Preparation,Structure And Application Of Antimicrobial Polystyrene-Acrylate Emulsion

Polyhexamethyleneguanidine chloride (PHGH) is a kind of eco-friendly cationic oligomer with properties of high antimicrobial, nontoxic and broad-spectrum, and is widely applied in the fields of medicine, food, agricultural and industrial products. However, PHGH oligomers is difficult to maintain a long-term antimicrobial activity in the application, especially in antibacterial paper or packaging materials of cellulose fibres, due to its good water soluble and low molecular weight.In order to dealing with the leaching of PHGH from the surface of materials, improving the security and antibacterial durability, PHGH was reacted with GMA to obtain GPHGH with unsaturated double bonds at the terminal. The cationic styrene-acrylate copolymer emulsion was prepared by styrene (St), bulty acrylate (BA), bulty methacrylate (BMA) and GPHGH as co-monomers in a process of semi-continuous seed emulsion polymerization.The composition, particle size and distribution, morphology, structural and performance of the emulsion are characterized by particle size analyzer, fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). The influence of the ammount of initiator and emulsifier, the monomer ratio and reaction temperature on the emulsion properties were investigated. The antimicrobial activity of series of latexes against gram positive, gram negative bacterium and fungus were studied by using the method of broth dilution and bacteriostatic ring. Finally, the effect of emulsion on the cell proliferation of human liver cancer cell line (SMMC-7721), human urinary bladder carcinoma cells (T24) and skeletal muscle cells (HSKMC) were explored by MTT assay. The main conclusions of the study are given as follows:1. When the molar ratio of monomers St/BA/MBA/GPHGH was at 20/20/20/1, initiator amount as of 0.4-0.5%(wt%,based on the weigh of total monomer), emulsifier amount was 4%-6%(wt%), reaction temperature was at 70-80℃, the styrene-acrylate emulsion, which has uniform particle size, good stability and more than 80% of monomer conversion, was successfully synthesized.2. The results of FTIR showed that the functional cationic monomer GPHGH and St, BA and BMA participated in the polymerization reaction. TEM and particle size analysis showed the emulsion products had uniform structure, little size distribution and good dispersion. When the reaction temperature was at 80℃, the initiator amount was 0.5%(wt%), the emulsifier amount was 4% (wt%), and the molar ratio of St/BA/BMA/GPHGH was at 20:20:20:1, the average particle size of the latex particles was 115 nm, and the PDI was 0.230.3. The antimicrobial activity of series of latex against E. coli and S. aureus was studied by using the broth dilution method. The MIC values of E. coli and S. aureus were from 1 to 16 ppm, and the minimum values were low to 4 and 1 ppm, respectively. Meantime, the MBC values of E. coli and S. aureus were from 4 to 64 ppm, and the minimum values were low to 8 and 4 ppm, respectively. The experimental results demonstrated that the cationic styrene-acrylate copolymer emulsion has excellent antimicrobial activity against E. coli and S. aureus and the antimicrobial activity of the emulsion against E. coli is stronger than that of S. aureus.4. The MIC of C. albicans was 10 ppm, which showed that the cationic styrene-acrylate copolymer emulsion has excellent antimicrobial activity against fungus.5. The antimicrobial activity of emulsions of PA and PA-co-Gs was investigated by using bacteriostatic ring experiments method as well. The test results revealed that the pure polystyrene acrylic emulsion (PA) has no antibacterial effect, however, the new cationic copolymer emulsion (PA-co-Gs) has excellent and durable antimicrobial properties after the functional monomers GPHGH was introduced into the emulsion.6. Cell viability of SMMC-7721, T24 and HSKMC cells was assessed after the cells were treated with different concentrations of PA-co-Gs for 24h and 48h by MTT assay. The results displayed that the growth of cells was restricted obviously after the treatment of PA-co-Gs emulsion. The IC50 values of PA-co-Gs against SMMC-7721, T24 and HSKMC were 13.99±0.084, 14.97±0.028 and 16.19±0.026 ppm, respectively, after the cells were treated with PA-co-Gs for 24 h; and 5.34±0.095 ppm,10.32±0.031 ppm and 8.39±0.042 ppm, respectively, after the cells were treated for 48 h.