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Organic photovoltaic (PV) cells composed of a perylene derivative, N , N ′-di(pentan-3-yl)-perylene-3,4:9,10-bis(dicarboximide), PTCDI, acting as an acceptor and a π-conjugated polymer poly{1-phenyl-2-[4-(trimethylsilyl)phenyl]acetylene}, PDPA, acting as a donor of photogenerated free electrons are presented. Two types of starting double-layer samples were prepared: samples I composed of a spin-cast PDPA thin film bottom layer and a PTCDI upper layer deposited by the vacuum sublimation, and samples II composed of a spin-cast mixed PDPA/PTCDI layer and a vacuum-sublimation deposited PTCDI upper layer. The samples were treated with toluene vapors to induce changes in the morphology of heterojunctions due to recrystallization of PTCDI, which have been monitored by the optical absorption spectra and AFM images, and the influence of the morphology changes on photovoltaic characteristics of the samples has been studied. A short-time (2–5 min) toluene-vapor treatment positively influences the PV efficiency of system I due to a formation of larger PTCDI crystals, which improves the collection efficiency of the upper layer. However, a longer-time treatment of a system I results in a decrease in its PV efficiency owing to a significant decrease in the PDPA–PTCDI interfacial area accompanying further growth of PTCDI crystals, which lowers the photogeneration efficiency of the system. A combination of molecularly dissolved (in PDPA) and crystalline PTCDI in the system II has been proved to provide better PV efficiency due to a combination of improved free charge carrier photogeneration in the composite bottom layer and the collection efficiency of charge carriers of the upper layer.

A new series of associating polymers were prepared by grafting highly hydrophobic side chains: poly( n -butyl acrylate), PNBA ; poly( n -butyl methacrylate), PNBMA ; and poly( N -( tert -butyl)acrylamide), PTBA of different sizes onto a poly(sodium acrylate), PAANa , backbone. Due to the strong hydrophobic character of the stickers, the dynamics of the associations is very slow as compared to more conventional water-soluble polymers modified with short alkyl chains and the physical associations mainly behave as chemical ones in the experimental conditions. As a consequence, all the copolymers readily self-assemble in aqueous solution forming clusters in very dilute conditions and then gels at higher concentrations. From dynamic measurements, it was shown that the copolymer solutions follow the same scaling relation η ∗ ∼ c a , where a is a frequency dependent exponent. In these conditions, all the copolymer solutions exhibit a sol–gel transition which obeys the main rules of the percolation theory. For each copolymer, the critical gel concentration c g depends strongly on the hydrophobic character of the stickers and a single master curve can be drawn by plotting the complex viscosity vs. the reduced concentration, c / c g . Although the temperature dependence of the viscoelastic properties is very weak, due to the slow dynamics of the associations, it was clearly evidenced that the alkyl acrylamide derivative (PAANa- g -PTBA) exhibits a slight thermothickening behavior which contrasts with the thermothinning behavior of alkyl(meth)acrylate derivatives (PAANa- g -PNBA and PAANa- g -PNBMA). The opposite type of behavior is explained by the presence of the amide function which is known to play an important role in the LCST (lower critical solution temperature) phase diagram of N -alkyl derivatives.

The solution behavior and self-assembly of a ‘hairy’ heteroarm star copolymer polystyrene/poly(2-vinylpyridine) containing 20 fairly short polystyrene and 20 long poly(2-vinylpyridine) arms was studied in 1,4-dioxane–methanol mixtures and in acidic aqueous solutions. The copolymer forms reversible micelles in 1,4-dioxane–methanol mixtures. Since the conformation of the unimolecular heteroarm star (unimer) with collapsed insoluble PS arms and stretched soluble PVP arms resembles the spherical core/shell micelle, the solubility of the copolymer in the selective solvent is fairly high and the multimolecular micelles are formed by only few heteroarm stars. Both heteroarm stars (in pure 1,4-dioxane) and micellar systems (composed of both micelles and unimolecular heteroarm stars (unimers) in 1,4-dioxane–methanol mixtures) may be transferred in acidic aqueous media by dialysis. Polyelectrolyte behavior of unimer stars was studied in detail in acidic aqueous media. Static and dynamic light scattering measurements show that heteroarm stars interact electrostatically over long distances in low ionic strength solutions. Experimental data indicate that the charged stars may form temporary shell interacting (electrostatically stabilized) aggregates at elevated concentrations.