RCTFF x SFT Distinguished Lecture

Topic

Nanofiber Technology for Personal Protection Equipment

Abstract

Airborne transmission via aerosolized droplets is the major mode of transmission for many respiratory viruses including SARS-CoV-2 (COVID-19).  The global COVID-19 pandemic demonstrated the effectiveness of respiratory PPE (facemasks and respirators) as a tool for mitigating the spread of viral disease, but it also highlighted certain deficiencies with conventional meltblown polypropylene filter media, such as performance degradation in the presence of heat or humidity, limited shelf life and potentially large environmental footprint. To address these problems, Prof. Rutledge's team are motivated to develop alternative technologies that are more robust and can be scaled up quickly and reliably. Electrospinning is one such technology, suitable for manufacturing nonwoven filter media comprising submicron fibers (“nanofibers”) with controlled morphology from a wide selection of materials. Electrospun media have found applications in tissue engineering, green energy, high performance materials, catalysis and industrial filtration, to name a few. Previous experiments and modelling suggest that nanofiber media can have a much higher aerosol collection efficiency compared to microfibers for a comparable air resistance. Electrospun technology thus has the potential to open up new space for the design of filtering facepiece respirators (FFR) that satisfy international standards. Prof. Rutledge's team first discuss the design of electrospun polyacrylonitrile (PAN) aerosol filters for FFRs and propose a simple graphical method that facilitates the design process.  They also compare their experimental observations for a subset of materials to existing models for aerosol filtration and pressure drop and observe quantitative agreement that can be used to further guide the design of electrospun PPE.  They also consider issues related to the practical implementation of these materials into respirators and demonstrate the fabrication and testing of face masks that meet the N95 standard.  They then extend their process to the development of electrospun filtration media based on polycaprolactone (PCL), a commercially available, biodegradable polymer, and demonstrate that these materials can also show good filtration performance and meet the N95 standard.

Biography

Prof. Gregory C. Rutledge is the Lammot du Pont Professor of Chemical Engineering at the Massachusetts Institute of Technology (MIT). He served as Director of the Program in Polymer Science and Technology and Executive Officer in Chemical Engineering. He is a Fellow of the American Institute of Chemical Engineers, American Physical Society, and PMSE Division of the American Chemical Society. He received the AIChE Braskem Award for Excellence in Materials Engineering and Science, Fiber Society Founders Award, Morton Distinguished Visiting Professorship (University of Akron), and Thinker-in-Residence (Deakin University). His research entails the molecular engineering of soft matter, with over 250 publications on process-structureproperty relationships for polymers and the fabrication, properties and applications of nanofibers. Prof. Rutledge is editor for the Journal of Materials Science.