Projekte

Emulsion polymerization of olefinic monomers is one of the most important, and also versatile polymerization processes. Polymer latices are obtained, i.e. stable aqueous dispersions of polymer microparticles in the size range of 50 to 1000 nm. To date, polymer latices are produced industrially by free radical processes exclusively. However, catalytic polymerization in emulsion is receiving strongly increased interest.

Currently, little systematic knowledge of the reactivity of the particular late transition metal complexes suited for aqueous olefin polymerization towards water exists. Fundamental reaction steps of interest comprise:

1) the relative binding of water vs. olefinic monomers to the metal centers.

2) hydrolysis of metal alkyl bonds.

3) the reactivity of metal-bound monomer towards water.

These reactions will be investigated experimentally, especially by NMR monitoring and by study of catalytic oligomeriation and polymerization reactions. Neutral nickel (II) complexes with salicylaldimine ligands, known to be well suited for the synthesis of high-molecular-weight polyethylene dispersions, and cationic palladium diimine complexes, which are particularly well suited as model compounds will be employed. In a close collaboration these reactions will be modelled by the Ziegler group at the same time, with a continuous feedback between experimental and theoretical studies.mulsion polymerization of olefinic monomers is one of the most important, and also versatile polymerization processes. Polymer latices are obtained, i.e. stable aqueous dispersions of polymer microparticles in the size range of 50 to 1000 nm. To date, polymer latices are produced industrially by free radical processes exclusively. However, catalytic polymerization in emulsion is receiving strongly increased interest.

Currently, little systematic knowledge of the reactivity of the particular late transition metal complexes suited for aqueous olefin polymerization towards water exists, Fundamental reaction steps of interest comprise:

1) the relative binding of water vs. olefinic monomers to the metal centres.

2) hydrolysis of metal alkyl bonds.

3) the reactivity of metal-bound monomer towards water.

These reactions will be investigated experimentally, especially by NMR monitoring and by study of catalytic oligomeriation and polymerization reactions. Neutral nickel (II) complexes with salicvlaldimine ligands, known to be well suited for the synthesis of high-molecular-weight polyethylene dispersions, and cationic palladium diimine complexes, which are particularly well suited as model compounds will be employed. In a close collaboration these reactions will be modelled by the Ziegler group at the same time, with a continuous feedback between experimental and theoretical studies.

• Mecking, Stefan - Projektleiter*in

• FB Chemie