▎ 摘　　要

NOVELTY - Coating material comprises a barrier layer, a self-cleaning coating, and an antibacterial layer arranged on the surface of the polylactic acid base film. The barrier layer is nano-silica/graphene composite modified polylactic acid layer. The self-cleaning coating is nitrogen-functionalized carbon dot-modified cellulose nanofiber layer. The antibacterial layer is nano-silicon oxide/silver oxide modified polyvinylidene fluoride layer. USE - The coating material is useful for resisting Escherichia coli and Staphylococcus aureus, chemical, physical and biological sensor, microelectronic device, non-linear optical, and molecular device. ADVANTAGE - The coating material not only has good barrier and antibacterial properties, but also has excellent mechanical properties and a simple preparation method. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the coating material, comprising (1) adopting melt extrusion, tape casting process to obtain polylactic acid base film, (2) dispersing graphene in deionized water to make graphene dispersion, dissolving polylactic acid in tetrahydrofuran, then adding gamma-isocyanatopropyltriethoxysilane, and preparing the modified polylactic acid solution after uniformly mixing, (3) mixing and stirring ethyl orthosilicate, deionized water, and absolute ethanol, then adding hydrochloric acid solution as catalyst, hydrolyzing at room temperature to prepare silica-containing sol, then adding the above prepared graphene dispersion and modified polylactic acid solution, stirring vigorously at room temperature to prepare a composite sol, uniformly coating the prepared composite sol on the polylactic acid base film, drying, and aging to obtain a polylactic acid base film containing a barrier layer, (4) dissolving glucose and urea in deionized water to obtain solution, then transferring the solution in the reactor to react, cooling to room temperature after finishing, centrifuging the reaction product, filtering the supernatant collected by centrifugation, and then freeze-drying to obtain nitrogen-doped carbon dots, (5) mixing cellulose nanofibers, glycerol and deionized water, heating up and stirring vigorously, then adding the nitrogen-doped carbon dots obtained above while stirring, stirring to prepare coating liquid, uniformly coating the coating liquid on the surface of the polylactic acid base film containing the barrier layer, and drying to prepare the polylactic acid base film containing the barrier layer and the self-cleaning coating, and (6) fully uniformly mixing polyvinylidene fluoride, silver oxide, and nano-silicon oxide, then using a tablet machine to process to obtain flaky mixed particles, using the prepared flake mixed particles as the target, using vacuum low-power electron beam evaporation method to deposit antibacterial layer on the surface of a polylactic acid base film containing a barrier layer and a self-cleaning coating, and obtaining coating material.