Preparation And Mechanism Of Benzoxazinebased Underwater Superoleophobic/Underoil Superhydrophobic Materials

Surface functional materials are widely used in bioengineering,energy saving,environmental protection and chemical engineering.In recent years,due to the progress in the preparation of surface functional materials using various matrixs or molecules,many preparation methods based on controlling surface chemical composition and micro-nano structures have emerged,which promotes the rapid development of surface chemistry.However,using the same matrix and adjusting different preparation conditions to prepare superwetting materials with different properties is still a new research field with great application potential.In this article,the benzoxazine molecules were synthesized as matrix molecules by using phenol,formaldehyde and melamine.Using the phase separation agent,curing temperature,substrate,curing rate and other factors to regulate the aggregation behavior of benzoxazine molecules,an underwater superoleophobic material was synthesized.Using metal chloride,aging time,curing temperature,substrate and other factors to regulate the aggregation behavior of benzoxazine molecules,an underoil superhydrophobic material was synthesized.The wettability,surface morphology,surface element composition,existence state and structures of the two materials were measured by contact angle(CA),scanning electron microscope(SEM),energy dispersive spectrometer(EDS),differential scanning calorimeter(DSC),fourier transform infrared spectroscopy(FTIR)and Raman.It was discussed that the influence of related factors on the molecular aggregation behavior during the synthesis process.It was discussed that the manipulation mechanism of benzoxazine molecular aggregation behavior.There were analyzed that the synthetic mechanism and chemical principle of the materials.There were discussed that the changes of matrix molecular aggregation behavior,the causes of microscopic phase separation,the thermodynamic driving force of molecular aggregation behavior,and the relationship between molecular aggregation behavior and properties of materials.Finally,these two superwetting materials were applied to the separation of water-in-oil and oil-in-water emulsions.The experimental results show that the surface morphology of benzoxazine-based underwater superoleophobic materials is like fish skin structures,and the surface chemical composition is mainly composed of polar groups.The contact angles of hexane,toluene and silicone oil underwater are 153.2°,155.8°and 155.7°.The surface morphology of benzoxazine-based underoil superhydrophobic materials is like fold structures,and its surface chemical composition is mainly composed of non-polar groups.The water contact angles under hexane,toluene,and silicone oil were 155.4°,153.8°,and 159.0°.The synthesis mechanism is that under different preparation conditions,in order to achieve the most stable state(where the Gibbs free energy is the smallest under constant temperature and pressure),the same matrix molecule would adopt different aggregation behaviors,achieve different aggregation manners,and form gel materials with opposite superwetting properties.The efficiency of these two materials in separating oil-water emulsions is greater than 99.95%,and the separation rates are 265 L/m~2h and 598 L/m~2h.Using external environmental conditions to regulate the aggregation behavior of the same matrix molecule,two superwetting materials with opposite wetting properties are obtained,which opens up a new way to design and prepare high-performance wetting materials.It also provides new ideas for the design and synthesis of other surface functional materials.