Preparation And Studies On Antibacterial Property Of Grafting Cationic Polymer Of Quaternary Pyridine Salt-Type On SiO₂

The copolymer of acrylamide and 4-vinyl pyridine was synthesized. Then it wasquaternarized by using sulphate of dimethyl, and two series of cationic polyacrylamide ofquaternary pyridine salt-type(Quaternary P(4VP -co-AM), QPVA) has been synthesized,which have different cationic degree and molecular weight respectively. This paperinvestigated mainly the antibacterial property of QPVA using Escherichia Coli asdisease-leading bacterium, examined influence of various factors on the antibacterial property,such as cationic degree, molecular weight and pH value with the method of plate countinglive bacterium, and studied the antibacterial mechanism of QPVA by using the method ofmeasuring the activity of β-D-galactosidase and TTC-DHE. Then micrometer-sized silica gelwas modified chemically by using γ-methacryloxypropyl trimethoxysilane (MPTMS) ascoupling agent, and double bond was introduced onto silica gel particle surface. Afterwardsboth solution polymerization method and dispersion polymerization method were adopted,grafting polymerization of polystyrene on silica surface was performed, and the effect ofpolymerization method on grafting degree was examined mainly. Finally micrometer-sizedsilica gel , used as the carrier of insoluble antibacterial material ,was modified chemically byγ-methacryloxypropyl trimethoxysilane (MPTMS) ,and double bond was introduced ontosilica gel particle surface. With the dispersion polymerization method, graftingcopolymerization of 4-vinyl pyridine and acrylamide on silica surface was performed. Thenthe copolymer on silica surface was quaternarized by using benzyl chloride and sulphate ofdimethyl, and a series of grafting cationic polyacrylamide of quaternary pyridine salt-type onsilica surface (Quaternary P(4VP -co-AM)/SiO2, QPVA/SiO2) has been synthesized, whichhave different grafting degree. This paper investigated mainly the antibacterial property ofQPVA/SiO2 using Escherichia Coli as disease-leading bacterium, examined influence ofvarious factors on the antibacterial property, such as grafting degree and the quaternarizedmethods with the method of plate counting live bacterium, and studied the antibacterialmechanism of QPVA/SiO2 by using the method of measuring the activity ofβ-D-galactosidase and TTC-DHE. The experimental results are as follows:(1)cationicpolyacrylamide of quaternary pyridine salt-type possesses excellent antibacterial property.The higher cationic degree of QPVA is, the stronger antibacterial property is. In certain rangeof molecular weight, the higher molecular weight of QPVA, the better antibacterial effect is.The isoelectric point of E.Coli protein is probably pH=4.4.The greater pH value is, the betterantibacterial effect of QPVA is as pH>4.4, and antibacterial ratio remain nearly constant aspH>5.3. Whereas as pH<4.4, the apparent antibacterial ratio increases with the decrease ofpH value, and the phenomenonis probably resulted in by the cooperation of effect of QPVAand action of H+ ions on microbe. The antibacterial effect of QPVA is based on sterilizationaction certainly and is not only a restraining action;(2)the percentage of the graftingpolymerization reaction, which occurs on the interface between silica particle and solutionand is a king of heterogenetic reaction, depends on the amount of the double bondimmobilized on the silica particle surface, and under certain condition, the greater the amountof the double bond on the silica particle surface, the higher the grafting degree. Comparedwith solution polymerization method, dispersion polymerization method has higher graftingpolymerization rate and grafting degree, and the grafting degree can get up to 47% because ofsmaller kinetic barrier than solution polymerization. Except polymerization method, there stillare other factors, such as the concentration of monomer, used amount of initiator, temperatureand so on. For dispersion polymerization system, the property of solvent, the property ofdispersant and its used amount also influence the grafting degree;(3)QPVA/SiO2 possessesexcellent antibacte-rial property, and that the higher grafting degree of QPVA/SiO2 is, thestronger antibacterial property is;The antibacterial effect of QPVA/SiO2 is similar to that ofQPVA. Insoluble macromolecular antibacterial has more higher antibacterial activity relativeto smaller molecular antibacterial owing to higher density of antibacterial groups onmolecular chain;Furthermore, this insoluble antibacterial material protects the water frombeing polluted again due to macromolecular antibacterial immobilized on the insolublecarriers.