Bacteriostatic photocatalytic properties of cotton modified with TiO2 and TiO2/aminopropyltriethoxysilane

Abstract

A new route for the functionalization of cotton fibres with organic-inorganic hybrid materials is proposed using titanium tetraisopropoxide (TiP) and aminopropyltriethoxysilane (APTES). The antimicrobial and photocatalytic activities of the new cotton finishes based on titania and mixed titania/amino-silica hybrids were tested by monitoring the growth of Escherichia coli (ATCC 25922) on the surfaces of functionalized fabrics under exposure to UV radiation and in the dark. Transmission electron microscopy revealed the amorphous nature of the hybrids and confirmed their similarity to other bactericidal aminofunctionalized polymers. Attenuated total reflection infrared spectra showed the protonated amino groups of the APTES in the TiP/APTES hybrid and the presence of Si-O-Ti bonding within the sol-gel hybrids between silica and titania by analogy with previous transmission and ATR infrared studies. Several analytical techniques were employed to establish the presence of the TiP and TiP/APTES modified cotton fibres. ATR measurements proved to be a very useful tool to study also the silane/-C-OH interactions between the hybrid materials and the cotton fibres, revealing the presence of covalent (i.e., -Si-O-C-) bonding with the OH functional group of cellulose. The advantages of the cotton finishes were demonstrated by the measured photocatalytic bacteriostatic effect, which persisted even after 15 washings; in contrast, the aminofunctionalized polymeric finishes, only showed a sufficient bacteriostatic effect. Furthermore, the TiP finishes were photocatalytically active, while the TiP/APTES finishes were not. The ultraviolet protective factor, degree of polymerization of the finished cotton samples were also investigated and revealed the suitability of the proposed method.

In-Situ Functionalization of Cotton Fabric by TiO2: The Influence of Application Routes

“…Nevertheless, compared to samples 4S, 4H, and 4E, sample NP had 2.3, 2.9 and 2.0 higher Ti content, respectively, and thus a much thicker deposition, which also contributed to its excellent UV protective effect. Nonetheless, "good" to "very good" UV protection provided by the xS and xH samples functionalized according to the sol-gel pad-dry-cure and pad-hydrothermal application routes is in good agreement with results obtained by others [22,23,32,38]. Therefore, despite the low deposition and amorphous structure of TiO 2 , synthesized TiO 2 provided satisfactory UV protection, which exceeded our expectations considering that the TiO 2 synthesis was performed at a low temperature compared to the energy-consuming calcination process of commercial TiO 2 at high temperatures, which assures the formation of anatase TiO…”

“…When conducting a pad-dry-cure application route, the formation of amorphous TiO2 was also confirmed by other researchers [38]. In contrast, the absence of the characteristic anatase TiO2 peaks in the case of sample 4H was a surprise, since in a previous study [23], a few minutes of hydrothermal treatment caused the formation of crystalline TiO2. However, in this case, the XRD analysis was performed on a TiO2 powder synthesized in the same way as for the TiO2 in-situ functionalization of fabric.…”

“…In the functionalization of textiles, TiO 2 synthesis can be carried out using various precursors, the most common of which include titanium tetraisopropoxide [15,[18][19][20][21][22][23], titanium butoxide [24][25][26], titanium chloride [27][28][29], titanium oxysulfate hydrate [30], ammonium hexafluorotitanate [31], potassium titanium oxalate [32], and tetrabutyl titanate [33]. Both ex-situ and in-situ methods can be used for TiO 2 synthesis; however, in-situ synthesis has several advantages.…”

“…In addition, in-situ hydrothermal synthesis is also commonly used to produce TiO 2 and results in a coating with optimal thickness and the high adhesion of TiO 2 to the textile surface [18,20,25,27,32,33]. In addition to surface deposition, TiO 2 absorption inside the fibers has also been reported [23]. Moreover, the phase composition, TiO 2 particle size, and crystalline homogeneity of the coated cotton fabric can be more precisely controlled with the hydrothermal process.…”

Enhanced photocatalytic activity of wool fibers having titanium dioxide nanoparticles formed inside their cortex

“…Immobilization of a wide variety of catalysts [5] like metal complexes, metal oxides, metallic particles, enzymes, microbes and small organic molecules on various polymers including polyacrylonitrile [6], polyester [7], cotton [8][9][10], sackcloth [11], plastic [12], glass [13], active carbon [14] and wool fiber is a new technical route to achieve functionalized textile materials. For wool fibers, some of these catalysts (e.g., gold nanoparticles in different sizes) are chemically bonded both onto wool fiber surface and within the wool fiber matrix [15] via potential covalent disulfide bonds, electrovalent forces and salt linkages [16] because wool fibers could provide reactive hydroxyl, carboxyl, amide, and disulfide groups [17] to form cross-links between neighboring polypeptide chains [18] and these catalysts.…”