Polypropylene-Rendered Antiviral by Three-Dimensionally Surface-Grafted Poly(N-benzyl-4-vinylpyridinium bromide)

To inhibit viral infection, it is necessary for the surface of polypropylene (PP), a polymer of significant industrial relevance, to possess biocidal properties. However, due to its low surface energy, PP weakly interacts with other organic molecules. The biocidal effects of quaternary ammonium compounds (QACs) have inspired the development of nonwoven PP fibers with surface-bound quaternary ammonium (QA). Despite this advancement, there is limited knowledge regarding the durability of these coatings against scratching and abrasion. It is hypothesized that the durability could be improved if the thickness of the coating layer were controlled and increased. We herein functionalized PP with three-dimensionally surface-grafted poly(N-benzyl-4-vinylpyridinium bromide) (PBVP) by a simple and rapid method involving graft polymerization and benzylation and examined the influence of different factors on the antiviral effect of the resulting plastic by using a plaque assay. The thickness of the PBVP coating, surface roughness, and amount of QACs, which jointly determine biocidal activity, could be controlled by adjusting the duration and intensity of the ultraviolet irradiation used for grafting. The best-performing sample reduced the viral infection titer of an enveloped model virus (bacteriophage ϕ6) by approximately 5 orders of magnitude after 60 min of contact and retained its antiviral activity after surface polishing-simulated scratching and abrasion, which indicated the localization of QACs across the coating interior. Our method may expand the scope of application to resin plates as well as fibers of PP. Given that the developed approach is not limited to PP and may be applied to other low-surface-energy olefinic polymers such as polyethylene and polybutene, our work paves the way for the fabrication of a wide range of biocidal surfaces for use in diverse environments, helping to prevent viral infection.