Jukka V. Seppälä

Effects of the Structure of External Alkoxy Silane Donor in High Activity Ziegler-Natta Catalyst on the Microstructure of Polypropylene

Correlations were sought between the structure of external alkoxy silane donors and the microstructure of the obtained polymer chain. Propylene was polymerized in liquid monomer with a heterogeneous high activity Ziegler-Natta catalyst. Fifteen different alkoxy silanes of structure R n Si(OR′) 4-n , where n=1–3, R = Ph or alkyl and R′ = C 1–3 alkyl, were used as external donors. Polymers were fractionated by boiling heptane extraction. Microstructures of the polymers were studied by means of 13 C NMR.

Conformational analysis of some ion-conducting helix polyethers by molecular modelling

Abstract Molecular mechanics calculations and computer graphics are made in order to model the interactions between a number of helix-structured polyethers and a Li ion. The structures of the helix and double-helix polyethers were optimized by minimizing the intra-molecular and intermolecular energies. The interactions potentials between the Li ion and the optimized helix-structured polyether were determined by translating the Li ion through the helix along the x -axis in steps of 0.1 A. This is only preliminary research relating to the use of molecular modelling in a study of the electric conduction properties of polyether-salt systems. Even this static model, however, can provide an explanation as to why some polyether-salt systems conduct electricity better than others.