Cationic fluorene-thiophene diblock copolymers: Aggregation behaviour in methanol/water and its relation to thin film structures

resumo

Optical spectroscopy and photophysical measurements on cationic fluorene-thiophene diblock copolymers in solution show distinct properties for the two blocks, with clear indications of singlet exciton migration from the polyfluorene to polythiophene blocks. Electrical conductivity measurements and small angle X-ray scattering studies show that different aggregates are formed in water and methanol. This may be associated both with different solubilities of the two blocks and with the effect of solvent on the degree of dissociation of the ionic part. Atomic force microscopy (AFM) shows that different nano-structures are deposited from the two solvents, with large, vesicular structures deposited on mica from methanolic solution. Aggregation behavior is also found to be modulated, and to lead to more rigid thiophene blocks, by addition of the oppositely charged surfactant sodium dodecylsulfate. (C) 2010 Elsevier Ltd. All rights reserved.

palavras-chave

CONJUGATED BLOCK-COPOLYMERS; AIR-WATER-INTERFACE; CONFORMATIONAL RELAXATION; ENERGY-TRANSFER; SOLUTION-STATE; TRIPLET-STATE; POLYFLUORENE; PHOTOPHYSICS; POLYMERS; POLYELECTROLYTES

categoria

Polymer Science

autores

Gutacker, A; Koenen, N; Scherf, U; Adamczyk, S; Pina, J; Fonseca, SM; Valente, AJM; Evans, RC; de Melo, JS; Burrows, HD; Knaapila, M

Grupos

agradecimentos

We thank MAX-lab, Lund for beam time for SAXS measurements. JP. SMF and RCE thank FCT for postdoctoral fellowships (SFRH/BPD/65507/2009, 34703/2007 and/42450/2007).

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