Temperature-Induced Nucleation of Poly(p-phenylene vinylene-co-2,5-dioctyloxy-m-phenylene vinylene) Crystallization by HiPco Single-Walled Carbon Nanotubes

Abstract

Hybrid systems of the conjugated organic polymer poly(p-phenylene vinylene-co-2,5-dioctyloxy-m-phenylene vinylene)(PmPV) and HiPco single-walled carbon nanotubes (SWNTs) are explored using spectroscopic and thermal techniques to determine specific interactions. Vibrational spectroscopy indicates a weak interaction, and this is further elucidated using differential scanning calorimetry (DSC), confocal laser scanning microscopy, temperature-dependent Raman spectroscopy, and temperature-dependent infrared spectroscopy of the raw materials and the composite. An endothermic transition is observed in the DSC of both the polymer and the 0.1% HiPco composite in the region of 50 degrees C. Also observed in the DSC of the composite is a double-peaked endotherm at -39 and -49 degrees C, which does not appear in the polymer. The Raman spectroscopy of the polymer upon increasing the temperature to 60 degrees C shows a diminished cis-vinylene mode at 1575 cm(-1), with an increase in relative intensity of the trans-vinylene mode at 1630 cm(-1). Partially irreversible change in isomerization suggests increased order in the polymer. This change in the polymer is also manifest in the Raman composite spectrum upon increase of the temperature to 60 degrees C, where the spectrum becomes abruptly dominated by nanotubes. Raman spectroscopy of the composite shows no change at -35 degrees C; however, infrared absorption measurements suggest that the transition at -35 degrees C derives from the polymer side chains. Here the composite at -35 degrees C shows a change in the absorbance of the polymer side chain aryl-oxide linkage at 1250 cm(-1) and alkyl-oxide stretch at 1050 cm(-1). Infrared spectra thus suggest that the transitions in the lower temperature region around -35 degrees C are side chain-induced, while Raman spectra suggest that the transition at 60 degrees C is backbone-induced. Furthermore, temperature cycling induces an irreversible decrease in the mean fluorescence intensity of the polymer, coupled with a further reduction in the mean fluorescence intensity of the composite. This suggests that an increase in crystallization of the composite is supported and enhanced by an increase in ordering of the polymer. Implications are discussed.

Single walled carbon nanotubes induce indirect cytotoxicity by medium depletion in A549 lung cells

“…3a and b). Fluorescence studies have been shown to aid in the elucidation of the interaction of nanotubes with different molecular species (Keogh et al, 2005;Hedderman et al, 2006). In an earlier study (Casey et al, 2007a) a model derived by Coleman et al (2004) was adapted and employed to assess the degree of interaction between SWCNT and cell culture medium.…”

Single-walled carbon nanotube-induced crystallinity on the electropolymeric film of tetraaminophthalocyaninatonickel(II) complex: Impact on the rate of heterogeneous electron transfer

“…The obtained crystalline NiTAPc electropolymers are concentrated on these microscopic pieces of the immobilized SWCNTs, further confirming the ability of the SWCNT to induce crystallinity on the NiTAPc electropolymer. Although, it has been widely reported that CNTs are capable of inducing crystallinity on polymeric species [11], [12], [13], [14], [15], [16], [17], [18] and [19], this represents the first report of such observation for an electropolymer and especially for an MPc electropolymer.…”

“…One of the many intriguing properties of CNTs is their ability to induce crystallinity on polymers prepared by solution or melt-processing techniques [12], [13], [14], [15], [16], [17], [18] and [19]. To our knowledge, the induction of crystallinity by CNTs on polymers prepared by electrochemical techniques has not been reported, and we are not aware of any such observation for the electropolymerized films of metallophthalocyanine (MPc).…”

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

“…16 We have shown that temperature cycling facilitates a change in isomerization above the glass transition temperature of the polymer, resulting in an increased polymer tube backbone binding. 16 Raman spectroscopy has been demonstrated to be a key technique for the characterization of SWNTs. This is because of the strong resonant enhancement of the RBMs with respect to tube diameters.…”