Preparation And Durability Of Hydrophobic Porous Films Based On Droplet Self-assembly

Honeycomb like ordered porous films are widely used in the field of selfcleaning coatings due to their unique micro cavity interconnection structure and excellent hydrophobic properties.The preparation of porous films based on droplet microfluidic chip and evaporation induced self-assembly technology has the advantages of high throughput,low cost,simple process and strong controllability,which provides a powerful means to accurately control the surface morphology and structure of porous films.Hydrophobicity and durability are the basic requirements of porous films for practical applications.At present,most of the studies in the related fields are the preparation of porous films by breathing pattern method and microemulsion droplet template method.However,the pore size dispersibility of these films is poor,and there are great limitations in the choice of film forming materials.Therefore,in this paper,a kind of honeycomb ordered porous film was prepared by combining droplet microfluidic technology and evaporation induced self-assembly method,and its hydrophobicity and durability were further studied.Based on the theory of wall wettability,Young's equation and interfacial instability,the mechanism of droplet formation and self-assembly was revealed.Based on the simulation model,the influence of two-phase flow velocity and other parameters on droplet formation in coaxial flow method was analyzed,and the basic process of droplet self-assembly forming large-scale network arrangement induced by evaporation was analyzed,which provided a theoretical basis for the experiment of porous film preparation.Subsequently,the droplet generation experiment was carried out,and a capillary microfluidic chip was designed and manufactured for producing single emulsion droplets.The experimental system was built to complete the droplet generation and enrichment,and the effects of the key parameters such as the twophase flow rate ratio and the concentration of continuous phase liquid on the droplet generation were determined.In addition,based on 3D printing technology,a five channel chip bracket was designed and processed to achieve more mass droplet generation.The preparation of ordered porous films was carried out by using a single emulsion droplet as template.The honeycomb ordered porous films were prepared by evaporation induced self-assembly.The characterization and quantification method of the surface morphology and structure of the porous film were determined.The influence of the key parameters such as the concentration of the external phase solution and the amount of emulsion casting on the surface morphology and structure of the porous film was determined by combining the relationship between the droplet size and the diameter of the microcavity unit.The hydrophobicity and durability of the porous films were tested.The water resistance of honeycomb ordered porous film was obtained by acetal reaction treatment by chemical crosslinking method.The hydrophobicity of the film surface was tested by contrast experiment,and the contact angle measurement system was built.The influence of key parameters such as continuous phase flow rate on the water contact angle of the porous film surface was discussed.The mechanical durability experiment system was built to reveal the failure process of porous film surface structure;The chemical stability of the porous film was verified,and the acid and alkali resistance of the porous film was tested by immersion method.