Promoting antibacterial activity of polyurethane blend films by regulating surface-enrichment of SiO₂ bactericidal agent

Polyurethane (PU) blended with nano-bactericidal agents was one of the most ways to obtain PU with antimicrobial properties. However, the bactericidal agent nanoparticles cannot effectively enrich the PU surface to reduce their antimicrobial properties. In this study, nano-silica particles with a large number of polar quaternary ammonium salt (N,N-dimethyl-3-aminopropyl-12-alkyl-ammonium bromide trimethylsilyl, denoted as QAC) can easily enrich the PU surface to endow PU with excellent antibacterial properties after they were blended with PU film. The QAC on the surface of silica with different diameters (denoted as SiO2-Q-X) can endow silica with antimicrobial properties and improve the repulsion between silica and PU to enhance the enrichment on PU surface of silica. A series of SiO2-Q-X/PU blend films were prepared and applied to inhibit the growth of the bacterial colony. The SiO2-Q-X/PU films can inhibit the growth of Gram-negative Escherichia coli and Gram-positive Staphylococcus epidermidis. The SiO2-Q-X with more polar QAC was easily enriched on the surface of PU and had a better bactericidal effect than those of SiO2-Q-X with a minor polar QAC. Moreover, the aging of the SiO2-Q-X/PU films did not affect their antibacterial effect.