Polymerization of Bisphenol A Epoxy Resin with Polyethylene glycol

The catalyst boron trifluoride etherate was used to catalyze the reaction of epoxy resin with polyethylene glycol (PEG), and the effect of the concentration of the catalyst on the reaction is studied. It is shown that there exist two competitive reactions : I, self polymerization of epoxy resin via chain growth and II, copolymerization of epoxy resin with PEG via step growth. At high concentration of the catalyst reaction I dominates and reaction II is negligible. On the contrary, at low concentration of the catalyst, reaction II dominates and block copolymers are formed In the intermediate case, the two reactions are comparable with the result that a gel structure is obtained.

EFFECTS OF REACTION AND PROCESSING PARAMETERS ON ETHYLENE POLYMERIZATION USING DIFFERENT ZIEGLER-NATTA CATALYSTS:EMPLOYMENT OF TAGUCHI EXPERIMENTAL DESIGN AND RESPONSE SURFACE METHOD

Different Ziegler-Natta catalysts were employed to polymerize ethylene. To investigate the influences of reaction parameters, namely Al/Ti molar ratio, hydrogen and processing parameters, i.e. ethylene pressure and temperature, a Taguchi experimental design was worked out. An L27 orthogonal array was chosen to take the above-mentioned parameters and relevant interactions into account. Response surface method was the tool used to analyze the experimental design results. Al/Ti, ethylene pressure and temperature were selected as experimental design factors, and catalyst activity and polymerization yield were the response parameters. Increasing pressure, due to an increment in monomer accessibility, and rising Al/Ti, because of higher reduction in the catalysts, cause an increase in both polymerization yield and catalyst activity. Nonetheless, a higher temperature, thanks to reducing ethylene solubility in the slurry medium and partially catalyst destruction, lead to a reduction in both response parameters. A synergistic effect was also observed between temperature and pressure. All catalyst activities will reduce in the presence of hydrogen. Molecular weight also shows a decline in the presence of hydrogen as a transfer agent. However, the polydispersity index remains approximately intact. Using SEM, various morphologies, owing to different catalyst morphologies, were seen for the polyethylene.

Tunable monoenergy positron annihilation spectroscopy of polyethylene glycol thin films

Doppler broadening and coincidence Doppler broadening of annihilation radiation experiments have been performed in three kinds of polyethylene glycol（PEG） membrane formed with different average molecular weight using the tunable monoenergy slow positron probe as a function of implantion energy. The obtained positron annihilation parameters are interpreted from two aspects： surface effect and differences in micro-structure or chemical environment of positron annihilation. The experimental results show that the regulation of densification of PEG molecular packing and distribution uniformity from the near surface layer to the bulk region in the film forming process can be well realized by changing its molecular weight. Combining a variable monoenergetic slow positron beam and these two positron annihilation spectroscopy methods is a powerful tool to study positron annihilation characteristics and for polymeric thin-film fine structure analysis.

Perylene Bisimide In-chain Polyethylene with Unique Self-assembly Nanostructure through Acyclic Diene Metathesis(ADMET)Polymerization

A novel perylene tetracarboxylic acid bisimide（PTCBI） in-chain polyethylene（PE） was first prepared via acyclic diene metathesis（ADMET） polymerization of PTCBI-functionalized α,ω-diene monomer. The polymers could spontaneously self-assemble into hollow cylindrical structures in which the π-π interaction between adjacent PTCBI moieties was enhanced and the electron mobility was possibly promoted. The hydrogenation of as-obtained polymer was readily accomplished, affording the desired precision PTCBI in-chain PE with a saturated backbone, which showed high glass transition temperature（Tg = 63 °C）, relatively wide range of light absorption（λ = 200-575 nm）, and higher LUMO level（-3.62 e V）. It can therefore serve as a superior model for facile construction of functional polyolefin and soluble PTCBI polymer with ordered architecture.

Vapor Pressure Osmometry and Its Applications in the Osmotic Coefficients Determination of the Aqueous Monomer Glycol and Polymer Polyethylene Glycol Solutions at Various Temperature

Based on the principle and calibration of vapor pressure os-mometer and itsapplication in the thermodynamics of the aqueous solutions, the results on aqueous solutions ofmonomer glycol, PEG_(200), PEG_(400), PEG_(1500) and PEG_(2000) over the different concentrationrange at various temperatures were reported. Using a linear least-square fitting routing, theosmotic coefficients were fitted by a simple polynomial equation. It was found that the relationshipbetween the molar osmotic coefficients (Φ) and the molar concentration (c) of the solutions are ina quite good agreement with the fitted polynomial equation at various temperatures over thedifferent concentration range. The experimental results also show that over the studiedconcentration range and at various temperatures, the concentration dependence of the molar osmoticcoefficients of the aqueous solution systems with the solutes of PEG_(200), PEG_(400), PEG_(1500)and PEG_(2000) are totally presented in a rising trend, and their temperature dependence of theosmotic coefficients of the aqueous solution systems of the molar concentration exhibits their ownregularities, respectively. The aqueous glycol solution system exhibits the properties of the dilutesolution.

Trichlorozirconium η~2-Hydrazonides： Synthesis, Characterization and Their Catalytic Behavior toward Ethylene Polymerization

The trichlorozirconium η~2-hydrazonides（R=H, A; R=CH_3, B） were synthesized through the finely controlled stoichiometrical reactions of anhydrous zirconium tetrachloride with the lithium salt of either 1-（furan-2-ylmethylene）-2-phenylhydrazonide or 1-（furan-2-ylethylidene）-2-phenyl hydrazonide in the solvent tetrahydrofuran（THF）, respectively. These complexes were highly sensitive to air and moisture due to solely using less bulky ligand of hydrazonides. The molecular structures of the title complexes, determined by means of single crystal X-ray diffraction, were found to be the distorted pentagonal bipyramid geometry around zirconium atom, with three chlorides and the hydrazonato ligand acting as the η~2-coordination mode as well as two incorporated THF molecules. Upon activation with either methylaluminoxane（MAO） or modified methylaluminoxane（MMAO）, both complexes A and B exhibited catalytic activities toward ethylene polymerization, producing polyethylenes with ultra-high molecular weights.

Synthesis of a PEG-PNIPAm Thermosensitive Dendritic Copolymer and Investigation of Its Self-association

A Novel thermosensitive dendritic copolymer based on polyethylene glycol（PEG） and poly（Nisopropylacrylamide）（PNIPAm） with a cloud point（CP） around 36 ？C was successfully synthesized by preparation of a dendritic polyol and followed by atom transfer radical polymerization（ATRP） of N-isopropylacrylamide. The dendritic copolymer was characterized using gel-permeation chromatography（GPC）, FTIR and 1H-NMR spectroscopy. The selfassociation behavior of the copolymer in aqueous medium was investigated by dynamic light scattering（DLS） and transmission electron microscopy（TEM）. These investigations confirmed that the dendritic copolymer showed different association behaviors at various temperatures.