Study Of The Prevention Of Marine Biofouling On PMMA Surface By Ultrasonic Treatment And Nano-SiO₂ Coating

Marine sensors are important equipments for data monitoring.High light transmittance of sensor optical window is essential to ensure data monitoring accuracy.Marine biofouling,even initial microfouling,will reduce the light transmittance of the optical window,resulting in a significant deviation of measurement.Therefore,effective anti-fouling treatment in optical window is very important for marine sensors to work in ocean.In the thesis,the influence of ultrasonic parameters on PMMA surface antifouling effect was investigated by single factor and response surface tests with laser confocal scanning microscope and light transmittance tester,considering that PMMA is a commonly used optical window material in marine sensors.In addition,a series of antifouling coatings were prepared with modified nano-SiO₂ particles on the surface of PMMA by the combination of spin coating and spraying coating.An optimal coating was determined by the characterization of its hydrophobic properties,light transmission and durability,and then the time-dependency of the coating antifouling behavior on the PMMA surface was investigated.The couple antifouling effect of the coating and ultrasonic wave was also explored.The main conclusions are as follows:(1)Regarding the removal of biofilm on PMMA surface by ultrasonic wave,there is a positive correlation between antifouling efficiency and ultrasonic power and duration,but a negative relation between antifouling efficiency and ultrasonic frequency.Ultrasonic frequency has the greatest impact on the antifouling efficiency,followed by ultrasonic power and ultrasonic duration.(2)Based on the results of response surface experiment,a regression equation between the anti-fouling efficiency and ultrasonic parameters(frequency,power and duration)has been obtained by fitting calculation.The accuracy of this regression equation can reach 91.11%.From the requirements of actual working conditions,an optimal ultrasonic antifouling condition for the marine fouling biofilm on PMMA surface is 70 k Hz,40 W and 10 min,and its antifouling efficiency is 95.11%.(3)The contact angle and light transmittance of the nano-SiO₂ coating are closely associated with the binder content in coating.The nano-SiO₂ coating with a binder content of0.1 g is of superhydrophobicity,and it exhibits good light transmittance,durability,and antifouling ability in seawater environment.Compared with the PMMA,the PMMA with the nano-SiO₂ coating has a slightly lower light transmittance,but it shows a much weaker compromise of light transmittance in seawater because the coating can effectively inhibit the adhesion of bacteria.(4)The combination of superhydrophobic nano-SiO₂ coating with ultrasonic treatment can effectively prevent marine fouling biofilm from forming on PMMA surface.