Abstract
Single site olefin polymerisation catalysts are suitable candidates for modelling purposes. Their well-defined structure and the almost complete elucidation of their polymerisation mechanisms, make these organometallic complexes ideal for studies based on quantitative structure-activity relationships (QSAR). Although the QSAR technique is extensively used in drug design, there are very few reports on its application to metallocene-based polymerisation catalysis. This probably has something to do with the difficulties inherent in controlling experimental conditions during the polymerisation process. In the present study, we obtained ethylene polymerisation data using a number of zirconocene catalysts under carefully controlled experimental conditions, i.e. keeping all polymerisation variables constant except catalyst structure. The catalytic activity and molecular weight of the resulting polyethylenes were experimentally determined. We then applied 3D-QSAR methodology to explain the experimental data in terms of three-dimensional (3D) field descriptors related to the structure of the metallocene catalyst. Our results provide useful correlations between experimental ethylene polymerisation activities and the steric, LUMO and local softness fields of the catalysts. The molecular weights calculated from comparative molecular field analysis (CoMFA) models including LUMO and local softness fields correlate well with the experimental ones. The predictive capacity of the models was also tested. Based on the proposed models, steric and electronic factors affecting polymerisation performance are discussed.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.