Nano-partical Modified Silicone-based Polyurea Marine Antifouling Material

Marine biological fouling refers to the phenomenon that microorganisms,algae and animals attach to the solid surface immersed in seawater,it is the main economic burden of the marine industry.Anti-fouling coating technology was developed to prevent the settling of fouling organisms.As early as 2008,the use of organotin antifouling agents has been completely banned worldwide.The development of new green and effective antifouling coatings is a priority issue in this field,especially low surface energy fouling release coatings.Silicone-based antifouling materials have the characteristics of low surface energy and low elastic modulus,which can effectively inhibit or release marine biological fouling without releasing any toxic and harmful substances.It is one of the most promising marine fouling release antifouling materials.However,traditional silicone substrates antifouling coatings have low mechanical strength,are not resistant to damage,and easy to split,also have poor adhesion to the substrate.It is only effective when the ship speed reaches 15 knots or more,and the antifouling effect at low speed is difficult to meet the requirements,which limits its use.To address above mentioned problems,this paper designed and synthesized a silicon-based polyurea marine antifouling coating.The main results are as follows:(1)Using polydimethylsiloxane and dicyclohexylmethane 4,4-diisocyanate and1,6-hexamethylene diamine as raw materials,a series of silicone-based polyureas with different hard segment content were prepared.Compared with traditional silicone-based antifouling materials,silicone-based polyurea coatings have good mechanical performance,and the adhesion to the substrate is enhanced.The water contact angle of the coating surface was analyzed,and the surface free energy was calculated.Analysis showed that with the rises of the hard part content,the surface contact angle of the coating decreased from 108.7oto 98.7o,and the surface free energy changed from 23.00 m J/m² to 26.07 m J/m²,the coating still maintained the advantages of hydrophobicity and low surface energy.The self-healing performance of the coating was studied in air and artificial sea water.The material showed good self-healing performance.After 60 hours of self-healing,the coating cracks were basically completely repaired.(2)The nano Ag@SiO₂ material with core-shell structure was made.Preparation of nano silver by reduction of silver nitrate with sodium borohydride,using cetyltrimethylammonium bromide as protective agent and synthesis of monodisperse nano Ag@SiO₂ with a core-shell structure using ethyl orthosilicate as the silicon source.The core-shell structure of nano Ag@SiO₂ was loaded in the silicone-based polyurea material,and the anti-protein character of the coating surface was analyzed.The results showed that the nano-silver modified silicone polyurea composite coating showed good anti-protein performance,and the coating with nano-silver addition of 0.5 wt%showed the best anti-protein adsorption effect.Furthermore,the results of antibacterial experiments showed that after 6 hours of shaking culture,the coating surface showed good effects against Escherichia coli and Staphylococcus aureus,and the capability of antibacterial of the composite coating with the adjunction of nano-silver 0.5 wt%was the best.In the antifouling test of the real sea siding,the 60-day real sea siding test results showed that the nano-silver modified silicone-based polyurea material showed good antifouling performance in the initial stage of fouling.The silver core continuously releases silver ions through the porous silica shell,resistance the formation of micro bacillary membrane on the surface of the coating,avoids subsequent biofouling,and improves the static antifouling ability of the coating.