Epoxy Resin Coatings Modified By Doped Nano-SiO₂

Marine biofouling refers to the damages for the marine facilities caused by the attachment and invasion of a large number of marine microorganisms,algae and animals in the environment.The utilization of antifouling coatings on the surface of marine facilities is one of the most widely used and the simplest antifouling technology.Traditional method that prevent marine biofouling is to use the coatings containing toxic antifouling agents on the surface of marine facilities,while it will inevitably cause damage to environment.With the development of nanotechnology,the combination of nanotechnology and marine antifouling provides a new direction for the development of antifouling technology.Nanomaterials are widely used for the modification of antifouling coatings due to their various excellent properties such as photocatalysis and ultraviolet absorption.Epoxy resin coatings are usually utilized for the protection of marine structures,which can be attributed to their outstanding performances,such as their excellent corrosion resistance,permeability resistance and adhesion strength.At present,the method that nano-modification is widely utilized to improve various properties of the epoxy resin coatings such as antifouling and anti-aging properties.In this paper,nano-SiO₂ with small particle size was successfully prepared by chemical precipitation method.Three different nano-SiO₂ samples were obtained by annealing the prepared nano-silica precursors in hydrogen,nitrogen and oxygen,respectively?signed H-SiO₂,N-SiO₂ and O-SiO₂?.In addition,the B and P doped nano-silica with different doping content?1%,3%,5%?were successfully prepared.The products were characterized by XRD,SEM,TEM,XPS,FTIR and UV-Vis.The effects of different nano-SiO₂ samples?N-SiO₂,H-SiO₂,O-SiO₂,B or P doped nano-SiO₂?on the antifouling properties and UV aging resistance of the coatings were investigated.The experimental results show that the prepared nano-SiO₂ samples are amorphous nano-SiO₂ and B as well as P doped nano-SiO₂ are successfully prepared.The results of UV-Vis show that the UV absorption properties of nano-SiO₂ are significantly enhanced after annealing at high temperature in nitrogen and hydrogen atmosphere.Among the nano-SiO₂ samples doped with B and P,the UV absorption properties for the nano-SiO₂ sample doped with 5%P improved significantly.There is no significant change in the UV absorption properties of B doped nano-SiO₂ and the nano-SiO₂ sample annealed at high temperature in oxygen atmosphere.The results of contact angle test show that the contact angle for the coatings without modification is about 83°,and when the additive amount of nano-SiO₂ samples reaches 40%,the contact angles of the coatings after modification by the N-SiO₂ and H-SiO₂ achieve the maximum values,126° and 125°,respectively,while the maximum contact angles values for the coatings modificated by the nano-SiO₂ without any treatment and O-SiO₂ are 102° and 107°,separately.Seen from the experimental results,the contact angles of the coatings modified by N-SiO₂ and H-SiO₂ improved significantly,which means the hydrophobic and the antifouling properties for the modified coatings enhanced,greatly.Among the coatings modified by B and P doped nano-SiO₂,when the additive amount of the nano-SiO₂ samples reaches 30%,the contact angles for the coatings modified by 5-P-SiO₂ and 5-B-SiO₂ reach the maximunm values,142° and 135°,which means strong hydrophobic and excellent antifouling properties for the coatings.SEM images of the coating show that the changes of coating contact angles are related to the micro-nano structures on the surface of the coatings.After 30 days of UV accelerated aging,compared with the coatings without modification and modified by the nano-SiO₂ without any treatment and O-SiO₂,respectively,the chromatic aberration for the coatings modified by N-SiO₂ and H-SiO₂ are the smallest,and their surfaces of the coatings are relatively intact,indicating that the UV-resistant aging properties of the coatings modified by N-SiO₂ and H-SiO₂ are improved,significantly.Among the coatings modified by P-doped and B-doped nano-SiO₂,the chromatic aberration of the coatings modified by 5-P-SiO₂ is the smallest,indicating the UV aging resistance of the coatings is significantly improved after been modified by the 5-P-SiO₂.