An innovative nanofiber production method known as 'centrifugal multispinning' has been developed by scientists from the Korea Advanced Institute of Science and Technology (KAIST). The new method will pave the way for safe and economical mass production of high performance polymer nanofibers.
The latest method has exhibited up to 300 times higher nanofiber production rate for every hour compared to the traditional electrospinning method and could find several possible applications such as the development of face mask filters for coronavirus protection.
Nanofibers can be used to create ideal face mask filters since their mechanical interactions with aerosol particles give them a higher capability to trap over 90% of detrimental particles like fine dust and virus-containing droplets.
In recent years, the effect of the COVID-19 pandemic has additionally expedited the increasing demand for a better type of face mask. A polymer nanofiber-based mask filter that can more efficiently capture detrimental particles has been in greater demand as the pandemic tends to continue.
'Electrospinning' has been a general process to make fine and even polymer nanofibers, but with regard to cost-effectiveness, mass production, and safety, it has various disadvantages.
The electrospinning technique needs an electrically conductive target and a high voltage electric field, and this impedes the safe and economical mass production of polymer nanofibers.
As a response to this drawback, 'centrifugal spinning' that involves the use of centrifugal force rather than high voltage to generate polymer nanofibers has been proposed as a safer and more cost-effective substitute to electrospinning.
Simple scalability is one more advantage because this technology just needs a collector and a rotating spinneret.
But as the present centrifugal force-based spinning technology used just a single rotating spinneret, productivity is restricted and not much greater compared to a few advanced electrospinning technologies like 'multi-nozzle electrospinning' and 'nozzleless electrospinning.' This issue continues even when the size of the spinneret is scaled up.
Drawing inspiration from such drawbacks, a group of researchers under the guidance of Professor Do Hyun Kim from the Department of Chemical and Biomolecular Engineering at KAIST has designed a centrifugal multispinning spinneret with mass-producibility. They achieved this by partitioning a rotating spinneret into three sub-disks.
This research was published as a front cover article in the journal ACS Macro Letters, Volume 10, Issue 3 in March 2021.
Byeong Eun Kwak, the lead author of the paper and a PhD candidate, and his colleagues Hyo Jeong Yoo and Eungjun Lee used this new centrifugal multispinning spinneret with three sub-disks to illustrate the gram-scale synthesis of several polymer nanofibers with an optimum production rate of up to 25 g/hour, which is around 300 times higher compared to that of the traditional electrospinning system.
The production rate of up to 25 g/hour of polymer nanofibers matches with the production rate of around 30 face mask filters every day in a lab-scale manufacturing system.
The team was able to fabricate face masks with a filtration performance comparable to that of the KF94 and KF80 face masks available at present in the Korean market by combining the mass-produced polymer nanofibers in the form of a mask filter.
The KF94 and KF80 masks have obtained approval from the Ministry of Food and Drug Safety of Korea to remove at least 94% and 80% of detrimental particles respectively.
When our system is scaled up from the lab scale to an industrial scale, the large-scale production of centrifugal multispun polymer nanofibers will be made possible, and the cost of polymer nanofiber-based face mask filters will also be lowered dramatically.
Byeong Eun Kwak, Study Author and PhD Candidate, Korea Advanced Institute of Science and Technology
This study was financially supported by the KAIST-funded Global Singularity Research Program for 2020.
Kwak, B. E., et al. (2021) Large-Scale Centrifugal Multispinning Production of Polymer Micro- and Nanofibers for Mask Filter Application with a Potential of Cospinning Mixed Multicomponent Fibers. ACS Macro Letters. doi.org/10.1021/acsmacrolett.0c00829.