Controlling the collidal size of conducting polymers

The preparation of acetonitrile-toluene suspension and the electrophoretic deposition of poly(9,9-dioctyfluorenyl-2,7-yleneethynylene) have been carried out. It was found that the size of colloidal particles in the acetonitrile-toluene suspension increases with decreasing toluene content. Atomic force microscopy (AFM) observation clearly indicated that a polymer film deposited from a suspension with a low toluene content consists of the large particles, reflecting the colloidal size in the parent suspension. A simple recipe for controlling average size of the colloidal particles in the nanostructured film mentioned here, which involves changing the nonsolvent : solvent ratio, may be useful for contolling the nanoporosity of the film, which is very important in optoelectronic, electronic, and electrochemical applications.