0000000000480558
AUTHOR
Rolf Mülhaupt
showing 10 related works from this author
Hydrothermally resistant thermally reduced graphene oxide and multi-wall carbon nanotube based epoxy nanocomposites
2013
This study is focused on the investigation of thermo-mechanical properties of an epoxy resin filled with thermally reduced graphene oxide (TRGO) and multi-wall carbon nanotubes (MWCNT) after exposure of samples to hot distilled water. Addition of low contents of TRGO and MWCNTs greatly reduces the water sorption capacity of the epoxy polymer and improves its resistance to hydrothermal ageing. The glassy and rubbery moduli of the neat epoxy decreased for about 20% and 80%, respectively, while TRGO-based epoxy filled with 0.3 wt.% of TRGO showed only 6% reduction of both moduli. Hydrothermal ageing resulted in an enormous drop in the glass transition temperature (Tg) of the neat epoxy, by abo…
Ni(II) and Pd(II) complexes of camphor-derived diazadiene ligands: steric bulk tuning and ethylene polymerization
1998
Abstract Nickel(II) and palladium(II) centers were coordinated to a series of chiral 1,4-diazadiene ligands. The ligand backbones are camphor derivatives and the imine nitrogens are attached to independently varied 2- and 2,6-substituted aryl groups. Upon activation with methyl-aluminoxane, the dibromo nickel complexes polymerize ethylene and 1-hexene. The polymerization properties are dependent on the steric features of the aryl substituents on the imine nitrogens.
Ethylene polymerization catalysts based on nickel(II) 1,4-diazadiene complexes: the influence of the 1,4-diazadiene backbone substituents on structur…
1998
Abstract Thermally sensitive dialkyl nickel complexes {DAD(H,H)}Ni(CH2SiMe3)2 and {DAD(Me,Me)}Ni(CH2SiMe3)2 [DAD(X,X)=2,6-iPr2C6H4–NC(X)–C(X)N–C6H4iPr2-2,6] were synthesized and were characterized by X-ray diffraction studies on single crystals. The substituents X on the backbone of the α-diimine ligand significantly influence the conformation of the 2,6-diisopropylphenyl substituents. This effect is thought to be of crucial importance for the polymerization of ethylene when {DAD(X,X)}NiBr2/MAO is used as catalyst. The influence of the catalyst structure, pressure, and temperature on the polymerization activity, molar mass, glass transition temperature, melting temperature and branching o…
Transition Metal Catalyzed Olefin, Cycloolefin, and Styrene Polymerization
2013
The sections in this article are History and Trends Polymerization Processes Supported Catalysts and Morphology Control Polymerization Mechanisms and Stereoselectivity History and Principles of Metallocene Catalysis Regio- and Stereoselective Polymerization of α-Olefins Polymerization of Cyclic Olefins, Cyclopolymerization, and Stereoselective Polymerization of Styrene Late Transition Metal Catalysts Transition Metal Catalyzed Copolymerization Acknowledgements
Copolymerization of ethene with styrene using different methylalumoxane activated half-sandwich complexes
1997
Ethene was copolymerized with styrene using five different methylalumoxane (MAO) activated half-sandwich complexes of the general formula Me 2 Si(Cp)(N-R)MCl 2 , varying the substituents on the cyclopentadienyl ring and the substituent on the amide (Cp = tetramethylcyclopentadiene CBT, 1-indenyl IBT, 3-trimethylsilyl-1-indenyl SIBT, or fluorenyl FBZ, R = tert-butyl (complexes CBT,IBT, SIBT, FBZ ) or benzyl CAT), as well as the metal center ( M = Ti, except FBZ: M = Zr). Polymerization behavior was analyzed with respect to catalyst activity and polymerization kinetics, styrene incorporation, copolymer microstructure, and molecular weight. All complexes produced random poly(ethene-co-styrene)…
Ancillary Ligand Effect on Single-Site Styrene Polymerization: Isospecificity of Group 4 Metal Bis(phenolate) Catalysts
2003
Styrene is polymerized isospecifically by group 4 metal complexes that contain a C2-symmetrically coordinated 1,4-dithiabutane-linked bis(phenolato) ligand activated by methylaluminoxane.
Titanium and zirconium complexes that contain a tridentate bis(phenolato) ligand of the [OOO]-type
2003
Abstract The oxygen-linked bis(phenol) 2-oxapropanediyl-1,3-bis(2-tert-butyl-4-methylphenol), [OOO]H2, was prepared in good yield by the condensation of 2-tert-butyl-6-hydroxymethyl-4-methylphenol at 155 °C. This bis(phenol) reacted cleanly with titanium tetrachloride to give the orange titanium dichloro complex [OOO]TiCl2 in virtually quantitative yield. The solubility in pentane indicates a monomeric structure for [OOO]TiCl2 in solution. The reaction of titanium tetra(isopropoxide) gave the di(isopropoxy) complex [OOO]Ti(OiPr)2 which also adopts a monomeric structure of C2v-symmetry in solution. The reaction of the dichloro complex [OOO]TiCl2 with benzyl Grignard reagent in diethyl ether …
Novel polyolefin materials via catalysis and reactive processing
1998
Recent advances in transition metal catalyzed olefin polymerization and melt processing stimulate the production of new polymers derived from old monomers Modern polyolefin processes do not require polymer purification and give excellent control of molecular and supermolecular polyolefin architectures. Progress in catalyst design and preparation of tailor-made homo-and copolymers is highlighted for isotactic, syndiotactic, atactic and stereoblock polypropylene (PP), novel 1-olefin copolymers, and ethylene copolymers with polar monomers, e.g., CO and acrylics Today polyethylene short-and long-chain-branching is controlled either by uniform ethylene copolymerization with 1-olefins using singl…
Light-Fueled, Spatiotemporal Modulation of Mechanical Properties and Rapid Self-Healing of Graphene-Doped Supramolecular Elastomers
2017
Gaining spatially resolved control over the mechanical properties of materials in a remote, programmable, and fast-responding way is a great challenge toward the design of adaptive structural and functional materials. Reversible, temperature-sensitive systems, such as polymers equipped with supramolecular units, are a good model system to gain detailed information and target large-scale property changes by exploiting reversible crosslinking scenarios. Here, it is demonstrated that coassembled elastomers based on polyglycidols functionalized with complementary cyanuric acid and diaminotriazine hydrogen bonding couples can be remotely modulated in their mechanical properties by spatially conf…
Synthesis of reactive hyperbranched and star-like polyethers and their use for toughening of vinylester–urethane hybrid resins
2004
A vinylester – urethane hybrid resin (VEUH) was toughened by adding various vinyl-functionalized branched polyethers in 10 and 20 wt%. Two sets of hyperbranched polymers (HBPs) with different branching density were compared with a set of six-arm star polymers. Besides the architecture, the polymers also varied in their characteristics (molecular mass and mass distribution, vinyl/hydroxy ratio). The morphology of the modified VEUH was studied by dynamic-mechanical thermal analysis (DMTA), transmission (TEM) and scanning electron microscopy (SEM). The toughness was characterized by the fracture energy ðGcÞ determined on compact tension specimens at room temperature. It was established that th…