Grafting Functional Modification Of Wool Fabrics Catalyzed By HRP Enzyme

Wool,a natural protein fiber,has distinctive natural properties such as softness,warmth,lightness,resisting wrinkle,anti-static electricity,and so on,and has been widely used for high-grade textile.However,the presence of scales on wool,covalently bonded fatty acids,and the large number of disulfide bridges on the outermost fiber surface results in poor properties such as felting shrinkage,wettability,electrical conductivity,and easy mildew,and so on.Hence,it is necessary to improve machine washability,aesthetics and dressed comfortability of wool fabrics.In recent years,bio-enzymes have often been used as an agent to improve the properties of fabric,which has attracted widespread attention from researchers at home and abroad.In the present work,firstly the p-hydroxyphenylacetamide（PHAD）was used as model compound to explore the mechanism of chitosan（CS）grafted onto wool fabrics using horseradish peroxidase（HRP）.The products of the CS-grafted p-hydroxyphenylacetamide（CS-g-PHAD）were characterized by UV-Vis spectroscopy and FT-IR spectroscopy.The results showed the UV-Vis absorption peaks of the reaction solution shift to high wavelength direction due to the oxidative coupling of phenolic hydroxyl groups and the increase of conjugate length in PHAD.And new bands appeared at 1635 cm^-1 in the infrared spectra of the reaction products corresponding to the C=N and C=C stretching vibrations,which could be attributed to the Michael addition or Schiff base reaction of amino groups on chitosan and phenolic hydroxyl groups on PHAD.These results suggested that chitosan could be grafted onto PHAD.Then,wool fabric was pretreated with sodium dichloroisocyanurate（DCCA）,and hitosan was grafted onto pretreated wool fabric by HRP/H₂O₂ system.Wool fabrics were characterized by FI-IR and SEM.The effects of pretreatment and enzymatic grafting of Chitosan on the properties of wool fabrics were studied by Allworden reaction,bromophenol blue method,wettability,felting resistance and antimicrobial property.Results showed that pretreated could damage wool scales,which was quite effective in improving the grafting percentage of chitosan.The grafting percentage of wool grafting chitosan（W-g-CS）was 4.8%,and that of W-g-CS was 12.6%.Compared with untreated wool,the hydrophilicity,felting resistance and antimicrobial activity of W-g-CS were significantly improved.The stactic contact angle of pretreated W-g-CS was 46°at 15 s,the felting rate was 4.3%,and the antimicrobial activity was 99.9%.On the based above study,ferulic acid（FA）was grafted onto wool fabrics by EDC/NHS to increase the amount of phenolic hydroxyl groups on fibers surfaces,then HRP-mediated grafting chitosan onto wool fiber surfaces.Raman,FTIR,XPS and XPS were determined to pretreated wool fabrics grafting ferulic acid and chitosan（W-g-FA-CS）.The properties of W-g-FA-CS were studied by differential scanning calorimetry,thermogravimetric analysis,whiteness,stactic contact angle,felting shrinkage and tensile breaking strength.The results showed that compared with untreated wool and W-g-CS,W-g-FA-CS has better hydrophilicity and felting resistance.The wetting time of W-g-FA-CS was 21 s and felting shrinkage was3.80%.The tensile breaking strength and thermal stability of W-g-FA-CS was improved,and the whiteness decreased from 79.47 to 76.27.Polyethyleneimine（PEI）was grafted onto wool fabric by HRP/H₂O₂ system in order to investigate grafting different functional compounds on wool fabrics to the effects of properties of wool fabrics.Pretreated wool grafting polyethyleneimine（W-g-PEI）and pretreated wool grafting ferulic acid and polyethyleneimine（W-g-FA-PEI）were characterized by FT-IR and XPS spectrum.The thermal stability,whiteness,felting shrinkage and tensile breaking strength of wool fabrics were tested.The results showed that compared with other samples,W-g-FA-PEI had better anti-felting effect,the felting shrinkage was 4.22%,and the strength was not lost,whiteness and thermal stability were slightly reduced.