Bundling and Diameter Selectivity in HiPco SWNTs Poly(p-phenylene vinylene-co-2,5-dioctyloxy-m-phenylene vinylene) Composites

Abstract

Temperature-dependent (TD) Raman measurements at laser excitation 514.5 nm were performed at different concentrations. The spectral profile of the radial breathing modes were investigated up to a polymer concentration of 1 g/L and were found to be dominated by approximately 1.2-1.4 nm diameter tubes at room temperature. Upon heating above the glass transition of the polymer (60 degrees C) the smaller tubes around approximately 0.9 nm increased significantly in relative intensity. This suggests that below the glass transition of the polymer (60 degrees C) RBMs within the composite are damped and spectral changes cannot be interpreted as diameter selective solubilization. The observed RBM damping at room temperature only occurred up to a concentration of approximately 1.2 x 10(-4) g/L and below this no damping was observed. Photoluminescence intensity (PL) measurements were taken for a range of PmPV concentrations, in which HiPco single walled carbon nanotubes (SWNTs) at 100%, 10%, 1%, 0.1%, 0.01%, and 0% mass fractions were added. Fitting of the concentration dependence to a dynamic absorption/desorption model indicates that the polymer interacts with nanotube bundles until a critical concentration of approximately 1.2 x 10(-4) g/L is reached, below which the nanotubes are isolated. The polymer and or solvent has a significant effect on the debundling and aggregation within these systems. Aggregation and/or interaction with the polymer at higher concentrations can effect the RBM profile in the composite at ambient temperatures, providing an incomplete representation of the selection of diameters present within composites at a particular wavelength.

A Comprehensive Review on Separation Methods and Techniques for Single-Walled Carbon Nanotubes

“…If the agent can recognize the electrical property and/or structural character of SWNTs, separation of SWNTs can be realized through the extraction [123]. The solubilizing agents reported so far include simple molecule such as alkylamine for M/S separation [124,125,126,127,128,129,130], polymers such as fluorene-based ones for extracting specific ( n , m ) structure [66,89,131,132,133], poly(phenylenevinylene) [134,135,136,137,138] and designed host molecules such as tweezer-type ones for discrimination of diameter, ( n , m ) and handedness [26,28,29,34]. Although the SWNTs have been optically resolved by selective solubilization with chiral nanotweezers [26,27,28,29] and DGU with chiral detergent [25,30], the absolute configuration of the resolved SWNTs were determined only by theoretical calculations [139].…”

Non-covalent polymer wrapping of carbon nanotubes and the role of wrapped polymers as functional dispersants

“…The CNTs formed a stable dispersion in the organic solution of PPVs, suggesting the formation of the polymer-wrapped CNTs. In addition to the dispersion of CNTs [ 66 – 82 ], the PPV wrapping was also utilized for the extraction of single-walled carbon nanotubes (SWCNTs) with specific chiral indices. Keogh et al and Coleman et al used the poly( m -phenylene-co-2,5-dioctoxy- p -phenylenevinylene) (PmPV, figure 5 ) to preferentially disperse SWCNTs with specific chiral indices, leaving the others in the precipitate [ 83 – 86 ].…”

Supramolecular complexes of single walled carbon nanotubes with conjugated polymers

“…5,19,20 Conversely, when non-covalent functionalization is used, the structural integrity of carbon nanotubes remains unchanged, allowing retention of the CNT properties, and enabling the use of both their conductive and mechanical properties in eventual applications. It has been shown that various conjugated structures, such as pyrene, 19,21,22 porphyrins, [12][13][14] and p-conjugated polymers 10,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] can form supramolecular complexes with nanotubes, and the resulting complex materials exhibit good solubility. In recent years, composite materials based on conjugated polymers and SWNTs have generated significant interest due to the combination of optical, electrical, and processability properties of the conjugated polymers with the strength and conductivity properties of carbon nanotubes.…”

“…In recent years, composite materials based on conjugated polymers and SWNTs have generated significant interest due to the combination of optical, electrical, and processability properties of the conjugated polymers with the strength and conductivity properties of carbon nanotubes. A number of conjugated polymers, including poly(mphenylene vinylene) (PmPV), [23][24][25][26][27] poly(thiophene) (PT), [28][29][30][31][32][33][34][35] poly-(phenylene ethynylene) (PPE), 10,41,42 and poly(fluorene) [36][37][38][39][40] have been successfully used to modify and strongly interact with the carbon nanotube surface through p-stacking or helical wrapping.…”