Syntheses of novel water-soluble antimicrobial polymers and their application in papermaking

To render cellulose products with long-term antimicrobial effectiveness, three approaches were developed, including host-guest systems of antibiotics and cationic β-cyclodextrin polymers (CPβCDs), modification of starch and cellulose fibers with guanidine polymers (PHGH). The preparation and characterization of these cationic anti-microbial polymers were systematically investigated in this thesis.;PHGH was obtained via the condensation polymerization of hexamethylene diamine with guanidine hydrochloride; and further used to the anti-microbial modification of starches and cellulose fibers via in-situ copolymerization or coupling reaction. Under the optimal conditions, the graft efficiency could reach as high as 90.2% and 50% for the modified starch and cellulose fibers, respectively. The adsorption of PHGH modified starches on cellulose fibers was investigated along with the systematic studies on various influencing factors including temperature, pH, ionic strength and charge density of the starches. Due the comb molecular structure, the adsorption capacity of the novel cationic starch reached 124.3 mg/g, which was much higher than those reported previously.;Anti-microbial activities of the novel cationic polymers and their application in papermaking were investigated. The paper sheets treated with those polymers exhibited excellent anti-microbial activity against both Gram positive ( S. aureus) and Gram negative (E. coli and Salmonella) bacteria. In the presence of 0.5%wt triclosan, butylparaben or PHGH in wood fibers, the growth inhibition reached over 99%. AFM analysis revealed that pathogen deactivation mechanism of PHGH was to destroy the membrane of the cells. Anti-microbial results also indicated that the shaking flask method was more suitable for non-released anti-microbial agents such PHGH modified starch and cellulose fibers. The techniques developed in this work provided safety and long-term efficiency solutions to the antimicrobial modification of various cellulose products.;By forming inclusion with CPβCDs, the water solubility of triclosan or butylparaben was significantly improved. The spectra of FT-IR and 1H NMR confirmed that the antibiotics could be included inside of the lipophilic cavities of CPβCDs. Due to the targeting effect after the inclusion with CPβCDs, the antimicrobial activity of butylparaben can be significantly improved, though the similar improvement was not obvious for triclosan.