نتایج جستجو برای: setereoselective polymerization
تعداد نتایج: 30371 فیلتر نتایج به سال:
Stereolithography that uses a femtosecond laser was employed as a method for multiphoton-sensitized polymerization. We studied the stereolithography method, which produces duplicate solid shapes corresponding to the trajectory of the laser focus point and can be used to build a three-dimensional (3D) structure using a conductive polymer. To achieve this, we first considered a suitable polymeriz...
A series of α-diimine Ni(II) complexes containing bulky phenyl groups, [ArN = C(Naphth)C = NAr]NiBr2 (Naphth: 1,8-naphthdiyl, Ar = 2,6-Me2-4-PhC6H2 (C1); Ar = 2,4-Me2-6-PhC6H2 (C2); Ar = 2-Me-4,6-Ph2C6H2 (C3); Ar = 4-Me-2,6-Ph2C6H2 (C4); Ar = 4-Me-2-PhC6H3 (C5); Ar = 2,4,6-Ph3C6H2 (C6)), were synthesized and characterized. Upon activation with either diethylaluminum chloride (Et2AlCl) or modifi...
CTP Synthetase (CtpS) is a universally conserved and essential metabolic enzyme. While many enzymes form small oligomers, CtpS forms large-scale filamentous structures of unknown function in prokaryotes and eukaryotes. By simultaneously monitoring CtpS polymerization and enzymatic activity, we show that polymerization inhibits activity, and CtpS's product, CTP, induces assembly. To understand h...
highly active metallocenes and other single site catalysts have opened up the possibility of polymerizing cycloolefins such as norbornene (n) or of copolymerizing them with ethene (e) or propene (p). the polymers obtained show exciting structures and properties. e-n copolymers are industrially produced materials, with variable and high glass transitions depending on the wide range of their micr...
We have found that benzene-fused TTFs bearing polymerization sites could prolong the cycle life of LIBs via “in-cell polymerization”.
Monolayers of a polymerizable phospholipid on water have been studied both before and after polymerization. Before polymerization, the phase diagram is established by isotherm measurements and optical microscopy (epifluorescence and direct observation between crossed polarizer and analyzer). This allows us to bring into evidence a coexistence region between a condensed and an expanded phase, ab...
The synthesis and characterization of a series of 8-quinolinolato gallium complexes is presented, and the complexes are analogous to a series of aluminum complexes previously reported. The complexes have been shown to be active initiators for the ring-opening polymerization of rac-lactide. High degrees of polymerization control are demonstrated, as exemplified by the linear evolution of molecul...
The data on the effect of ethylene concentration on polymerization rate for several modifications of modern highly active titanium–magnesium catalysts TiCl4/MgCl2 are presented. These catalysts differ in titanium content and conditions of support preparation, activities, and the shape of kinetic curves. It is found that the observed order of polymerization rate with respect to ethylene in the r...
A two-dimensional single particle finite element model was used to examine the effects of particle fragmental pattern on the average molecular weights, polymerization rate and particle overheating in heterogeneous Ziegler-Natta olefin polymerization. A two-site catalyst kinetic mechanism was employed together with a dynamic two-dimensional molecular species in diffusion-reaction equation. The i...
Of all polymerization methods, catalytic polymerization offers the broadest scope of microstructure control. Stereoregularity, comonomer incorporation and sequences, molecular weights, and molecular weight distributions can be controlled by the catalyst structure. Polyolefins are produced on a vast scale of nearly 100 million tons annually, predominantly by catalytic polymerization. High-densit...
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