Synthesis And Application Of Menthol-based Antibacterial Polymer

Bacterial infections have been a serious threat to human survival,and the bacterial resistance has greatly reduced the effectiveness of antibiotics.There is an urgent need to develop antibacterial materials with antibacterial mechanisms different from those of antibiotics.Menthol is an active substance derived from natural mint,with a special chiral structure and a certain antibacterial activity.However,its application is greatly limited due to its hydrophobicity and volatile properties.In this paper,menthol-containing antibacterial polymers were prepared by atom transfer radical polymerization(ATRP)with menthol ATRP initiator.The hydrophilic polymer poly(dimethylaminoethyl methacrylate)(PDMAEMA)was introduced into the hydrophobic menthol molecule.The PDMAEMA block not only improved the water solubility of menthol,but also enhanced its antibacterial properties,achieving synergistic antibacterial properties.In addition,the monomer poly(ethylene glycol)methacrylate(PEGMA)was introduced into the polymer,which could form hydrogen bonds with polyvinyl alcohol(PVA)to prepare a non-leaching PVA antibacterial material.The main research contents and results are as follows:(1)The menthol ATRP initiator Menthol-Br(M-Br)was prepared by acylation reaction,and the DMAEMA monomer was polymerized to prepare the menthol-containing antibacterial polymer Menthol-PDMAEMA(MD).By changing the ratio of initiator and monomer,a series of MDs with different degrees of polymerization were prepared.The structure,molecular weight and molecular weight distribution of the polymer were characterized by ~1H NMR and Gel Permeation Chromatography.(2)The antibacterial and bactericidal activities of MD with different molecular weights were characterized by the minimum inhibitory concentration,minimum bactericidal concentration,bacterial growth curve and time-killing assay,and the bactericidal kinetics of MD was studied.It was found that in the same series of polymers,the lower the molecular weight of MD,the better the bacteriostatic and bactericidal effects,and better than that of menthol and PDMAEMA homopolymer of the same molecular weight.The minimum inhibition concentration of MD1 was 62.5μg/m L against E.coli and 125μg/m L against S.aureus.The morphology of live/dead bacteria were characterized by transmission electron microscopy.Combined with the antibacterial results,a synergistic antibacterial mechanism combining membrane rupture damage and electric charge was proposed.(3)PEGMA monomer was introduced into MD to obtain the polymer MBP.The hemolysis experiment showed that it has good biocompatibility.PVA/MD and PVA/MBP composite membranes were prepared by solution blending of PVA with MD and MBP polymers respectively.The antibacterial properties and antibacterial modes of the two composite membranes were characterized by inhibition zone and bactericidal contact methods.PVA/MD mainly achieved sterilization through the leach of MD polymer.Due to the hydrogen bond cross-linking effect of PEGMA and PVA,sterilization of PVA/MBP is mainly achieved by contact.PVA/MBP composite membranes have great potential in the field of wound dressing.