Synthesis And Properties Of Antibacterial And Antimildew Graphene Oxide/Vanillin Based Simulated Styrene Acrylate Emulsion

Traditional styrene-acrylate emulsion is easy to breed bacteria,mold and other microorganisms on the surface of the film when used as film-forming materials,which affects the hygiene and safety of related coating products such as leather products.In addition,the raw material styrene(St)used in the preparation of styrene-acrylate emulsion is not only derived from non-renewable petrochemical resources,but also recognized by the World Health Organization as 2B carcinogens and harmful volatiles.In response to the above two issues,this study first introduces hexafluorobutyl methacrylate(G02)into the traditional styrene-acrylate emulsion,and using G02 with low surface energy to reduce the adhesion of microorganisms to the styrene-acrylate latex film.On this basis,double-bonded modified vanillin(DV),a modified biomass-based monomer with antibacterial properties,is used as a substitute for petroleum-based carcinogen styrene,and together with butyl acrylate(BA)as two main monomers to prepare styrene-acrylate emulsion,and meanwhile,double-bonded eugenol(DE)is used as a biomass-based crosslinking agent.A green and sustainable antibacterial vanillin-based simulated styrene-acrylate emulsion P(DV-BA-DE)is prepared.In order to further improve the anti-mold property of P(DV-BA-DE)latex film,the inorganic nano-antibacterial material graphene oxide-silver-iron oxide(GO-Ag-Fe3O4)prepared by one-step hydrothermal method,is introduced into P(DV-BA-DE)emulsion to prepare GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite emulsion.During the film forming process of the nanocomposite emulsion,the intensity of the applied magnetic field is adjusted to make GO-Ag-Fe3O4 with both magnetic response performance and antibacterial materials migrate to the surface of the nanocomposite film,and thus,a magnetically induced GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite film with gradient microstructure is constructed.The nano-antibacterial material GO-Ag-Fe3O4 that oriented on the surface of the nanocomposite film can not only fully contact with bacteria,molds and other microorganisms in the environment,but also efficiently release antibacterial components and reactive oxygen species(ROS),and thus achieving organic/inorganic synergistic antibacterial due to the presence of the aldehyde group within P(DV-BA-DE),so as to maximize the anti-bacterial and anti-mildew effect.The main contents are as follows:(1)The fluorine-containing styrene-acrylate emulsion P(St-BA-F)is prepared by miniemulsion polymerization using styrene(St)and butyl acrylate(BA)as the main monomers,and the fluorine-containing monomer G02 as a low surface energy functional monomer.The optimal process of P(St-BA-F)emulsion is obtained.The P(St-BA-F)latex particles have a regular spherical morphology with a particle size about 250 nm and a unimodal distribution.P(St-BA-F)is successfully prepared,and the fluoroalkyl chain can migrate to the surface of the latex film during the film formation process,reducing the surface energy of the film.P(St-BA-F)film effectively preventes the gram-negative bacteria Escherichia coli,the gram-positive bacteria Staphylococcus aureus and the mold Aspergillus niger from adhering and growing to the surface of the film,thereby improving the hygienic performance of the coating.These results indicate that the introduction of low surface energy functional monomer G02 can significantly improve the antimicrobial adhesion properties of traditional styrene-acrylate emulsion films.(2)Using bio-based vanillin and eugenol with antibacterial properties as raw materials,double-bonded vanillin(DV)and double bond eugenol(DE)are prepared through Steglich esterification reaction.A green and sustainable vanillin-based simulated styrene-acrylate emulsion P(DV-BA-DE)is prepared by miniemulsion polymerization using DV,DEand butyl acrylate(BA).The optimal preparation process is obtained.The particle size of P(DV-BA-DE)latex particles is a regular spherical structure with a particle size about 150 nm and a unimodal distribution.The stableility of P(DV-BA-DE)emulsion is significantly better than that of the traditional petroleum-based styrene-acrylate emulsion.The P(DV-BA-DE)latex film have obvious antibacterial effects against gram-negative bacteria Escherichia coli and gram-positive bacteria Staphylococcus aureus,and the antibacterial performance against Staphylococcus aureus is better than Escherichia coli.However,P(DV-BA-DE)latex film has no obvious anti-mold effect against the mold Aspergillus niger.(3)Graphene oxide(GO)is prepared by the modified Hummer's method with flake graphite as raw material.GO-Ag-Fe3O4 inorganic antibacterial material with both magnetic response characteristics and antibacterial properties is prepared by one-step hydrothermal method using GO,AgNO3 and FeCl2·4H2O as raw materials.The optimal preparation process is obtained.The prepared GO-Ag-Fe3O4 is introduced into the P(DV-BA-DE)emulsion to prepare the GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite emulsion.During the film forming process of the nanocomposite emulsion,the magnetic field is applied to make the magnetically responsive GO-Ag-Fe3O4 migrates to the surface of the latex film,and thus constructing a magnetically induced GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite antibacterial coating.The amount of GO-Ag-Fe3O4 is 4.0 wt%.When the magnetic force is 240 mT,the optimal distance between the nanocomposite emulsion and the magnetic source is about 3.0 cm,which can be adjusted to control the GO-Ag-Fe3O4 migrate to the surface of the film.GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite coating constructed by magnetic induction has obvious antibacterial effect against gram-negative bacteria Escherichia coli,gram-positive bacteria Staphylococcus aureus and mold Aspergillus niger,and the antibacterial performance against Staphylococcus aureus is better than that of the Escherichia coli.In addition,compared to the GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite film prepared by the layer-by-layer spraying method and the physical blending method,the GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite film constructed by the magnetic induction method has good wet rubbing fastness,and the film can maintain good antibacterial and mildew resistance after wet rubbing treatment.(4)The gram-negative bacteria Escherichia coli,gram-positive bacteria Staphylococcus aureus and the mold Aspergillus niger are used as the research objects.FT-IR,SEM,XRD,thermal infrared imaging,electron paramagnetic resonance and fluorescence confocal microscopy are used to study the antibacterial and antifungal mechanism of P(DV-BA-DE)latex film and GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite films.P(DV-BA-DE)latex film contains aldehyde groups,which makes P(DV-BA-DE)latex film exhibit certain antibacterial properties.GO-Ag-Fe3O4 nano antibacterial material with magnetic response properties migrates to the surface of the nanocomposite film under the directional induction of an external magnetic field.GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite film constructed by the magnetic induction method is irradiated under a xenon lamp simulated visible light for 10 min,and the upper surface temperature of the film increases from the original 33.0? to 46.5?,confirming that GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite film can produce antibacterial and anti-mildew effect through photothermal effect.GO-Ag-Fe3O4 nano-antibacterial materials can generate more hydroxyl radicals(·OH)and superoxide radicals(·O2-),and the amount of ·OH is significantly greater than·O2-,indicating that the antibacterial and antifungal properties of GO-Ag-Fe3O4 nanocomposites are mainly derived from the destruction of ·OH to bacterial structure.In addition,compared to the GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite film prepared by the physical blending method,the GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite film prepared by the magnetic induction method produces more ·OH and ·O2-,indicating that GO-Ag-Fe3O4 migrates to the surface of the latex film under the induction of an external magnetic field,which increases the release of antibacterial active oxygen.The GO-Ag-Fe3O4/P(DV-BA-DE)nanocomposite film constructed by the magnetic induction method has a species-specific mechanism for killing bacteria and molds.For bacteria,the nano-antibacterial materials mainly destroy the integrity of the cell wall and cell membrane,causing the leakage of the bacterial cytoplasm,and achieves the killing effect;for the mold,the nano-antibacterial materials has the effect of inhibiting the growth of mold by causing the structure of the mold to collapse.