Design,Preparation And Performance Study Of Fouling Release Coatings

The undesirable accumulation of marine organisms on any surfaces immersed in seawater is termed as marine fouling.This natural phenomenon contributes a major economic concern for marine engineering equipment and marine materials,e.g.for vessels,petroleum drill sea-platforms,pipeline for seawater cooling water by limiting the performances of the devices and materials.The prolonged utilization of conventional antifouling paints containing biocides have caused severe damage to non-objected aquatic life.The promising alternative to AF paints slowly releasing toxins into water is fouling release(FR)coatings.Ecofriendly fouling release coating has poor mechanical strength and limited antifouling efficiency under static conditions.In this paper,fluorosilicone polymer and compound functional filler were incorporated into the three-dimensional network structure of original fouling release antifouling coatings to enhance its performance.The research results are as follows:(1)A series of fluorosilicon oligomers were obtained through free radical polymerization,and the effects of different synthesis conditions on the polymerization products were studied.Representative silane coupling agent and three different types of vinyl unsaturated fluoromonomers were used as raw materials to prepare a series of copolymers by varying the polymerization process.We studied the influence of polymerization conditions(reaction temperature,the types and application amount of initiator)on the products.The polymerization process was analyzed through online calorimetric system,Raman spectroscopy,infrared spectroscopy,and online infrared technology.The experimental results show that the functional oligomers were obtained through the free radical copolymerization of the alkene group,and the exothermic reaction is concentrated in the first dripping stage of initiator.The measures such as using azo initiators,increasing the reaction temperature and the amount of initiators are beneficial to reduce the molecular weight of the polymerized product and polydispersity.The solvent were prepared by mixing propylene glycol methyl(50 wt.%)and xylene(50wt.%).The fluorosilicone oligomer whose weight average molecular weight and number average molecular weight is 749 and 730 respectively were prepared when the initiator used was 2 wt.%azobisisovaleronitrileat at 110 degrees.The polydispersity is 1.025 and the heat of reaction is 44.24 k J/mol.(2)A variety of fluorosilicone polymers with excellent performance were obtained and their impact to the performance and structure of the coatings were studied.The results show that fluorosilicone oligomers introduced into the network structure can generally decrease the glass-transition temperature value of coating samples and increase the contact angle of coating surface.The fluorosilicone oligomers which were prepared when the initiator used was 2 wt.%or 4 wt.%azobisisovaleronitrile at the temperature of 110°C can improve the tensile properties,tearing properties,elastic modulus of coating samples.Most fluorosilicone oligomers can improve the stability of the coatings’contact angle in seawater immersion and the contact angle of the best sample was increased from 55.6°to86.6°.A series of commercially available fluorosilicone polymers introduced in the coating network structure can reduce the surface area ratio of the coating samples and increase the surface contact angle.The tridecylfluorooctyltrimethoxysilane is effective in improving the tearing performance of the coating.Compared with the original formula,the maximum tearing force is increased from 7.54 N to 15.20 N,and the tearing strength is increased from 4.06 kg/cm~2to 9.50 kg/cm~2.The antifouling effect of coatings introduced hexafluorohexyltriethoxysilane has improvedsignificantly.Thecoatingintroducedwith heptafluorodecyltrimethoxysilane has improved in all aspects.The contact angle reached 104.5°.The maximum tearing force was increased from 7.54 N to 10.28 N,and the tearing strength was increased from 4.06 kg/cm~2to 6.39 kg/cm~2.The hardness of the coating with improved foul release performance is increased to H.(3)A series of improved antifouling coatings were obtained by adding low viscosity resins,ecofriendly antifouling agent and compound functional fillers to the film former of the fouling release antifouling coating physically.After soaking in the sea for eight months,the biomass of fouler organism of coatings samples modified with low viscosity silicone resin were significantly reduced compared with the original formula when the mass ratio silicone of 4000 c P resin and silicone 750 c P resin is no more than 9.The antifouling performance were improved significantly by adding an appropriate amount of antifouling agent into the fouling release coating for the synergistic effect of the antifouling agent and the fouling release coating even that the antifouling agent has certain adverse effects on the mechanical properties of the coating.The tear strength of coating samples added 3 wt.%antifouling agent is increased from 4.1 MPa to 4.3 Mpa compared with the original formula.The biomass of fouling organisms attached on the coating samples is rare after soaking in the sea for 7 months.The contact angle of the coating rein-forced by 6 wt.%compound padding mixed by silica powder and fumed silica 810 in a mass ratio of 8:3 is increased to 99.3°,and the anti-fouling effect of the coating improved remarkably comparing to the original formula.The anti-fouling effect can be maintained for more than 11 months.The use of ceramic microsphere fillers can generally improve the anti-fouling effect of the coatings,and coating added 6 wt.%mixed ceramic microsphere 210 and 410 at the mass ratio of 1:1 perform best.The tensile strength increased from 1.1 MPa to 1.25 MPa.The maximum tear strength increased from 7.54 N to 8.47 N,and the tear strength increased from 4.06 kg/cm~2to5.27 kg/cm~2.The hardness increased to 2 H.The water absorption rate of seawater was reduced from 1%to 0.34%.There are obvious microstructures of burr protrusions on the surface.Compared with the original formula,the biomass of fouler organism of coatings samples modified with low viscosity silicone resin were significantly reduced compared after soaking in the sea for eight months.