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.