-assembled films as well.The possible reason is the excessive PAA in LbL films made the counter PAH-FITC chains coil overlap,increasing the aggregation degree.Additionally,the H aggregates with weak fluorescence were effectively inhibited in PAH-FITC films,which were prepared by a multiimmersion in the PAH-FITC solution.This work shows the concentration-dependent dye aggregation in LbL assembly,providing a new strategy for the applications of dye molecules on fabrics.UV radiation can cause degradation or aging of many polymers and shorten the working-life of their products.Thus,UV protective coating is required in various occasions.Textiles with the UV-shielding function possess unique properties compared to those covers in board or film shapes.TiO2 nanoparticles were reported to provide superior UV blocking function,can be used to produce UV protective covers in combination with fabric.However,efficient and environmentally friendly immobilization of TiO2 nanoparticles onto the fabrics is challenging.Polydopamine(PDA),a biomimetic synthetic polymer,has attracted recently due to its superior affinity to various materials for facile application procedure.Hence,in this research,the surface of nylon fabrics was modified by PDA to immobilize TiO2 nanoparticles.The modification conditions were systematically optimized.The immobilization of the nanoparticles was confirmed by FTIR and SEM.The functionalized nylon fabrics were proved to exhibit improved UV protection property even after washing.This work provides a new and versatile surface modification technique for textile materials.Three surface modification approaches highlighted in this research shows significant improvements in gas filtration,textile dyeing and UV protection applications.These nano and submicron scale surface functionalization techniques have their own benefits for different applications.Thereby,the works done here will be a definite baseline towards the betterment of new scientific research and business areas of textiles.