Preparation And Antifouling Mechanism Of Elastic Bionic Antifouling Membranes Based On Harmonic Motion Effect

Biofouling is the accumulation of marine organisms on ship hulls and equipment surfaces,and it has caused enormous economic losses worldwide.To solve these problems,toxic-coatings were used to combat biofouling in the early stage.However,it was found that these coatings caused a series of negative impacts to the marine environment.Many countries have introduced laws to ban these toxic coatings.Thus,develop new non-toxic antifouling coatings is urgent.Recently,new non-toxic antifouling coatings have aroused a huge concern.These coatings,such as resin and polyurethane antifouling coatings,biomimetic antifouling surfaces with microstructure,and antifouling coatings containing natural antibacterial substances such as capsaicin have also been extensively studied.However,several challenges must still be overcome for the application of these coatings.For example,they are high cost,low durability,and does not have broad spectrum antimicrobial properties.The dolphins and soft corals(Sarcophyton trocheliophorum)form unstable surfaces under turbulent flow,which is conducive to combating biofouling.Based on this antifouling strategy,we proposed"harmonic motion"effect in this study.According to the bionic similarity principle,Silicone rubber with low elastic modulus was used as the base material to simulate the skin of dolphins,and graphene nanosheets was used as fillers to adjust elastic modulus of the silicone rubber.The preparation and mechanism of elastic bionic antifouling membranes based on"harmonic motion"antifouling strategy were studied.Mechanical blending method was used to fabricate the elastic bionic antifouling membranes.Four different graphene were dispersed in silicone rubber,and these were0,0.16,0.36 and 0.64 wt%of graphene,respectively.These membranes show low surface energies(18.1-19.7 mJ/m~2),low elastic moduli(0.56-0.87 MPa),and low roughness,which are conducive to combating biofouling.The elastic bionic antifouling film containing 0.36 wt%graphene shows the lowest elastic modulus,and its value is approximately 0.56 MPa.In order to conduct dynamic antifouling experiments,we made a marine dynamic antifouling evaluation system.The range of the flow rate is 0-1.5 m/s,and the temperature of the water flow can be adjusted,and the stability is good.We evaluated the antifouling performance of graphene-silicone rubber composite membranes by using Paracoccus pantotrophus as a stain organism.In the tests,polystyrene(PS)rigid material with low surface energy was used as a control.Bacterial attachment test under static conditions showed that the quantities of bacterial films on the PS and elastic membranes were similar.In the bacterial attachment test under hydrodynamic condition,PS showed a poor antifouling performance.The comparison between static and dynamic attachment test revealed that the water flow took effect to elastic membrane,which is called"harmonic motion"effect.The"Harmonic motion effect"was proposed to reveal effect of elastic materials on antifouling performance.A mathematical model was established to calculate the deformation of elastic materials under turbulent flow.The results showed that micron-scale deformations were present on the elastic surface.In order to verify the deformations,we built a micro deformation measurement system that combined a laser displacement sensor.The minimum resolution of the sensor is one micron.The obtained results by the laser sensor showed that micron-scale deformations were present on the elastic surface,and the maximum amplitude was approximately 4μm.According to the ANSYS simulation and contact mechanics,the effect of micron-scale deformations on antifouling performance was revealed.According to the results derived from the mathematical model,when the elastic modulus of the material is 0.2 MPa,the deformation is the lowest,and if the elastic modulus of the material is greater than 0.4MPa,the elastic modulus is higher the deformation is lower.Therefore,when designing new antifouling materials,the elastic modulus should not be less than 0.2 MPa.At the end,according to"Harmonic motion"effect,we extend applications of the elastic materials on antifouling filed.We prepared graphene oxide/silicone rubber composite membranes,and test their properties and anti-diatom adhesion performance.The results indicate that lighter colors and low elastic modulus provide superior performance.We used the derived mathematical model to verify the total deformation,which also conformed to the experimental results.The experimental results in this paper provide support for using graphene/graphene oxide as fillers to improve the antifouling performance of materials,and they also provide a new method to synthesize antifouling materials.Specifically,the synthesis of materials with lower elastic modulus,but higher than 0.2 MPa.The 0.36 wt%graphene-silicone rubber elastic bionic antifouling membrane and 0.36 wt%,0.64 wt%graphene-silicone rubber elastic antifouling membranes synthesized in this paper show good antifouling performance,providing a possibility for practical application.This study also provides new insights into the effect of elastic modulus on antifouling performance.