Preparation And Property Of QACs(quaternary Ammonium Compounds)-containing Antimicrobial Materials Via Contact-killing

In this work,QACs(quaternary ammonium compounds)-containing materials with excellent antimicrobial property were prepared on the basis of contact killing and there was no leaching of antimicrobial species from the materials,including QACs-containing antimicrobial polyurethane films,antimicrobial waterborne polyurethane films and antimicrobial polypropylene films.Firstly,two reactive quaternary ammonium methacrylate compounds(QAC-10 and QAC-12)bearing a hydrophobic tail with different alkyl chain length were prepared.Cross-linked films with excellent antimicrobial property were obtained from a mixture of a polyurethane acrylate prepolymer and a reactive QAC via one-step UV curing.ATR-IR and~1H NMR indicated that the reactive QACs(QAC-10 and QAC-12)were successfully covalently bonded to a polyurethane acrylic network.The water contact angle test showed that the significant decrease of the water contact angle was likely the consequence of the enrichment of QACs at the film surface.The increment of the QAC content in the film led to a gradual decrease in water CAs,the more hydrophobic alkyl tail led to the opposite,reaching low value of 66°for the Q-10-3.The surface enrichment of QACs was further confirmed by XPS.It was obvious that the stronger surface enrichment for QACs was due to the longer hydrophobic alkyl chain and higher QACs loading.The QAC/PUA molar ratio in Q-10-1reached 0.14 in the top 5 nm and 0.132 in the top 10 nm,respectively;compared to the estimated bulk ratio,this indicated a surface enrichment factor of>5.The QAC-containing films showed total kill against both Gram-negative Escherichia coli(E.coli)and Gram-positive Staphylococcus epidermidis(S.epidermidis)at a QAC-12 concentration as low as~2 wt%and a QAC-10 concentration as low as~3 wt%relative to the polyurethane acrylate prepolymer.The higher antimicrobial potency was the consequence of the higher QACs content and longer hydrophobic alkyl chain,pointing to the stronger surface enrichment of QAC and greater surface charge density.A zone of inhibition test confirmed that the antimicrobial effect of these films was on the basis of contact killing.Secondly,the waterborne polyurethane dispersion and films were developed by the introduction of tertiary amine with double–OH groups and the quaternization of tertiary amine.FTIR indicated that the WUPU dispersions were successfully prepared.The particle size and distribution of WUPU-10-10 reached the lowest value,while the Zeta potential reached the highest value of 70.12 mV,indicating the greatest degree of quaternization.The successful quaternization of tertiary amine was further confirmed by XPS.The Q value of0.21 in the WUPU-10-10 films was higher than any other PU films,pointing to the strongest degree of quaternization.WUPU-10-10,WUPU-10-12 and WUPU-11-12 showed total kill against both E.coli and S.epidermidis.A zone of inhibition test confirmed that the antimicrobial effect of these films was on the basis of contact killing.The quaternization of tertiary amine in WUPU films did not has much influence over mechanical property.At last,two silicon-containing quaternary ammonium compounds(ND-22-10 and ND-22-12)bearing a hydrophobic tail with different alkyl chain length were prepared.PP films with superb antimicrobial performance were developed by covalently bonding silicon-containing QACs(ND-22-10 and ND-22-12)to PP treated with corona via hydrolysis of silica.ATR-IR and ~1H NMR indicated that QACs(ND-22-10 and ND-22-12)were successfully prepared.The water contact angle test showed that the significant decrease of the water CA was likely the consequence of the enrichment of QACs at the film surface.The increment of the QAC content in the film and the pH value led to a significant decrease in water CAs,the more hydrophobic alkyl tail led to the opposite,reaching low value of 24.8°for the ND-10-5.The PP films showed total kill against both E.coli and S.epidermidis at a bacterial log reduction value of 5 when the concentration of QACs was as low as 0.05 g/ml as well as the pH value was 7 or 8.A zone of inhibition test confirmed that the antimicrobial effect of PP films was on the basis of contact killing.