Electrical property-selective noncovalent dispersion of carbon nanotubes by poly(perylene diimide-thiophene): a molecular dynamics study

Abstract

ABSTRACT Thiophene polymers have been widely used to selectively disperse semiconducting single-walled carbon nanotubes (sc-SWNTs). Important questions concern the influence of the solvent on the adsorbability and adsorption-conformation of such polymers, along with the relation between the thiophene polymer structure and selectivity to SWNTs. These concerns about the behaviour of poly(perylene diimide (PDI)-thiophene) have been addressed in this study via molecular dynamics simulation. It is observed that the polymer does not adsorb to SWNTs in a solvent with strong polarity and shows an effective adsorbability in a solvent with moderate polarity or non-polarity. Its selectivity turns from metallic SWNTs to semi-conducting SWNTs in a solvent with a decreasing polarity. In addition, the rigid part in the polymer backbone (PDI) enlarges adsorbability significantly, and the flexible part (two thiophene units) adjusts its adsorption conformation onto SWNTs, which offers the selectivity. The study offers theoretical clues for designing the structure of thiophene polymers with respect to SWNTs-extraction.