Nano‐sized latex support in metallocene polymerization is known to be able to avoid fuming or leaching and leads to a powder‐like and well‐processable polymer. Focus has been put on the fragmentation behaviour of the particles, a key parameter to morphology control. To study the different behaviour of the new systems as classical inorganic supported metallocenes, e.g. SiO2, a wide range of analytical methods were applied. Fluorescence microscopy, polymerization videomicroscopy, as well as kinetic studies led to a better understanding of the process. The performance of the supports was approved by several phenoxy‐imine type catalysts (“FI‐Catalyst”), which were combined with a tailored latex support. Ultra high molecular weight polyethylene (UHMWPE) was synthesized without any reactor fouling thereby. A different approach towards the metallocene catalyzed olefin polymerization is also presented. Based on emulsion polymerization, it enables very good control over product morphology. The completely hydrophobic system consists of perfluorinated solvent as a continuous phase and a hydrocarbon solvent as a dispersed phase. In contrast to the already existing water based emulsion polymerization of olefins, very high molecular weights are achieved.
Two in one: A replication effect allows the formation of core–shell particles in a single olefin polymerization step, which occurs through the simultaneous use of spatially resolved metallocene catalysts immobilized on a hybrid inorganic–organic support (see picture). Catalyst A was exclusively supported in the inorganic core, while catalyst B was immobilized in the organic shell.
Zwei in einem: Ein Replikationseffekt ermöglicht die Bildung von Kern‐Schale‐Partikeln in einem einzigen Olefinpolymerisationsschritt durch simultanes Nutzen räumlich getrennter Metallocenkatalysatoren, die auf einem anorganisch‐organischen Träger immobilisiert sind (siehe Bild). Katalysator A befand sich ausschließlich im anorganischen Kern, Katalysator B dagegen in der organischen Schale.
As an alternative to inorganic supports, emulsions and organic carriers were developed for metallocene-catalyzed polyolefin synthesis in the last years. Oil-in-oil emulsions based on a perfluorinated solvent provide the possibility to synthesize polymer particles on the nanometer length scale, while the latex particles consisting of polystyrene with different surface functionalities yield particles on the micrometer range. To obtain a deeper insight to the reaction course of both techniques and to the product morphology and fragmentation behavior of the organic carriers, substantial information concerning the kinetics of these reactions is crucial. Thus, standard analytical methods were combined with real-time video microscopy and laser scanning fluorescence microscopy (LSCFM) of perylene labeled particles for improving these methods for polyolefin synthesis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.