Investigation Of Dialkyl Quaternary Ammonium Salt In Nano Cationic Emulsion And Antibacterial Properties

Cationic polymer emulsion is of incomparable capacities to neither anionic polymer emulsion nor nonionic polymer emulsion due to its well balance to positive and negative charge. Thus it was widely used in coatings, adhesives, flocculation agent, antistatic agent, finishing agent of paper, and has great vitality and potential applications in a variety of fields, such as medicine, biology, environmental protection. Therefore, it is of great practical significance to develop new process on the synthesis and application of cationic polymer emulsion. In addition, with the improvement of social development and people’s living standard, the consciousness to health and environmental protection were enhanced, the development of the antibacterial material is unstoppable. So preparation of cationic polymer emulsion with antibacterial properties is very meaningful.On basis of large number of literature, the preparation of cationic polymer emulsion and development of antibacterial material were reviewed. Then the dialkyl quaternary ammonium salt cationic surfactants which were well antibacterial were chosen as emulsifier to prepare cationic nano poly sty rene(PSt) emulsion and nano styrene-butyl acrylate(PSt/BA) copolymer emulsion. The emulsion properties and antibacterial properties were also studied. It provided a valuable data for application of dialkyl quaternary ammonium salt surfactants in preparing cationic nano emulsions with good stability and antibacterial property. The main contents of this dissertation consist of the following points.The cationic gemini surfmer dibromo-bis(dimethyl propyl methylacrylamide) ammonium adipate (G6) was synthesized and characterized by1H-NMR and FTIR.The critical micelle concentrations(CMCs) of dimethyldioctylammonium chloride(D821), didecyldimethylammonium chloride(D1021), didodecyldimethylammonium chloride(D1221), dioctadecyldimethylammonium chloride(D1821) and G6were determined by electrical conductivity and surface tension methods. The results indicated that the CMC of dialkyl quaternary ammonium salt surfactants were decreased with the increase of alkyl chain. The CMC values of cationic gemini surfmer G6is smaller than D1021which with relatively the same carbon atom number. The interaction parameter βM of binary system D821/CTAB and the G6/CTAB is less than zero. The cationic nano polystyrene(PSt) emulsion and nano styrene-butyl acrylate(PSt/BA) copolymer emulsion were prepared using dialkyl quaternary ammonium salts as emulsifier. The influence of polymerization factors on the properties of nano-emulsion was explored.Compared with emulsions prepared with unitary emulsifier such as D821, D1021or D1221, PSt emulsions prepared with binary emulsifiers like D821/CTAB, D821/G12-6-12or D821/OP-10displayed much higher polymerization stability and monomer conversion. The latex particles were small and the average particle diameter was about65nm. The particle size distribution was narrow. TEM results demonstrated that the latex particles were spheroidal and uniform. The polymerization stability, centrifugal stability and diluted stability were good. The emulsion properties were best using D821/CTAB as emulsifiers with the ratio at9:1.PSt/BA emulsion with D821/CTAB as emulsifier and G6as functional monomer displayed similar properties to PSt emulsion such as high polymerization stability and high monomer conversion and good stability. But the latex particles were smaller which average particle diameter was about55nm and the particle size distribution was narrower. The optimum conditions for synthesis of PSt/BA emulsion were polymerization temperature75℃, and AIBA dosage0.6%, D821/CTAB dosage of3.75%with mass ratio at4:1, G6dosage is1.5%, monomer dosage(St/BA=1:1) is30g respectively.PSt/BA emulsion is of good film-forming property. The thermal stability of latex films was good. With G6content increased, the thermal stability was changed little while the water resistance and solubility in organic solvent were decreased.The MIC, MBC and inhibitory zone tests of cationic surfactants, PSt/BA emulsions and latex films for E.coli and S.aureus were conducted. The results show that the antibacterial performances of D821, CTAB, D821/CTAB were all good. For the same emulsifier, the antibacterial property to S.aureus was better than E.coli. The antibacterial performance of D821/CTAB was best among the three kinds of emulsifiers, that is to say, synergistic effect existed in mixed emulsifiers on antibacterial. PSt/BA emulsions and the latex films were also with good antibacterial performance. The antibacterial property to S.aureus was also better than E.coli which was consistent with the antibacterial results of emulsifier.