Preparation And Antibacterial Properties Of Fluorinated Difunctional Copolymer

Biological pollution is a major challenge in medical and health fields,Marine industry,food processing and many other fields.Infections caused by bacterial biofilms,which account for 80%of human microbial infections,have become one of the growing problems in the field of medicine and health care.Mature biofilms are difficult to eliminate due to their greater tolerance to the host immune defense system,starvation,dehydration,and antibiotics.Compared with planktonic bacteria,biofilm bacteria are 10 to 1000 times more tolerant to various antibiotics.Surfaces of various materials are often effective hosts for disease-causing bacteria,and the colonization of material surfaces by bacteria caused by bacterial contamination and the subsequent formation of biofilms is one of the serious threats facing our healthcare system.Therefore,it is of great significance to develop new antibacterial materials with the ability to prevent biofilm formation and remove mature biofilm to solve the problem of bacterial infection.In this work,quaternary ammonium salt with broad bactericidal properties was used as bactericidal block and fluoropolymer with low surface energy was used as antiadhesion block to resist bacterial adhesion.A series of block copolymers containing fluoride were synthesized and a copolymer coating with both antibacterial and antifouling properties was constructed.In order to improve the water solubility and adhesion of the fluorine-containing block copolymer to the substrate,dopamine groups were introduced into the molecular chain.The obtained fluorine-containing triblock copolymer micelles can effectively remove mature biofilms,and the coating has anti-bacterial contamination and bactericidal properties.The details are as follows:1.Preparation and antibacterial properties of QPDMAEMA-PDFHMA（1）PreparationofQPDMAEMA-PDFHMAdiblockcopolymer:poly（2-（dimethylamino）ethyl methacrylate）-poly（dodecafluoroheptyl methacrylate）（PDMAEMA-PDFHMA）block copolymers were synthesized by RAFT polymerization using a reversible addition-break chain transfer（RAFT）reagent S-dodecyl-S′-（a,a′-dimethyl-a″-acetic acid）trithiocarbonate.The synthesized block copolymer was quaternized with 1-bromooctane to obtain QPDMAEMA-PDFHMA,diblock copolymers with different fluorine chain segment lengths（PDMAEMA₈-PDFHMA_n）were prepared by adjusting the monomer ratio,and quaternized.FTIR and NMR results showed that QPDMAEMA₈-PDFHMA_n with different chain lengths was successfully prepared.（2）Construction of QPDMAEMA₈-PDFHMA_n diblock copolymer coating and its anti-adhesion and bactericidal properties:the fluorine copolymer coating was constructed by drip coating.The anti-bacterial adhesion of copolymer coatings with different length of fluorine chain segments was tested.The experimental results showed that when the degree of polymerization of fluorine chain segments n=7,14,there was no bacterial adhesion on the surface of the paving plate.From the anti-bacterial experiment,it can be obtained that:compared with the original silicon wafer,when the polymerization degree of fluorine block n=3,7,there was almost no bacterial growth on the surface of the paving plate.When the polymerization degree of fluorine block n=14,some bacteria grew on the surface of the paving plate.The results of SEM and CLSM were consistent with the above results,that is,when the block ratio of QDMAEMA to PDFHMA was 8:7,the coating had the best antifouling and antibacterial effects.2.Preparation and antibacterial properties of QPDMAEMA-PDA-PDFHMA（1）Preparation of triblock copolymer:In order to improve the adhesion between the fluorine-containing block copolymer coating and the substrate,dopamine block was introduced on the basis of fluorine diblock copolymer to enhance the adhesion force of the coating.Copolymers of poly（2-（dimethylamino）ethyl methacrylate）-Poly（N-3,4-dihydroxyphenyl methacrylamide）-poly（dodecafluoroheptyl methacrylate）（PDMAEMA-PDA-PDFHMA）were synthesized by RAFT polymerization.The block copolymer was then quaternized with1-bromooctane to obtain QPDMAEMA-PDA-PDFHMA.The quaternary ammonium triblock copolymer QPDMAEMA-PDA-PDFHMA was successfully synthesized by FTIR,NMR and XPS elemental analysis.The copolymer can be dispersed into water to form a micellar solution.（2）QPDMAEMA-PDA-PDFHMA biofilm removal performance research:The QPDMAEMA-PDA-PDFHMA Triblock copolymer micelles could effectively remove mature Gram-positive bacterial biofilms by crystal violet staining experiment,agar plate colony counting assay,SEM and CLSM.（3）Study on the construction of QPDMAEMA-PDA-PDFHMA coating and its anti-adhesion and bactericidal properties:The anti-bacterial adhesion and bactericidal properties of QPDMAEMA-PDA-PDFHMA coating were determined by agar plate colony counting assay,SEM and CLSM.The results showed that QPDMAEMA-PDA-PDFHMA had excellent anti-adhesion and antibacterial properties.In part,this is due to the broad spectrum bactericidal properties of quaternary ammonium salts,which effectively kill bacteria attached to the coating surface.On the other hand,hydrophobic fluorine chains with low surface energy can promote the rapid release of bacteria from the coating surface.（4）Substrate adhesion properties of QPDMAEMA-PDA-PDFHMA coating:Adhesive force between coating and substrate was tested by tape stripping experiment.The experimental results show that,compared with the diblock fluorine-containing copolymer coating,the introduction of dopamine increases the adhesion of the coating to the substrate,and the contact Angle of the surface of QPDMAEMA₇-PDA₄-PDFHMA₇ is only slightly reduced after the tape has been spalling for 100 times,which still ensures its hydrophobicity,indicating that the coating has good adhesion to the substrate.This study provides a new method for the preparation of polymer antibacterial materials with super antibacterial and antifouling properties,which has potential applications in medical devices and public utilities.