Study On Relationship Of Properties And Cotton Fiber Surface Modified By Diphenolic Acid

In recent years,infectious diseases reached epidemic repeatedly.The coronavirus pandemic,which brought disaster to the world since late 2019,has done harm to the public health and social economy enormously,which are yet to be fully recovered even now.The personal protective textiles widely used in the epidemic have been playing important roles in epidemic prevention by prevent pathogens from entering the respiratory tract through physical filtration.However,the pathogens remaining on the fabric surface remain infectious activity for a long time,and the risk of cross infection cannot be fully eliminated.The outbreak also revealed the contradiction between the shortage of resources for protective textiles and the lack of emergency production capacity in an uncertain period of time.Therefore,it is of great significance to develop textiles that can effectively inactivate infectious pathogens and to develop corresponding large-scale production processes.Textile finishing auxiliaries with antibacterial and antiviral properties are rarely reported.The biological activity of polyphenols such as tea polyphenols has been widely discussed,but it has not been used for functional finishing of textiles so far.Diphenolic acid(DPA)is available from bio-based materials and has both phenolic and carboxylic structures.Before beginning this work,it was assumed that DPA plays antibacterial and antiviral effect via phenol group,while providing carboxylic groups to undergo esterification reaction with hydroxyl groups on the surface of cotton fibers to form covalent bonds.Therefore,this work aims at preparation of highly effective antibacterial and antiviral cotton fabric,basing on the combination of bisphenol acid and general "pad-drycure" process,to construct a coating of antibacterial and antiviral effects onto cotton fiber surfaces.This work demonstrates antibacterial and antiviral effect of the micro-nano structures on fiber surfaces,ascertaining the negative effects of the modification process on the fabric contributes such as air permeability and moisture permeability,assessing the toxicity of the obtained fabric to human body,and confirming the possibility of largescale production conversion.The specific research contents are as follows:(1)In this paper,the widely used "pad-dry-cure" process was adopted to prepare cotton fabric having antibacterial and antiviral effects.DPA is anchored to cotton fiber surfaces via an esterification reaction.The results of antibacterial experiment showed that the modified cotton fabric has excellent antibacterial effect,and the inhibition rate of E.coli and S.aureus was more than 99.99%.Also,the fabric showed an antiviral effect that can effectively inactivate phage phi-x174 within 30 minutes.The modification process has insignificant effect on the textile properties,as the important properties of the modified fabric,such as moisture absorption capability,air permeability,tensile strength and softness,have not changed significantly.Cytotoxicity evaluation tests showed that the modified fabrics are safe and non-toxic for human.(2)In order to further improve the biological activity of DPA modified textiles,cellulose nanofibers(CNF)were used to construct micro-nano multilevel coating on cotton fiber surfaces,to increase the specific surface area and the density of active hydroxyl groups.As a result,the density of DPA on the fiber surfaces increased by about10 times.The resultant CNF nanonetworks enhanced the ability of fiber to capture pathogens,increasing the action area of phenolic surface to contact pathogen proteins,and inducing pathogen shell damage.When compared to the previous work,the modified fabric was effective in killing E.coli,S.aureus and phage phi-x174 in a shorter time.In particular,the modified fabric was able to deactivate more than 99.5% of influenza A(H1N1)viruses,showing strong pathogen inactivation ability.The micro-nano multilevel structures on the modified surfaces have excellent washing resistance.After 60 times of washing resistance tests,inhibition rate of the pathogens was maintained at above 95%.X-Ray Diffraction(XRD)results show that the modification process has no obvious damage to the inner structure of cotton fiber.Cytotoxicity tests and animal skin experiments confirmed that the modified fabric has good biocompatibility and has no toxic effect on human skin.The modification process was also performed on an industrial "pad-dry-cure" line,and its potential for large-scale production was demonstrated.The research results mentioned above can develop a new effective way for the preparation of antibacterial and antiviral cotton fabrics.