Study On The Modification Preparation And Wettability Of Silicon-based Superhydrophobic Materials

Wettability is the most common phenomenon in nature.The surface wettability is determined by the chemical composition of the substance and surface micro-topography.Roughness and surface free energy are two key factors that determine the wettability of the solid surface.The main idea of designing superhydrophobic materials includes: building rough structures on existing hydrophobic materials or modifying low surface energy substances on the surface of rough materials.That is,solid materials with different wettability can be obtained by adjusting the solid surface morphology and surface free energy.In this thesis,silicon dioxide was used as the raw material,hydrothermal treatment was performed,and then modified with silane coupling agent,to prepare super-hydrophobic coating.A rough structure was constructed using silicon dioxide with different particle sizes and a silane coupling agent was used to reduce the surface free energy,moreover the effects of particle size and modifier on the wettability of the material were studied.The wettability,surface composition and micromorphology of modified silicon dioxide were analyzed by optical contact angle measuring instrument,infrared spectrometer and field emission scanning electron microscope;the self-cleaning performance of the sample was analyzed and the modified sample was tested in the environment changes in wettability;By monitoring the scaling of the superhydrophobic coating of the modified material in supersaturated calcium carbonate solution,the antiscaling and anti-scaling effects of the samples were studied.The specific research results are as follows:(1)After being modified by triethoxyvinylsilane,the surface energy of silicon dioxide decreases and the hydrophobicity of the modified material increases.There is a negative correlation between the particle size and the hydrophobic strength of the material.When the particle size of silicon dioxide is reduced,the surface roughness of the modified material becomes larger,and the microscopic morphology becomes more complicated.When the particle size of silicon dioxide decreases from micrometer to nanometer,the wettability changes from Wenzel state to Cassie state.When the silicon dioxide particle size is 20 nm,the contact angle of the modified material reaches 158.0 ± 5.4 °,and the rolling angle is less than 3 °.(2)Silicon dioxide was modified with different modifiers to obtain super-hydrophobic nanocomposites with a contact angle higher than 150 °and a rolling angle smaller than 10 °.The modifier significantly reduces the surface energy of silicon dioxide and solves the problem of agglomeration effectively.After low surface energy modification,the contact angle of the material is greater than 150 °,and the rolling angle is less than 10 °.MTMS modified silicon dioxide composites have the best super-hydrophobic effect,with a contact angle of 161.3 ° and a rolling angle as low as 4.1 °.(3)The prepared modified material has stable super-hydrophobic performance and self-cleaning function in the environment.The selfcleaning performance of the modified material can prevent the dust in the application.Compared with the blank substrate,after being immersed in calcium carbonate solution for 100 h,the total amount of calcium carbonate scale on the surface of the super-hydrophobic coating is less and the hardness is lower.The super-hydrophobic coating inhibits the nucleation process of calcium carbonate crystals,and the anti-scaling and anti-scaling effects are obvious.