Este trabajo realizado bajo los auspicios del Departamento de Energía de Estados Unidos por el Laboratorio Nacional Lawrence Livermore bajo contrato DE-AC52-07NA27344.

1. Preparación de soluciones <ol><li> Filtra 60 g de lactato de etilo utilizando una jeringa y un filtro de jeringa de 0,20 micras. Añadir 0,3 g de polivinil formal al lactato de etilo. Coloque la solución en el horno a 50 ° C durante 4 h. Agitar el vial suavemente para ver si el polímero se ha disuelto por completo. <ol><li> Si la solución está turbia o aún muestra inhomogeneidades ópticas, devuelva el vial al horno por otro 2 hr. Esta receta es para una solución de polímero de 0,5% en peso, que se utiliza típicamente para espesores de película alrededor de 30 nm. Soluciones con mayor contenido en peso de polímero se pueden utilizar para películas más gruesas. </li></ol></li><li> Preparar una solución PDAC pesando 1,0 g de reactivo PDAC en un matraz aforado de 20 ml y llenar el frasco a la línea de medición con agua desionizada (DI). Agitar la solución con suavidad antes de transferirla a un contenedor de almacenamiento. </li></ol> 2. Preparación del soporte <ol><li> PRECAUCIÓN. Verter 60 ml de ácido sulfúrico concentradoácido en un vaso de precipitados de 250 ml limpio. Poco a poco agregue 20 ml de peróxido de hidrógeno al 30%. Espere hasta que echando humo subsidios, a continuación, haga girar la solución suavemente. La solución y el vaso de precipitados se alcanzan temperaturas muy elevadas y la mezcla es corrosiva. </li><li> Coloque una placa de Petri de 150 mm sobre la placa caliente y verter el ácido en el plato. Ajuste la placa caliente a 100 ° C. <ol><li> Coloque una oblea de 4 &#39;de silicio en el ácido con el lado brillante hacia arriba. Empuje suavemente la oblea en el centro con un par de pinzas para asegurarse de que toda la superficie se humedece. Deja la oblea en el ácido durante 30 minutos. </li></ol></li><li> Retire la oblea a partir del ácido con un par de pinzas y enjuague la parte delantera y trasera de la oblea a fondo con agua DI a partir de una botella con atomizador. El agua debe sábana en un patrón regular. Seque la oblea en un banco limpio. </li><li> Enjuague una jeringa desechable de 3 ml y un filtro primero con agua DI 0,2 micras y luego con solución PDAC dibujando el líquido en la jeringa, el montaje del filtro, y eln empujando el líquido hacia fuera a través del filtro. </li><li> Montar una oblea limpiado en el revestidor de giro. Elabore 1,0-1,2 ml de solución PDAC en la jeringa y dispensarla aunque el filtro en el medio de la oblea. Centrifugado a 4.000 rpm durante 15 segundos, a continuación, transferir la oblea a una placa caliente (precalentado a 50 ° C) y dejar reposar durante 30 segundos. </li><li> Enjuague la capa PDAC seca con agua DI y dejar que la oblea seco en la mesa de trabajo limpia. </li></ol> Fabricación 3. Cine <ol><li> Coloque una oblea tratada con PDAC seco sobre la recubridora de rotación. </li><li> Enjuague una jeringuilla disponible 3 ml y un filtro de 0,45 micras con la solución de lactato de etilo utilizando el procedimiento descrito en 2.4). </li><li> Depósito de 2,5 ml de la solución de lactato de etilo a través del filtro con la jeringa en el medio de la oblea y centrifugado durante 10 segundos a 200 rpm, entonces para 3 segundos a 1.700 rpm (dependiente de espesor de película deseado). No debe haber una película líquida uniforme en la oblea. </li><li> Deje secar la película en el dispositivo de recubrimiento espínhasta que esté visiblemente seca (por lo general 10 a 15 min), luego se coloca sobre una placa caliente (precalentado a 50 ° C) durante 10 minutos. </li><li> Cortar las películas en cuadrados más pequeños para el despegue, típicamente 2 cm x 2 cm, pero puede ser mayor, dependiendo del tamaño del soporte de película utilizada (3.5.1-3.5.2). Alternativamente, haga dos escribas de deslaminación una película-oblea de tamaño (3.5.3). Nota: Los soportes de película estándar son 19 x 19 mm, con una abertura circular de 13 mm de diámetro en el centro. Para películas de la oblea de tamaño, utilizar un aro de alambre (por ejemplo, alambre de acero inoxidable formado en un círculo) con un diámetro que es 1 &quot;más pequeño que la oblea. Una abertura circular es elegido porque las películas se suelen absorber el agua durante el despegue y el oleaje. Como las películas secas en el soporte, se elimina el agua y la película se contraerá. Una abertura circular permite una distribución uniforme de la tensión. <ol><li> Coloque la oblea en una plantilla de corte. Utilice una plantilla cuadrada en la que todos los bordes son más altos que la oblea para prevenir la recta eDGE utiliza para guiar la hoja durante trazado de tocar la oblea. Marque los bordes en intervalos de 2 cm para guiar la colocación de la regla durante el corte en dados. Empuje la oblea contra dos bordes para alinearlo. </li><li> Coloque una regla a lo largo de dos marcas de alineación, y trazar una hoja de afeitar suavemente a lo largo del borde recto para trazar la película. Aplique la presión suficiente para marcar la película, pero no demasiado, para marcar la propia oblea y producir partículas. En películas más gruesas, la línea de corte será claramente visible. </li><li> Para el despegue de una película en una sola pieza a partir de la oblea, trazar el borde de la oblea con una hoja de afeitar. Entre las dos partes planas de la oblea, trazar una tira lo suficientemente amplia como para sujetar la oblea sobre la cremallera y piñón. </li></ol></li><li> Llene un plato de 190 mm x 100 cultivo con agua DI. Sujete la oblea por el gran apartamento de un estante y piñón montado en una etapa de inclinación y baje lentamente en el agua DI. La película debe separarse de la oblea en la línea de agua. <ol><li> Continuar bajando el WAFer a una velocidad que da el tiempo suficiente película de separar de la oblea, en lugar de empujar la interfaz de lift-off por debajo de la línea de agua. Cuando la primera fila de cuadrados ha separado de la oblea y se flotando en la superficie, hacer una pausa en la reducción de la oblea. Para una película-oblea de tamaño, continúe sumergiendo la oblea hasta que la película se separa por completo. </li><li> Sumergir la cabeza del soporte para películas en el agua y moverla por debajo de la película. Alinee el borde mango del aro con uno de los bordes de la película y tocar el aro con la película. Si tiene éxito, la película se pegará al aro. <ol><li> Para una película oblea grande, colocar el aro de alambre debajo de la sección describe, sólo un centímetro de distancia de la orilla. Asegúrese de que el aro se centra debajo de la película antes de comenzar la captura, mantener cierta distancia entre borde de la película y el borde del aro para que la película puede envolver alrededor del aro y doblar sobre sí mismo. </li></ol></li><li> Retraer el aro lentamente desde el agua a unaángulo de 35 °. Levante la película fuera del agua muy lentamente. Nota: Para las películas de menos de 20 nm de espesor, aumentar el ángulo después de aproximadamente la mitad de la película ha sido sacado del agua a casi 90 ° (es decir, normal a la superficie del agua) para evitar tirar la película a través del soporte. Al cambiar el ángulo de elevación hacia fuera, hacerlo lentamente para evitar tirar de la película a través del aro. </li><li> Cuando el aro esté completamente retraído, colóquelo a un lado para que se seque. Asegúrese de que la parte inferior del aro es libre de gotas antes de poner el aro hacia abajo, y el uso de una superficie curva (como una bandeja de obleas) para evitar la creación de un sello líquido entre aro y superficie. </li><li> Si cuadrados más trazadas permanecen en la oblea, seguir bajando la oblea en el agua y repetir los pasos 3.6.1-3.6.4 anteriormente para los cuadrados restantes. </li><li> Que las películas seco O / N. </li></ol></li></ol>

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Los autores no tienen nada que revelar.

El tratamiento sustrato PDAC se basa en las interacciones electrostáticas auto-limitación, es decir, los sustratos de cualquier tamaño pueden ser tratados siempre con facilidad que tienen carga negativa (por ejemplo, silicio o vidrio). Figuras 1-2 muestra muy grandes películas delgadas (hasta 13 cm de diámetro) fabricados utilizando este protocolo, con el único cambio es el volumen de los reactivos utilizados. El tamaño final alcanzable parece estar limitada sólo por el equipo de deposi...

Autoportante películas poliméricas delgadas se utilizan en una variedad de aplicaciones, incluyendo sensores, 1-3 MEM, la catálisis o filtración, 4 y la ingeniería de tejidos. 8.5 También se utilizan para estudios fundamentales que exploran el comportamiento de los polímeros en un espacio limitado. 9- 13 Una película independiente es uno que está soportado sobre un sustrato no continuo, tal como un anillo anular o aro en contraposición a una oblea de silicio o portaobjetos de vidrio. Este trabajo describe un procedimiento sencillo y repetible para la fabricación de películas de polímeros ultrafinos exentas que es adecuado para películas de gran superficie o la producción de alto rendimiento. Es compatible con una variedad de diferentes polímeros, incluyendo poli (vinil formal), poliestireno y poli (metacrilato de metilo). Se puede utilizar para fabricar películas de pie libres que son tan grandes como 13 cm de diámetro o tan delgado como 10 nm. La fabricación de polímeros exentas consiste en tres pasos básicos: 1) deposition de película de polímero sobre un sustrato tradicional tal como una oblea o diapositiva, 2) la liberación o el despegue de la película del sustrato, y 3) la captura de la película resultante sobre un soporte. En este trabajo se detalla un procedimiento que se informó en un estudio anterior sobre diversos métodos de liberación. 14 La deposición se puede lograr por cualquier número de tecnologías de película de polímero finas básicas tales como spin-revestimiento, deposición de vapor, o recubrimiento por inmersión. En este trabajo, utilizamos técnicas spin-revestimiento estándar. El &quot;flotar fuera del ascensor en&quot; técnica es el método más común para la liberación de una película ultrafina de su sustrato. 15 En esta técnica, la película y el sustrato se sumergen en un baño de disolvente adecuado. El disolvente se hincha la película e induce la delaminación espontánea, la liberación de la película y permitiendo que flote a la parte superior de la bañera. El espesor mínimo de película que puedeser liberados mediante ascensor fuera de flotador en está determinada por el equilibrio de la energía peeling interfacial con la energía de deformación inducida por la inflamación-: 16 <img alt="Ecuación 1" src="/files/ftp_upload/52832/52832eq1.jpg" width="200" /> (1) Donde L es el espesor de la película, ν f es la relación de la película de Poisson, E es el módulo de Young de la película, ξ es la relación de hinchamiento de la película, y γ es la energía interfacial de pelar. La forma típica de eludir la limitación impuesta por la ecuación (1) es depositar una capa intermedia sacrificial entre la película y el sustrato de deposición. 17-20 Cuando esta capa intermedia se disuelve en un baño de disolvente, la película se libera y puede ser capturada sobre un soporte . Un método relacionado es el método sobrecapa sacrificial, que utiliza pelado mecánico de la película sobre una capa de sacrificio prIOR a la disolución. 21 El uso de materiales de sacrificio tiene varios inconvenientes principales. En primer lugar, la adición de un material de proceso adicional y paso puede requerir un compromiso entre las condiciones de fabricación de película óptimas y condiciones de procesamiento material de sacrificio. En segundo lugar, los materiales de sacrificio pueden ser difíciles de depósito sin afectar a las propiedades mecánicas o la pureza de la película independiente final. En tercer lugar, el proceso para depositar el material de sacrificio debe ser optimizado y monitoreado por la calidad como una operación en la fabricación total de la película de independiente. 14 En este trabajo se describe una técnica de modificación de la superficie que disminuye la energía interfacial pelado, lo que permite el ascensor fuera de flotador en la técnica que se utiliza para las películas ultrafinas. El sustrato de deposición es modificado por el montaje de un autolimitada, la auto-optimización casi monocapa del cloruro polydiallyldiammonium policatión (PDAC). Debido a lafuerza de la unión entre el policatión y el sustrato, esta modificación de la superficie es robusto a pasos de proceso subsiguientes. La naturaleza autolimitante y la auto-optimización de la formación cercana a la monocapa requiere prácticamente nula optimización y es fácilmente escalable a grandes áreas. Después de la retirada, la película flota en la superficie del baño de disolvente en el que se captura en un soporte de aro. Si bien no se da mucha atención en la literatura existente, en este trabajo vamos a describir las técnicas para la captura de películas de gran superficie sobre soportes que reducen la probabilidad de romper o dañar de otro modo la película.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Vinylec E</td>
			<td>SPI</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ethyl lactate, &#62;98%, FCC, FG,</td>
			<td>Sigma-Aldrich</td>
			<td>W244007-1KG-K</td>
			<td></td>
		</tr>
		<tr>
			<td>4&#34; silicon wafers &#60;100&#62;, Single side polished</td>
			<td>International Wafer Service</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>sulfuric acid, 98%, ACS reagent grade</td>
			<td>Sigma-Aldrich</td>
			<td>320501-6X500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>hydrogen peroxide, 30%, semiconductor grade</td>
			<td>Sigma-Aldrich</td>
			<td>316989-3.7L</td>
			<td></td>
		</tr>
		<tr>
			<td>isopropanol, ACS grade, 4 L</td>
			<td>Fisher Scientific</td>
			<td>A464-4</td>
			<td></td>
		</tr>
		<tr>
			<td>dichloromethane, ACS grade</td>
			<td>Alfa-Aesar</td>
			<td>22917</td>
			<td></td>
		</tr>
		<tr>
			<td>deionized water , distilled</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PDAC reagent (Sigma-Aldrich 409014)</td>
			<td>Sigma-Aldrich</td>
			<td>409014</td>
			<td></td>
		</tr>
		<tr>
			<td>Spin Coater</td>
			<td>Laurell Technologies&#160;</td>
			<td>WS-650-23</td>
			<td></td>
		</tr>
		<tr>
			<td>Barnstead/Thermolyne Super Nuova explosion-proof hot plate&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>explosion-proof forced air oven</td>
			<td>VWR&#160;</td>
			<td>1330 FMS&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>balance with a range of 1 mg to 1020 g</td>
			<td>Mettler Toledo</td>
			<td>MS1003S</td>
			<td></td>
		</tr>
		<tr>
			<td>reflectance spectrometer</td>
			<td>Filmetrics</td>
			<td>F20-UV</td>
			<td></td>
		</tr>
		<tr>
			<td>manipulator consisting of a Klinger tilt stage, a Brinkman rack-and-pinion and a lab jack&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cutting tool/template, LLNL-built, no drawings</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>straight edge, LLNL, no drawings</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tent hoop, LLNL</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>culture dish 190 mm x 100 mm, Pyrex</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>20 ml beaker, Pyrex</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>250 ml beaker, Pyrex</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1000 ml beaker, Pyrex</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>60 ml glass vial with plastic stopper&#160;</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>petri dish, 150 mm diameter x2, Pyrex</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>600 ml beaker x2, Pyrex</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>tweezers, stainless steel</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>cutting blade</td>
			<td>Exacto</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>clean room wipes</td>
			<td>Contec&#160;</td>
			<td>PNHS-99</td>
			<td></td>
		</tr>
		<tr>
			<td>polyester knit 9/91 IPA/DI water wipes</td>
			<td>Contec&#160;</td>
			<td>Prosat&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluoroware wafer trays</td>
			<td>Ted Pella</td>
			<td>1395-40</td>
			<td></td>
		</tr>
		<tr>
			<td>Nylon Micro fiber (camel hair)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable BD 3-mL plastic syringe</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>0.2 um&#160; Luer-lock PTFE filters</td>
			<td>Acrodisc&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>0.45 um&#160; Luer-lock PTFE filters</td>
			<td>Acrodisc&#160;</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

La Figura 1 muestra un ejemplo de una película delgada de polímero independiente sobre un área grande. Este 55 nm de espesor de película de polivinilo formal fue fabricado usando el procedimiento descrito aquí y está montado en un aro de acero de diámetro 13 cm. La delaminación se produce en grandes áreas sin introducir defectos que conducen a la rotura de la película. Por lo tanto, la fuerza intrínseca de polivinilformal puede ser explotado incluso para películas muy delgadas. La fi...

Watch this Scientific Journal Video about Fabrication of Large-area Free-standing Ultrathin Polymer Films at JoVE.com

Fabrication of Large-area Free-standing Ultrathin Polymer Films

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.

La fabricación de superficies de gran autoportante ultrafinos Polymer Films

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

fabrication-of-large-area-free-standing-ultrathin-polymer-films

Research

JoVE Journal

Chemistry

15.2K vistas.  Lawrence Livermore National Laboratory. 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.

Video: Fabrication of Large-area Free-standing Ultrathin Polymer Films

Towards Biomimicking Wood: Fabricated Free-standing Films of Nanocellulose, Lignin, and a Synthetic Polycation

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and lignin. Layer-by-layer (LbL) assembly process which relies on the assembly of oppositely charged molecules from aqueous solutions was used to build a freestanding composite film of isolated wood polymers of lignin and oxidized nanofibril cellulose (NFC). To facilitate the assembly of these negatively charged polymers, a positively charged polyelectrolyte, poly(diallyldimethylammomium chloride) (PDDA), was used as a linking layer to create this simplified model cell wall. The layered adsorption process was studied quantitatively using quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry. The results showed that layer mass/thickness per adsorbed layer increased as a function of total number of layers. The surface coverage of the adsorbed layers was studied with atomic force microscopy (AFM). Complete coverage of the surface with lignin in all the deposition cycles was found for the system, however, surface coverage by NFC increased with the number of layers. The adsorption process was carried out for 250 cycles (500 bilayers) on a cellulose acetate (CA) substrate. Transparent free-standing LBL assembled nanocomposite films were obtained when the CA substrate was later dissolved in acetone. Scanning electron microscopy (SEM) of the fractured cross-sections showed a lamellar structure, and the thickness per adsorption cycle (PDDA-Lignin-PDDA-NC) was estimated to be 17 nm for two different lignin types used in the study. The data indicates a film with highly controlled architecture where nanocellulose and lignin are spatially deposited on the nanoscale (a polymer-polymer nanocomposites), similar to what is observed in the native cell wall.

The objective of this research was to form synthetic plant cell wall tissue using layer-by-layer assembly of nanocellulose fibrils and isolated lignin assembled from dilute aqueous suspensions.&#160; Surface measurement techniques of quartz crystal microbalance and atomic force microscopy were used to monitor the formation of the polymer-polymer nanocomposite material.

Hacia Biomimicking Madera: Fabricada en monobloque películas de nanocellulose, lignina, y una Policatión sintético

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and ...

Investigación

Química

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.

Imagen confocal de Confinados en reposo y que fluye mezclas de coloide y polímeros

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

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.

Preparación de altamente poroso Coordinación Polymer Coatings en macroporosas Polymer Monolitos de Enriquecimiento mejorada de Phosphopeptides

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

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).

Terapia fotodinámica con Blended polímero conductor / Fullerene nanopartículas fotosensibilizadores

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

Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements are simple high-throughput characterization experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glassy states for a variety of glassy materials. This technique allows for these parameters to be measured in a single experiment, while other methods must combine a variety of different techniques to investigate all of these properties. Measurements of dynamics close to Tg are particularly challenging. The advantage of cooling rate dependent Tg measurements over other methods which directly probe bulk and surface relaxation dynamics is that they are relatively quick and simple experiments, which do not utilize fluorophores or other complicated experimental techniques. Furthermore, this technique probes the average dynamics of technologically relevant thin films in temperature and relaxation time (&#964;&#945;) regimes relevant to the glass transition (&#964;&#945; &#62; 100 sec). The limitation to using ellipsometry for cooling rate dependent Tg experiments is that it cannot probe relaxation times relevant to measurements of viscosity (&#964;&#945; &#60;&#60; 1 sec). Other cooling rate dependent Tg measurement techniques, however, can extend the CR-Tg method to faster relaxation times. Furthermore, this technique can be used for any glassy system so long as the integrity of the film remains throughout the experiment.

Here, we present a protocol for cooling rate dependent ellipsometry experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glass for a variety of glassy materials.

Enfriamiento Puntúa Medidas Elipsometría Dependientes para determinar la dinámica de Thin Films vidriosos

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements ...

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.

La preparación y propiedades de termo-reversible reticulado Química Caucho Vía de Diels-Alder

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

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.

La electroforesis capilar para supervisar Péptido injerto sobre quitosano películas en tiempo real

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

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.

Seco de microfluidos-spinning y caracterización de las fibras regeneradas fibroína de seda

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

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.

Tiempo-resolved fotofísicas caracterización de trío cosecha compuestos orgánicos en un libre de oxígeno ambiente usando un iCCD cámara

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

Raman and IR Spectroelectrochemical Methods as Tools to Analyze Conjugated Organic Compounds

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule on the vibrational level of energy. Raman and IR spectroelectrochemistry can be used for advanced characterization of the structural changes in the organic electroactive compounds. Here, the step-by-step analysis by means of Raman and IR spectroelectrochemistry is shown. Raman and IR spectroelectrochemical techniques provide complementary information about structural changes occurring during an electrochemical process, i.e. allows for the investigation of redox processes and their products. The examples of IR and Raman spectroelectrochemical analysis are presented, in which the products of the redox reactions, both in solution and solid state, are identified.

A protocol of step-by-step Raman and IR spectroelectrochemical analysis is presented.

Raman y métodos IR electroquímicas como herramientas para analizar compuestos orgánicos conjugados

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule ...

Methods Article

La fabricación de superficies de gran autoportante ultrafinos Polymer Films