The overall goal of this procedure is to modify fabrics with catalytically active sorbent materials, offering the potential for development of garments providing chemical protection in a daily wear format. This method can be applied to different fabrics and in combination with a wide range of organosilicate sorbents to address the broad needs of chemical protective applications. The main advantage of this technique is that the treatment is conformal to the fibers of the fabric, providing chemical protection without compromising breathability.
First, prepare the initiation solution by combining 10 millimeters of ammonium hydroxide with 184 milliliters of isopropanol in a glass beaker and mixing at 150 rpm. Then, add six milliliters of tetraethylorthosilicate to the ammonium hydroxide solution. To initiate the sample, fully submerge a fabric substrate in the tetraethylorthosilicate mixture and then transfer to a glass, microwave-safe dish.
Next, microwave the saturated fabric sample using 1200 watts for 30 seconds. After repeating the soaking and microwave treatment, dry the treated fabric at 100 degrees Celsius for 30 minutes in a drying oven. To prepare the sol, mix 1.9 grams of Pluronic P123, 0.5 grams of mesitylene, and 2.12 grams of BTE in a plastic vial at room temperature.
Add two grams of methanol and a magnetic stir bar. Then, seal the vial and stir at 150 rpm. When the stirred solution appears homogeneous, add 6.07 grams of 0.1 molar nitric acid dropwise, and continuing stirring the mixture for six hours.
Addition of nitric acid is exothermic, so add it slowly and evenly. Dip the tetraethylorthosilicate-treated fabric into the prepared sol at a rate of 150 millimeters per minute. Following this, dry the sample in a 60 degree Celsius oven for 24 hours.
After drying at 80 degrees Celsius for an additional 24 hours, immerse the fabric sample in excess ethanol at 65 degrees Celsius for 48 hours to extract surfactant. Then, rinse the fabric with additional ethanol. Dry the fabric overnight at 60 to 65 degrees Celsius.
To functionalize the sorbent material with primary amine groups, prepare a solution of 3-aminopropyltriethoxysilane in toluene at 0.5%volume by volume. Submerge the fabric in the silane solution, cover, and incubate for one hour. Then, rinse the sample thoroughly with toluene.
Dry the fabric sample overnight at 100 degrees Celsius. Next, add a previously prepared porphyrin solution to 15 milliliters of 0.1 molar MES buffer at pH 5.5. Add five milligrams of EDC to the solution, and immediately submerge the fabric sample.
Then, cover the sample, and incubate overnight. On the following day, rinse the sample thoroughly with water. Finally, dry the fabric sample overnight at 100 degrees Celsius.
Images of the fabric at each stage in the coating process are shown here. The average mass of sorbent deposited on the cotton support was 01 grams per gram, an increase in weight of approximately 1%from the original fabric. The expected nitrogen sorption isotherm was obtained for the porous coating.
Negligible nitrogen adsorption was noted for the fabric alone and following microwave treatment. A Type IV-like isotherm was observed for a thick film version of the sorbent with significant hysteresis. Nitrogen porosimetry indicated a BET surface area of 968 with pore volume 0.78 and pore diameter of 39.
Microwave initiation of the fabric caused a slight reduction in water vapor transport as compared to the untreated cotton. No additional changes in water vapor transport were noted following sorbent deposition or functionalization with porphyrin. Time-dependent FID responses for permeation of 2-chloroethyl ethyl sulfide are shown here.
A peak rate of 67 grams per meter squared per hour with no retention of the target was observed for the cotton fabric. The porous treatment resulted in significant reduction to the peak rate of transport and the total transport of target through the fabric with porphyrin functionalization further reducing the peak rate. While using this procedure, it's important to remember that the density of the fabric weave will impact the performance of the final product.
This procedure can be performed for deposition of other organosilicate materials and porphyrins to produce fabrics with different chemical selectivity.
