Norbornene is polymerized by employing zirconium catalysts with (OSSO)-type bis(phenolate) ligands. The racemic precatalyst rac-1 produces high molecular weight poly(norbornene) with slight optical activity. Enantiopure precatalysts (S,S)-1 and (R,R)-1 are used to study the optical induction in the poly(norbornene)s formed. To overcome the insolubility of poly(norbornene)s in common solvents, their microstructure is studied using copolymers with ethylene as well as hydrooligomers. The crystal structure of a norbornene tetramer is reported.

Poly(styrene) microgels are known, but the influence of tacticity on particle formation and behavior has not been investigated yet. Isotactic poly(styrene) (iPS) with M n 5 15-120 kg/mol is synthesized by coordinate polymerization and cross-linked by Friedel-Crafts alkylation in a miniemulsion. Nuclear magnetic resonance (NMR) spectroscopy, light microscopy, cryogenic transmission electron microscopy, and wide-angle powder diffraction are applied to understand the structure of microgels obtained. Typically, spherical microgels with overall diameter of 40-500 nm are found. Isotacticity of the polymer is retained during microgel formation. Increase of cross-linker content leads to partial crystallinity inside the microgel.