Colloidal dispersions of nanometer sized palladium colloids with very high stability were prepared in block copolymer micelles of polystyrene-b-poly-4-vinylpyridine and analyzed by electron microscopy and X-ray analysis. The resulting polymer/metal hybrids can easily be dissolved and handled in standard organic solvents such as toluene, tetrahydrofuran, and cyclohexane. They were successfully used for the Pd-catalyzed carboncarbon coupling of aryl halides with alkenes (Heck reaction). Such block copolymer stabilized palladium colloids exhibit about the same reactivity as low molecular weight Pd complexes classically used for the Heck reaction, but show a much higher stability: in most reactions, the hybrids remain catalytically active even after 50000 turn-over cycles. Reaction rates were significantly controlled by the reactivity of the educts, but also respond to micelle architecture and dispersity of the palladium. Other advantages of the block copolymer stabilizer are that they are more simple and readily accessible than the phosphor-containing chelates, and that they dissolve even in "simple" solvents such as toluene (instead of amidic solvents).

The vinylic polymerization of norbornenes upon catalysis with Pd2' complexes with norbornylnitrile as ligands is reported. The polynorbornenes (a,,, = lo6) display a set of unique properties including a dense packing in the amorphous state, high glass transition temperatures, large refractive index, low birefringence and significant brittleness. To test the concept that these properties can be traced back to the conformational constraints of the polymer chains, we performed ab initio calculations, semi-empirical quantum mechanical calculations and force-field calculations employing a force field developed by us for polynorbornenes.

The polymerization of ethylene carbonate using different metal alkoxides results in poly(oxyethylene-ukthylene carbonate). Polymers containing low amounts of CO, or pure poly(oxyethylene) are formed with anionic and cationic initiators. Poly(ethy1ene carbonate) is not accessible from ethylene carbonate by variation of temperatures and concentration. The reason is not the low ceiling temperature. but the positive enthalpy of polymerization. A AH,-value of 125,6 kJ/mol was obtained from calorimetric investigations.

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