Separation of single-walled carbon nanotubes with aromatic group functionalized polymethacrylates and building blocks contribution to the enrichment

We previously showed that in N,N-dimethylformamide (DMF), poly(9-anthracenylmethyl methacrylate) (PAMMA) and poly(2-naphthylmethacrylate) selectively disperse semiconducting and metallic single-walled carbon nanotubes (SWNTs), respectively. We have also proposed a new noncovalent polymer interaction based on photon induced dipole-dipole interaction to account for the metallicity-based selectivity. In this article, we investigate two other polymethacrylates, that is, poly(benzyl methacrylate) (PBMA) and poly(methylmethacrylate)-co-(9-anthracenylmethyl acrylate) (PMMA-c-PAMA) in the light of our previously proposed photon-induced dipole-dipole interaction. We find that PBMA and PMM-c-PAMMA in DMF show no metallicity selectivity. The different selective behavior of the four polymers in DMF manifests the decisive influence of the side aromatic group in determining their metallicity selectivity. The nonpreferential energy transfer from PMMA-c-PAMA to SWNTs and the nonoverlap of PBMA fluorescence (in the ultraviolet range) with nanotube absorption account for their nonselectivity of specific nanotube species. Further, the parallel relationship between the diameters of extracted tube species and the affinity between polymers and solvents suggests the leading role of the polymeric conformation on the diameter selectivity. A sufficient (i.e., 2 weeks) standing time of the SWNTs solution after sonication, during which the polymers presumably optimize their conformation to the SWNTs, was found to be essential to the enrichment.