Temperature Dependent Spectroscopic studies of HiPco SWNT composites.

Hybrid systems of the conjugated organic polymer poly(p-phenylene vinylene-co-2,5-dioctyIoxy-m-phenylene vinylene)(PmPV) and HiPco 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, 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 60 °C. Also observed in the DSC of the composite is a doubly peaked endotherm at -39 °C and -49 °C, which does not appear in the polymer film. The Raman of the polymer backbone upon increasing the temperature to 60 °C shows diminished phenyl Ag modes at 1557 cm−1 and 1575 cm−1, with an increase in the relative intensity of the vinyl mode at 1630 cm−1. This change in the Raman of the polymer is translated to the Raman of the composite upon increase to 60 °C, where the spectrum becomes abruptly dominated by nanotubes. The Raman of the composite shows no change in the lower temperature regions, however infrared suggests that the transition at -39 °C derives from an interaction with the polymer side chains. The composite at -39 °C shows a change in the absorption of the polymer side chain aryl-oxide linkage at 1250 cm−1. while Raman suggests a change to the polymer backbone configuration at 60 °C. Implications are discussed.