Study On Preparation Of Polyamide Composite Film Based On Inkjet Printing Coating Technology

The surface modification engineering of solid materials is playing an increasingly important role in physics,chemistry and biomedical sciences^[1,2].The main way is to modify the surface of solid materials to give some new properties to the surface of the materials or optimize the existing performance.As an upstream industry in the field of membrane separation,membrane materials have always been the focus of research.Surface modification of the substrate for preparing interfacial polymer membranes can break the trade-off phenomenon between the rejection rate and the water flux of the composite membrane.In this paper,inkjet printer technology is used for surface modification to prepare hydrophilic coatings.First,a metal-polyphenol（MPN）network hydrophilic coating complexed with tannic acid（TA）and ferric chloride hexahydrate（Fe Cl₃·6H₂O）is printed on a polysulfone（PSF）substrate.The printing conditions of the coating can be controlled by setting the parameters of the printing program to adjust the hydrophilicity,electronegativity and surface morphology of the coating.The printing method condition factors such as the printing ratio of the coating solution and coating printing volume have an impact on the hydrophilicity of the coating.The study found that the printing method can successfully and accurately prepare hydrophilic coatings with different degrees of hydrophilicity.Within a certain printing volume,the hydrophilicity is proportional to the printing volume.And the PSF substrate hydrophilicity has nearly doubled under certain coating printing conditions.In addition,with the controllability of inkjet printing area,in the field of coating research,coatings with different conditions can be printed on different positions on the same substrate,which provides convenience for laboratory coating research.At the same time the wide versatility of inkjet printing coating technology was verified and its universality was proved by selecting and changing the coordination metal,substrate and other MPN coating systems,.Secondly,in this paper,the inkjet printing coating is used as the intermediate layer to prepare high-performance composite film.To control the performance of the composite film by setting the printing ratio of the intermediate layer and print the intermediate layer at a fixed point and area through printing.The results showed that the flux of the piperazinyl nanofiltration composite membrane prepared by the printing program reached 207 L·m^-2·h^-1·Mpa^-1,and the rejection rate of sodium sulfate（Na₂SO₄）Higher than 98%.The performance has been improved compare with the traditional plate and frame method.As the printing volume of the intermediate layer increases,the morphology of the prepared interfacial polymerization membrane changes regularly from the nodular structure to the fold structure,and the hydrophilicity also increases,while maintaining a high rejection rate of sodium sulfate,and the flux increase continuously to reach the maximum value.The regionalization of the intermediate layer can be adjusted to different surface structures and other surface properties in a fixed area on the continuous polyamide film.Interfacial polymerization is carried out on the bottom film with different intermediate layer coverage,and the resulting composite film has a retention rejection stability of more than 98%.A linear positive correlation is formed between the fluxes.The linear relationship between the fitted water flux F and the intermediate layer coverage x（%）is F(L·m^-2·h^-1·Mpa^-1)=0.9456x（%）+55.53.