Research On Newly Developed Nontoxic Releasing Coatings For Anti-fouling Purpose

For new ocean development requests, more and more infrastructures and ships will be built, which need protection by anti-fouling coatings. The existing anti-fouling coatings function by releasing poisonous substance to kill marine biofouling organisms, and they have been polluting and contaminating ocean environment heavily. Currently, effective antifouling coatings and technology are not environmentally friendly, therefore the research on environment-friendly antifouling coatings is very important and extremely urgent. This project developed two new nontoxic-releasing antifouling coatings, studied their antifouling performances with the geographical advantage of Hainan Island and explored their antifouling mechanism.The first is a hydrophobic, release coating. To develop this environmentally friendly anti-biofouling coating in virtue of bionics, a block copolymer containing fluorine (SBF) of low surface energy was prepared using copolymerization technique. The Ag-loaded mesoporous silica (Ag@SBA) acting as a controlled-release antifoulant was prepared from the mesoporous silica (SBA-15). The nano hybrid coating (SBF/Ag@SBA) composing of the SBF and Ag@SBA was to biomimetically simulate the lotus micro structure. The concentration of fluorine element on the surface was analyzed by the energy dispersive spectroscopy (EDS) and was found rising to1.45%after hybridation, which could be explained by the driving effect of SBA-15via the hydrogen bond. This nanoscale morphology of the hybrid coating was measured and found highly semblable to the microstructure of the lotus surface. The contact angle was determined to be131°, which showed the superhydrophobicity and lotus effect. The adhesion behaviors of Pseudomonas fluorescens, Diatoms, and Chlorella on the surface of the nano hybrid coating (SBF/Ag@SBA) were studied and good effects of anti-biofouling were observed in the laboratory. However, the results of real-sea tests indicate that the releasing property will lose if the coatings are immersed in the ocean for a long period of time.Inspired by the basic and results of the first coatings, another amphiphilic, release coating was prepared. The fluorated block copolymer(SBF) and polyethylene glycol (PEG) were chosen to synthesize a kind of amphiphilic polymer which was used to prepare a new type of antifouling coating later. In order to assess the antifouling performance and the mechanism of the coating, an artificial simulation tests and real-sea tests of samples were prepared respectively. IR and1H NMR were utilized to characterize the structure of the polymer, and changes of parameters such as surface contact angle, XPS, elastic modulus, TEM were used to analyze the reasons of its antifouling effect and explore its antifouling mechanism. Results of antifouling test show that the new amphiphilic antifouling coating has very good antifouling performance and it can still release fouls to restore clean surface after testing in the real-sea environment for6months. All of these can be explained as that, hydrophilic PEG migrates to the surface forming a comb-type structure which reduces the adhesion strength of fouling organisms to the surface, therefore biofouling organisms can be self-cleaned by roving water from the coated surface.