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. 2022 Jul 21;14(14):2952.
doi: 10.3390/polym14142952.

Single-Side Superhydrophobicity in Si3N4-Doped and SiO2-Treated Polypropylene Nonwoven Webs with Antibacterial Activity

Ming-Chao Han  1 , Shun-Zhong Cai  1 , Ji Wang  1 , Hong-Wei He  1   2
Affiliations

Single-Side Superhydrophobicity in Si3N4-Doped and SiO2-Treated Polypropylene Nonwoven Webs with Antibacterial Activity

Ming-Chao Han et al. Polymers (Basel). .

Abstract

Meltblown (MB) nonwovens as air filter materials have played an important role in protecting people from microbe infection in the COVID-19 pandemic. As the pandemic enters the third year in this current global event, it becomes more and more beneficial to develop more functional MB nonwovens with special surface selectivity as well as antibacterial activities. In this article, an antibacterial polypropylene MB nonwoven doped with nano silicon nitride (Si3N4), one of ceramic materials, was developed. With the introduction of Si3N4, both the average diameter of the fibers and the pore diameter and porosity of the nonwovens can be tailored. Moreover, the nonwovens having a single-side moisture transportation, which would be more comfortable in use for respirators or masks, was designed by imparting a hydrophobicity gradient through the single-side superhydrophobic finishing of reactive organic/inorganic silicon coprecipitation in situ. After a nano/micro structural SiO2 precipitation on one side of the fabric surfaces, the contact angles were up to 161.7° from 141.0° originally. The nonwovens were evaluated on antibacterial activity, the result of which indicated that they had a high antibacterial activity when the dosage of Si3N4 was 0.6 wt%. The bacteriostatic rate against E. coli and S. aureus was up to over 96%. Due to the nontoxicity and excellent antibacterial activity of Si3N4, this MB nonwovens are promising as a high-efficiency air filter material, particularly during the pandemic.

Keywords: PP meltblown nonwoven; antibacterial materials; filtration; silicon nitrile (Si3N4); superhydrophobicity.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Preparation of PP/Si3N4 pellets: (a) twin-extruder process diagram, (b) PP/Si3N4 masterbatch and other pellets.
Figure 2
Figure 2
An illustration of the melt-blown process.
Figure 3
Figure 3
SEM images and fiber diameter distributions of the as-produced nonwovens with different Si3N4 content: (a) 0.0%, (b) 0.6%, (c) 0.8% and (d) 1.0%.
Figure 4
Figure 4
(a) Preparation of finishing solution, (b) hydrophobic finishing of SiO2 precipitation on lower side of nonwovens, (c) after the finishing, SEM photograph of lower side of nonwovens. The CAs of as-prepared MB nonwovens: (d) the upper side and (e) the lower side prior to finishing; correspondingly, (f) the upper side and (g) the lower side after the finishing.
Figure 5
Figure 5
Thermal properties of PP with different Si3N4 contents: (a) heat flow curve (DSC), (b) melting temperature, (c) thermal decomposition curve and (d) decomposition temperature.
Figure 6
Figure 6
IR spectra of Si3N4 and PP with different Si3N4 contents.
Figure 7
Figure 7
Pore size and permeability of nonwovens with different Si3N4 content: (a) pore size distribution and (b) average pore size and permeability.
Figure 8
Figure 8
Filtration performance diagram of nonwoven materials with different Si3N4 content: (a) filtration efficiency and pressure drop; (b) quality factor.
See this image and copyright information in PMC

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