Synthesis And Antibacterial Properties Of Multiwalled Carbon Nanotubes/Chitosan Composites

Today, people’s development and utilization of the ocean has entered into acomprehensive development of the era. Marine fouling has caused harm to the marinefacilities, and brought huge losses to mankind, wasting a lot of resources. In order tosolve the problem of marine biofouling, the application of marine antifouling coatingsgradually attracted attention. The antifouling paint rely mainly the antibacterialproperty of antifouling agents. Therefore, the development of environment-friendlyantifouling agent becomes particularly important.In this thesis, the method of covalent grafting was used to prepare carbon nanotubesgraft-carboxymethyl chitosan composite materials successfully. First, carboxyl groupsof MWCNT-COOH were converted into acyl chloride groups to generateMWCNT-COCl. Then carboxymethyl chitosan (cmCs) was added to react withcarbon nanotubes (MWNT). On this basis, Cu2+and Zn2+were introduced, using thereactivity of the carboxyl group and part of unreacted amino, hydroxy whichcontained in the molecule of carboxymethyl chitosan. The MWNT-cmCs metalcomplex were obtained. Fourier transform infrared analysis shows after graftedcarboxymethyl chitosan, vibration peak of the amide grou and ester group appear inthe spectroscopy, which shows that the covalent grafting reaction accured betweencmCs and MWNT. TEM photos show that carboxymethyl chitosan is evenly coatedon the surface of the carbon tubes, forming the core-shell structure; covalent graftingsolved the problem of the dispersion of carbon nanotubes, and made MWNT showgood dispersibility and stability in aqueous solution. TGA analysis shows that thegrafting amount of CmCs in MWCNT-CmCs was approximately38wt%. The releaerate of metal ions in MWNT-cmCs metal complexs was tested by conductivity meter.The results showed that the presence of the carbon nanotubes on delay the rate ofrelease of metal ions in environment. Antibacterial tests showed that MWNT-cmCs, MWNT-cmCs-Zn and MWNT-cmCs-Cu possess bactericidal activity against S.aureus and E. coli, and the antimicrobial activity: MWNT-cmCs-Cu＞MWNT-cmCs-Zn＞MWNT-cmCs, the antibacterial susceptibility against S.aureuswas more pronounced than E.coli.To further enhance the loading of the metal elements and antibacterial effects ofmaterials, we use glucosamine and nano-silver to solve this problem. Carbonnanotubes-glucosamine composites were prepared by the method of covalentlygrafting. On this basis, nano-silver was introduced by UV-reduction method, andcarbon nanotubes-glucosamine-AgNPs were obtained. Fourier transform infraredanalysis shows that carbon nanotubes and glucosamine are connected through amidebond. TEM photos show that carbon nanotubes were wrapped with glucosamine. Andafter nano-silver was introduced, the particles are evenly distributed to the outside ofthe carbon nanotubes. Both MWNT-glucosamine and MWNT-glucosamine-AgNPsshowed excellent solubility and stability in aqueous solution. XRD analysis showedthat the nano-silver is in the form of simple substance, and the structure of nano-silveris a face-centered cubic structure. TGA analysis shows that the introduced amount ofnano-silver is about6wt%. Antibacterial tests shows that the antibacterial property ofMWNT-glucosamine-AgNPs is more marked than that of MWNT-cmCs metalcomplex. And the antibacterial susceptibility against S.aureus was more pronouncedthan E.coli. This will provide the conditions for the application of composite in thefield of marine antifouling.Thanks to the sponsorship of National Nature Science Foundation (51072188).