Protective Multifunctional Fibrous Systems Based on Natural Fibers and Metal Oxide Nanoparticles

Abstract

In recent years, an unprecedented increase in the development of products and technologies to protect the human being has been observed. Now, more than ever, the world population is exposed to several threats, harmful to their well-being and health. Chemical and biological hazardous agents stand out as one of the biggest threats, not only for the military forces, but also for the civilians. Consequently, it's essential to develop personal protective systems that are able to protect their user, not only passively, but actively, being able to detect, adsorb, degrade and decontaminate pesticides, pollutants, microorganisms and most importantly: chemical/biological warfare agents. One recent strategy for the development of active fibrous structures with improved functions and new properties is their functionalization with nanoparticles (NPs), especially metal oxides. Although their known effectiveness in the decomposition of harmful agents, the NPs could also include other functionalities in the same structure using low quantities of material, without adding extra weight, which is of huge importance for a soldier in the battlefield. The use of natural fibers as the substrate is also very interesting, since this material is a much sustainable alternative when compared to synthetic ones, also providing excellent properties.

Keywords: BWAs; CWAs; advanced protection; metal oxide nanoparticles; multifunctional fibrous structures; natural fibers.

Figure 1

Molecular structures of the most cited CWAs in literature, VX, GD e HD.

Figure 2

Classification of CWAs depending on their target and the severity of the damage.

Figure 3

The possible mechanisms of antimicrobial activities exhibited by photocatalytic semiconductors in the right side of the figure and in the left side, the activation of the photocatalytic semiconductor by visible light. Created with BioRender.com.

Figure 4

FESEM images of flax fabric functionalized with both Ag and ZnO NPs (a). Gauge Factor (GF) values for the flax fabrics functionalized with different ZnO NPs concentrations (b). WCA measurements of the flax fabrics functionalized with Ag and ZnO NPs (c) [79].

Figure 5

Digital photo and FESEM images of the jute fabrics functionalized with CaO and CaO-SiO₂ NPs and WCA values. Used with permission from [13].

Figure 6

SEM images of: (a,b) linen fabric after alkaline treatment and dip-coating with 5% wt. of CuO-SiO₂, (c,d) linen fabric after enzymatic treatment with 2.5 U/g of laccase and dip-coating with 5% wt. of CuO-SiO₂, (e,f) linen fabric after enzymatic treatment with 5.0 U/g of laccase and dip-coating with 5% wt. of CuO-SiO₂ [11].

Figure 7

Jute fabric impregnated with Ag⁰-PEG suspension (a). Jute fabric with Ag⁰-PEG NPs (b). Dependence of the resistivity values on AgNO₃ concentration (c) FESEM images of jute fabrics functionalized with Ag NPs (d) [85].

Figure 8

Average GF values (a) and relation between electrical conductivity and GF (b). WCA values obtained for the flax sample and the flax samples functionalized with the polymeric formulation with different concentrations of GNPs (c) [111].

Figure 9

FESEM images of PCL microfibers with GNPs (a). Piezoresistive response of GNPs-PCL membrane (b). Electrical conductivity and GF in relation to the GNPs concentration of GNPs-PCL membrane (c) [115].

Figure 10

FESEM images of the chitosan, poly(ethylene) oxide, cellulose nanocrystals nanofibers incorporated with acacia extract (a). Diameter distribution histogram (b). Used with permission from [116].