An effect of side chain length on the solution structure of poly(9,9-dialkylfluorene)s in toluene

• Autor(a) principal: Knaapila, M.
• Data de Publicação: 2008
• Outros Autores: Almásy, L., Garamus, V. M., Ramos, M. L., Justino, L. L. G., Galbrecht, F., Preis, E., Scherf, U., Burrows, H. D., Monkman, A. P.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/5021; https://doi.org/10.1016/j.polymer.2008.02.046
• topic: Conjugated polymers; Polyfluorene; Solutions

The effect of side chain length of [pi]-conjugated poly(9,9-dialkylfluorene)s has been studied in semi-dilute (10 mg/mL) toluene solutions using small-angle neutron scattering (SANS) and 1H and 2H NMR spectroscopies. Under these conditions, SANS data indicate that poly(9,9-dinonylfluorene) and poly(9,9-dioctylfluorene) are dissolved down to the molecule level and appear as elongated one-dimensional chains (length >20-30 nm). In contrast, the shorter side chain polymers exhibit a self-association so that poly(9,9-diheptylfluorene) forms thin sheet-like (~1 nm) and poly(9,9-dihexylfluorene) thin (~1 nm) and thick sheet-like (>6 nm) aggregates. 1H NMR data, together with the density functional theory (DFT) calculations, however, show that this occurs without changes in the conformation of the polymer backbone.