International audienceA new polymer blend formed by poly(3-hexylthiophene)-poly(4-vinylpyridine) (P3HT-P4VP) block copolymers and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is reported. The P4VP and PCBM are mixed together by weak supramolecular interactions, and the resulting materials exhibit microphase separated morphologies of electron-donor and electron-acceptor rich domains. The properties of the blend, used in photovoltaic devices as active layers, are also discussed

Control of the free‐radical polymerization of styrene was achieved using a series of eight xanthates of the general structure RS(CS)OEt as reversible addition fragmentation chain‐transfer agents. The influence of the nature of the R leaving group was explored. It was found that the transfer ability of the xanthate is markedly improved with increasing stability of R and its steric hindrance. Group R strongly influences the Mn evolution profile during polymerization, but only influences the polydispersities to a small extent. The cyanoisopropyl group was shown to be the best leaving group, leading to an increase in the molecular weight during polymerization that was close to linearity. The living character of the polymerization and the high purity of the chain structures were supported by matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectrometry and 13C NMR spectroscopy. A zero‐order dependence of the kinetics of polymerization on the xanthate concentration was observed.

We describe the synthesis, the morphology, and self-assembly behavior of semiconducting poly-(4-vinylpyridine-b-diethylhexyloxy-p-phenylenevinylene) (P4VP-b-PPV) rod-coil block copolymer systems. Three different block copolymers with 55%, 80%, and 88% coil volume fraction were synthesized by convergent anionic polymerization in THF using lithium R-methylstyrene as initiator. The morphology of the block copolymers was studied by transmission electron microscopy, small-angle X-ray scattering, and small-angle neutron scattering as a function of the volume fraction of the rod block as well as different annealing conditions. The microphaseseparated morphologies in these block copolymers vary from lamellar, to hexagonal, and spherical, when the volume fraction of the rod is progressively reduced. By combining the lattice parameter measured by scattering techniques with the volume fraction of rod domains obtained by nuclear magnetic resonance, it was shown that the block copolymers in the lamellar structure are organized in a smectic C double layer, while in the hexagonal phase they self-organize in a homeotropic arrangement, with the rod blocks forming the dispersed phase. Furthermore, while self-assembly of rod-coil block copolymers in columnar hexagonal phase prevents close rod packing, for the lamellar phase evidence of this configuration among rods is shown by wide-angle X-ray scattering. As a consequence, the morphology and long-range order in the lamellar phase are the result of simultaneous inter-rods liquid crystalline interactions and the tendency to microphase segregation of rod and coil. As a result, depending on temperature, the lamellar phase can exist both with rods oriented in a smectic configuration and with randomly packed rods. We show that annealing the lamellar phase below its order-disorder transition temperature, T ODT , but above the maximum affordable temperature for inter-rods liquid crystalline interactions, called smectic-in-lamellar to lamellar order-disorder transition temperature, T SL (with T SL < T ODT ), leads to highly improved long-range lamellar order, which is then preserved when the system is cooled below T SL , at which temperature rod close packing is fully recovered.