This research was sponsored by the Defense Threat Reduction Agency (DTRA BA08PRO015) and the U.S. Office of Naval Research through Naval Research Laboratory base funds. The views expressed here are those of the authors and do not represent those of the U.S. Navy, the U.S. Department of Defense, or the U.S. Government.

1. Microwave Initiation
<ol>
	<li>Prepare the initiation solution by mixing 10 mL of ammonium hydroxide (28 - 30%) with 184 mL of isopropanol in a glass beaker using a magnetic stir bar at 150 rpm. Add 6 mL of tetraethyl orthosilicate (TEOS) to the ammonium hydroxide solution5. 
	Caution: Ammonium Hydroxide is an alkali solution that poses irritation and burn hazards on contact with eyes and skin as well as toxicity upon inhalation or ingestion. 
	Caution: Tetraethyl orthosilicate is flammable and toxic.</li>
	<li>To initiate the sample, submerge fabric substrate fully in the TEOS mixture and remove to a glass, microwave safe dish. 
	NOTE: The fabric used here was a light weight, unbleached cotton obtained from a specialty crafts and fabrics retailer. The described process is suitable to a wide range of fabrics with the limitation that they must have available hydroxyl or amine groups5. The size of the dish is not important provided the cloth can lie flat within it.
	<ol>
		<li>Microwave the saturated fabric sample using 1,200 W for 30 s. 
		Caution: Fabric sample and dish will be hot following treatment. Microwave samples with sufficient ventilation and avoid inhalation of resulting vapors.</li>
		<li>Repeat soaking and microwave treatment for a total of three cycles. 
		NOTE: TEOS mixture becomes cloudy quickly as precipitation occurs. Use immediately.</li>
		<li>Dry treated fabric at 100 &#176;C for 30 min in a drying oven. Once dry, the fabric can be stored under ambient conditions. 
		NOTE: The oven used here was a gravity oven, but any oven of sufficient size is suitable for drying the materials.</li>
	</ol>
	</li>
</ol>
2. Preparation of Sol for Dip Coating
<ol>
	<li>To prepare the sol, mix 1.9 g of Pluronic P123, 0.5 g of mesitylene, and 2.12 g of 1,2-bis(trimethyoxysilyl)ethane (BTE) in a plastic vial at room temperature15,16,17,18,20,21. 
	Caution: 1,2-Bis(trimethyoxysilyl)ethane is flammable and toxic. Avoid skin contact and inhalation. Mesitylene is flammable and toxic. Avoid skin contact and inhalation.
	<ol>
		<li>Add 2.0 g of methanol and a magnetic stir bar. Seal the container and stir at 150 rpm. 
		Caution: Methanol is flammable and toxic and may present other health hazards. Avoid skin contact and inhalation. 
		NOTE: In variations of this deposition, ethanol may be used in place of the methanol of this protocol. Additional information is provided in the Discussion.</li>
		<li>When the stirred solution appears homogeneous, add 6.07 g of 0.1 M HNO3 dropwise. 
		Caution: Nitric acid is corrosive and can cause skin, eye, and respiratory system irritation. Avoid skin contact and inhalation.</li>
		<li>Continuing stirring the mixture for 6 h. 
		NOTE: The mixture is stable overnight at this point, but only in the absence of evaporation. If methanol evaporates during storage, changes to the sol-gel will occur.</li>
	</ol>
	</li>
</ol>
3. Dip Coating Fabric
<ol>
	<li>Dip the TEOS treated fabric into the prepared sol at a rate of 150 mm/min. 
	NOTE: Faster rates of up to 270 mm/min can be used with no negative impact on the resulting materials. Here, any equipment achieving dip and draw rates between 150 and 270 mm/min is suitable.
	<ol>
		<li>Transfer the sample to hang dry in a 60 &#176;C oven for 24 h.</li>
		<li>Continue curing at 80 &#176;C for an additional 24 h. 
		NOTE: Higher curing temperatures of up to 120 &#176;C are acceptable at this point. After curing, the fabric can be stored at ambient temperature, allowing for later extraction.</li>
	</ol>
	</li>
	<li>Immerse the fabric sample in excess ethanol at 65 &#176;C for 48 h to extract surfactant. 
	Caution: Ethanol is flammable. 
	NOTE: Ensure the container will tolerate necessary temperatures.
	<ol>
		<li>Rinse the fabric with additional ethanol.</li>
	</ol>
	</li>
	<li>Dry the fabric overnight at 60 - 65 &#176;C. Once dry, the fabric can be stored under ambient conditions.</li>
</ol>
4. Porphyrin Functionalization of Coated Fabrics
<ol>
	<li>To functionalize the sorbent material with primary amine groups, prepare a solution of 3-aminopropyltriethoxy silane (APS) in toluene at 0.5% volume/volume15,16. 
	Caution: 3-Aminopropyltriethoxy silane is corrosive and toxic. Avoid skin contact and inhalation. Toluene is flammable, toxic, and a known carcinogen. Avoid skin contact and inhalation.
	<ol>
		<li>Submerge fabric in the solution and incubate for 1 h, covered.</li>
		<li>Rinse the samples thoroughly with toluene.</li>
		<li>Dry the fabric samples overnight at 100 &#176;C.</li>
	</ol>
	</li>
	<li>To prepare the copper complex of Deuteroporphyrin IX 2,4 bis ethylene glycol (DIX), dissolve 20 mg of the porphyrin in 2 mL dimethyl sulfoxide22. 
	Caution: Porphyrins may present health hazards; follow recommended precautionary procedures.
	<ol>
		<li>Add the porphyrin solution to 100 mL of water with 12.8 mg of copper (II) chloride in a round bottom flask. 
		Caution: Copper chloride is corrosive, toxic, and presents hazards to the aquatic environment. Avoid skin contact and inhalation.</li>
		<li>Reflux the solution overnight.</li>
		<li>Use rotary evaporation to reduce total sample volume to 5 mL. 
		NOTE: The porphyrin can be prepared in larger quantities for later use. Prepared porphyrin should be stored in the dark at room temperature.</li>
	</ol>
	</li>
	<li>Add the prepared porphyrin solution to 15 mL of 0.1 M 2-(N-morpholino)ethansulfonic acid (MES) buffer pH 5.5.
	<ol>
		<li>Add 5 mg of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) to the solution and immediately submerge the fabric samples.</li>
		<li>Cover the samples and incubate overnight.</li>
		<li>Rinse the samples thoroughly using water.</li>
		<li>Dry the fabric samples overnight at 100 &#176;C.</li>
	</ol>
	</li>
</ol>
5. Characterization of Fabrics
<ol>
	<li>Use any commercially available nitrogen adsorption characterization system according to manufacturer protocols to characterize the porosity of the fabric samples. 
	NOTE: Here, nitrogen adsorption analysis was completed 77 K. Depending on the system used, it may be necessary to weigh samples or degas at &#8805;65 &#176;C prior to analysis.
	<ol>
		<li>Use the Brunauer-Emmett-Teller (BET) method for determination of surface area.</li>
		<li>Use the Barrett-Joyner-Halenda (BJH) method for determination of the pore size from the adsorption branch of the isotherm.</li>
		<li>Use the single point method to determine the pore volume at relative pressure (P/P0) 0.97.</li>
	</ol>
	</li>
	<li>Characterize the permeation of 2-chloroethyl ethyl sulfide (CEES) through fabric samples by following the guidance provided by Test Operations Procedure (TOP) 8-2-501, Permeation Testing of Materials with Chemical Agents or Simulants (Swatch Testing)23,24. 
	Caution: 2-Chloroethyl ethyl sulfide is flammable, corrosive, toxic, and presents a health hazard. Avoid skin contact and inhalation. 
	NOTE: Under this study, an internal, probe driven heater was used to control the temperature within a custom environmental. The ratio of humid to dry air entering this chamber is addressed using probe driven mass flow controllers. The stainless-steel aerosol-vapor-liquid-assessment group (AVLAG) cell holds the sample horizontally with O-ring seals. Diffusive permeation testing uses a nitrogen stream. The headspace above the swatch, in which the target is placed, is stagnant with no pressure difference above and below the swatch. The sample is supported between two solid support discs with aligned 0.64 cm2 circular openings. This assembly is placed in the AVLAG cell, and humidity is equilibrated for 2 h. Target is introduced as liquid droplets using a repeating dispenser. A dedicated FID allows for continuous monitoring of target concentrations.</li>
	<li>Follow the guidance provided by ASTM E96, Water Vapor Transport: Upright Open Cup Method to characterize water vapor transport through the fabric samples4,24,25.
	<ol>
		<li>Modify an incubator to provide an enclosure for this analysis at 25 &#176;C.</li>
		<li>Fill a scintillation vial (20 mL) with 16.9 mL deionized water. Seal the sample material over this vial, and weigh the vial. Use desiccant to drive a humidity differential in the incubator, and align a dry nitrogen stream so that it flowed across the surface of the sample (0.25 L/min).</li>
		<li>Measure the weight of the sample covered vial at 30 to 45 min intervals using an analytical balance.</li>
	</ol>
	</li>
</ol>

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The authors declare that they have no competing financial interests.

Here, we have shown that the microwave-initiated deposition of TEOS can be used to prepare fabric for subsequent deposition of a porous organosilicate sorbent. The approach leads to loading of the fabric with 1.12 g sorbent per m2 of fabric surface. Analysis of the coated fabric by nitrogen adsorption indicated deposition of a porous coating with significant differences between the full treated material and that of the initiated fabric. The surface area was, however, less than that observed for a similarly composed material synthesized as a monolith. The sorbent alone reduced the rate of CEES transport across the fabric by 85%. Addition of the porphyrin functionalization to the supported sorbent further decreased transport (93% total reduction). Initial breakthrough for the porphyrin functionalized treated fabric occurred at 2 min; initial breakthrough the cotton fabric was at 0.6 min. This reduction in chemical permeation was achieved with little impact on the water vapor transport of the fabric.
The deposited sorbent is not a continuous thin film. The approach produces a coating that is more closely conformal to the yarn of the fabric. As a result, reduction to permeation is limited by the weave of the fabric. Here, a light-weight cotton fabric is used as the support material. The microwave initiation is suitable for use on other fabrics that provide amine or hydroxyl groups for modification. A more densely woven fabric, such as the nylon and cotton blend used in the US Army Combat Uniform (ACU), would produce greater reduction to target transport simply on the basis of reduction in void spaces within the weave. A densely woven fabric used as a shelter material would provide similar advantages. Recalling that the sorbent treatment is not limited to the surface of the fabric, a material providing some depth in the manner of a fleece or heavy knit fabric would also be expected to produce additional reductions in permeation. This concept would also apply to the three-dimensional pleated materials used in air filtration.
The treatment outlined here is not limited to use on traditional fabrics. It provides the potential for modification of the paper, layered, and pleated materials more typically applied in filtration approaches as well as nonwoven textiles. In some cases, the conditions described here may need to be gentled to maintain the integrity of the supporting material. Reducing the concentration of the base (ammonium hydroxide) may be necessary, as in the case of polyethylene fabrics. Shortening the duration of the microwave period may be necessary to avoid scorching (paper materials). Some synthetic fabrics, polypropylene for example, require reduction in the drying temperatures used. Changes to sol aging temperatures and durations should be avoided as these conditions have significant impact on the morphology of the resulting sorbent.
Ethanol may be substituted for methanol in the dip coating sol. This is encouraged when scaling up a synthesis and using a larger volume of sol, because ethanol presents a lesser health hazard. The sol can be diluted considerably with alcohol, e.g., 4 to 12 g ethanol instead of 2 g methanol) to prepare a greater volume of the mixture without a proportional increase in the masses of BTE, Pluronic P123, mesitylene, and acid. Relative amounts of reactants and solvent can also be multiplied to prepare a sol for generation of larger samples of coated materials. The degree of dilution or concentration of a sol may impact the resulting mass loading of sorbent material on a particular fabric. Multiple cycles of dipping into a sol mixture should also lead to changes in total loading.
Optimization of the deposition approach for other support materials is ongoing. Modification of the ACU nylon and cotton blend fabric is of particular interest for a daily wear solution providing baseline chemical protection as are jersey knit based materials. The deposition of other sorbent materials is also being explored. The diethylbenzene bridged sorbents developed for capture of pesticide targets, for example, use a sol preparation that differs from the one described here17,20,27 and catalysis is based on a different porphyrin. Finally, evaluation of the fabric supported materials against aerosol, liquid, and vapor targets is ongoing.

Currently available chemical protective garments used by the US Department of Defense (DoD) either provide a full barrier, the Level A chemical protective suit, for example, or use multiple layers of fabric for protection, as in the Joint Service Lightweight Integrated Suit Technology (JSLIST). Full barrier garments impose a significant burden on the user. With no water vapor transport through the material, thermal regulation is hindered. As a result, the duration of use (mission length) is restricted; the garment is appropriate to a limited range of scenarios. The JSLIST, on the other hand, uses a layer of carbon adsorbent between a shell fabric and a comfort layer. The resulting burden on the user is reduced but not eliminated, and protective capabilities are reduced in comparison to the barrier suits. Beyond the thermal burden, the JSLIST suit is suitable for only 24 hours of continuous use. Neither of these types of technology are suitable for providing a baseline protective capability in a long term, daily wear garment. Baseline protection would be of use for low hazard environments, conditions suitable to MOPP 0 through 2 (MOPP - Mission Oriented Protective Posture), and other low risk conditions. Beyond DoD concerns, baseline protection would be of utility to first responders who may enter contaminated environments with no prior warning.
Research seeking improvements to DoD protective garments is ongoing and continuous1,2,3,4. A previous effort identified the potential of a microwave initiated process for deposition of heptadecafluoro-1,1,2,2-tetrahydrodecyl)trimethoxysilane on fabrics to produce oleophobic behavior5. The intention was to produce a fabric that may enhance the shell layer of the JSLIST garment. While this oleophobicity may improve the chemical resistance of the layered garment, it will not address the thermal burden imposed by the suit. There is additional ongoing work focused on sorbents and catalysts for capture and/or decomposition of chemical threats6,7,8,9,10,11,12,13,14. A recently described approach used porous organosilicate sorbents combined with porphyrins to capture and degrade phosgene and used similar materials for capture of toxic industrial compounds (TICS) as well as pesticide simulants and nitroenergetics15,16,17,18,19,20. While promising, these powdered materials are not directly applicable to garment technologies.
Organosilicate systems have been widely applied in dip and spin coating approaches, typically, on glass and silicon wafers. The microwave deposition technique described above provides a mechanism for application of these materials to fabrics. Here, we use the described process in combination with tetraethylorthosilicate to prepare fabrics. They are then treated with the porous sorbents through a dip coating approach. Morphological characterization demonstrates the presence of the porous sorbent on the fabric. Evaluation of 2-chloroethyl ethyl sulfide (CEES) permeation through the fabric with and without this treatment shows a significant impact on transport of the target across the material.

<table border="0" cellpadding="0" cellspacing="0" width="1345">
	<tbody>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">unbleached 100% cotton fabric</td>
			<td style="width:239px;">JOANN Stores</td>
			<td style="width:275px;">N/A</td>
			<td style="width:471px;">Protocol is suitable for use on a variety of fabrics</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">ammonium hydroxide</td>
			<td style="width:239px;">Aldrich</td>
			<td style="width:275px;">32,014-5</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">tetraethyl orthosilicate</td>
			<td style="width:239px;">Aldrich</td>
			<td style="width:275px;">13,190-3</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Pluronic P123</td>
			<td style="width:239px;">Aldrich</td>
			<td style="width:275px;">435465</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">mesitylene</td>
			<td style="width:239px;">Sigma-Aldrich</td>
			<td style="width:275px;">M7200</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">1,2-bis(trimethoxysilyl)ethane</td>
			<td style="width:239px;">Aldrich</td>
			<td style="width:275px;">447242</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">methanol</td>
			<td style="width:239px;">Fisher Chemical</td>
			<td style="width:275px;">A454SK-4</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">nitric acid</td>
			<td style="width:239px;">Sigma-Aldrich</td>
			<td style="width:275px;">438073</td>
			<td style="width:471px;">Prepare 0.1 M aqueous solution</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">3-aminopropyltriethoxysilane</td>
			<td style="width:239px;">Gelest</td>
			<td style="width:275px;">SIA0603.4</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">toluene</td>
			<td style="width:239px;">Sigma-Aldrich</td>
			<td style="width:275px;">650579</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Deuteroporphyrin IX bis ethylene glycol</td>
			<td style="width:239px;">Frontier Scientific</td>
			<td style="width:275px;">D630-9</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">dimethyl sulfoxide</td>
			<td style="width:239px;">Sigma-Aldrich</td>
			<td style="width:275px;">276855</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">copper chloride</td>
			<td style="width:239px;">Sigma-Aldrich</td>
			<td style="width:275px;">256528</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">2-(N-morpholino)ethansulfonic acid</td>
			<td style="width:239px;">Sigma-Aldrich</td>
			<td style="width:275px;">M3671</td>
			<td style="width:471px;">Prepare 0.1M buffer at pH 5.5</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">1-ethyl-3-(3-dimethylaminopropyl)carbodiimide</td>
			<td style="width:239px;">Sigma-Aldrich</td>
			<td style="width:275px;">E6383</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">ethyl alcohol</td>
			<td style="width:239px;">Warner-Graham</td>
			<td style="width:275px;">64-17-5</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Drierite</td>
			<td style="width:239px;">Sigma-Aldrich</td>
			<td style="width:275px;">737828</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Microwave</td>
			<td style="width:239px;">Daewoo</td>
			<td style="width:275px;">KOR-630A</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Nitrogen adsorption instrument</td>
			<td>Micromeritics</td>
			<td style="width:275px;">&#160;TriStar II Plus&#160;</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Environmental chamber</td>
			<td style="width:239px;">custom part</td>
			<td style="width:275px;">N/A</td>
			<td style="width:471px;">Here, a modified Thermolyne incubator, Compact Series 5000 was used</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Flame ionization detector (FID)</td>
			<td style="width:239px;">SRI Instruments</td>
			<td style="width:275px;">8690-0010</td>
			<td style="width:471px;">Model 110</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Humidity probe</td>
			<td style="width:239px;">Vaisala</td>
			<td>HMT3303E0A193BCAC100A0CCABEA1</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">AVLAG Cell</td>
			<td style="width:239px;">custom part</td>
			<td style="width:275px;">N/A</td>
			<td style="width:471px;">AERO-Space Tooling and Machining, P/N RS0010 Permeation cell</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Computer controlled heater</td>
			<td style="width:239px;">World Precision Instruments</td>
			<td>AIRTHERMY-ATX</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Mass flow controller</td>
			<td style="width:239px;">MKS Instruments</td>
			<td style="width:275px;">1179A01312CS</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Dipper mechanism Type D1L</td>
			<td style="width:239px;">NIMA Technology Ltd</td>
			<td style="width:275px;">D1L</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Gravity oven</td>
			<td style="width:239px;">Fisher Scientific</td>
			<td style="width:275px;">15-103-0520</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Stirring hotplate</td>
			<td style="width:239px;">Fisherbrand</td>
			<td style="width:275px;">S28482</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Octagon spinbar, magnetic stirring bar</td>
			<td style="width:239px;">Fisherbrand</td>
			<td style="width:275px;">14-513-82</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">PSI-Plot version 9.5</td>
			<td style="width:239px;">Poly Software International, Inc</td>
			<td style="width:275px;">N/A</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:363px;">Microsoft Office Professional Plus - Excel 2013 32-bit</td>
			<td style="width:239px;">Microsoft</td>
			<td style="width:275px;">N/A</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:363px;">MicroActive TriStar II Plus Software</td>
			<td>Micromeritics</td>
			<td style="width:275px;">packaged with the TriStar II nitrogen adsorption instrument</td>
			<td style="width:471px;"></td>
		</tr>
	</tbody>
</table>

deposition of porous sorbents on fabric supports

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material that can be subsequently treated by dip coating. Dip coating with a sol preparation provides a supported porous layer on the fabric. In this case, the porous layer is a porphyrin functionalized sorbent system based on a powdered material that has been demonstrated previously for the capture and conversion of phosgene. A representative coating is applied to cotton fabric at a loading level of 10 mg/g. This coating has minimal impact on water vapor transport through the fabric (93% of the support fabric rate) while significantly reducing transport of 2-chloroethyl ethyl sulfide (CEES) through the material (7% of support fabric rate). The described approaches are suitable for use with other fabrics providing amine and hydroxyl groups for modification and can be used in combination with other sol preparations to produce varying functionality.

Nitrogen adsorption was used to evaluate the treated fabric following the dip coating procedure. As shown in Figure 1, the expected isotherm was obtained for the porous coating. This contrasts with the behaviors noted for the untreated fabric and for the microwave-initiated fabric. Negligible nitrogen adsorption was noted for the fabric alone and the fabric following microwave treatment. No pore sizes were determined. The porous coating produced a surface area of 3.39 m2/g with pore volume 0.013 cm3/g. While the instrument reported a BJH adsorption pore size of 76 &#197;, no significant features are observed in the pore size distribution. Images of the fabric at each stage in the coating process are provided in Figure 2. The average mass of sorbent deposited on the cotton support was determined to be 0.01 g/g based on the differential weight of samples before deposition and after the final drying process, an increase in weight of ~1% from the original fabric. If the measured surface area and pore volume are corrected to account for only the sorbent mass component of the material, the surface area for the sorbent is 339 m2/g with pore volume 1.3 cm3/g. For comparison, when this sorbent was synthesized as a monolith in a closed reactor, nitrogen porosimetry indicated a BET surface area of 1143 m2/g with pore volume 1.01 m2/g and pore diameter 76 &#197;26. A type IV-like isotherm was observed for this material with significant hysteresis (Figure 3). A thick film sample was prepared by curing the dip-coating sol in a Petri dish and processing based on the protocol used for coated fabric samples. Nitrogen porosimetry indicated a BET surface area of 968 m2/g with pore volume 0.78 cm3/g and pore diameter 39 &#197; for this material (Figure 3).
The water vapor transport (WVT) rate for the treated fabrics was evaluated using a two chambered cell4,24,25. This evaluation used a circular fabric sample with a total exposed area of 1.65 cm2. As shown in Figure 4, 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. The WVT rate for the cotton fabric was determined to be 121 g/h/m2. The WVT rate was reduced to 112 g/h/m2 upon microwave initiation. A WVT rate of 113 g/h/m2 was determined for the full porphyrin-functionalized treatment.
2-Chloroethyl ethyl sulfide (CEES) was used as a simulant to determine whether deposition of the porous treatment resulted in changes to chemical transport properties for the fabric. CEES is commonly used as a simulant for sulfur mustard, a chemical warfare agent. The sorbent material used here consists of ethane-bridging groups and has been functionalized with a copper Deuteroporphyrin IX 2,4 bis ethylene glycol (CuDIX) metalloporphyrin. This reflects the characteristics of the sorbent system demonstrated previously for use in capture of phosgene15,16. Chemical vapor transport was determined using aerosol-vapor-liquid-assessment group (AVLAG) cells23,24. The method uses continuous flow with flame ionization detection (FID) under controlled temperature (40 &#176;C) and relative humidity (50%) for total exposed area of 0.64 cm2. Figure 5 provides time-dependent FID responses. When the cotton fabric alone was evaluated, a peak rate of 67 g/h/m2 was noted with no retention of the target (214 &#181;g total). The porous treatment resulted in significant reduction to both the peak rate of transport (9.6 g/h/m2) and the total transport of target through the fabric. Only 78 &#181;g of the 214 &#181;g CEES originally applied was recovered over an 83 h period. The porphyrin functionalized porous treatment further reduced the peak rate of transport to 4.5 g/h/m2 with a total transport of 39 &#181;g CEES over the 83 h experiment.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57331/57331fig1.jpg" /> 
Figure 1: Morphological characterization of fabrics. Shown here are representative nitrogen sorption isotherms (A) and pore size distributions (B) for a typical fabric swatch (red), a similar swatch following the microwave initiation process (blue), the fabric following application of the sorbent (green), and the fabric following application of the full sorbent system (black). <a href="/files/ftp_upload/57331/57331fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57331/57331fig2.jpg" /> 
Figure 2: Photographs of fabric. The photograph here shows the microwave initiated, sorbent coated material (A), the CuDIX porphyrin alone on cotton (B), and a full porphyrin functionalized coating on the cotton (C). The treated swatches are overlaid on the untreated cotton fabric. <a href="/files/ftp_upload/57331/57331fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57331/57331fig3.jpg" /> 
Figure 3: Morphological characterization of unsupported sorbent. Shown here are representative nitrogen sorption isotherms (A) and pore size distributions (B) for the sorbent when synthesized as a monolith (black) and when synthesized as a thick film (red)26. <a href="/files/ftp_upload/57331/57331fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57331/57331fig4.jpg" /> 
Figure 4: Water vapor permeation. Results from water vapor permeation analysis are presented for the complete CuDIX porphyrin functionalized sorbent on cotton fabric (black). Cotton fabric only (red) and cotton fabric with only the sorbent component (blue) are presented for comparison. <a href="/files/ftp_upload/57331/57331fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/57331/57331fig5.jpg" /> 
Figure 5: Permeation of CEES. Permeation of CEES through a complete porphyrin functionalized sorbent coating on cotton fabric is presented (black). Fabric only (red) and fabric with only the sorbent component (blue) are presented for comparison. The inset provides a zoomed view of the initial breakthrough period for the three materials. <a href="/files/ftp_upload/57331/57331fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Deposition of Porous Sorbents on Fabric Supports at JoVE.com

Deposition of Porous Sorbents on Fabric Supports

This report details a microwave-initiated approach for deposition of porphyrin functionalized porous organosilicate sorbents on a cotton fabric and demonstrates reduction in 2-chloroethyl ethyl sulfide (CEES) transport through the fabric resulting from this treatment.

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material ...

deposition-of-porous-sorbents-on-fabric-supports

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Chemistry

6.5K Views.  Naval Research Laboratory. This report details a microwave-initiated approach for deposition of porphyrin functionalized porous organosilicate sorbents on a cotton fabric and demonstrates reduction in 2-chloroethyl ethyl sulfide (CEES) transport through the fabric resulting from this treatment.

Video: Deposition of Porous Sorbents on Fabric Supports

Supercritical Nitrogen Processing for the Purification of Reactive Porous Materials

Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. Herein, nitrogen is presented as a novel supercritical drying fluid for specialized applications such as in the processing of reactive porous materials, where carbon dioxide and other fluids are not appropriate due to their higher chemical reactivity. Nitrogen exhibits similar physical properties in the near-critical region of its phase diagram as compared to carbon dioxide: a widely tunable density up to ~1 g ml-1, modest critical pressure (3.4 MPa), and small molecular diameter of ~3.6 &#197;. The key to achieving a high solvation power of nitrogen is to apply a processing temperature in the range of 80-150 K, where the density of nitrogen is an order of magnitude higher than at similar pressures near ambient temperature. The detailed solvation properties of nitrogen, and especially its selectivity, across a wide range of common target species of extraction still require further investigation. Herein we describe a protocol for the supercritical nitrogen processing of porous magnesium borohydride.

Nitrogen is an effective supercritical fluid for extraction or drying processes due to its small molecular size, high density in the near-liquid supercritical regime, and chemical inertness. We present a supercritical nitrogen drying protocol for the purification treatment of reactive, porous materials.

Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. ...

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in traditional materials, including low cost and mechanical flexibility. In a similar vein, it would be advantageous to expand the use of organics into high frequency electronics and spin-based electronics. This work presents a synthetic process for the growth of thin films of the room temperature organic ferrimagnet, vanadium tetracyanoethylene (V[TCNE]x, x~2) by low temperature chemical vapor deposition (CVD). The thin film is grown at &#60;60 &#176;C, and can accommodate a wide variety of substrates including, but not limited to, silicon, glass, Teflon and flexible substrates. The conformal deposition is conducive to pre-patterned and three-dimensional structures as well. Additionally this technique can yield films with thicknesses ranging from 30 nm to several microns. Recent progress in optimization of film growth creates a film whose qualities, such as higher Curie temperature (600 K), improved magnetic homogeneity, and narrow ferromagnetic resonance line-width (1.5 G) show promise for a variety of applications in spintronics and microwave electronics.

We present the synthesis of the organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]x, x~2) via low temperature chemical vapor deposition (CVD). This optimized recipe yields an increase in Curie temperature from 400 K to over 600 K and a dramatic improvement in magnetic resonance properties.

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in ...

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Preparation of Macroporous Epitaxial Quartz Films on Silicon by Chemical Solution Deposition

This work describes the detailed protocol for preparing piezoelectric macroporous epitaxial quartz films on silicon(100) substrates. This is a three-step process based on the preparation of a sol in a one-pot synthesis which is followed by the deposition of a gel film on Si(100) substrates by evaporation induced self-assembly using the dip-coating technique and ends with a thermal treatment of the material to induce the gel crystallization and the growth of the quartz film. The formation of a silica gel is based on the reaction of a tetraethyl orthosilicate and water, catalyzed by HCl, in ethanol. However, the solution contains two additional components that are essential for preparing mesoporous epitaxial quartz films from these silica gels dip-coated on Si. Alkaline earth ions, like Sr2+ act as glass melting agents that facilitate the crystallization of silica and in combination with cetyl trimethylammonium bromide (CTAB) amphiphilic template form a phase separation responsible of the macroporosity of the films. The good matching between the quartz and silicon cell parameters is also essential in the stabilization of quartz over other SiO2 polymorphs and is at the origin of the epitaxial growth.

A protocol is presented for the preparation of piezoelectric macroporous epitaxial films of quartz on silicon by solution chemistry using dip-coating and thermal treatments in air.

This work describes the detailed protocol for preparing piezoelectric macroporous epitaxial quartz films on silicon(100) substrates. This is a three-step ...

Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and conformality by taking advantage of self-limiting reactions between vapor-phase precursors and the growing film. Perovskite oxides present potential for next-generation electronic materials, but to-date have mostly been deposited by physical methods. This work outlines a method for depositing SrTiO3 (STO) on germanium using ALD. Germanium has higher carrier mobilities than silicon and therefore offers an alternative semiconductor material with faster device operation. This method takes advantage of the instability of germanium's native oxide by using thermal deoxidation to clean and reconstruct the Ge (001) surface to the 2&#215;1 structure. 2-nm thick, amorphous STO is then deposited by ALD. The STO film is annealed under ultra-high vacuum and crystallizes on the reconstructed Ge surface. Reflection high-energy electron diffraction (RHEED) is used during this annealing step to monitor the STO crystallization. The thin, crystalline layer of STO acts as a template for subsequent growth of STO that is crystalline as-grown, as confirmed by RHEED. In situ X-ray photoelectron spectroscopy is used to verify film stoichiometry before and after the annealing step, as well as after subsequent STO growth. This procedure provides framework for additional perovskite oxides to be deposited on semiconductors via chemical methods in addition to the integration of more sophisticated heterostructures already achievable by physical methods.

This work details the procedures for the growth and characterization of crystalline SrTiO3 directly on germanium substrates by atomic layer deposition. The procedure illustrates the ability of an all-chemical growth method to integrate oxides monolithically onto semiconductors for metal-oxide semiconductor devices.

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and ...

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene

A reliable, intermediate scale preparation of 1,2,3,4,5-pentamethylcyclopentadiene (Cp*H) is presented, based on modifications of existing protocols that derive from initial 2-bromo-2-butene lithiation followed by acid mediated dienol cyclization. The revised synthesis and purification of the ligand avoids the use of mechanical stirring while still permitting access to significant quantities (39 g) of Cp*H in good yield (58%). The procedure offers other additional benefits, including a more controlled quench of excess lithium during the production of the intermediate heptadienols and a simplified isolation of Cp*H of sufficient purity for metallation with transition metals. The ligand was subsequently used to synthesize [Cp*MCl2]2 complexes of both iridium and ruthenium to demonstrate the utility of the Cp*H prepared and purified by our method. The procedure outlined herein affords substantial quantities of a ubiquitous ancillary ligand support used in organometallic chemistry while minimizing the need for specialized laboratory equipment, thus providing a simpler and more accessible entry point into the chemistry of 1,2,3,4,5-pentamethylcyclopentadiene.

Reliable, intermediate scale preparation of 1,2,3,4,5-pentamethylcyclopentadiene (Cp*H) is presented. The revised protocol for the synthesis and purification of the ligand minimizes the need for specialized laboratory equipment while simplifying reaction workups and product purification. Use of Cp*H in the synthesis of [Cp*MCl2]2 complexes (M = Ru, Ir) is also described.

A reliable, intermediate scale preparation of 1,2,3,4,5-pentamethylcyclopentadiene (Cp*H) is presented, based on modifications of existing protocols that ...

Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, their high cost production and/or incompatibility with microfabrication technologies, due to the use of pre-deposited catalyst-seeds and/or high processing temperatures exceeding 900 &#176;C, represent a drawback for a widespread use of these methods. Here, however, we report the synthesis of ZnO rods via a non-catalyzed vapor-solid mechanism enabled by using an aerosol-assisted chemical vapor deposition (CVD) method at 400 &#176;C with zinc chloride (ZnCl2) as the precursor and ethanol as the carrier solvent. This method provides both single-step formation of ZnO rods and the possibility of their direct integration with various substrate types, including silicon, silicon-based micromachined platforms, quartz, or high heat resistant polymers. This potentially facilitates the use of this method at a large-scale, due to its compatibility with state-of-the-art microfabrication processes for device manufacture. This report also describes the properties of these structures (e.g., morphology, crystalline phase, optical band gap, chemical composition, electrical resistance) and validates its gas sensing functionality towards carbon monoxide.

Columnar zinc oxide structures in the form of rods are synthesized via aerosol-assisted chemical vapor deposition without the use of pre-deposited catalyst-seed particles. This method is scalable and compatible with various substrates based on either silicon, quartz or polymers.

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, ...

Nanothermite with Meringue-like Morphology: From Loose Powder to Ultra-porous Objects

The goal of the protocol described in this article is to prepare aluminothermic compositions (nanothermites) in the form of porous, monolithic objects. Nanothermites are combustible materials made up of inorganic fuel and an oxidizer. In nanothermite foams, aluminum is the fuel and aluminum phosphate and tungsten trioxide are the oxidizing moieties. The highest flame propagation velocities (FPVs) in nanothermites are observed in loose powders and FPVs are strongly decreased by pelletizing nanothermite powders. From a physical standpoint, nanothermite loose powders are metastable systems. Their properties can be altered by unintentional compaction induced by shocks or vibrations or by the segregation of particles over time by settling phenomena, which originates from the density differences of their components. Moving from a powder to an object is the challenge that must be overcome to integrate nanothermites in pyrotechnic systems. Nanothermite objects must have both a high open porosity and good mechanical strength. Nanothermite foams meet both of these criteria, and they are prepared by dispersing a nano-sized aluminothermic mixture (Al/WO3) in orthophosphoric acid. The reaction of aluminum with the acid solution gives the AlPO4 &#34;cement&#34; in which Al and WO3 nanoparticles are embedded. In nanothermite foams, aluminum phosphate plays the dual role of binder and oxidizer. This method can be used with tungsten trioxide, which is not altered by the preparation process. It could probably be extended to some oxides, which are commonly used for the preparation of high performance nanothermites. The WO3-based nanothermite foams described in this article are particularly insensitive to impact and friction, which makes them far safer to handle than loose Al/WO3 powder. The fast combustion of these materials has interesting applications in pyrotechnic igniters. Their use in detonators as primers would require the incorporation of a secondary explosive in their composition.

This manuscript describes the synthesis of combustible aluminophosphate matrices by the reaction of orthophosphoric acid (H3PO4) with aluminum nanopowder. When this reaction is carried out with excess aluminum in the presence of tungsten trioxide nanopowder, it leads to a solid, porous nanothermite foam.

The goal of the protocol described in this article is to prepare aluminothermic compositions (nanothermites) in the form of porous, monolithic objects. ...

Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. Conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and a semiconducting polymer, poly(thieno[3,2-b]thiophene) (PTT), were deposited on unconventional highly-disordered and textured substrates with high surface areas, such as paper, towels and fabrics. This reported deposition chamber is an improvement of previous vapor reactors because our system can accommodate both volatile and nonvolatile monomers, such as 3,4-propylenedioxythiophene and thieno[3,2-b]thiophene. Utilization of both solid and liquid oxidants are also demonstrated. One limitation of this method is that it lacks sophisticated in situ thickness monitors. Polymer coatings made by the commonly used solution-based coating methods, such as spin-coating and surface grafting, are often not uniform or susceptible to mechanical degradation. This reported vapor phase deposition method overcomes those drawbacks and is a strong alternative to common solution-based coating methods. Notably, polymer films coated by the reported method are uniform and conformal on rough surfaces, even at a micrometer scale. This feature allows for future application of vapor deposited polymers in electronics devices on flexible and highly textured substrates.

This paper presents a protocol for reactive vapor deposition of poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), and poly(thieno[3,2-b]thiophene) films on glass slides and rough substrates, such as textiles and paper.

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. ...

The Effect of Ultraviolet Radiation on the Chemical Bath Deposition of Bis(thiourea) Cadmium Chloride Crystals and the Subsequent CdS Obtention

In this work, the effects on the preparation of bis(thiourea) cadmium chloride crystals when illuminated with ultraviolet (UV) light at a wavelength of 367 nm using the chemical bath deposition technique are studied comparatively. Two experiments are performed to make a comparison: one without UV light and the other with the aid of UV light. Both experiments are performed under equal conditions, at a temperature of 343 K and with a pH of 3.2. The precursors used are cadmium chloride (CdCl2) and thiourea [CS(NH2)2], which are dissolved in 50 mL of deionized water with an acidic pH. In this experiment, the interaction of electromagnetic radiation is sought at the moment the chemical reaction is carried out. The results demonstrate the existence of an interaction between the crystals and the UV light; the UV light assistance causes crystal growths in an acicular shape. Also, the final product obtained is cadmium sulfide and shows no evident difference when synthesized with or without the use of UV light.

The Effect of Ultraviolet Radiation on the Chemical Bath Deposition of Bisthiourea Cadmium Chloride Crystals and the Subsequent CdS Obtention

This article presents a protocol for the synthesis of bis(thiourea) cadmium chloride crystals by chemical bath deposition. Two experiments are described: one aided by ultraviolet light compared to one without ultraviolet light.

In this work, the effects on the preparation of bis(thiourea) cadmium chloride crystals when illuminated with ultraviolet (UV) light at a wavelength of ...