Abstract:

Objective Fabrics offer a growth environment for pathogenic microorganisms, which bring health risks to humans and affect the use of fabrics. It is an important demand to develop antibacterial fabrics that are harmful to different pathogenic microorganisms but benign to humans. Metal-based nanoparticles including ZnO nanoparticles are one of the most widely used antibacterial agents in the field due to their efficient and broad-spectrum antimicrobial activities in attacking bacteria and fungi. However, they often do not strongly bond with the fabric, causing the material to show poor laundering durability and suffer low stability in performance.
Method Aiming for achieving efficient and durable antibacterial fabrics via a facile and applicable approach, a kind of one-pot hydrothermal reaction containing catechol, hexamethylenetetramine, and ZnCl₂ was performed, by which a kind of coatings composed of ZnO nanoparticles/catechol-formaldehyde resins (ZnO/CFR) were in-situ constructed on surfaces of both cellulosic and polyamide fabrics, and thus a series of mussel-inspired durable antimicrobial cotton, polyamide, and polyamide/cotton fabrics were obtained. In the system, catechol moieties of the resin are the origin of the superior adhesion capacity of the coating, contributing to the strong interfacial bonding with the material via covalent bonds and noncovalent interactions. Micro morphologies and chemical compositions of the fabric were studied by using scanning electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry, and the antimicrobial activities,laundering durability,tensile strength,hand feel,mammalian cell viability and formaldehyde content of the fabric were tested and analyzed,respectively.
Results It was found that all the coated fabrics turned yellow and some particles appeared randomly on surfaces of the fabrics (Fig. 1). ZnO/CFR coated samples presented Zn2p spectra with a double band corresponding to Zn2p_1/2 and Zn3p_3/2, having two peaks at 1 045.1 and 1 022.2 eV (Fig. 2). After the zone of inhibition determination test, no microbial colony grows in the area in contact with the fabric and no inhibition zone appears around the edge of the sample (Fig. 3). All the agar plates corresponding to ZnO/CFR coated fabrics before and after washing presented no or very few microbial colonies, while all the agar plates corresponding to uncoated fabrics had some microbial growth of microbial colonies (Fig. 4). ZnO/CFR coated sample kept a relatively high content of zinc and exhibited a very high bacteriostasis and fungistasis rate of 99.99% even after 50 accelerated laundering cycles (Fig. 5). ZnO/CFR coated fabrics showed no or very few decreases in weft and warp directional tensile strength compared with uncoated ones (Fig. 6), and achieved softness, resilience, and smoothness scores nearly equivalent to those of the untreated samples (Fig. 7). ZnO/CFR coated fabrics exhibited a little decrease in the relative cell viability value compared to the control sample, while no formaldehyde was detected in the fabric using a test with a detection limit of 20 mg/kg (Tab. 1).
Conclusion ZnO nanoparticles were anchored onto surfaces of cotton, polyamide, and polyamide/cotton fabrics by catechol-formaldehyde resins, where the morphology and distribution of the nanoparticles were different on the surface of cellulosic and polyamide fibers. ZnO/CFR coated fabrics presented an antimicrobial activity with non-dissolution behaviors to Gram-positive bacteria, Gram-negative bacteria, and fungi. ZnO/CFR coated fabrics had high laundering durability and showed high inhibiting activities to bacteria and fungi even after 50 times accelerated laundering cycles. ZnO/CFR coatings did not deteriorate the wearing comfort of the fabric and nor the human health.

Key words: cotton fabric, polyamide fabric, polyamide/cotton fabric, antimicrobial fabric, ZnO nanoparticle, catechol, laundering durability, hydrothermal reaction