نتایج جستجو برای: ethylene polymerization
تعداد نتایج: 57827 فیلتر نتایج به سال:
Poly(diethylaminoethyl-g-ethylene glycol) microparticles were prepared by suspension polymerization of diethylaminoethyl methacrylate, poly(ethylene glycol) monomethacrylate and the crosslinking agent tetra(ethylene glycol) dimethacrylate in silicone oil using redox initiators. Particles of different sizes, crosslinking ratios and graft molecular weights were prepared. The changes in the swelli...
This paper reports on experimental results of aqueous heterophase polymerizations with monomers of quite different solubility in water ranging from the water-soluble 2-hydroxyethyl methacrylate to lauryl methacrylate with solubility in water of only about 10 mM. A calorimetric study revealed the strong influence of both the hydrophilicity of the monomer and the stirrer speed on the rate of poly...
A series of new binuclear neutral κ-N,O-chelated Ni(II) complexes [(H2C)n{[(2,6-R2-4-yl-C6H2)NdC(H)-(3,5-I2-2-O-C6H2)-κ-N,O]Ni(CH3)(pyridine)}2] (R ) iPr, 3,5-(CF3)2C6H3; n ) 0, 1) are reported. The complexes are single-component catalyst precursors for ethylene polymerization. Catalyst activities exceed those of mononuclear analogues studied substantially. With 3.4 × 10 TO h, high molecular we...
Mononuclear Cr(III) surface sites were synthesized from grafting [Cr(OSi(O(t)Bu)3)3(tetrahydrofurano)2] on silica partially dehydroxylated at 700 °C, followed by a thermal treatment under vacuum, and characterized by infrared, ultraviolet-visible, electron paramagnetic resonance (EPR), and X-ray absorption spectroscopy (XAS). These sites are highly active in ethylene polymerization to yield pol...
The design of reactive species that can either serve to initiate the ring-opening polymerization epoxides for synthesis high molar mass polyethers or be alternatively used catalyze polyether telechelics in presence chain transfer agents has long been an elusive goal. Here, we report a series bifunctional borinane-based catalysts enable living with unprecedented activity (TOF ? 1.8 × 105 h–1) an...
Poly(ethylene glycol)-based nanoparticles have received significant attention in the field of biomedicine. When they are copolymerized with pHor temperature-sensitive comonomers, their small size allows them to respond very quickly to changes in the environment, including changes in the pH, ionic strength, and temperature. In addition, the high surface-to-volume ratio makes them highly function...
: a new fibrous adsorbent was prepared by grafting acrylic acid /acryl amide (aa/aam) co-monomers onto poly(ethylene terephtalat) (pet) fibers. the resulting sorbent has been characterized by fourier transform infrared spectroscopy (ft-ir), thermo gravimetric analysis (tga), scanning electron microscopy (sem) and elemental analysis and studied for the preconcentration and determination of trace...
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