Spherical Polyolefin Particles from Olefin Polymerization in the Confined Geometry of Porous Hollow Silica Particles

Freudensprung, Ines; Joe, Daejune; Nietzel, Sven; Vollmer, Doris; Klapper, Markus; Müllen, Kläus

doi:10.1002/marc.201600295

Cited by 3 publications

(2 citation statements)

References 22 publications

(36 reference statements)

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“…The most common strategy for synthesis of HSPs involves the use of polymer or copolymer particles (e.g., polystyrene, polyresorcinol, polymethylmethacrylate (PMMA), poly(methylmethacrylate-co-2-diethylaminomethyl methacrylate)) as templates [50][51][52][53][54][55]. This is followed by deposition of silica (using the Stöber method) using various silica precursors such as TEOS, TMOS, and sodium silicate.…”

Section: Synthesismentioning

confidence: 99%

Hollow Silica Particles: Recent Progress and Future Perspectives

Sharma

Polizos

2020

Nanomaterials

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Hollow silica particles (or mesoporous hollow silica particles) are sought after for applications across several fields, including drug delivery, battery anodes, catalysis, thermal insulation, and functional coatings. Significant progress has been made in hollow silica particle synthesis and several new methods are being explored to use these particles in real-world applications. This review article presents a brief and critical discussion of synthesis strategies, characterization techniques, and current and possible future applications of these particles.

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Section: Synthesismentioning

confidence: 99%

Hollow Silica Particles: Recent Progress and Future Perspectives

Sharma

Polizos

2020

Nanomaterials

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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A procedure to obtain very uniform polyolefin copolymers by supported metallocenes is presented. Conventional metallocene or Ziegler–Natta catalysts, both immobilized on inorganic supports, yield only copolymers with inhomogeneous comonomer incorporation and broad short-chain branching distribution. The main reasons are diffusional limitations of the monomers or the multisite character of the catalysts. By comparing inorganic and organic supports, we demonstrate that metallocenes immobilized on organic supports solve these problems. In this regard, organic and soft nanosized polystyrene particles (nPS) versus industrially used, hard, and inorganic SiO2 were used to support [Me2Si(Ind)2ZrCl2/MAO (I) and Me2Si(Benz[e]-Ind)2ZrCl2/MAO (BI)] catalysts for ethylene/1-hexene copolymerization. In the inorganic case, the catalyst systems show a substantial inconsistency in the copolymers’ branching distribution, resulting in phase separation. One phase is hexene-poor with high melting temperature (T m) and high molecular weight (MW). The second, hexene-rich phase, however, shows lower T m and MW. By using organic supports, comonomers are uniformly inserted into the polymer chain and homogeneous microstructured copolymers are obtained. These findings are mainly attributed to diffusion processes of the monomers into the soft organic material. To prove this conclusion and to elucidate the structure of the catalyst system, various characterization techniques such as time-of-flight secondary ion mass spectrometry and scanning electron microscopy–energy-dispersive X-ray were performed.

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Silica‐Grafted Neodymium Catalysts for the Production of Ultrahigh‐Molecular‐Weight cis‐1,4‐Polyisoprene

2018

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Supported neodymium‐based Ziegler‐type catalysts are obtained by grafting homoleptic methylaluminate Nd(AlMe4)3 onto high‐surface silica materials including periodic mesoporous silicas MCM‐41, SBA‐15, and KIT‐6. Low [Et2AlCl]‐cocatalyst contents allow for the fabrication of polyisoprenes with ultrahigh molecular weight (UHMWPI). The synthetic rubbers display molecular weights as high as 3×106 g mol−1, polydispersity indices as low as 1.2, and microstructures with 99 % cis‐stereospecificity. Combined analysis of the organolanthanide/silica hybrid materials by nitrogen physisorption, FTIR and magic angle spinning NMR spectroscopies, and elemental (metal) analysis assist in elucidating the intrapore surface organometallic chemistry and suggest the formation of unprecedented organolanthanide species.

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Spherical Polyolefin Particles from Olefin Polymerization in the Confined Geometry of Porous Hollow Silica Particles

Cited by 3 publications

References 22 publications

Hollow Silica Particles: Recent Progress and Future Perspectives

Hollow Silica Particles: Recent Progress and Future Perspectives

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

Silica‐Grafted Neodymium Catalysts for the Production of Ultrahigh‐Molecular‐Weight cis‐1,4‐Polyisoprene

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