Particulate matter (PM) pollution poses a significant
risk to public
health, as it can carry pathogens such as bacteria and viruses into
the body through the respiratory tract, leading to a variety of illnesses.
Electrospun nanofibrous membranes (ENMs) exhibit substantial promise
for air filtration applications. However, most nanofibrous membranes
have a trade-off between filtration efficiency and pressure drop.
The bead-on-string structured membranes are characterized by their
ability to achieve a higher efficiency and lower pressure drop. Here,
we prepared a bead-on-string-like structure of ENM with fluxible poly(p-phenylene terephthalamide) (f-PPTA) and
silver nanoparticles (Ag NPs) on a polypropylene (PP) nonwoven fabric
substrate. The two layers of membranes enable graded filtration and
reduce the pressure drop. The f-PPTA plays a role
in controlling both the diameter and roughness of nanofibrous membranes,
and its grafted quaternary ammonium salts impart antimicrobial properties
to the membrane. Ag NPs serve as a skeleton and form a bead-on-string-like
structure with f-PPTA/PA6 nanofibers. In conclusion,
this membrane achieves a 99.39% efficiency for PM0.3, a
low-pressure drop of 21 Pa, and a quality factor (QF) value of 0.24
Pa–1 and exhibits antibacterial properties against
both E. coli and S.
aureus. This study indicates that the nanofiber structure
can be transformed into a bead-on-string-like structure with low-pressure
drop by reasonable matching of the size of nanoparticles and nanofibers,
and the combined action of f-PPTA and Ag NPs can
effectively improve the antibacterial effect of nanofiber membranes,
which is of significant importance for the research on high-efficiency
particulate air (HEPA) filter.