Silicone particles with polymeric grafts for VOC removal and bacterial killing on HEPA filters
Composite silicone elastomer micro-particles functionalized with polymer grafts that simultaneously capture volatile organic compounds and kill bacteria. Designed to retrofit existing HEPA filters, adding VOC absorption, antimicrobial contact-killing, and antifouling capabilities without replacing current filtration infrastructure.
Overview
Standard HEPA filters capture airborne particulates but cannot remove volatile organic compounds (VOCs) or inactivate pathogens that collect on the filter surface. This solution addresses both gaps with a single composite material: silicone elastomer micro-particles decorated with polymer grafts bearing quaternized and zwitterionic moieties. The silicone core acts as a sponge for VOC absorption, while the grafted polymer layers deliver contact-killing of bacteria and antifouling behavior to keep the filter surface clean.
Technical specifications
- Silicone elastomer core: Poly(vinyl methyl siloxane) (PVMS) particles formed by drop-casting a PVMS, tetraethoxysilane (TEOS), and tin-catalyst mixture into a stirred aqueous bath at 50 degrees C, producing soft, deformable particles.
- Polymer grafts: Poly(dimethylaminoethyl methacrylate) (PDMAEMA) chains grafted onto the particle surface, sequentially quaternized and betainized to introduce positively charged units and zwitterionic groups.
- VOC capture: Silicone elastomer absorbs VOCs such as benzene, toluene, hexanes, acetone, and alcohols from airstreams.
- Antimicrobial action: Quaternized units in the grafts kill bacteria on contact.
- Antifouling action: Zwitterionic groups resist non-specific bioadsorption and help remove bacterial debris, reducing particle contamination.
- Filter integration: Particles are delivered as a low-concentration mist onto HEPA filter surfaces, where they attach via hydrophobic interactions between PVMS and the filter and may mechanically interlock within the fiber mat.
Technology readiness level
The individual components have been validated separately. Silicone particles and sheets have demonstrated removal of benzene and toluene from aqueous solutions, with additional VOCs studied. PDMAEMA-based grafts with quaternized and zwitterionic units have shown effective killing of E. coli and removal of bacterial debris from surfaces. The combined dual-function material, however, has not yet been characterized. Next steps include fabricating the integrated composite particles, depositing them on HEPA filter media, and benchmarking VOC uptake, bacterial kill rates, and antifouling performance under realistic airflow conditions.
About North Carolina State University
North Carolina State University is a large, comprehensive public land‑grant research university in Raleigh. Its on‑campus research and technology park co‑locates corporate R&D groups, government partners, and faculty labs, enabling shared facilities, prototyping, and agile contracting. Located in North Carolina’s Research Triangle, partners tap a dense regional ecosystem while engaging through a statewide extension network and a mature co‑op program that deliver field deployment and workforce pipelines. Multiple pilot and demonstration facilities support scale‑up and validation toward pre‑commercial readiness. Research is supported by competitive funding from major federal agencies, including NSF, USDA, DOE, and DOD, and a dedicated technology transfer office with clear IP pathways helps accelerate commercialization.
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