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Showing 1 to 16 of 16 for “"syndiotactic"”.
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The Effect of Ionomer Architecture on the Morphology in Gel State Functionalized Sulfonated Syndiotactic Polystyrene
… of blocky and randomly functionalized sulfonated syndiotactic polystyrene copolymers. These copolymers have been prepared over a range of functionalization (from 2% to 10%) in order to assess the effect of the incorporation of these polar side groups on both the thermal behavior and morphology of …
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The Effect of Nanoscale Particles and Ionomer Architecture on the Crystallization Behavior of Sulfonated Syndiotactic Polystyrene
… relationships for these materials. Sulfonated syndiotactic polystyrene (SsPS) is used as a model semicrystalline ionomer and two approaches are utilized to control the rate of crystallization of the SsPS ionomer in the presence of ionic aggregates. The first approach investigates the effect of …
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Tailored Chain Sequences of Brominated Syndiotactic Polystyrene Copolymers via Post-Polymerization Functionalization in the Heterogeneous Gel State
… the preparation of blocky brominated syndiotactic polystyrene (sPS-co-sPS-Br) copolymers with tailored chain sequences using a simple, post-polymerization functionalization method conducted in the heterogeneous gel state, and investigates the effect of sPS reaction state and …
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Z-selective olefin metathesis processes and Cis/syndioselective ROMP with high oxidation state molybdenum alkylidenes
… The tacticity of this polymer is proved to be syndiotactic through polymerization of DCMenthNBD (2,3-dicarbomenthoxynorbomadiene) and IH- H COSY. A variety of related MAP alkylidene compounds are also investigated towards the ROMP of DCMNBD and found to produce polyDCMNBD in a range of …
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Dipole moments and Kerr effect of poly(n-vinylcarbazole) and its complexes with trinitrofluorenone
… the 3/1 helical isotactic and 2/1 helical syndiotactic forms of poly(N-vinylcarbazole). These models were used to calculate the pitch distances of helices and the results were interpreted in terms of van der Waal's radii on TNF. This study indicated that the pitch distance in 3/1 isotactic …
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Investigations of sterically demanding ligands in molybdenum and tungsten monopyrrolide monoalkoxide catalysts for olefin metathesis
… OTPP = 2,3,5,6-tetraphenylphenoxide). Cissyndiotactic poly(MPCP) is obtained at -78 °C, while atactic poly(MPCP) is obtained at ambient temperature. The syn initiator (syn refers to the isomer in which the substituent on the alkylidene points towards the imido ligand and anti where the …
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Development of Controlled Ring-Opening Polymerization of O-Carboxyanhydrides
… either using light or electricity, to synthesize syndiotactic or stereoblock copolymers with different thermal properties. Additionally, simple purification protocols of OCAs have also been initially studied, which potentially paves the way to bulk production of functional monomers. In this …
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Thermoreversible Gelation, Crystallization and Phase Separation Kinetics in Polymer Solutions under High Pressure
… [P4MP1] in n-pentane + CO₂ and in solutions of syndiotactic polystyrene [sPS] in toluene + CO₂, and also in acetophenone + CO₂ fluid mixtures over a pressure range up to 55 MPa and carbon dioxide levels up to 50 wt %. In pure pentane, P4MP1 undergoes crystallization and leads to Form III …
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Novel Group 4 Metal Amido Complexes - syntheses, reactivity and olefin polymerization catalysis
… polymerization when activated with d-MAO giving syndiotactic polystyrene of high molecular weight and aluminum terminated polyethylene. The low activity of these complexes was attributed to the ligand transfer to aluminum during catalysis. Mono Ap trialkyl hafnium complexes were synthesized by …
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Study of the dilute solution properties of various homo- and block co-polymers by variable temperature size exclusion chromatography
… behavior and found to indicate that both syndiotactic and isotactic stereosequences are required for stereoassociation. Two new VTSEC data reduction procedures were devised in order to correct for the temperature drifts due to instrumentation in the first and to neutralize the effect of …
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Order phenomena in polymer crystallization
… In particular the so-called memory effect in syndiotactic polypropylene (s-PP) and the influence of entangled polymer chains (entanglements) on the crystal growth rate have been the key points of investigation. Qualitative differences in the degree of order of chain segments were measured …
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Synthesis and reactivity of high oxidation state tungsten and molybdenum olefin metathesis catalysts bearing new imido ligands
… the NHIPT ligand yields predominantly cis,syndiotactic poly(MPCP) and in the homo-metathesis of 1 -octene yields ~81% cis-7-tetradecene. The possible source of trans olefinic product is addressed. Chapter 3 presents the synthesis of the first (1-adamantyl)imido species of tungsten. The …
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Structural analysis of nanoparticles by small angle X-ray scattering
… particles. Freely suspended nanoparticles of syndiotactic polybutadiene have been studied. By using the combination of cryo-TEM and SAXS, it has been shown that they consist of remarkably thin polymer crystalline lamella. Different models have been compared in order to theoretically fit the …
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Study of the phase behavior of poly(n-alkyl methacrylate-b-methyl methacrylate) diblock copolymers and its influence on the wettability of polymer surfaces
… chloride (LiCl). Under these conditions highly syndiotactic products, rr ~ 0.82, with very narrow molar mass distribution, Mw/Mn ~ 1.1, were obtained. The phase behavior of PnAlkMA-b-PMMA diblock copolymers in bulk was investigated by means of DSC and SAXS measurements. The DSC analysis revealed …
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Understanding of the mechanical response of semicrystalline polymers based on the block-like substructure of crystalline lamellae
We investigated the mechanical response of a range of PE and sPP samples as models of semi-crystalline polymer systems under tensile deformation. Splitting the total tensile deformation into elastic and plastic parts shows four characteristic points (A,B,C and D) from the true stress-true strain …
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Katalytische Styrol-Homo- und Copolymerisation und neue Cycloolefinpolymere auf der Basis von 1,3-Cyclohexadien
Ziel der Arbeit waren Untersuchungen zur Styrol Homo- und Copolymerisation an neuartigen Gruppe-4-Metall-Bis(phenolat)-Katalysatoren sowie die Herstellung von Homo- und Copolymeren des 1,3-Cyclohexadiens (CHD) mit variablen molekularen Architekturen. <br>Mit Methylaluminoxan (MAO)-aktivierten …