Organic nanoparticles as fragmentable support for Ziegler–Natta catalysts

Abstract

A fragmentable support material for Ziegler–Natta catalysts is presented based on micrometer‐sized aggregates of polystyrene nanoparticles. Hydroxyl anchoring groups are introduced by copolymerization of hydroxymethylstyrene in emulsion process to immobilize the catalysts. The catalytic activity in ethylene slurry polymerizations is found to be directly correlated to the hydroxyl group content of the supports. Furthermore, the fragmentation behavior of dye‐labeled support aggregates into the initial nanoparticles is demonstrated using laser scanning confocal fluorescence microscopy as a nondestructive method. These supported catalysts fulfill two important design criteria, high fragmentability and high catalyst loading, and produce high‐density polyethylene with medium molecular weight distributions (MWDs = 3–4). These values lie between those obtained using single‐site metallocene‐based (narrow MWD < 3) or inorganic supported multi‐site Ziegler–Natta‐based (broad MWD = 4–12) polymerizations without the need of blending. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 15–22

Organic Versus Inorganic Supports for Metallocenes: The Influence of Rigidity on the Homogeneity of the Polyolefin Microstructure and Properties

“…Nanopolystyrene latex particles containing PEG chains, as a stabilizer, were prepared via miniemulsion polymerization. , Suitable stabilizers stay physically connected to the particles and allow noncovalent immobilization of active MAO/metallocene complexes (Figure b) . In ethylene (co)­polymerization, these aggregated clusters fragmented down to primary latex particles to guarantee high activity and high bulk density …”

“…Two main fragmentation models, that is, multigrain and layer-by-layer, are established and developed so far by scanning electron microscopy (SEM), transmission electron microscopy, and laser scanning confocal fluorescence microscopy (LSCFM). ,− For example, MgCl 2 used for Ziegler–Natta catalysts undergoes multigrain polymerization, where fragmentation occurs from the onset of the polymerization throughout the whole particle simultaneously. However, silica supports follow a gradually layer-by-layer fragmentation model.…”

Experimental Evaluation of a Catalyst Fragmentation Model for Olefin Polymerization

“…Laser scanning confocal fluorescence microscopy (LSCFM) [ 6 ] and X‐ray computed microtomography (µCT) [ 13,14 ] were also used to investigate the polymer morphology and the distribution of the catalyst fragments in polymer matrix. LSCFM can provide image of fragments at different steps of polymerization, but requires the modification of support by the addition of a fluorescent marker.…”

“…[2,3] Most of the experimental studies on fragmentation are focused on the early stages of the polymerization reaction, using polymer accumulation and the changes in the morphology of the catalyst particles as reference to follow the time evolution of the fragmentation process. [4][5][6] Monitoring the early stages of the polymerization process requires special techniques of measurements or the slowing-down of the reaction. The Stopped-Flow system is one of these techniques.…”

Synthesis of Perylene-Tagged Internal and External Electron Donors for Magnesium Dichloride Supported Ziegler–Natta Catalysts

“…In recent years, laser scanning confocal fluorescence microscopy (LSCFM) has been introduced as a powerful method to study fragmentation of Ziegler-Natta catalysts. 10 This method is very simple and appeared to be a faster alternative to electron microscopy. 11 For example, catalyst fragmentation was investigated by this technique by using tagged supports, but there are no examples of using perylene-tagged or other tagged electron donors in the literature (although applications of perylene-based compounds were reported in the fields of development of semiconducting materials, 12 OLEDs, 13 and cell imaging 14 ).…”