Preparation And Properties Of Biomimetic Polydimethylsiloxane-based Antifouling Surface

Marine fouling organisms attach to ships and other man-made structures while humans engage in marine activities.This phenomenon not only causes damage to the structure,but also impacts economic development.To mitigate the harm and loss due to fouling organisms,antifouling coatings are widely used.However,traditional antifouling coatings have potential biotoxicity,which limits their development.Therefore,there is an urgent need to develop sustainable and non-toxic antifouling technologys,and designing green and efficient antifouling surfaces inspired by biology is a promising solution.In this paper,the common marine high-speed fish(shark)was taken as the research object,and its surface morphology was reproduced to prepare the bionic polydimethylsiloxane shark skin material(PDMS-SK).By combining two kinds of functional hydrogels,the bionic polydimethylsiloxane shark skin/functional hydrogel composite antifouling surface was prepared.The antifouling performance of the composite surface was investigated by evaluating its inhibition of algal adhesion,bacterial adhesion,and selective adhesion of mussels.The structures of shark skin and PDMS-SK material were characterized by SEM,optical microscope,and other characterization methods.It was found that the shark skin has a nonsmooth and stable surface morphology with dense and orderly arranged micron-scale scales.These scales possess grooves and protrusions with a polygonal micron structure.The shark epidermis can inhibit the adhesion of algae and mussel adhesion to extent by inhibiting algal adhesion and selective mussel adhesion experiments.The surface morphology of PDMS-SK materials was similar to that of shark skin.The hydrophobicity of PDMS-SK materials were significantly higher than that of PDMS materials by CA,and the water contact angle was 140°.The PDMS-SK material had inhibited adhesion to both Escherichia coli and Staphylococcus aureus;The algae adhesion inhibition test demonstrated that the amount of algae adhesion on the surface of PDMS-SK material decreased significantly compared to shark skin and smooth PDMS materials;The PDMS-SK surface exhibited a "repelling" effect on mussels as demonstrated by mussel selective adhesion experiments.The polylysine-polyvinyl alcohol hydrogel(P-PL)was used to simulate the mucous substance of shark skin,which was crosslinked on the surface of PDMS-SK material to prepare the bionic polydimethylsiloxane shark skin/polylysine-polyvinyl alcohol composite antifouling surface(PDMS-SK/P-PL).The microstructure of the original reproduced shark skin was unchanged of the PDMS-SK/P-PL composite antifouling surface,and the surface roughness was reduced.The experiment inhibiting algae adhesion was conducted,and it was revealed that the amount of algae adhesion was reduced.The inhibition ratio of the PDMSSK/P-PL composite antifouling surface against Escherichia coli,Staphylococcus aureus,Pseudomonas aeruginosa and Pseudomonas marinum were 94.15%,66.25%,87.36% and86.24%,respectively.The PDMS-SK/P-PL composite surface exhibited a "repelling" effect on mussels as demonstrated by mussel selective adhesion experiments.In addition the modified composite antifouling surface has no effect on the growth of algae in the growth curve of Nitzschia closterium,which proved that the modified composite antifouling surface not only inhibited the adhesion and growth of marine organisms but also had good environmental friendliness.To simulate biologically dynamic antifouling,the polyvinyl alcohol-poly N-isopro pylacrylamide-polypyrrole thermosensitive hydrogel(P-N-P)was prepared and cross-li nked onto a PDMS-SK material to create a biomimetic polydimethylsiloxane shark s kin/polyvinyl alcohol-poly N-isopropylacrylamide-polypyrrole composite antifouling surf ace(PDMS-SK/P-N-P).Based on the photothermal action of polypyrrole and the dyn amic change of polyvinyl alcohol-poly-n-isopropyl acrylamide hydrogel(PN),the anti fouling performance of the composite surface was enhanced.The algae adhesion exp eriments demonstrated a decrease in attachment number compared to PDMS-SK mate rial.The inhibition ratio of PDMS-SK/P-N-P composite antifouling surface against Es cherichia coli,Staphylococcus aureus,Pseudomonas aeruginosa and Pseudomonas ma rinum were 76.7%,70.17%,82.64% and 72.58%,respectively.The results of selectiv e adhesion experiment of mussel confirmed that the modified composite antifouling s urface has certain antifouling performance.Furthermore,the growth curve of Nitzschi a closterium indicated that the modified composite antifouling surface remained envir onmentally friendly and did not significantly affect algae growth.