This work has been performed at the Molecular Foundry, Lawrence Berkeley National Laboratory and supported by the Office of Science, Office of Basic Energy Sciences, Scientific User Facilities Division of the US Department of Energy, under Contract No. DE-AC02&#8211;05CH11231. The financial support of F.M. by a ME-Fulbright fellowship and A.S. by Higher Education Commission of Pakistan are gratefully acknowledged.

NOTE: Before beginning, check all relevant material data sheets (MSDSs). Several of the chemicals used in the synthetic and application procedures are toxic. Please follow all appropriate safety practices and use adequate protective equipment (lab coat, full-length pants, closed-toe shoes, safety glasses, gloves). Please use all cryogenic personal protective equipment when handling liquid nitrogen for the nitrogen adsorption measurements (insulated gloves, face shield).
1. Porous Polymer Monolith Preparation in Bulk and Capillary Column Format
<ol>
	<li>Bulk Polymer Monolith for Characterization
	<ol>
		<li>Purify styrene, divinylbenzene and methacrylic acid through a column of basic alumina, in order to remove the polymerization inhibitors. Place 10 g of basic alumina in a 25 ml disposable plastic syringe with a plug of glass wool fiber packed in the syringe tip. Percolate approximately 10 ml of the monomer through the column.</li>
		<li>Load the monomers (50 mg styrene, 100 mg divinylbenzene and 50 mg methacrylic acid) and the pore forming agents (300 mg toluene and 300 mg isooctane) in a 1 ml glass vial. Add the initiator of the polymerization, 4 mg of 2,2&#8217;-azobisisobutyronitrile (AIBN, 1% with respect to monomers).</li>
		<li>Homogenize by sonication for 10 min. Remove dissolved oxygen by bubbling nitrogen through the liquid for 10 min. Seal the vial cap with paraffin film and place it in a water bath at 60&#160;&#176;C for 6 hr to polymerize the mixture.</li>
		<li>Cool to room temperature and break the vial carefully. Transfer the polymer monolith into a cellulose extraction thimble. Place the extraction thimble into a Soxhlet extraction chamber and assemble it to a round bottom flask that contains a volume of methanol, which is at least three times the volume of the extraction chamber. Assemble a condenser to the upper part of the extraction chamber. Perform Soxhlet extraction by boiling the methanol for 16 hr, ensuring the complete removal of the unreacted monomers and pore forming agents.</li>
		<li>Dry overnight in a vacuum oven at 60 &#176;C. Confirm the presence of carboxylic functional groups to attach the PCP by Fourier Transform Infrared Spectroscopy (FT-IR). Measure surface area by nitrogen adsorption porosimetry.</li>
	</ol>
	</li>
	<li>Functionalization of Silica Capillaries for the Preparation of Monolithic Columns
	<ol>
		<li>Cut 2 m of a polyimide-coated 100 &#181;m i.d. fused silica capillary. Connect it to a 0.25-0.50 ml glass syringe and wash the capillary with acetone. Remove the acetone by rinsing the capillary with water.</li>
		<li>In order to activate the internal silica coating of the capillary, use a syringe pump to flow a 0.2 M aqueous NaOH solution at 0.25 &#181;l/min for 30 min. Rinse with water until the effluent is neutral.</li>
		<li>Use pH paper strips to check effluent pH. In order to protonate the silanol groups of the capillary, pump a 0.2 M aqueous HCl solution through the capillary at 0.25 &#181;l/min for 30 min. Rinse with water until the effluent is neutral. Rinse with ethanol.</li>
		<li>Pump a 20% (w/w) ethanol solution of 3-(trimethoxysilyl)propyl methacrylate (pH 5 adjusted with acetic acid) at 0.25 &#181;l/min for 1 hr. In this step, the silica capillary is functionalized with vinyl groups in order to attach the polymer monolith to the capillary inner surface.</li>
		<li>Rinse with acetone, dry in a nitrogen stream and leave at room temperature overnight before use. Cut the capillary into shorter pieces of length 20 cm.</li>
	</ol>
	</li>
	<li>Preparation of Monolithic Capillary Columns
	<ol>
		<li>Prepare an identical polymerization mixture as for the bulk polymer monolith (section 1.1) in a 1 ml glass vial with a rubber septum. Add initiator 1% AIBN with respect to monomers. Homogenize by sonication for 10 min.</li>
		<li>Purge the polymerization mixture with nitrogen by coupling a non-functionalized silica capillary to a nitrogen stream.
		<ol>
			<li>Insert the nitrogen stream capillary through the rubber septum of the vial and immerse it into the polymerization mixture so that the nitrogen bubbles through the liquid. Leave the vial cap slightly loose to avoid overpressure. Purge for 10 min.</li>
			<li>Lift the nitrogen stream capillary from the polymerization mixture to the headspace of the vial, and close tightly the cap. Insert a functionalized capillary through the septum into the polymerization mixture. The excess of pressure generated into the capillary through the nitrogen injected into the headspace pumps the polymerization mixture through the functionalized capillary.</li>
			<li>Collect several drops of polymerization mixture from the effluent of the capillary to ensure that it is completely filled and close it with a rubber septum. Take the capillary out of the vial very carefully and close the inlet of the capillary with a rubber septum.</li>
		</ol>
		</li>
		<li>Polymerize the mixture contained in the capillary in a water bath at 60 &#176;C for 6 hr. Cool at room temperature and cut a few millimeters of both ends of the capillary. Remove unreacted monomers and pore forming agents by flushing the column with acetonitrile using an HPLC pump at 3 &#181;l/min for 30 min. Check backpressure of the capillary column.</li>
	</ol>
	</li>
</ol>
2. Growth of the Iron-benzenetrycarboxylate (FeBTC) PCP
<ol>
	<li>Growth of the FeBTC MOPH on a Bulk Polymer Monolith for Characterization
	<ol>
		<li>Grind the previously dried monolith using a mortar and pestle.</li>
		<li>Immerse 100 mg of the monolith powder in 5 ml of 2 mM FeCl3&#183;6H2O in ethanol for 15 min. Vacuum filter using a nylon filter (0.22 &#181;m) and wash the powder with ethanol. Immerse the monolith powder in 5 ml of 2 mM 1,3,5-benzenetricarboxylic acid (BTC) in ethanol for 15 min. Vacuum filter using a nylon filter (0.22 &#181;m) and wash the powder with ethanol.</li>
		<li>Repeat step number 2 as desired. The growth of the final metal-organic coating will be defined by the number of applied cycles. Typically, between 10 and 30 cycles are performed. Confirm the presence of new pores by nitrogen adsorption porosimetry. Measure the amount of additional metal sites by thermogravimetric analysis (TGA).</li>
	</ol>
	</li>
	<li>Growth of the FeBTC MOPH on a capillary monolithic column for the enrichment of phosphopeptides
	<ol>
		<li>Using a syringe pump. Flush the capillary monolith with 2 mM FeCl3&#183;6H2O in ethanol for 15 min at 2 &#181;l/min. Wash with ethanol for 15 min at 2 &#181;l/min. Flush the capillary monolith with a 2 mM BTC in ethanol for 15 min at 2 &#181;l/min. Wash with ethanol for 15 min at 2 &#181;l/min.</li>
		<li>Repeat step 1 as desired. The growth of the final metal-organic coating will be defined by the number of cycles performed.</li>
	</ol>
	</li>
</ol>
3. Protein Digestion and Enrichment of Phosphopeptides
<ol>
	<li>Protein Digestion
	<ol>
		<li>Dissolve 0.5 ml of non-fat milk in 1 ml of water and divide it into 200 &#181;l fractions.</li>
		<li>For the protein digestion add 160 &#181;l 1 M ammonium bicarbonate and 50 &#181;l 45 mM dithiothreitol to each fraction, in order to cleave the disulfide bonds. Incubate at 50 &#176;C in a thermomixer for 15 min.</li>
		<li>Add gradually 50 &#181;l of an aqueous solution of iodoacetamide 100 mM, while the solution cooled down to room temperature. Iodoacetamide will prevent the formation of new disulfide bonds.</li>
		<li>Incubate in the dark for 15 min at room temperature. Add 1 ml deionized water. Add 2 &#181;g trypsin and digest proteins in a thermomixer at 37 &#176;C for 14 hr.</li>
		<li>Terminate digestion by acidification with 10 &#181;l of 1% trifluoroacetic acid, and placing it in the thermomixer for 5 min at room temperature. Store the digested proteins at &#8211;20 &#176;C.</li>
	</ol>
	</li>
	<li>Enrichment of phosphopeptides using a capillary MOPH column.
	<ol>
		<li>Flush the column with 100 &#181;l of a 4:1 mixture of acetonitrile containing a 0.1% trifluoroacetic acid for 10 min at a flow rate of 1 &#181;l/min. Pump the protein digestion through the column at 2 &#181;l/min for 30 min.</li>
		<li>Wash out the non-phosphorylated peptides again with a 4:1 mixture of acetonitrile containing a 0.1% trifluoroacetic acid for 10 min at a flow rate of 1 &#181;l/min. Wash with water for 10 min at a flow rate of 1 &#181;l/min.</li>
		<li>Elute phosphopeptides using a 250 mM pH 7 phosphate buffer solution pumped at 1 &#181;l/min for 15 min. Collect the eluent in a vial and desalt the solution using a standard protocol19. Prepare a 2 mg/ml 2,5-dihydroxybenzoic acid to use it as the matrix for the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Drawn 2 &#181;l of the 2,5-dihydroxybenzoic acid into the tip to elute the phosphopeptides and spot them directly on to the MALDI plate.</li>
		<li>Analyze the spots by MALDI-TOF-MS and regenerate the column by flushing thoroughly with water and then methanol.</li>
	</ol>
	</li>
</ol>

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The authors have nothing to disclose.

The original polymer monolith contains carboxylic functional groups able to bind to metals. Coordinating the initial metal sites on the original material, we are able to grow a PCP coating (Figure 1A), incorporating a number of additional metal sites shaping a microporous network. This makes the presented MOPH materials attractive for extraction or purification procedures where metallic species are involved, such as the immobilized metal-ion affinity chromatography (IMAC) technique. The general procedure...

Porous coordination polymers (PCPs) are coordination compounds based on metal centers linked by organic ligands with repeating coordination entities extending in 1, 2 or 3 dimensions that can be amorphous or crystalline1-3. In recent years, this class of porous materials has attracted widespread attention due to their high porosity, wide chemical tunability, and their stability. PCPs have been explored for a range of applications including gas storage, gas separation, and catalysis3-6, and very recently, the first analytical applications of PCPs have been described7.
Because of their enhanced chemical functionality and high porosity PCPs have been targeted for their huge potential for the improvement of purification processes and chromatographic separations, and a number of reports concerning this topic have been published7-13. However, the performance of PCPs is not currently at an equivalent level with existing chromatographic materials likely due to fast diffusion through large interparticle voids in packed beds of these solids due to their typically irregularly shaped morphologies of their particles or crystals. This irregularly distributed packing leads to a lower than expected performance, as well as high column backpressures and undesirable peak shape morphologies14,15.
In order to solve the problem of fast diffusion through the inter-particle voids and concomitantly enhance the performance of PCPs for analytical applications, the development of a hybrid material based on a macroporous polymer monolith16 that contains the PCP on the surface of the macropores would be desirable. Polymer monoliths are self-contained, single-piece materials that can sustain convective flow through their pores, which makes them one of the most efficient alternatives to bead packings and have been successfully commercialized by several companies17,18.&#160;Porous polymer monoliths are usually based on the polymerization of a monomer and a crosslinker in the presence of porogens, which are typically binary mixtures of organic solvents. The obtained monolithic materials have a microglobular structure and a high porosity and flow permeability.
A simple approach to unify these materials to prepare a polymer monolith containing a PCP is based on the direct addition of as-synthesized PCPs in the polymerization mixture of the monolith. This approach resulted in PCPs mostly buried within a polymer scaffold, and not being active for the further application of the final material14,15. A different synthetic approach is clearly needed in order to, for example, develop uniform films of PCPs, or crystalline metal-organic frameworks (MOFs) where the majority of the pores contained within the crystal are accessible from the macropores of the polymer monolith.
Herein we report a simple protocol for the preparation of a metal-organic polymer hybrid material (MOPH) based on a macroporous polymer support with suitable functional groups for the attachment of PCPs, which can be easily implemented as a self-contained single-piece polymer monolith in a column format with optimum properties for flow-through applications. The polymer synthesis procedure is followed by a simple room temperature solution-based&#160;method to grow a PCP coating on the internal surface of the pores of the monolith19-20. As the first example, we describe the preparation of an iron(III) benzenetricarboxylate (FeBTC) coordination polymer film within a macroporous poly(styrene-divinylbenzene-methacrylic acid) monolith. This method is effective for the preparation of bulk powders as well as capillary columns and the described protocol is readily implementable to other PCPs. As an example of the potential of MOPHs as functional materials for flow-through applications, we applied the developed FeBTC MOPH which contains a dense coating of Fe(III) centers to enrich phosphopeptides from digested protein mixtures exploiting the binding affinity of phosphopeptides to Fe(III). The developed protocol21 comprises three main parts: Preparation of the macroporous organic polymer monolith support; growth of the PCP coating on the surface of the pores of the monolith; application for the enrichment of phosphopeptides.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Polyimide-coated capillaries</td>
			<td>Polymicro Technologies</td>
			<td>TSP100375</td>
			<td>100 &#956;m i.d.</td>
		</tr>
		<tr>
			<td>3-(trimethoxysilyl)propyl methacrylate, 98%</td>
			<td>Sigma-Aldrich</td>
			<td>440159</td>
			<td></td>
		</tr>
		<tr>
			<td>Styrene, 99%</td>
			<td>Sigma-Aldrich</td>
			<td>W323306</td>
			<td>Technical grade</td>
		</tr>
		<tr>
			<td>Divinylbenzene, 80%</td>
			<td>Sigma-Aldrich</td>
			<td>414565</td>
			<td></td>
		</tr>
		<tr>
			<td>Methacrylic acid, 98%</td>
			<td>Mallinckrodt</td>
			<td>MK150659</td>
			<td></td>
		</tr>
		<tr>
			<td>Toluene, &#8805;99.5%</td>
			<td>EMD chemicals</td>
			<td>MTX0735-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Isooctane, &#8805;99.5%</td>
			<td>Sigma-Aldrich</td>
			<td>650439</td>
			<td></td>
		</tr>
		<tr>
			<td>2,2&#39;-azobisisobutyronitrile, 98%</td>
			<td>Sigma-Aldrich</td>
			<td>441090</td>
			<td></td>
		</tr>
		<tr>
			<td>Aluminium oxide (basic alumina)</td>
			<td>Sigma-Aldrich</td>
			<td>199443</td>
			<td></td>
		</tr>
		<tr>
			<td>Iron (III) chloride hexahydrate, 97%</td>
			<td>Sigma-Aldrich</td>
			<td>236489</td>
			<td></td>
		</tr>
		<tr>
			<td>1,3,5-benzenetrycarboxylic acid, 95%</td>
			<td>Sigma-Aldrich</td>
			<td>482749</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetonitrile, &#8805;99.5%</td>
			<td>Sigma-Aldrich</td>
			<td>360457</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium bicarbonate, &#8805;99.5%</td>
			<td>Sigma-Aldrich</td>
			<td>9830</td>
			<td></td>
		</tr>
		<tr>
			<td>Trifluoroacetic acid, &#8805;99%</td>
			<td>Sigma-Aldrich</td>
			<td>302031</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol, &#8805;99.8%</td>
			<td>Sigma-Aldrich</td>
			<td>2854</td>
			<td></td>
		</tr>
		<tr>
			<td>Iodoacetamide, &#8805;99%</td>
			<td>Sigma-Aldrich</td>
			<td>I1149</td>
			<td></td>
		</tr>
		<tr>
			<td>Dithiothreitol, &#8805;99%</td>
			<td>Sigma-Aldrich</td>
			<td>43819</td>
			<td></td>
		</tr>
		<tr>
			<td>Monobasic sodium phosphate dihydrate, &#8805;99%</td>
			<td>Sigma-Aldrich</td>
			<td>71505</td>
			<td></td>
		</tr>
		<tr>
			<td>Dibasic sodium phosphate dihydrate, &#8805;99%</td>
			<td>Sigma-Aldrich</td>
			<td>71643</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphoric acid, &#8805;85%</td>
			<td>Sigma-Aldrich</td>
			<td>438081</td>
			<td></td>
		</tr>
		<tr>
			<td>2,5-dihydroxybenzoic acid, &#8805;99%</td>
			<td>Sigma-Aldrich</td>
			<td>85707</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin</td>
			<td>Sigma-Aldrich</td>
			<td>T8003</td>
			<td>Bovine pancreas</td>
		</tr>
		<tr>
			<td>&#946;-casein</td>
			<td>Sigma-Aldrich</td>
			<td>C6905</td>
			<td>Bovine milk</td>
		</tr>
		<tr>
			<td>ZipTip pipette tips</td>
			<td>Merck Millipore</td>
			<td>ZTC18S096</td>
			<td>C18 resin</td>
		</tr>
	</tbody>
</table>

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 schematic illustration of the PCP growth on the pore surface of the organic polymer monolith is shown in Figure 1. In this figure, we illustrate the initial Fe(III) atoms retained on the pore surface of the original polymer monolith coordinated to carboxylic functional groups. Using the protocol described herein additional organic ligand and Fe(III) ions are added to the surface, shaping a porous coordination network within the polymer monolith. Figure 1 also shows schematically the us...

Watch this Scientific Journal Video about Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides at JoVE.com

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

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 ...

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JoVE Journal

Chemistry

10.0K vistas.  E. O. Lawrence Berkeley National Laboratory. 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.

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

Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures

The behavior of confined colloidal suspensions with attractive interparticle interactions is critical to the rational design of materials for directed assembly1-3, drug delivery4, improved hydrocarbon recovery5-7, and flowable electrodes for energy storage8. Suspensions containing fluorescent colloids and non-adsorbing polymers are appealing model systems, as the ratio of the polymer radius of gyration to the particle radius&#160;and concentration of polymer control the range and strength of the interparticle attraction, respectively. By tuning the polymer properties and the volume fraction of the colloids, colloid fluids, fluids of clusters, gels, crystals, and glasses can be obtained9.&#160;Confocal microscopy, a variant of fluorescence microscopy, allows an optically transparent and fluorescent sample to be imaged with high spatial and temporal resolution in three dimensions. In this technique, a small pinhole or slit blocks the emitted fluorescent light from regions of the sample that are outside the focal volume of the microscope optical system. As a result, only a thin section of the sample in the focal plane is imaged. This technique is particularly well suited to probe the structure and dynamics in dense colloidal suspensions at the single-particle scale: the particles are large enough to be resolved using visible light and diffuse slowly enough to be captured at typical scan speeds of commercial confocal systems10. Improvements in scan speeds and analysis algorithms have also enabled quantitative confocal imaging of flowing suspensions11-16,37.&#160;In this paper, we demonstrate confocal microscopy experiments to probe the confined phase behavior and flow properties of colloid-polymer mixtures. We first prepare colloid-polymer mixtures that are density- and refractive-index matched. Next, we report a standard protocol for imaging quiescent dense colloid-polymer mixtures under varying confinement in thin wedge-shaped cells. Finally, we demonstrate a protocol for imaging colloid-polymer mixtures during microchannel flow.

Confocal microscopy is used to image quiescent and flowing colloid-polymer mixtures, which are studied as model systems for attractive suspensions. Image analysis algorithms are used to calculate structural and dynamic metrics for the colloidal particles that measure changes due to geometric confinement.

The behavior of confined colloidal suspensions with attractive interparticle interactions is critical to the rational design of materials for directed ...

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 ...

Photodynamic Therapy with Blended Conducting Polymer/Fullerene Nanoparticle Photosensitizers

In this article a method for the fabrication and reproducible in-vitro evaluation of conducting polymer nanoparticles blended with fullerene as the next generation photosensitizers for Photodynamic Therapy (PDT) is reported. The nanoparticles are formed by hydrophobic interaction of the semiconducting polymer MEH-PPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]) with the fullerene PCBM (phenyl-C61-butyric acid methyl ester) in the presence of a non-compatible solvent. MEH-PPV has a high extinction coefficient that leads to high rates of triplet formation, and efficient charge and energy transfer to the fullerene PCBM. The latter processes enhance the efficiency of the PDT system through fullerene assisted triplet and radical formation, and ultrafast deactivation of MEH-PPV excited stated. The results reported here show that this nanoparticle PDT sensitizing system is highly effective and shows unexpected specificity to cancer cell lines.

This protocol describes a method for the fabrication of conducting polymer nanoparticles blended with fullerene. These nanoparticles were investigated for their potential use as a next generation photosensitizers for Photodynamic Therapy (PDT).

In this article a method for the fabrication and reproducible in-vitro evaluation of conducting polymer nanoparticles blended with fullerene as the next ...

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 ...

Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous solution. In a carbon nanotube/PEO105-PPO70-PEO105 (poloxamer 407) aqueous solution, the amphiphilic poloxamer 407 adsorbs onto the carbon nanotube surfaces and self-assembles into continuous layers, driven by intermolecular interactions between constituent molecules. The addition of 5-methylsalicylic acid changes the self-assembled structure from spherical-micellar to a cylindrical morphology. The fabricated poloxamer 407/carbon nanotube hybrid particles exhibit thermo-responsive structural features so that the density and thickness of poloxamer 407 layers are also reversibly controllable by varying temperature. The detailed structural properties of the poloxamer 407/carbon nanotube particles in suspension can be characterized by small-angle neutron scattering experiments and model fit analyses. The distinct curve shapes of the scattering intensities depending on temperature control or addition of aromatic additives are well described by a modified core-shell cylinder model consisting of a carbon nanotube core cylinder, a hydrophobic shell, and a hydrated polymer layer. This method can provide a simple but efficient way for the fabrication and in-situ characterization of carbon nanotube-based nano particles with a structure-tunable encapsulation.

A method for the functionalization of carbon nanotubes with structure-tunable polymeric encapsulation layers and structural characterization using small-angle neutron scattering is presented.

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous ...

The Preparation and Properties of Thermo-reversibly Cross-linked Rubber Via Diels-Alder Chemistry

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ethylene-propylene rubber, grafted with maleic anhydride, is thermo-reversibly cross-linked in two steps. The pending anhydride moieties are first modified with furfurylamine to graft furan groups to the rubber backbone. These pendant furan groups are then cross-linked with a bis-maleimide via a Diels-Alder coupling reaction. Both reactions can be performed under a broad range of experimental conditions and can easily be applied on a large scale. The material properties of the resulting Diels-Alder cross-linked rubbers are similar to a peroxide-cured ethylene/propylene/diene rubber (EPDM) reference. The cross-links break at elevated temperatures (&#62; 150 &#176;C) via the retro-Diels-Alder reaction and can be reformed by thermal annealing at lower temperatures (50-70 &#176;C). Reversibility of the system was proven with infrared spectroscopy, solubility tests and mechanical properties. Recyclability of the material was also shown in a practical way, i.e., by cutting a cross-linked sample into small parts and compression molding them into new samples displaying comparable mechanical properties, which is not possible for conventionally cross-linked rubbers.

A simple two-step approach involving rubber modification and cross-linking yields fully reworkable, elastic rubber products.

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ...

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 ...

Microfluidic Dry-spinning and Characterization of Regenerated Silk Fibroin Fibers

The protocol demonstrates a method for mimicking the spinning process of silkworm. In the native spinning process, the contracting spinning duct enables the silk proteins to be compact and ordered by shearing and elongation forces. Here, a biomimetic microfluidic channel was designed to mimic the specific geometry of the spinning duct of the silkworm. Regenerated silk fibroin (RSF) spinning doped with high concentration, was extruded through the microchannel to dry-spin fibers at ambient temperature and pressure. In the post-treated process, the as-spun fibers were drawn and stored in ethanol aqueous solution. Synchrotron radiation wide-angle X-ray diffraction (SR-WAXD) technology was used to investigate the microstructure of single RSF fibers, which were fixed to a sample holder with the RSF fiber axis normal to the microbeam of the X-ray. The crystallinity, crystallite size, and crystalline orientation of the fiber were calculated from the WAXD data. The diffraction arcs near the equator of the two-dimensional WAXD pattern indicate that the post-treated RSF fiber has a high orientation degree.

A protocol for the microfluidic spinning and microstructure characterization of regenerated silk fibroin monofilament is presented.

The protocol demonstrates a method for mimicking the spinning process of silkworm. In the native spinning process, the contracting spinning duct enables ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Time-resolved Photophysical Characterization of Triplet-harvesting Organic Compounds at an Oxygen-free Environment Using an iCCD Camera

Here, we present a sensible method of the acquisition and analysis of time-resolved photoluminescence using an ultrafast iCCD camera. This system enables the acquisition of photoluminescence spectra covering the time regime from nanoseconds up to 0.1 s. This enables us to follow the changes in the intensity (decay) and emission of the spectra over time. Using this method, it is possible to study diverse photophysical phenomena, such as the emission of phosphorescence, and the contributions of prompt and delayed fluorescence in molecules showing thermally activated delayed fluorescence (TADF). Remarkably, all spectra and decays are obtained in a single experiment. This can be done for solids (thin film, powder, crystal) and liquid samples, where the only limitations are the spectral sensitivity of the camera and the excitation wavelength (532 nm, 355 nm, 337 nm, and 266 nm). This technique is, thus, very important when investigating the excited state dynamics in organic emitters for their application in organic light-emitting diodes and other areas where triplet harvesting is of paramount importance. Since triplet states are strongly quenched by oxygen, emitters with efficient TADF luminescence, or those showing room temperature phosphorescence (RTP), must be correctly prepared in order to remove any dissolved oxygen from solutions and films. Otherwise, no long-lived emission will be observed. The method of degassing solid samples as presented in this work is basic and simple, but the degassing of liquid samples creates additional difficulties and is particularly interesting. A method of minimizing solvent loss and changing the sample concentration, while still enabling to remove oxygen in a very efficient and a repeatable manner, is presented in this work.

Here, we present a method of the spectroscopic characterization of organic molecules by means of time-resolved photoluminescence spectroscopy on the nanosecond-to-millisecond timescale in oxygen-free conditions. Methods to efficiently remove oxygen from the samples and, thus, limit luminescence quenching are also described.

Here, we present a sensible method of the acquisition and analysis of time-resolved photoluminescence using an ultrafast iCCD camera. This system enables ...