Synthesis Of Dopmine-modified Multiwalled Carbon Nanotubes/chitosan Composites And Research On Antifouling Effect

Nowadays, environment-friendly antifouling agent plays an increasingly important role in marine biofouling. Chitosan (CS) is a biocompatible, non-toxic biopolymer as a carbohydrate polymer. The structure of carbon nanotubes is similar to chitosan. The compound not only can improve the dispersibility of carbon nanotubes by utilizing hydrophilic biological macromolecules, and more likely to achieve complementary or synergistic effects, which would be widely used in the field of antifouling.In this paper, multi-wall carbon nanotubes (MWCNTs) and CS were chosed as matrix materials, dopamine (DA) as a bridge material for preparing nanocomposites, and investigate the anti-corrosion and anti-biofilm properties by electrochemical testing technology, bacteriostatic experiments and diatom inhibition experiments. The major contents can be summarized as follows:(1) The prepare method of moderate-modified MWCNTs was utilizing by self-polymerization of dopamine under different pH conditions reaction mode. Both approaches were effective to improve the dispersibility of MWCNTs, micaDA-coated carbon nanotubes has useful functional groups such as amino groups, so it can provide a significant increase in dispersion and stability. The TEM results indicate that carbon nanotubes were wrapped with 4 nm of polydopamine (PDA) layer, while the film thickness of single-layer dopamine film-coated carbon nanotubes (micaDA-MWCNTs) is thin. In this instance, the weight loss of micaDA-MWCNTs is far below than that of PDA-MWCNTs.(2) Using the pre-synthesis PDA layer as a nanoscale guide to form uniform Ag nanoparticles (AgNPs) on the surface of PDA/MWCNTs. In this system, CS plays a role of protective agent and stabilizer. CS/PDA-MWCNTs/Ag composite sol was prepared by liquid-phase reduction. Transmission electron microscopy (TEM) photos showed AgNPs distributed adequately in the wall of PDA/MWCNTs and the composite sol. Composition of CS and PDA-MWCNTs composite improved thermal stability of CS. According to the results of antibacterial tests, the minimum bactericidal concentration of composite sol against E. coli, S. aureus and Vibrio anguillarum is 4 ?g/mL,5 ?g/mL and 5.5 ?g/mL, respectively. Electrochemical impedance spectroscopy and polarization tests showed CS/PDA-MWCNTs/Ag composite sol is a mixed-type inhibitor. Synergies of several materials form a multi-substrate surface protective film on substrate, which substantially enhanced the corrosion performance of materials.(3) By controlling the pH of the solution, micaDA/MWCNTs were prepared under acid condition. CS/micaDA/MWCNTs composites were prepared by covalent grafting method with glutaraldehyde as a bridge material between chitosan and multi-walled carbon nanotubes (MWCNTs). TEM photographs show that about 6 nm membrane layer of Chitosan is well-distributed coated on the surface of micaDA-MWCNTs. The effective biocompatible strategy of dopamine monolayer film coated carbon nanotubes not only can achieve the object of modified without breaking the carbon nanotube structure, and more likely to increase significant amounts of surface active groups of MWCNTs, thereby increasing the content of grafted chitosan. Thermogravimetry analysis (TGA) data showed chitosan graft was approximately 71.78%. Diatom growth inhibition experiments indicated that due to the sustained-release effect and the diatom inhibition of carbon nanotubes, CS/micaDA-MWCNTs composites showed long-lasting inhibition performance against Navicula parva and Navicula rows.Antibacterial tests showed that CS/micaDA-MWCNTs can obtain good antibacterial property against E. coli, S. aureus and Vibrio anguillarum.