Name: grafting multiwalled carbon nanotubes with polystyrene to enable self-assembly and anisotropic patchiness
Uploaded: 2018-04-01T13:00:00
Description: Watch this Scientific Journal Video about Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness at JoVE.com

Nos gustaría reconocer los programas de FQ-PAIP y DGAPA-PAPIIT de la Universidad Nacional Autónoma de México (números de concesión 9158 5000, 5000-9156, IA205616 y IA205316) y el Consejo Nacional de ciencia y tecnología de México - CONACYT-(número de concesión 251533).

PRECAUCIÓN: Consulte todas las hojas de datos de seguridad del material (MSDS) antes de su uso. Varios de los productos químicos utilizados en el presente Protocolo son muy tóxicos y cancerígenos. Derivados de nanotubos de carbono pueden tener peligros respiratorios adicionales comparados con otros alótropos del carbono tradicional a granel. Se sospecha que los nanotubos de carbono en aerosol pueden afectar los pulmones de una manera similar que el amianto, aunque sus propiedades carcinogénicas no sido totalmente a...

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En este método, hay algunos pasos que resultan fundamentales para garantizar un exitoso proceso de injerto. En primer lugar, la reacción de oxidación bifásico catalítico mediada (paso 1.1) debe llevarse a cabo con nanotubos de carbono recientemente dispersos (paso 1.1.1.5). Si la dispersión resulta inviable según las recomendaciones contenidas en el protocolo, el uso de un sonicador ultrasónico punta sería útil si usa las mismas indicaciones (paso 1.1.1.6). Utilización de ello más corto también puede ayudar ...

Desde el descubrimiento de los nanotubos de carbono de pared única (SWCNTs),1,2 las comunidades científicas han aplicado sus excelentes propiedades eléctricas, mecánicas y térmicas3 en una amplia gama de vanguardia aplicaciones por sus propiedades de superficie vía covalente4 y no covalentes5 estrategias de modulación. Ejemplos de estas aplicaciones incluyen su uso como transductores sensores,6,7 electrodos en celdas solares,8 heterogéneos admite en catálisis, nanoreactors9 en síntesis,10 antiincrustantes agentes de películas protectoras,11 rellenos en materiales compuestos,12etcetera. Sin embargo, la posibilidad de modular las propiedades superficiales de los más robustos, pero industrialmente disponible pirólisis contrapartes, a saber, ello, para el control de la direccionalidad en sus interacciones no covalentes en la nanoescala, ha mantenido una difícil tarea hasta ahora. 13
Supramolecular uno mismo-Asamblea moleculares de bloques de construcción es una de las estrategias más versátiles para el control de la organización de la materia a escala nanométrica. 14 , 15 en este sentido, las interacciones supramoleculares implican direccional, de corto alcance y gama media interacciones no covalentes tales como H-enlaza, Van der Waals, dipolo-dipolo, ion-dipolo, dipolo dipolo inducido, apilamiento π-π, catión-π, anión-π, coulombic, entre otros. 16 Desafortunadamente, direccionalidad en uno mismo-montaje de estructuras más grandes como ello no es espontáneo y requiere generalmente las fuerzas motivo externo (por ejemplo, plantillas o sistemas de disipación de energía). 17 un envoltorio no covalentes de reciente informe utilizado de nanotubos con copolímeros a medida para perseguir el objetivo último,18 pero el uso de estrategias covalentes para ofrecer nuevas alternativas para resolver el problema han permanecido apenas explorado.
Modificación química de nanotubos de carbono puede realizarse selectivamente para introducir diferentes grupos funcionales a la termini o a las paredes laterales de la misma. 19 , 20 uno de los métodos más útiles para adaptar las propiedades superficiales en nanoestructuras de carbono es el polímero de injerto a través de rutas de polimerización standard. Por lo general, los métodos implican la introducción preliminar de polimerizables o grupos de iniciador (acrílico, vinilo, etcetera) en la superficie de nanoestructura y su polimerización sucesiva con un monómero adecuado. 21 en el caso de ello, la introducción covalente de las cadenas de polímero en las paredes laterales para el control de sus pliegues de forma anisotrópica sigue siendo un desafío.
Aquí mostramos cómo se puede aplicar una serie de pasos de fácil modificación química22,23 para insertar cadenas de PS en las paredes laterales de ello con el fin de modificar sus pliegues superficiales y para promover su anisotrópico uno mismo-Asamblea23 a escala nanométrica. Durante el recorrido de la modificación, un primer paso permite la hidroxilación selectiva de ello inmaculado en las paredes laterales siguiendo un bifásico catalítico mediada por reacción de oxidación para producir, a saber, las contrapartes hidroxiladas MWCNT-OH. Un segundo paso utiliza 3-(trimetoxisilil) metacrilato de propilo (TMSPMA) para introducir moléculas de metacrilato sililada a los grupos del oxhidrilo creado anteriormente (MWCNT-O-TMSPMA). Estas piezas se ofrecen sitios reactivos superficiales durante un tercer paso, cuando se polimeriza el monómero de estireno de las moléculas de metacrilato así que las cadenas de polímero injertadas a las paredes laterales de los nanotubos en el final (es decir MWCNT-O-PS).

<table border="0" cellpadding="0" cellspacing="0" width="1573">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Tetrapropylammonium bromide, 99 % (TPABr)</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">88104</td>
			<td style="width:895px;">Irritant, toxic</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:379px;">Potassium permanganate, 99 % (KMnO4)</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">223468</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Acetic acid, 99.5 %</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">45726</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:379px;">Pristine multiwalled carbon nanotubes, 99 % (MWCNTs)</td>
			<td style="width:181px;">Bayer Technology Services</td>
			<td style="width:119px;">Donated sample</td>
			<td>Harmful dusts. &#62;1 mm in length and 13&#8211;16 nm in outer diameter. Alternative supplier: Nanocyl, Catalog N. NC7000, website: http://www.nanocyl.com/</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Sodium Chloride, 98 % (NaCl)</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td style="width:119px;">S3014</td>
			<td>Technical grade can also be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Ethanol, 99.8 % (EtOH)</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">32221</td>
			<td>Technical grade can also be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Methanol, 99.8 % (MeOH)</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">322415</td>
			<td>Highly toxic. Technical grade can also be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Hydroquinone, 99 %</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td style="width:119px;">H9003</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Toluene, 99.8 %</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">244511</td>
			<td>Anhydrous</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">3-(Trimethoxysilyl)propyl methacrylate, 98 % (TMSPMA)</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">440159</td>
			<td>Air sensitive, toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Azobisisobutyronitrile, 99 % (AIBN)</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">755745</td>
			<td>Explosive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Styrene, 99 %</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td style="width:119px;">S4972</td>
			<td>Purified using an alumina gel preparative column and stored at 4 &#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Acetone, 99.5 %</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">179124</td>
			<td>Technical grade can also be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Tetrahydrofuran, 99.9 % (THF)</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">494461</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Dichloromethane, 99.5 %</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">443484</td>
			<td>Highly toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Hydrochloric acid, 37 %</td>
			<td style="width:181px;">Sigma-Aldrich</td>
			<td align="right" style="width:119px;">435570</td>
			<td>Harmful fumes</td>
		</tr>
	</tbody>
</table>

grafting multiwalled carbon nanotubes with polystyrene to enable self-assembly and anisotropic patchiness

Demostramos un protocolo sencillo para injerto de nanotubos de carbono pirólisis prístina (ello) con cadenas de poliestireno (PS) en las paredes laterales a través de una estrategia de polimerización de radicales libres para permitir la modulación de las propiedades superficiales de nanotubos y producir uno mismo-montaje de las nanoestructuras supramoleculares. En primer lugar, una hidroxilación selectiva de los nanotubos prístinas a través de una reacción de oxidación bifásico catalítico mediada crea sitios reactivos superficialmente distribuidos en las paredes laterales. Los últimos sitios reactivos se modifican posteriormente con grupos metacrilato utilizando sililada metacrílico precursor para crear sitios polimerizables. Esos grupos polimerizables pueden abordar otra polimerización de estireno para producir un nanomaterial híbrido que contiene cadenas PS injertadas a los flancos de nanotubos. El contenido de polímero-injerto, cantidad de sililada metacrílico moieties introducido y modificación de la hidroxilación de los nanotubos son identificados y cuantificados por análisis termogravimétrico (TGA). Se confirma la presencia de grupos funcionales reactivos del oxhidrilo y sililada metacrilato por Fourier transforman espectroscopía infrarroja (FT-IR). Soluciones de nanotubos de carbono de poliestireno injertado en tetrahidrofurano (THF) proporcionan pared nanotubos collinearly uno mismo-montado cuando las muestras son analizadas por microscopia electrónica de transmisión (TEM). Ésos uno mismo-asambleas no se obtienen cuando espacios adecuados son asimismo de soluciones análogas con contrapartes no injertado. Por lo tanto, este método permite la modificación de los pliegues anisotrópico de nanotubos en las paredes laterales que se traduce en auto-organización espontánea en la nanoescala.

Se recogieron datos TGA de nanotubos prístinos, nanotubos hidroxilados, nanotubos modificados con partes de metacrilato sililada y nanotubos de poliestireno injertado (figura 1). Resultados de FT-IR se recolectaron de nanotubos hidroxilados y nanotubos modificación con sililada metacrílico fracciones (figura 2). Se recolectaron imágenes TEM de nanotubos de prístinos y nanotubos de poliestireno injertado (<strong class="xfig"...

Watch this Scientific Journal Video about Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness at JoVE.com

Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness

Un procedimiento para la síntesis de nanotubos de carbono de la pirólisis de poliestireno injertado mediante modificación química sucesivos pasos a selectivamente introducir las cadenas del polímero en las paredes laterales y su uno mismo-montaje mediante pliegues anisotrópico es presentado.

Injerto de nanotubos de carbono pirólisis con poliestireno para permitir uno mismo-Asamblea y pliegues anisotrópico

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a ...

The overall goal of this procedure is to offer a straightforward strategy for grafting multiwalled carbon nanotubes by polystyrene chains, which mediates a pro-molecular self-assembly and anisotropic patchiness. This method can help to modulate the surface properties of multiwalled carbon nanotubes, so as to establish improved processing conditions of the same in the field of thermoplastic polymers. The grafting strategy offers a straightforward alternative in processing protocols for carbon nanotubes in order to compatibilize them with industrially relevant, yet challenging polymers, such as polystyrene.In general, the method starts with the traditional hydroxyl groups on the side walls of pristine carbon nanotubes followed by the coupling of silylated methacrylic moieties to the OH groups, and their sequential free radical polymerization with styrene on the inner atmosphere. To find the yield, nanotubes grafted with polystyrene chains. The main advantage of this technique is that it can be easily deployed to mole surface properties of carbon nanotubes.And consequently, promote their anisotropic self assembly, which in turn may facilitate their inclusion in a polymer matrix. This technique opens promising alternatives to improve the supply chain of nanostructure carbon nanotropes in industrial processes, thus allowing for the creation of electrical percolation networks in polymer composites, which could find direct applications in electromagnetic shielding systems, mechanically reinforced parts, and electrically conducting materials under attractive cost-benefit conditions. Dry to 5 grams of pristine multi-walled carbon nanotubes, by introducing them into a vacuum oven at 80 Celsius degrees and 200 millimeters of mercury for 12 hours.Pour the dried carbon nanotubes into a 100 milliliter round-bottom flask. Afterwards, transfer 50 milliliters of dichloromethane, 99 percent, into the flask, and set the mechanical stirring at 60 rpm. This will be the organic phase of a bi-faceted chotilitically mediated reaction.In order to prepare the aqueous phase, dissolve 0.6 grams of tetroaropyl ammonium bromide in five milliliters of distilled water. Add five milliliters of acetic acid and five milliliters of an aqueous solution, containing potassium permanganate, 0.16 molar. Pour the latter solution into the round-bottom flask, already containing the organic phase and agitate vigorously, for example, about 80 rpm at room temperature for 24 hours.After that time, transfer the reaction mixture into a separatory funnel. Then, agrigate around 0.25 milliliters of concentrated hydrochloric acid, 36 percent, and carefully agitate the system and purge. Then, discard the supernatant aqueous phase.Once the aqueous phase was retired, the organic phase can be filtered using a vacuum filtration system as it is further described. Set this topper on base firmly into the neck of the filtered flask. With the small-tip forceps, center out 47 millimeter diameter membrane filter on the support surface.Make sure to use a membrane with a pore size between 0.45 micrometers and 20 micrometers. Smaller pore sizes will easily block, while larger pore sizes will retain lower amounts of filtered nanotubes. Without disturbing the filter, center the flange of the holder on top of the assembly and lock the funnel and base together with a spring clamp.Connect the filtering flask to the vacuum source, pour the sample into the funnel, and apply vacuum to filter the sample. Once the filter solid looks to be dried, wash with methanol 95 percent for at least five times the volume of the filtered solution. Afterward, transfer the solute into a petri dish and let it dry under vacuum for 24 hours at 80 Celsius degrees, at 200 millimeters of mercury.In order to insert polymerizable methacrylic moieties into the hydroxilated carbon nanotube walls, disperse about 2.5 grams of the nanotubes and five grams of hydrochinoin 99 percent, using a 100 milliliters schlenk flask. Then, with the aid of a cannula, carefully add 50 milliliters of Toluene under nitrogen atmosphere, using a vacuum inner gas manifold. Later, put it under vigorous mechanical agitation.Then, incorporate five milliliters of 3-thremethyl silane propel methacrylate 98 percent, and take it to reflux at 100 Celsius degrees for 12 hours. Once the reaction is complete, wash the obtained product with methanol in excess, using the vacuum filtration system and dry it overnight under vacuum at 80 Celsius degrees and 200 millimeters of mercury and store until needed. In order to graft the methacrylic modified nanotubes with acetoground polystyrene chains, disperse about 2.5 grams of the modified carbon nanotubes and 75 milligrams of AIBN in 50 milliliters of toluene.Using a shlenk flask, improach the system with nitrogen atmosphere, using the vacuum inner gas manifold. Then, add freshly purified 7.5 milliliters of styrene monomer. AIBN will act as the initiator of the free-radical polymerization.Subsequently, set the heating system at 70 Celsius degrees and stir it for 12 hours, under nitrogen atmosphere and reflux. Afterwards, filter the reaction mixture using the vacuum filtration system. Wash it with acetone, and finally wash it again with DHF 99 percent for at least five times to remove unbound polystyrene.Dry the product under vacuum for 24 hours at 80 Celsius degrees and 200 millimeters of mercury. The solid will contain carbon nanotubes grafted with polystyrene chains. The polymer grafted carbon nanotubes were characterized by TM.Here are representative TM images for dropcast samples in which polystyrene wraps its carbon nanotubes appear as partially aligned and self-assembled by the side walls.Such behavior is absent when pristine nanotubes are analyzed in a similar form. The values curve of thermogramemetric analysis for polymer-modified carbon nanotubes showed that the first weight loss, due to the loss of polystyrene chains starts at 270 Celsius degrees. Then, a second moderated step, which starts around 400 Celsius degrees, is caused by the loss of the siliyated methracrylic moieties, where as the final remark weight loss starting at around 600 Celsius degrees, corresponds to the carbon nanotubes.Here we show our representative weight loss present-age curve of grafted carbon nanotubes with polyester range in comparison with pristine ones, which confirms that the most significant alteration in the samples weighed is comprised between 270 Celsius degrees and 775 Celsius degrees. From TGA, it is possible to affirm that after the hydroxilation step, carbon nanotube-side walls will typically contain hydroxyl moieties at two percent to five percent in weight. It is important to mention that after co-insulating material moieties to the OH groups, modified carbon nanotubes will typically contain between eight and ten percent weight for methracrylic in comparison with the nanotube content.Once accomplished, the free radical polymerization with styrene, it is typically expected a grafting degree of about 30 to 40 percent relative to the nanotube weight. So, a selective modification of the surface properties of the nanotubes is obtained by successive chemical modification in steps to insert reactive functional robselectively to the side walls. We expect that this strategy can be reapplied to other acrylic or vinyl derivative polymer types and new hybrid materials and composites could arise in the future.After watching this video, you should have a good understanding of the different steps needed to chemically modify carbon nanotubes with acetogram polyester range chains, which might play an important role in the surface properties of that kind of carbon nanotubes via super-molecular forces. This can result in the creation of self-assembly nanotubes through anisotropic nanoscale interactions, with potential applications in wide areas, such as material science and engineering, nanoscience and nanotechnology, or macromolecular chemistry. While attempting this procedure, it is important to be aware of the hazardous conditions of all reactants used in this technique, and ensure the use of suitable laboratory equipment.

Research

JoVE Journal

Chemistry

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