Cellulose fibers modified with nano-sized antimicrobial polymer latex for pathogen deactivation

• Unique nano-sized latex with core–shell structure and excellent antimicrobial activities was prepared.
• Cellulose fibers modified by the latex are highly effective in pathogen deactivation.
• Electrostatic association enabled latex to adsorb on fiber surfaces strongly and form monolayer.
• Mechanical properties of the paper consisting of modified fibers were also enhanced.
• Resulting paper is promising as value-added antibacterial packaging and hygiene products.

Antimicrobial cellulose fibers and paper products are of great importance for various applications. In this work, novel core–shell antimicrobial latexes based on hydrophobic acrylate monomers and antimicrobial macromonomer (GPHGH) were successfully prepared via a seeded semi-continuous emulsion copolymerization in the presence of a cationic surfactant. The surface properties as well as size of latex were tailored by varying the amount of GPHGH incorporated during the copolymerization. The resulting cationic nano-sized latexes showed the strong adsorption and formed monolayer on the surfaces of bleached sulfite fibers, thus rendering the cellulose fibers antimicrobial. An excellent antimicrobial activity (>99.99% inhibition) of modified fiber toward Escherichia coli was achieved at 0.3 wt% of latex dosage (on dry fibers). Results of transmission electron microscopy (TEM) observation confirmed that the particles obtained indeed possessed a desired core–shell structure. The latexes themselves exhibited high antimicrobial activities against E. coli with the minimum inhibitory concentration (MIC) as low as 6.25 ppm (similar to that of pure guanidine-based polymer). Moreover, the mechanical strength of the hand-sheets made from latex-modified cellulose fibers was also improved due to the filming of the latex on fiber surfaces.