| Public security incidents caused by harmful bacteria and viruses occur frequently,how to effectively control and eliminate harmful bacteria and viruses,is still an important topic that closely related to human health and social stability.The antibacterial materials has developed rapidly in recent years,it has been widely used in daily necessities,textiles,medical,industrial,construction and other fields.Antibacterial agent is the key to the antimicrobial properties of antibacterial materials,Gemini quaternary ammonium salt antibacterial agent is a kind of highly effective antibacterial agent,however,the microbial drug resistance,which limits the development of Gemini quaternary ammonium antibacterial agent.Therefore,the synthesis of novel Gemini quaternary ammonium salt antibacterial agent to overcome these shortcomings is necessary.Meanwhile,Gemini quaternary ammonium salt antibacterial agents have a strong surface activity,that can be used as emulsifier of synthetic antimicrobial cationic polymer emulsion.Cationic polymer emulsion has small particle size,good emulsion stability,positive charged particles,it are widely used.Therefore the development of excellent antibacterial-containing cationic nano emulsion will bring more social benefits.There are two main traditional methods to prepare nano antibacterial polymer emulsion,one of them is blend,this method is simple,but will reduce the stability of polymer emulsion;another method is introduction functional monomer to polymer emulsion which with antibacterial groups,this method is difficult to polymerize,and have a high cost of synthesis.Therefore,to seek out simple,low cost method to preparation of cationic antimicrobial nano polymer emulsion is necessary.However,there is no literature clearly reported antibacterial mechanism of cationic nano polymer emulsion so far,figuring the antibacterial mechanism of polymer emulsion has a far-reaching guiding significance for the research and development of antibacterial emulsion.In this paper,we synthesized a series of Gemini quaternary ammonium surfactant with ester group in the spacer(Gm-4-m),and use them as emulsifiers,selected styrene(St)and butyl acrylate(BA)as main monomers,using conventional emulsion polymerization to synthesis cationic styrene-butyl acrylate polymer emulsions(P(St-BA)).Make key research on antibacterial activity of Gm-4-m surfactants and P(St-BA)emulsions,take a preliminary discussion on the antibacterial mechanism of cationic P(St-BA)emulsion.The main research contents are as follows:(1)Gemini surfactant Gm-4-m was synthesized by two steps,the structure of the surfactants are characterized by elemental analysis,IR and 1H NMR,The results showed that the products are the target products.The CMC values were determined by using conductivity method,results showed that as the hydrophobic chain length increases the CMC values reduced;The results shown that the Gm-4-m CMC values in the range of 1?1.7 mmol/L,moreover,CMC values decreased with the increase of the hydrophobic chain length and temperature.(2)Using Gm-4-m as emulsifier to synthesis of P(St-BA)emulsions,the latex particles particle size are less than 100 nm,the effect of different kinds of emulsifier on emulsion performance is not obvious,when the amount of emulsifier is 2%,the dosage of initiator is 0.70%,the polymerization temperature is 75?,synthetic polymer emulsion average particle size is about 65nm,at a minimum,particle size distribution is the most narrow at this time.In addition,the test results shown that the P(St-BA)emulsion has the following advantages:high stability,high monomer conversion,the storage stability,centrifugal stability,dilution stability of emulsion are better.TEM results shown that the morphology of latex particles are homogeneous spherical.(3)The results of antibacterial experiment shown that:Gm-4-m surfactants have strong inhibition and killing effect on E.coli and S.aureus,bactericidal concentrations are in the range of 2-256 ug/mL,the same antibacterial agent has a stronger antibacterial activity against S.aureus than E.coli,G10-4-10,G12-4-12,G14-4-14 MBC values against E.coli were higher than G16-4-16,G18-4-18,on the contrary,G10-4-10,G12-4-12,G14-4-14 MBC values against S.aureus were significantly lower than that of G16-4-16,G18-4-18.With the hydrophobic chain length increasing,antibacterial activity against S.aureus were increased,while against E.coli were reduced.Surfactants antibacterial activity against E.coli,the order is:G10-4-10= G12-4-12= G14-4-14>G16-4-16=G18-4-18;the order against S.Aureus is:G16-4-16= G18-4-18>G10-4-10= G12-4-12= G14-4-14.Cationic P(St-BA)emulsions antibacterial activities are stronger than the corresponding emulsifiers,results regular consistent.(4)The results of membrane sterilization rate assay as follows:polymer film sterilization rates against S.aureus up to 99.99%,higher than that of E.coli.(5)According to the TEM tracking test,preliminary concluded that the antibacterial mechanism of cationic polymer emulsion may be latex particles adsorbed on the surface of bacterias,damaged cell membrane,eventually lead to cell lysis to death. |
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