Synthesis,Characterization And Antimicrobial Activies Of Amphiphilic Polydimethylsiloxane Graft Quaternary Ammonium Salts

The breeding of many bacteria and fungi brings a lot of inconvenience to human's production and daily life.Some pathogenic microbials can even endanger human's health and live.Macromolecular quaternary ammonium salts are reported to have good inhibitory abilities on bacteria and fungi,with good chemical stabilitiy,relatively low residual toxicity and long-lasting antibacterial effect.However,most of the quaternary ammonium salts tend to be difficult to adhere to hydrophobic surfaces like skin surface,owing to their highly solubility in water.As a result,their antimicrobial abilities can hardly function on hydrophobic surfaces that are susceptible to contaminations.Based on our previous research,this paper introduces the hydrophobic PDMS-blocks to the chain end of benzyl ammonium chloride grafted PDMS(refered as: PDMS-g-BC)and a series of different grafting ratio of benzyl ammonium chloride groups polysiloxane block copolymers with certain hydrophobic blocks(referred as: quaternary ammonium polysiloxane grafted polysiloxane block copolymer,PDMS-b-(PDMS-g-BC)-b-PDMS,J series)are prepared,and their amphiphilicity,antimicrobial activities as well as skin penetration properties were studied.The main contents are as follows:1.A "three stage method" is adopted to synthesize a series of PDMS-b-(PDMS-g-BC)-b-PDMS(named “J series”)with different grafting ratios and hydrophilic length : the first stage: a series of primary amine grafted polysiloxanes [(NH2)2-PDMS-g-DMAA] of designed molecular weight,narrow polydistribution and the ratio of grafting are prepared via ring-opening copolymerization and hydrosilylation reaction.The second stage: by anionic ring-opening polymerization,hydrosilylation and ester-hydrolysis reaction,single carboxyl terminated polysiloxanes(PDMS-COOH)with controllable molecular weight and narrow distribution are synthesized.The third stage: J series products are obtained through the acylation reaction and quaternization reaction.During the synthesis process,the reaction conditions are optimized by comparing the different synthesis conditions and their yields.2.The performance of J series products are characterized.The results show that the J series products have the characteristics of cationic surfactants and can form micelles in water.Their critical micelle concentrations are relatively low.Their amphiphlic characters are confirmed and their effective adhesion is found to be able to alter the hydrophilicity or hydrophobicity of original surfaces.J series products show moderate abilities to inhibit the growth of Escherichia coli,Staphylococcua Albus and other bacterial.Increasing the grafting ratio of quaternary ammonium salts groups affords better inhibitory effects.The ability to inhibit the growth of Monilia albican shows dependence with not only the grafting ratio of quaternary ammonium salts groups,but also the molecular weights.The lower molecular weight products shows better antibacterial effects.Moreover,the penetration of J series compounds through rat skin is not found while small molecular quaternary ammonium compounds show large amounts of penetration.The bacteriostatic and transdermal properties provide a good basis for its application in the field of inhibition on skin surfaces.