Sustained Antifouling Composites With Antifoulant Encapsulaed In Clay Nanotubes

Biofouling is the undesirable accumulation of microorganisms,plants,and animals on water circulation system,aquaculture facilities,hull and even the submarine.The biological fouling have a great influence on ships and submarines,such as high frictional resistance,shorten service life and increased fuel consumption.So it is necessary to use antifouling coating in all structures immersed in a marine environment.Highly effective and "green"antifouling system should be low mammalian toxicity,no bioaccumulation in the food chain,not persistent in the environment,favorable price/performance and have long term release to provide prolonged antifouling efficacy.For the purpose,inexpensive,naturally occurring halloysite nanotubes can be used to encapsulate the environmental benign antifouling agents.Halloysite as a fine lumen have been developed as an entrapment system for loading,storage,and controlled release of significant amount of chemicals(drug,catalyst,antioxidant,etc.),pre-formed nanoparticles and large macromolecules like enzymes,DNA and globular proteins.Two types of sustained antifouling elastomer were prepared by mixed antifoulant loaded natural halloysite nanotubes with the elastomer.Specifically include the followings:(1)An antifouling ethylene-vinyl acetate copolymer(EVA)composite was prepared with the N-(2,4,6-trichlorophenyl)maleimide(TCPM)by using halloysite as a nanocontainner to extend the release time of TCPM.The release kinetics of antifoulant from halloysite indifferent medium,including polar solvent(water),nonpolar solvent(cyclohexane),and rubber matrix was studied.The inclusion of halloysite reinvests EVA composites the anisotropic properties by the reinforcement of halloysite and its parallel orientation.The release time of EVA polymer matrix was doubled when DCOIT loaded halloysite nanotubes incorporated in the EVA.The antifouling property of EVA composite is studied by the adhesion of marine bacteria(V.natriegens)on the composite surface using scanning electron microscope and hemocytometer.Compared with the EVA directly doped with anti foul ant TCPM,few bacteria can adhesive on the EVA composite with halloysite encapsulated TCPM,even after shaking in sea water for 60 days.The presence of halloysite loaded with TCPM endows EVA composite antifouling and anisotropic properties,which promise application as marine antifouling material.(2)An antifouling rubber(SBR)was prepared using the antifoulant DCOIT loaded inside halloysite clay nanotubes as fillers.Loading the antifoulant inside halloysite clay nanotubes allows for its sustained release and extended action time.The release kinetics of antifoulant from halloysite indifferent medium,including polar solvent(water),nonpolar solvent(cyclohexane),and rubber matrix was studied.The DCOIT loaded halloysite nanotubes incorporated in the SBR allowed for extended release of the drugs.The antifouling property of SBR composite is studied by the adhesion of marine bacteria(V.natriegens)on the composite surface using scanning electron microscope and hemocytometer.Compared with the SBR directly doped with antifoulant DCOIT,few bacteria can adhesive on the SBR composite with halloysite encapsulated SBR.The presence of halloysite loaded with antifoulant endows SBR composite excellent antifouling properties.In addition,adding halloysite nanomaterials can improve the mechanical properties of elastomer composites.