Colloque

Molecular modeling of the crystalline structures of optically active polyethers

Ilie Saracovan

Jean-François Revol

Ronald G. Brown

Membre a labase

Ilie Saracovan

Résumé du colloque

In recent years, the focus of solid state polymer physical chemistry has increasingly shifted towards the definition and the phenomenology of various intermediate crystalline structures, i.e., those transformation of the initial spatial geometries at the backbone level that are capable of generating complex macromolecular morphologies which manifest themselves in the final properties of the solid materials. Optically pure polymers are ideal models, both from experimental and theoretical perspectives, for the study of the chirality-induced morphologies in the advanced supermacromolecular organizations which are predominantly found in biopolymers. Structural analyses of crystallizing polymers capitalized on molecular modeling capability to perform energy calculations and to simulate and visualize complex spatial geometries of the crystalline structures. Both of the polyenantiomers (R and S) of poly(propylene oxide), PPO and poly(epichlorohydrin), PECH were used as models for the conformational analysis at the asymmetric unit and backbone helix levels. The results of these computations, which were performed with the SYBYL (Tripos Inc.) molecular modeling package, will be presented and compared with available wide angle X-ray diffraction data. Finally, the simulated electron diffraction data obtained by use of the CERIUS2 (Molecular Simulations) software package will be compared with the experimental results acquired on single crystals of the homochiral PPO and PECH.