Formation of Easy-to-Recover Polystyrene-block-Poly(4-vinylpyridine) Micelles Decorated with Pd Nanoparticles in Solutions of Self-Neutralizing Carbonic Acid.

It was found out that block copolymers of polystyrene and poly(4-vinylpyridine) with comparable lengths of blocks could be dissolved in a high-pressure reactor containing water phase saturated with carbon dioxide under high pressure at room temperature. This rather effective dissolution occurs due to a protonation of P4VP nitrogen-containing groups together with a plasticization of the polymer material to be dissolved by a compressed dense CO2 being contained in the autoclave. The selected block copolymers form rather monodispersed micelles with well-defined and reproducible spherical geometry. They apparently have a hydrophobic polystyrene core and a polycationic poly-4-vinylpyridine corona. The obtained micelles were characterized by various techniques such as DLS, AFM, TEM, and SEM. Further, it was revealed that the corona of such micelles could be decorated with Pd nanoparticles having the diameter around 3 nm.

Macromolecular dynamics of conjugated polymer in donor-acceptor blends with charge transfer complex.

Donor-acceptor blends based on conjugated polymers are the heart of state-of-the-art polymer solar cells, and the control of the blend morphology is crucial for their efficiency. As the film morphology can inherit the polymer conformational state from solution, the approaches for probing and controlling the polymer conformational state in the blends are of high importance. In this study, we show that the macromolecular dynamics in solutions of the archetypical conjugated polymer, MEH-PPV, is essentially changed upon addition of an acceptor 2,4,7-trinitrofluorenone (TNF) by using dynamic light scattering (DLS). We have observed four new types of the macromolecular dynamics absent in the parent polymer determined by the polymer and acceptor content. The MEH-PPV : TNF ground-state charge-transfer complex (CTC) is suggested to result in these dynamics. In the dilute polymer solution, the CTC formation leads to slower dynamics as compared with the pristine polymer. This is evidence of aggregates formed by intercoil links that are the CTCs involving two conjugated segments of different coils with acceptor molecules being sandwiched between them. At low acceptor content, the aggregates are not stable but at high acceptor content, they are. In the semidilute solution at low acceptor content, the dynamics becomes faster as compared with the pristine polymer that is explained by confinement of the coupled motions of entangled polymer chains. At high acceptor content, the dynamics is far much slower with a characteristic long-range correlation at the scale 3-5 µm that is explained by aggregation of polymer chains in clusters. One can expect that the DLS technique could become a useful tool to study the nano- and microstructure of donor-acceptor conjugated polymer blends to achieve controllable morphology in the corresponding blend films.