LSP - Laboratory of Stereoselective Polymerizations
Prof. Vincenzo Busico
Room 2P14; phone +39-081-674255
Email busico@unina.it;
Prof. Roberta Cipullo
Room 2P-11; phone +39-081-6744352
Email rcipullo@unina.it;
Prof. Petrus Henricus Maria Budzelaar
Room 2P-28; phone +39-081-674461
Email p.budzelaar@unina.it;
Prof. Andrea Correa
Room 2Mc-32; phone
Email andrea.correa@unina.it;
Dr Christian Ehm
Room 1N-34; phone +39-081-674357
Email christian.ehm@unina.it;
Dr Antonio Vittoria
Room 0N-18; phone +39-081-674061
Email antonio.vittoria@unina.it;
Dr Giuseppe Antinucci
Room 2P-15; phone +39-081-674361
Email giuseppe.antinucci@unina.it;
- Other staff members: Francesco Zaccaria, Room 2P-15; phone +39-081-674361; Email francesco.zaccaria@unina.it, orcid
- Website: http://www.lsp.unina.it/
Research topics
- Advanced microstructural analysis of vinyl polymers
- High Throughput Experimentation (HTE) methods for catalysts screening and understanding
- Fundamental and applied studies of ‘classical' Ziegler-Natta catalysts (ZNC)
- Structure-Properties Relationships (SPR) in molecular olefin polymerization catalysts
- Mechanistic studies on olefin polymerization catalysts
- New lines
Advanced microstructural analysis of vinyl polymers
Since its birth, LSP pioneered applications of high-field NMR spectroscopy to the microstructural elucidation of vinyl polymers. In particular, the statistical analysis of polypropylene 13C NMR stereosequence distribution as a powerful method of catalyst ‘fingerprinting', originally established by Prof. Adolfo Zambelli (CNR Milan), was refined up to unprecedented levels of detail in collaboration with Prof. Annalaura Segre (CNR Rome). This research line was recently boosted by the implementation of high-temperature cryoprobe NMR, with its incredibly high Signal-to-Noise ratio leading to highlight the microstructure of polyolefin samples made with industrial Ziegler-Natta, metallocene and post-metallocene catalyst systems.
Integration with other microstructure-related techniques such as high-temperature Gel Permeation Chromatography (GPC) and analytical Crystallization Elution Fractionation (A-CEF) makes NMR analysis able to unravel specially complicated cases such as polyolefin block copolymers made via ‘chain shuttling' and, in general, novel classes of olefin copolymers.
High Throughput Experimentation (HTE) methods for catalysts screening and understanding
In the early 2000s, LSP was among the first academic laboratories worldwide to embrace High Throughput Experimentation (HTE) in organometallic catalysis. Since then, state-of-the-art HTE platforms for catalysts synthesis and testing are front and center of nearly all lines of research of the group and have been integrated with an array of rapid high-end polymer characterization tools thus forming a truly comprehensive workflow.
Not only do we apply standard HTE protocols to the majority of our research projects, as is described in the following sections; more and more indeed we implement and improve original proprietary protocols, facing the challenges of miniaturization and exploiting to the utmost the great potential of robotics and automation. Over the last few years, we demonstrated the reliability and robustness of our HTE databases and overcame tough technical problems e.g., controlling the kinetics of super-active catalysts in the small (5 mL) reaction cells of our parallel polymerization platforms.
Fundamental and applied studies of ‘classical' Ziegler-Natta catalysts (ZNC)
Originally discovered in the 1950s and rejuvenated in the 1970s, heterogeneous Ti-based Ziegler-Natta catalysts (ZNC) still represent the work horse of polypropylene industrial production, and almost monopolize the market. Yet many aspects of their inner workings remain elusive. LSP represents a leading competence center for the structural elucidation of ZNC surfaces, with an original approach based on the combination of 13C NMR polymer analyses, HTE catalyst screening and quantum mechanical catalyst modelling.
In parallel with experiment, advanced studies of ZNC and model systems thereof are carried out by means of DFT(-D) modelling using a periodic and cluster approach, the latter down to the level of the active pocket. In particular, our unique ‘flexible-cluster' approach enables full relaxation of realistic model MgCl2 clusters with an effective compromise between computational time and accuracy, and proved able to capture the features of real nano-sized and highly disordered primary catalyst particles with complex adsorbate compositions.
Experiment and computational modeling are combined to better understand the roles played by the various classes of ZNC surface modifiers.
Structure-Properties Relationships (SPR) in molecular olefin polymerization catalysts
Catalyst discovery and, even, catalyst optimization is typically a trial-and-error process which can take years. Tuning of active metal, ancillary ligand framework, activator, and modifiers (if any) are often associated with non-additive effects, and intuition and common sense often meet their limits.
Combining High Throughput Experimentation (HTE) with deterministic and/or statistical computational modeling can shorten the timeframe for catalyst development and thus significantly reduce capital and resource expenditures by prioritizing targets for synthesis. At LSP we do that routinely, with highly efficient feedback loops. SPR (also known as Quantitative Structure Activity Relation, QSAR) models with heuristic potential rely on ‘massive' HTE databases and computationally derived descriptors for the catalytically active species.
Mechanistic studies on olefin polymerization catalysts
Along with the SPR studies, we cultivate fundamental investigations on the mechanisms of catalytic olefin polymerizations, aiming to identify the origin of the observed stereo-, regio- and chemo-selectivities for heterogeneous as well as molecular systems, and the dominant chain transfer pathways presiding over their polymer molecular weight capability. We typically do that by combining molecular kinetic observations with in-depth NMR polymer microstructure analyses.
Purely computational tools can be exploited to model the elementary reaction steps of the polymerization process when the structure of the active species can be assumed to be known. At LSP we have carried out a solid benchmark of DFT protocols for modelling various reactions of interest in olefin polymerization, from simple olefin insertion to metal-carbon bond homolysis. More often, experimental and computational tools are combined in highly integrated studies.
Furthermore, LSP has a long-standing tradition in investigating the complex cross reactivity of precatalysts and cocatalysts (activators). Recently, especially interesting results have been obtained on the structure and reactivity of methylaluminoxane (MAO) and some modifications thereof, by successfully integrating DFT modelling and advanced NMR spectroscopy (in collaboration with the research group of Prof. Alceo Macchioni at the University of Perugia).
New lines
Research at LSP is constantly being broadened and re-focused. New entries currently include, e.g. (co)polymerizations of functionalized olefins and non-olefinic monomers, development of sustainable materials and/or smart polymers. Furthermore, we are focusing part of our interest on the organometallic reactivity of group 4 and 13 metal complexes in catalytic reactions other than polymerization.
Last but not least, we are always seeking to expand our core competencies and carefully look at emerging trends. In recent years, artificial intelligence (AI) and machine learning (ML) made remarkable progress and are nowadays used for data analysis and predictions in many scientific fields. The development and implementation of these tools already represents a new focus for the group.
All above research lines are still in an embryonic stage, and updates will be provided at the LSP website in due course in due course. If you are interested, then, stay tuned!