An effect of side chain length on the solution structure of poly(9,9-dialkylflu...

• Author(s): Knaapila, M. ; Almásy, L. ; Garamus, V. M. ; Ramos, M. L. ; Justino, L. L. G. ; Galbrecht, F. ; Preis, E. ; Scherf, U. ; Burrows, H. D. ; Monkman, A. P.
• Date: 2008
• Persistent ID: http://hdl.handle.net/10316/5021
• Origin: Estudo Geral - Universidade de Coimbra
• Subject(s): Conjugated polymers; Polyfluorene; Solutions
• Document Type: Article
• Language: English

Description

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. http://www.sciencedirect.com/science/article/B6TXW-4RYNMH6-3/1/d98819d616b7fc68a2afa02dd94093d4