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Effect of the carbon nanotube surface characteristics on the conductivity and dielectric constant of carbon nanotube/poly(vinylidene fluoride) composites.

Carabineiro SA, Pereira MF, Pereira JN, Caparros C, Sencadas V, Lanceros-Mendez S - Nanoscale Res Lett (2011)

Bottom Line: Commercial multi-walled carbon nanotubes (CNT) were functionalized by oxidation with HNO3, to introduce oxygen-containing surface groups, and by thermal treatments at different temperatures for their selective removal.CNT/poly(vinylidene fluoride) composites were prepared using the above CNT samples, with different filler fractions up to 1 wt%.It was found that oxidation reduced composite conductivity for a given concentration, shifted the percolation threshold to higher concentrations, and had no significant effect in the dielectric response.

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Affiliation: Universidade do Porto, Faculdade de Engenharia, Laboratório de Catálise e Materiais (LCM), LSRE/LCM - Laboratório Associado, Rua Dr, Roberto Frias, s/n, 4200-465 Porto, Portugal. sonia.carabineiro@fe.up.pt.

ABSTRACT
Commercial multi-walled carbon nanotubes (CNT) were functionalized by oxidation with HNO3, to introduce oxygen-containing surface groups, and by thermal treatments at different temperatures for their selective removal. The obtained samples were characterized by adsorption of N2 at -196°C, temperature-programmed desorption and determination of pH at the point of zero charge. CNT/poly(vinylidene fluoride) composites were prepared using the above CNT samples, with different filler fractions up to 1 wt%. It was found that oxidation reduced composite conductivity for a given concentration, shifted the percolation threshold to higher concentrations, and had no significant effect in the dielectric response.

No MeSH data available.


Acidic and basic groups on CNT's surface.
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Figure 1: Acidic and basic groups on CNT's surface.

Mentions: Oxidations with HNO3 originate materials with large amounts of surface acidic groups, mainly carboxylic acids and, to a smaller extent, lactones, anhydrides, and phenol groups [10,13,14]. These oxygenated groups (Figure 1) are formed at the edges/ends and defects of graphitic sheets [15]. The different surface-oxygenated groups created upon oxidizing treatments decompose by heating, releasing CO and/or CO2, during a TPD experiment. As this release occurs at specific temperatures, identification of the surface groups is possible [10,13,14]. It is well known that CO2 formation results from the decomposition of carboxylic acids at low temperature, and lactones at higher temperature; carboxylic anhydrides originate both CO and CO2; phenols and carbonyl/quinone groups produce CO [10,13,14].


Effect of the carbon nanotube surface characteristics on the conductivity and dielectric constant of carbon nanotube/poly(vinylidene fluoride) composites.

Carabineiro SA, Pereira MF, Pereira JN, Caparros C, Sencadas V, Lanceros-Mendez S - Nanoscale Res Lett (2011)

Acidic and basic groups on CNT's surface.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211369&req=5

Figure 1: Acidic and basic groups on CNT's surface.
Mentions: Oxidations with HNO3 originate materials with large amounts of surface acidic groups, mainly carboxylic acids and, to a smaller extent, lactones, anhydrides, and phenol groups [10,13,14]. These oxygenated groups (Figure 1) are formed at the edges/ends and defects of graphitic sheets [15]. The different surface-oxygenated groups created upon oxidizing treatments decompose by heating, releasing CO and/or CO2, during a TPD experiment. As this release occurs at specific temperatures, identification of the surface groups is possible [10,13,14]. It is well known that CO2 formation results from the decomposition of carboxylic acids at low temperature, and lactones at higher temperature; carboxylic anhydrides originate both CO and CO2; phenols and carbonyl/quinone groups produce CO [10,13,14].

Bottom Line: Commercial multi-walled carbon nanotubes (CNT) were functionalized by oxidation with HNO3, to introduce oxygen-containing surface groups, and by thermal treatments at different temperatures for their selective removal.CNT/poly(vinylidene fluoride) composites were prepared using the above CNT samples, with different filler fractions up to 1 wt%.It was found that oxidation reduced composite conductivity for a given concentration, shifted the percolation threshold to higher concentrations, and had no significant effect in the dielectric response.

View Article: PubMed Central - HTML - PubMed

Affiliation: Universidade do Porto, Faculdade de Engenharia, Laboratório de Catálise e Materiais (LCM), LSRE/LCM - Laboratório Associado, Rua Dr, Roberto Frias, s/n, 4200-465 Porto, Portugal. sonia.carabineiro@fe.up.pt.

ABSTRACT
Commercial multi-walled carbon nanotubes (CNT) were functionalized by oxidation with HNO3, to introduce oxygen-containing surface groups, and by thermal treatments at different temperatures for their selective removal. The obtained samples were characterized by adsorption of N2 at -196°C, temperature-programmed desorption and determination of pH at the point of zero charge. CNT/poly(vinylidene fluoride) composites were prepared using the above CNT samples, with different filler fractions up to 1 wt%. It was found that oxidation reduced composite conductivity for a given concentration, shifted the percolation threshold to higher concentrations, and had no significant effect in the dielectric response.

No MeSH data available.