Name: reactive vapor deposition of conjugated polymer films on arbitrary substrates
Uploaded: 2018-01-17T10:55:00
Description: Watch this Scientific Journal Video about Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates at JoVE.com

The authors gratefully acknowledge financial support from the US Air Force Office of Scientific Research, under agreement number FA9550-14-1-0128. T. L. A. also gratefully acknowledges partial support by the David and Lucille Packard Foundation.

Read MSDS for reagents and follow all chemical safety measures as required by your institution.
1. Deposition of Cl-PProDOT and Cl-PTT
<ol>
	<li>Build the structure of the custom-built tubular vapor deposition chamber as shown in Figure 1.
	<ol>
		<li>Make a 1/4-in. (outer diameter, O.D.) fused quartz side inlet to a 2-in. (O.D.) fused quartz tube. Make a cold trap with a custom-built U-shape 1-in. stainless-steel tube and a Dewar flask.</li>
		<li>Connect the q...

<ol>
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F., Locklin, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+functionalization+of+Kevlar[registered+sign]+with+copolymers+containing+sulfonyl+nitrenes.">Direct functionalization of Kevlar[registered sign] with copolymers containing sulfonyl nitrenes.</a> Polym. Chem. 6, 3090-3097 (2015).</li><li>Musumeci, C., Hutchison, J. A., Samori, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlling+the+morphology+of+conductive+PEDOT+by+in+situ+electropolymerization:+from+thin+films+to+nanowires+with+variable+electrical+properties.">Controlling the morphology of conductive PEDOT by in situ electropolymerization: from thin films to nanowires with variable electrical properties.</a> Nanoscale. 5, 7756-7761 (2013).</li><li>Allison, L., Hoxie, S., Andrew, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+seamlessly-integrated+textile+electronics:+methods+to+coat+fabrics+and+fibers+with+conducting+polymers+for+electronic+applications.">Towards seamlessly-integrated textile electronics: methods to coat fabrics and fibers with conducting polymers for electronic applications.</a> Chem. Commun. 53, 7182-7193 (2017).</li><li>Alf, M. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+Vapor+Deposition+of+Conformal,+Functional,+and+Responsive+Polymer+Films.">Chemical Vapor Deposition of Conformal, Functional, and Responsive Polymer Films.</a> Adv. Mater. 22, 1993-2027 (2010).</li><li>Goktas, H., Wang, X., Boscher, N. D., Torosian, S., Gleason, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functionalizable+and+electrically+conductive+thin+films+formed+by+oxidative+chemical+vapor+deposition+(oCVD)+from+mixtures+of+3-thiopheneethanol+(3TE)+and+ethylene+dioxythiophene+(EDOT).">Functionalizable and electrically conductive thin films formed by oxidative chemical vapor deposition (oCVD) from mixtures of 3-thiopheneethanol (3TE) and ethylene dioxythiophene (EDOT).</a> J. Mater. Chem. C. 4, 3403-3414 (2016).</li><li>Sadki, S., Schottland, P., Brodie, N., Sabouraud, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mechanisms+of+pyrrole+electropolymerization.">The mechanisms of pyrrole electropolymerization.</a> Chem. Soc. Rev. 29, 283-293 (2000).</li><li>Bhattacharyya, D., Howden, R. M., Borrelli, D. C., Gleason, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vapor+phase+oxidative+synthesis+of+conjugated+polymers+and+applications.">Vapor phase oxidative synthesis of conjugated polymers and applications.</a> J. Polym. Sci., Part B: Polym. Phys. 50, 1329-1351 (2012).</li><li>Yamato, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+free-standing+poly(3,4-ethylenedioxythiophene)+conducting+polymer+films+on+a+pilot+scale.">Synthesis of free-standing poly(3,4-ethylenedioxythiophene) conducting polymer films on a pilot scale.</a> Synth. Met. 83, 125-130 (1996).</li><li>Cheng, N., Zhang, L., Joon Kim, J., Andrew, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vapor+phase+organic+chemistry+to+deposit+conjugated+polymer+films+on+arbitrary+substrates.">Vapor phase organic chemistry to deposit conjugated polymer films on arbitrary substrates.</a> J. Mater. Chem. C. 5, 5787-5796 (2017).</li><li>Borrelli, D. C., Lee, S., Gleason, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optoelectronic+properties+of+polythiophene+thin+films+and+organic+TFTs+fabricated+by+oxidative+chemical+vapor+deposition.">Optoelectronic properties of polythiophene thin films and organic TFTs fabricated by oxidative chemical vapor deposition.</a> J. Mater. Chem. C. 2, 7223-7231 (2014).</li><li>Jo, W. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxidative+Chemical+Vapor+Deposition+of+Neutral+Hole+Transporting+Polymer+for+Enhanced+Solar+Cell+Efficiency+and+Lifetime.">Oxidative Chemical Vapor Deposition of Neutral Hole Transporting Polymer for Enhanced Solar Cell Efficiency and Lifetime.</a> Adv. Mater. 28, 6399-6404 (2016).</li><li>Wang, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CVD+Polymers+for+Devices+and+Device+Fabrication.">CVD Polymers for Devices and Device Fabrication.</a> Adv. Mater. 29, 1604606 (2017).</li><li>Kovacik, P., Hierro, G. d., Livernois, W., Gleason, K. 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The mechanism of the reaction is oxidative polymerization. Polymer coating methods using the same mechanism include electropolymerization17 and vapor phase polymerization18. Electropolymerization requires a conductive substrate, lacks the advantage of uniform and conformal coating, and is an environmentally-unfriendly solution-based method19. The existing vapor phase polymerization method is similar to the method reported here but can only polymerize...

Polymeric conducting and semiconducting materials have unique properties, such as flexibility1, stretchability2, transparency3, and low density,4 which provide extraordinary opportunities for creating next-generation electronic devices on nontraditional substrates. Currently, many researchers are endeavoring to take advantage of the unique properties of polymeric materials to create flexible and/or wearable electronics5,6 and smart textiles7. However, the ability to conformally coat highly textured surfaces and non-robust substrates, such as paper, fabrics and threads/yarns, remains unmastered. Most commonly, polymers are synthesized and coated on surfaces using solution methods.8,9,10,11,12 Although solution methods provide polymer coated fibers/textiles, the coatings thus obtained are often non-uniform and easily damaged by small physical stresses13,14 . Solution methods are also not applicable to coating paper because of wetting problems.
Reactive vapor deposition can create conformal conjugated polymer films on a diverse range of substrates, irrespective of surface chemistry/composition, surface energy and surface roughness/topography15. In this approach, conjugated polymers are synthesized in the vapor phase by simultaneously delivering monomer and oxidant vapors to a surface. Polymerization and film formation occurs on the surface in a single, solvent-free step. This method is theoretically applicable to any conjugated polymer that can be synthesized by oxidative polymerization using solution methods. However, to date, protocols for depositing only a narrow set of conjugated polymer structures are known.15
Here, we demonstrate the deposition of conductive poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and semiconducting poly(thieno[3,2-b]thiophene) (PTT) films via reactive vapor deposition. Two kinds of oxidants, solid FeCl3 and liquid Br2, are used in the process. The corresponding polymers are named Cl-PProDOT, Cl-PTT, and Br-PEDOT. Both conventional substrates, glass slides, and unconventional textured substrates, such as paper, towels and fabrics, were coated with the polymer films.
This protocol describes the setup of the custom-built vapor deposition chamber and the details of the deposition process. It is intended to help new practitioners to build their deposition system and avoid common pitfalls associated with vapor-phase synthesis.

<table>
	<tbody>
		<tr>
			<td>3,4-Ethylenedioxythiophene, 97%</td>
			<td>Sigma Aldrich</td>
			<td>483028</td>
			<td></td>
		</tr>
		<tr>
			<td>3,4-Propylenedioxythiophene, 97%</td>
			<td>Sigma Aldrich</td>
			<td>660485</td>
			<td></td>
		</tr>
		<tr>
			<td>Thieno[3,2-b]thiophene, 95%</td>
			<td>Sigma Aldrich</td>
			<td>702668</td>
			<td></td>
		</tr>
		<tr>
			<td>FeCl3, 97%</td>
			<td>Sigma Aldrich</td>
			<td>157740</td>
			<td></td>
		</tr>
		<tr>
			<td>Br2</td>
			<td>Sigma Aldrich</td>
			<td>207888</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

The thickness of Cl-PProDOT films formed on 1.3 cm x 2.5 cm glass slides placed at discrete lateral positions along the central tube were measured by a profilometer (Figure 3). Conductivities were calculated from resistivity measurements using a home-built four-point probe test station. The measured conductivity of a 100-nm thick Cl-PProDOT film on glass slides is 106 S/cm, which is sufficient to qualify this film as a potential electrode material. <strong cl...

Watch this Scientific Journal Video about Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates at JoVE.com

Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary 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 overall goal of this experiment is to create conformal coatings of conducting or semi-conducting polymer films on rough and textured substrates using a custom designed reactive vapor deposition chamber. This method allows soft electronic materials to be deposited on unconventional substrates to fabricate unique devices such as textile electronics. The main advantage of our chamber is that a broad section of polymers can be vapor deposited, meaning that structured diverse conjugated polymer films can be created.To begin the procedure, place 50 milligrams of ProDOT in a quartz martimer ampoule. Connect the ampoule via one fourth inch quick connect couplings and a needle valve. Wrap the ampoule, the metal parts, and the temperature probe with a heating tape.Connect the ampoule to the tubular chamber, keeping the needle valve open. Then, use long tweezers to place five 1.3 centimeter by 2.5 centimeter substrates of the desired materials adjacent to one another in the substrate heating zone. Place a five milliliter alumina crucible containing 50 milligrams of iron 3 chloride in the oxidant heating zone.Close the end of the chamber, slowly close the inert gas inlet valve, and start the vacuum pump. Once the chamber pressure is below 525 millitorrs, fill the cold trap dewar with liquid nitrogen. Wrap each of the three heating zones in heating tape.Connect the tapes to temperature controllers. When the chamber reaches the processing pressure of 52.5 millitorrs, close the martimer ampoule needle valve. Set the oxidant heater to 170 degrees Celsius, and the substrate and martimer heaters to 80 degrees Celsius.Heat at those temperatures for about ten minutes to fully vaporize the iron 3 chloride from the crucible. Confirm that vaporized iron 3 chloride is depositing as a red solid in the cool region of the tube, between the oxidant and the gas inlet before proceeding. Then, open the needle valve of the martimer ampoule, allow the blue colored thin films to grow to the desired thickness on the substrates.The needle valve to the martimer ampoules should be opened after iron chloride vapor is formed in the chamber. Otherwise, the martimer vapor will react with oxidant in the crucible to form a polymer layer around the powder surface. Close the martimer ampoule needle valve when the desired film thickness is achieved.Turn off the heating tapes, and allow the system to cool to room temperature under vacuum. Once the system has cooled, open the inert gas valve, and stop the vacuum pump. Remove the samples from the chamber using long tweezers.Immerse the samples in methanol for 30 minutes to remove residual unreacted oxidant and martimer. Handle films thicker than 500 nanometers on glass substrates with care, as they may delaminate during rinsing. When the methanol rinsing is complete, carefully dry the samples under a gentle stream of nitrogen gas.To begin the procedure, place two milliliters of EDOT in a quartz martimer ampoule. Connect the ampoule to the needle valve, and wrap them with the heating tape. Connect the ampoule to the tubular chamber, keeping the needle valve open.Next, use long tweezers to place 1.3 centimeter by 2.5 centimeter substrates adjacent to one another between the two reagent vapor inlets. Then, close the end of the chamber. In a fume hood, load two milliliters of liquid bromine into a quartz oxidant ampoule.Equip the ampoule with a closed needle valve. Connect the oxidant ampoule to the chamber via the closed needle valve. Then, start the vacuum pump with the inert gas inlet valve closed.Once the chamber pressure is below 525 millitorrs, fill the cold trap dewar with liquid nitrogen. Connect the heat tape wrapped martimer heating region to a temperature controller. When the chamber reaches the processing pressure of 52.5 millitorrs, set the martimer heater to 80 degrees Celsius.Heat at that temperature for about ten minutes to vaporize the martimer. Then, open the oxidant needle valve only slightly as liquid bromine is highly volatile. Monitor the deposition of the blue PE-DOT films so when the flims have reached their desired thickness, close the martimer and oxidant needle valves, turn off the heating tape, and allow the chamber to cool to room temperature under vacuum.Then, open the inert gas inlet valve, and stop the vacuum pump. When using bromine as the oxidant, rinsing is not needed. The maximum chlorine dubbed polyproDOT film thickness was observed at about two inches from the martimer ampoule inlet.Atomic force microscophy was used to characterize the morphology. The conductivity of a 100 nanometer thick chlorine dubbed polyproDot film was 106 siemans per centimeter. The removal of residual iron 3 chloride was confirmed with x-ray photo electron spectroscopy indicating that the conductivity is solely from the polymer.Chlorine dubbed PTT films were deposited on paper, corduroy fabric, and cotton town fabric, ultimately making the pristine white substrates appear dark red. Scanning electron microscopy indicated that the films were uniform in conformal on the three textured surfaces at a micrometer scale. UV vis spectroscopy of the chlorine dubbed polyproDot and bromine dubbed PEDOT films, showed broad featureless absorption bands beyond 600 nanometers, indicating that the films remained P-dubbed after removal of excess oxidant with methanol.This band was not observed for chlorine dubbed PTT, indicating that it was fully D-dubbed during the methanol rinse. Once mastered, this technique can be done in 2 hours, if it is performed properly. After its development, this technique allowed researchers to transform commercial fabrics and fibers into electronic components, by simply coating them with conducting or semi-conducting polymer films in our chamber.

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Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

Herein the procedures for plasma enhanced chemical vapor deposition of perfluoroalkanes on microporous materials such as metal-organic frameworks to enhance their stability and hydrophobicity are described. Furthermore, breakthrough testing of milligram quantities of samples is described in detail.

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high ...

A Technique to Functionalize and Self-assemble Macroscopic Nanoparticle-ligand Monolayer Films onto Template-free Substrates

This protocol describes a self-assembly technique to create macroscopic monolayer films composed of ligand-coated nanoparticles1,2. The simple, robust and scalable technique efficiently functionalizes metallic nanoparticles with thiol-ligands in a miscible water/organic solvent mixture allowing for rapid grafting of thiol groups onto the gold nanoparticle surface. The hydrophobic ligands on the nanoparticles then quickly phase separate the nanoparticles from the aqueous based suspension and confine them to the air-fluid interface. This drives the ligand-capped nanoparticles to form monolayer domains at the air-fluid interface.&#160; The use of water-miscible organic solvents is important as it enables the transport of the nanoparticles from the interface onto template-free substrates.&#160; The flow is mediated by a surface tension gradient3,4 and creates macroscopic, high-density, monolayer nanoparticle-ligand films.&#160; This self-assembly technique may be generalized to include the use of particles of different compositions, size, and shape and may lead to an efficient assembly method to produce low-cost, macroscopic, high-density, monolayer nanoparticle films for wide-spread applications.

A simple, robust and scalable technique to functionalize and self-assemble macroscopic nanoparticle-ligand monolayer films onto template-free substrates is described in this protocol.

This protocol describes a self-assembly technique to create macroscopic monolayer films composed of ligand-coated nanoparticles1,2. The simple, robust and ...

Fabrication of Large-area Free-standing Ultrathin Polymer Films

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films. Typically, ultrathin films are prepared using either sacrificial layers, which may damage the film or affect its mechanical properties, or they are made on freshly cleaved mica, a substrate that is difficult to scale. Further, the size of ultrathin film is typically limited to a few square millimeters. In this method, we modify a surface with a polyelectrolyte that alters the strength of adhesion between polymer and deposition substrate. The polyelectrolyte can be shown to remain on the wafer using spectroscopy, and a treated wafer can be used to produce multiple films, indicating that at best minimal amounts of the polyelectrolyte are added to the film. The process has thus far been shown to be limited in scalability only by the size of the coating equipment, and is expected to be readily scalable to industrial processes. In this study, the protocol for making the solutions, preparing the deposition surface, and producing the films is described.

We describe a method for the fabrication of large-area (up to 13 cm diameter) and ultrathin (as thin as 8 nm) polymer films. Instead of using a sacrificial interlayer to delaminate the film from its substrate, we use a self-limiting surface treatment suitable for arbitrarily large areas.

This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films.  Typically, ultrathin films are prepared ...

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 ...

Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in combination with their outstanding thermal and chemical stability, and low densities. However, their insoluble nature causes problems in their processing since usually applied techniques such as spin coating are not available. Especially for membrane applications, where the processing of CMP as thin films is desirable, the processing problems have hindered their commercial application.
Here we describe the interfacial synthesis of CMP thin films on functionalized substrates via molecular layer-by-layer (l-b-l) synthesis. This process allows the preparation of films with desired thickness and composition and even desired composition gradients.
The use of sacrificial supports allows the preparation of freestanding membranes by dissolution of the support after the synthesis. To handle such ultra-thin freestanding membranes the protection with sacrificial coatings showed great promise, to avoid rupture of the nanomembranes. To transfer the nanomembranes to the desired substrate, the coated membranes are upfloated at the air-liquid interface and then transferred via dip coating.

In this paper we describe the interfacial synthesis of conjugated microporous polymers (CMP) on sacrificial substrates, and the dissolution of the substrate for the preparation of freestanding CMP nanomembranes. In addition, we will describe how the fragile nanomembranes can be transferred to other substrates.

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in ...

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 ...

Capillary Electrophoresis to Monitor Peptide Grafting onto Chitosan Films in Real Time

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. Compared to other analytical separation techniques, such as chromatography, CE is cheap, robust and effectively requires no sample preparation (for a number of complex natural matrices or polymeric samples). CE is fast and can be used to follow the evolution of mixtures in real time (e.g., chemical reaction kinetics), as the signals observed for the separated compounds are directly proportional to their quantity in solution.
Here, the efficiency of CE is demonstrated for monitoring the covalent grafting of peptides onto chitosan films for subsequent biomedical applications. Chitosan&#39;s antimicrobial and biocompatible properties make it an attractive material for biomedical applications such as cell growth substrates. Covalently grafting the peptide RGDS (arginine - glycine - aspartic acid - serine) onto the surface of chitosan films aims at improving cell attachment. Historically, chromatography and amino acid analysis have been used to provide a direct measurement of the amount of grafted peptide. However, the fast separation and absence of sample preparation provided by CE enables equally accurate yet real-time monitoring of the peptide grafting process. CE is able to separate and quantify the different components of the reaction mixture: the (non-grafted) peptide and the chemical coupling agents. In this way the use of CE results in improved films for downstream applications.
The chitosan films were characterized through solid-state NMR (nuclear magnetic resonance) spectroscopy. This technique is more time-consuming and cannot be applied in real time, but yields a direct measurement of the peptide and thus validates the CE technique.

Free solution capillary electrophoresis is a fast, cheap and robust analytical method that enables the quantitative monitoring of chemical reactions in real time. Its utility for rapid, convenient and precise analysis is demonstrated here through analysis of covalent peptide grafting onto chitosan films for improved cell adhesion.

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. ...

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, we present a protocol for the fabrication of this material via the low-pressure vapor assisted solution process (LP-VASP) method, which yields ~19% power conversion efficiency in planar heterojunction perovskite solar cells. First, we report the synthesis of methylammonium iodide (CH3NH3I) and methylammonium bromide (CH3NH3Br) from methylamine and the corresponding halide acid (HI or HBr). Then, we describe the fabrication of pinhole-free, continuous methylammonium-lead halide perovskite (CH3NH3PbX3 with X = I, Br, Cl and their mixture) films with the LP-VASP. This process is based on two steps: i) spin-coating of a homogenous layer of lead halide precursor onto a substrate, and ii) conversion of this layer to CH3NH3PbI3-xBrx by exposing the substrate to vapors of a mixture of CH3NH3I and CH3NH3Br at reduced pressure and 120 &#176;C. Through slow diffusion of the methylammonium halide vapor into the lead halide precursor, we achieve slow and controlled growth of a continuous, pinhole-free perovskite film. The LP-VASP allows synthetic access to the full halide composition space in CH3NH3PbI3-xBrx with 0&#160;&#8804; x&#160;&#8804; 3. Depending on the composition of the vapor phase, the bandgap can be tuned between 1.6 eV&#160;&#8804; Eg&#160;&#8804; 2.3 eV. In addition, by varying the composition of the halide precursor and of the vapor phase, we can also obtain CH3NH3PbI3-xClx. Films obtained from the LP-VASP are reproducible, phase pure as confirmed by X-ray diffraction measurements, and show high photoluminescence quantum yield. The process does not require the use of a glovebox.

Here, we present a protocol for the synthesis of CH3NH3I and CH3NH3Br precursors and the subsequent formation of pinhole-free, continuous CH3NH3PbI3-xBrx thin films for the application in high efficiency solar cells and other optoelectronic devices.

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, ...

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, ...

Monitoring the Effects of Illumination on the Structure of Conjugated Polymer Gels Using Neutron Scattering

We demonstrate a protocol to effectively monitor the gelation process of a high concentration solution of conjugated polymer both in the presence and absence of white light exposure. By instituting a controlled temperature ramp, the gelation of these materials can be precisely monitored as they proceed through this structural evolution, which effectively mirrors the conditions experienced during the solution deposition phase of organic electronic device fabrication. Using small angle neutron scattering (SANS) and ultra-small angle neutron scattering (USANS) along with appropriate fitting protocols we quantify the evolution of select structural parameters throughout this process. Thorough analysis indicates that continued light exposure throughout the gelation process significantly alters the structure of the ultimately formed gel. Specifically, the aggregation process of poly(3-hexylthiophene-2,5-diyl) (P3HT) nano-scale aggregates is negatively affected by the presence of illumination, ultimately resulting in the retardation of growth in conjugated polymer microstructures and the formation of smaller scale macro-aggregate clusters.

A protocol for the analysis of gels formed from the optoelectronic conjugated polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) using small and ultra-small angle neutron scattering in both the presence and absence of illumination is presented.

We demonstrate a protocol to effectively monitor the gelation process of a high concentration solution of conjugated polymer both in the presence and ...