Synthesis and antibacterial activities of quaternary ammonium salts with different alkyl chain lengths grafted on polyvinyl alcohol-formaldehyde sponges

Antibacterial polyvinyl alcohol-formaldehyde (PVF) sponges containing quaternary ammonium salts (QA) with different alkyl chain lengths are obtained through the grafting reaction of QA onto the PVF network under alkaline conditions. The grafting percentages of obtained PVF-g-QA sponges are in the range of 1.1–1.6%. As-prepared PVF-g-QA sponges show average pore sizes ranging from 60 μm to 90 μm with high porosity and interconnected pore structure. PVF-g-QA sponges with different alkyl chain lengths display the absorption capacity (Qs) of 13.3–14.2 g·g−1 in deionized water, 13.9–14.8 g·g−1 in saline solution, and 13.9–14.8 g·g−1 in artificial blood and can attain absorption equilibrium within 1 min. Notably, the PVF-g-QA sponges demonstrate excellent antibacterial effects on both S. aureus and E. coli bacteria strains. With high initial inoculum concentration (1 × 108 CFU/mL), with increasing the alkyl chain length of QA, the antibacterial activities of PVF-g-QA sponges against E. coli increase from 20.47% to 99.98% firstly and then decrease to 92.91%, the antibacterial activities against S. aureus increase from 16.67% to 99.96% and then decrease to 93.21%. None of the samples have cytotoxicity for cells. The as-prepared PVF-g-QA sponges with remarkable absorption capacity and excellent antibacterial performance can be considered as a new kind of antibacterial functional material.