Slow-Release Of PH-Responsive Environmental Protection Antifouling Agent And Application In The Marine

In the marine environment,marine facilities are damaged by the adhesion of large numbers of macroscopical marine organisms and microorganism,which has caused serious economic losses.The employment of antifouling coatings with biocides such as tributyl tin（TBT）and copper are one of the efficient solutions to this worldwide problem.However,the widespread use of these toxic biocides has caused serious pollution to marine ecosystems,and their use has been banned worldwide since 2008.Therefore,non-toxic and environment friendly marine antifouling coatings have become important alternatives.In this paper,nano-silica（Si O₂）,capsaicin（CAP）,and chitosan（CS）are used to synthesize a drug-loaded nanoparticle that has a large drug loading and can be dynamically released according to p H changes.The combination of drug-loaded nanoparticles and coatings has constructed a long-term effective and non-toxic antifouling coating,and the antifouling performance of the coating has been evaluated in detail.The experimental results show that the spherical nano-Si O₂ with disordered and radial pore different structure was synthesized by microemulsion method.By adjusting the content of different raw materials in the synthesis system,the maximum specific surface area of the two kinds of nano-Si O₂ with different morphologies is 247.93 m²/g and 749.15 m²/g,respectively.Different structure Si O₂ with high specific surface area were applied to the loading of non-toxic antifouling agent capsaicin,and chitosan was grafted on the surface.Chitosan coated drug-loaded nanoparticles（CS-CAP-Si O₂）were prepared successfully.The effects of different drug-loading grafting sequence and different morphology of Si O₂ on the loading capacity of drug-loading particles on capsaicin and the slow-release effect were investigated.According to formula calculation and drug release experiment,under the optimal preparation process of drug loading particles,the drug loading amount and sustained release effect of drug loading particles synthesized by radial pore structure Si O₂ are obviously higher than that of surface disorder Si O₂.The chitosan on the surface of the drug loading particles can selectively change the release rate of the drug according to the change of p H in the environment,so as to avoid the burst release and achieve the slow-release effect.Drug-loaded nano-SiO₂ composite coatings with different mass fractions were prepared.The mechanical property test and antifouling performance evaluation of the coatings showed that the mechanical property and antifouling performance of the coatings were significantly improved by CS-CAP-Si O₂ drug-loaded particles,of which 1%dosage was the best.Compared with the blank coating,the antibacterial rate of the composite coating was about85%after soaking in the seawater with bacteria for 10 days.CS-CAP-Si O₂ drug-loaded particle composite coating solves the problem of antifouling agent burst release in antifouling coating,and will release dynamically according to the change of p H of the surrounding environment after the metabolites are produced by bacteria in seawater,which improves the effective period of antifouling coating.The experimental results show that the CS-CAP-Si O₂ particles prepared in this experiment can be used as an effective filler for non-toxic marine coatings,which significantly improves the antifouling property and validity period of Marine coatings.