What does this research mean for the field?

Layer-selective functionalization of polypropylene-based surgical masks and HEPA filters enhances filtration efficiency by approximately 12% and provides broad-spectrum antimicrobial protection. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

The research aims to enhance the antimicrobial properties of polypropylene-based filtration materials while maintaining efficient filtration.

February 26, 2026

Layer-Selective Polyelectrolyte Functionalization of Surgical Mask and HEPA Filters for Enhanced Filtration Efficiency and Broad-Spectrum Antimicrobial Protection

Key Points

The research aims to enhance the antimicrobial properties of polypropylene-based filtration materials while maintaining efficient filtration.
Developed a layer-selective antimicrobial functionalization approach for polypropylene fabrics.
Applied cationic imidazolium-based antimicrobial polymers via UV-initiated photopolymerization.
Conducted interfacial grafting of anionic poly(4-styrenesulfonate) onto melt-blown filter surfaces.
Performed morphological, chemical, and wettability analyses on the modified fabrics.
Tested filtration efficiency and antimicrobial efficacy using aerosol particles and microbial assays.
Achieved approximately 12% enhancement in overall filtration efficiency.
Improved performance observed particularly in submicron particle size regimes.
Demonstrated significant reductions in pathogen viability, with log reductions of 2.2–4.0 for IMHC and 1.2–4.6 for PSS.
Maintained structural integrity and breathability standards despite modest pressure drop increases.

Abstract

Polypropylene (PP) fabrics are widely used in personal protective equipment, including surgical masks, respirators, and High-Efficiency Particulate Air (HEPA) filters, due to their favorable mechanical properties and filtration performance. However, their intrinsic chemical inertness and lack of antimicrobial activity limit their ability to mitigate contact-based pathogen transmission and long-term surface contamination. In this study, a layer-selective antimicrobial functionalization strategy was developed for PP-based filtration media using permanent charge engineering while preserving filtration efficiency and breathability. Cationic imidazolium-based antimicrobial polymers were applied as conformal coatings on spunbond (SB) fabrics via rapid UV-initiated photopolymerization, whereas anionic poly(4-styrenesulfonate) (PSS) was selectively grafted onto the air-facing outermost surface of melt-blown (MB) filters through an interfacial grafting reaction. This surface-localized approach enabled antimicrobial functionality to be introduced without disrupting the pore structure or electret characteristics of the MB layer. Comprehensive morphological, chemical, and wettability analyses confirmed uniform and selective functionalization. Filtration testing using NaCl and DOP aerosols demonstrated up to approximately 12% enhancement in overall filtration efficiency, with particularly improved performance in the submicron and most penetrating particle size regimes, while the pressure drop increases were modest, tunable, and remained within relevant breathability standards. Antimicrobial evaluations showed that IMHC and PSS coatings achieved 2.2–4.0 log and 1.2–4.6 log reductions in pathogen viability within 10 min, respectively, with IMHC providing rapid contact-mediated bactericidal activity and PSS reducing microbial adhesion while enhancing viral capture and inactivation. Collectively, these results establish a charge- and wettability-gradient multilayer architecture that integrates antimicrobial functionality into mask and HEPA filter systems without compromising structural integrity or functional usability, offering a practical pathway for advanced respiratory protection technologies.

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