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A facile synthesis of polypyrrole/carbon nanotube composites with ultrathin, uniform and thickness-tunable polypyrrole shells.

Zhang B, Xu Y, Zheng Y, Dai L, Zhang M, Yang J, Chen Y, Chen X, Zhou J - Nanoscale Res Lett (2011)

Bottom Line: An improved approach to assemble ultrathin and thickness-tunable polypyrrole (PPy) films onto multiwall carbon nanotubes (MWCNTs) has been investigated.The coated PPy films can be easily tuned by adding ethanol and adjusting a mass ratio of pyrrole to MWCNTs.Moreover, the thickness of PPy significantly influences the electronic conductivity and capacitive behavior of the PPy/MWCNT composites.

View Article: PubMed Central - HTML - PubMed

Affiliation: Key Lab Polymer Composite & Funct Mat, Key Lab Designed Synth & Applicat Polymer Mat, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275, China. lzdai@xmu.edu.cn.

ABSTRACT
An improved approach to assemble ultrathin and thickness-tunable polypyrrole (PPy) films onto multiwall carbon nanotubes (MWCNTs) has been investigated. A facile procedure is demonstrated for controlling the morphology and thickness of PPy film by adding ethanol in the reaction system and a possible mechanism of the coating formation process is proposed. The coated PPy films can be easily tuned by adding ethanol and adjusting a mass ratio of pyrrole to MWCNTs. Moreover, the thickness of PPy significantly influences the electronic conductivity and capacitive behavior of the PPy/MWCNT composites. The method may provide a facile strategy for tailoring the polymer coating on carbon nanotubes (CNTs) for carbon-based device applications.

No MeSH data available.


Diagram of synthesis process for PPy/MWCNT composites.
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Figure 1: Diagram of synthesis process for PPy/MWCNT composites.

Mentions: The preparation of the PPy/MWCNT composites based on a improved in situ chemical oxidation polymerization method which can be expressed in Figure 1. The surface modification of MWCNTs was performed with carboxylic acid groups yielding MWCNT-COOH. Importantly, two points should be noted in the improved reaction process: 1) The adding sequence of monomer and initiator is an effective way to achieve polymerization in the desired locations. The carboxylic acid groups are likely to offer the interfacial interaction between the polymer and the nanotubes due to the hydrogen bonds formed between -COOH groups of chemically modified MWCNTs and NH groups of the PPy[21]. The contact junctions between MWCNTs and PPy films can be remarkablely improved by avoiding the use of insulating surfactants and other organic solutions. 2) The CNTs easily precipitate into ropes or bundles due to the hydrophobic nature and strong van der Waals interactions between CNTs. So the homogeneous dispersion of nanotubes in solution with high surface area is particularly important. Ethanol is added in aqueous solution which is beneficial to well disperse the tubes and stabilize the MWCNTs to prevent agglomerations or precipitate. Moreover, ethanol is often used as the free radical collecting agent which exhibits a restraint effect on the polymerization reaction. The polymerization rate of pyrrole monomers is reduced by adding ethanol, this can control the self polymerization of pyrrole monomers and favor the even attachment of polymer film on the MWCNTs surface. It is clearly shown in the low resolution typical transmission electron microscopy (TEM) images (see Figure S1 in Additional file 1), compared with that prepared without adding ethanol, carbon nanotubes are better dispersed and not randomly entangled in the PPy/MWCNT composites by adding ethanol in solution. In addition, the surface of the PPy/MWCNT composites appears to be smooth and uniform, and no agglomerations or irregular nanoparticles of polymer are found. The various ratio of ethanol and acid solution as the reaction solution significantly influence the morphology of the PPy/MWCNT composites. The detail of synthesis process is described in ESM. The PPy films coating on the surface of CNTs synthesized in the mixed solution of Vethanol/Vacid solution = 1:1 are smoother and more uniform compared with those obtained in the Vethanol/Vacid solution = 1:5 solution, but the reaction time is prolonged markedly [24] (TEM images as shown in Figure S2 in Additional file 1). It proves our conjecture that the ethanol can effectively reduce the polymerization rate of PPy.


A facile synthesis of polypyrrole/carbon nanotube composites with ultrathin, uniform and thickness-tunable polypyrrole shells.

Zhang B, Xu Y, Zheng Y, Dai L, Zhang M, Yang J, Chen Y, Chen X, Zhou J - Nanoscale Res Lett (2011)

Diagram of synthesis process for PPy/MWCNT composites.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211849&req=5

Figure 1: Diagram of synthesis process for PPy/MWCNT composites.
Mentions: The preparation of the PPy/MWCNT composites based on a improved in situ chemical oxidation polymerization method which can be expressed in Figure 1. The surface modification of MWCNTs was performed with carboxylic acid groups yielding MWCNT-COOH. Importantly, two points should be noted in the improved reaction process: 1) The adding sequence of monomer and initiator is an effective way to achieve polymerization in the desired locations. The carboxylic acid groups are likely to offer the interfacial interaction between the polymer and the nanotubes due to the hydrogen bonds formed between -COOH groups of chemically modified MWCNTs and NH groups of the PPy[21]. The contact junctions between MWCNTs and PPy films can be remarkablely improved by avoiding the use of insulating surfactants and other organic solutions. 2) The CNTs easily precipitate into ropes or bundles due to the hydrophobic nature and strong van der Waals interactions between CNTs. So the homogeneous dispersion of nanotubes in solution with high surface area is particularly important. Ethanol is added in aqueous solution which is beneficial to well disperse the tubes and stabilize the MWCNTs to prevent agglomerations or precipitate. Moreover, ethanol is often used as the free radical collecting agent which exhibits a restraint effect on the polymerization reaction. The polymerization rate of pyrrole monomers is reduced by adding ethanol, this can control the self polymerization of pyrrole monomers and favor the even attachment of polymer film on the MWCNTs surface. It is clearly shown in the low resolution typical transmission electron microscopy (TEM) images (see Figure S1 in Additional file 1), compared with that prepared without adding ethanol, carbon nanotubes are better dispersed and not randomly entangled in the PPy/MWCNT composites by adding ethanol in solution. In addition, the surface of the PPy/MWCNT composites appears to be smooth and uniform, and no agglomerations or irregular nanoparticles of polymer are found. The various ratio of ethanol and acid solution as the reaction solution significantly influence the morphology of the PPy/MWCNT composites. The detail of synthesis process is described in ESM. The PPy films coating on the surface of CNTs synthesized in the mixed solution of Vethanol/Vacid solution = 1:1 are smoother and more uniform compared with those obtained in the Vethanol/Vacid solution = 1:5 solution, but the reaction time is prolonged markedly [24] (TEM images as shown in Figure S2 in Additional file 1). It proves our conjecture that the ethanol can effectively reduce the polymerization rate of PPy.

Bottom Line: An improved approach to assemble ultrathin and thickness-tunable polypyrrole (PPy) films onto multiwall carbon nanotubes (MWCNTs) has been investigated.The coated PPy films can be easily tuned by adding ethanol and adjusting a mass ratio of pyrrole to MWCNTs.Moreover, the thickness of PPy significantly influences the electronic conductivity and capacitive behavior of the PPy/MWCNT composites.

View Article: PubMed Central - HTML - PubMed

Affiliation: Key Lab Polymer Composite & Funct Mat, Key Lab Designed Synth & Applicat Polymer Mat, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275, China. lzdai@xmu.edu.cn.

ABSTRACT
An improved approach to assemble ultrathin and thickness-tunable polypyrrole (PPy) films onto multiwall carbon nanotubes (MWCNTs) has been investigated. A facile procedure is demonstrated for controlling the morphology and thickness of PPy film by adding ethanol in the reaction system and a possible mechanism of the coating formation process is proposed. The coated PPy films can be easily tuned by adding ethanol and adjusting a mass ratio of pyrrole to MWCNTs. Moreover, the thickness of PPy significantly influences the electronic conductivity and capacitive behavior of the PPy/MWCNT composites. The method may provide a facile strategy for tailoring the polymer coating on carbon nanotubes (CNTs) for carbon-based device applications.

No MeSH data available.