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Monomer Phase (monomer + phase)
Selected AbstractsPreparation of normal-phase HPLC stationary phase based on monodisperse hydrophilic polymeric beads and their applicationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Bolin Gong Abstract The monodisperse, 5.0 ,m hydrophilic macroporous poly(glycidymethacrylate- co -ethylenedimethacrylate) beads were first prepared based on monosized linear poly(glycidylmethacrylate) beads as seed by using a single-step swelling and polymerization method. The seed beads prepared by dispersion polymerization exhibited good absorption of the monomer phase. The pore size distribution of the beads was evaluated by mercury instrusion method. The surface area was calculated from the BET isotherms of nitrogen adsorption and desorption. The beads were modified to be a normal-phase liquid chromatographic (NPLC) stationary phase for high performance liquid chromatography (HPLC) in the following steps. First, the beads were completely hydrolyzed. Second, hydrolyzed particles were reacted with epichlorihydrin followed by another hydrolysis of the newly introduced epoxide groups. The retention properties of the NPLC stationary phase were easily modulated by changes in the composition of the mobile phase. The performance of theses beads was demonstrated with the separation of a variety of polar compounds. The satisfactory results were obtained. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Synthesis, characterization, and cure reaction of methacrylate-based multifunctional monomers for dental compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Mousa Ghaemy Abstract The synthesis of 2,2-bis[(4-(2-hydroxy-3-methacryloxyethoxy)phenyl]propane (BHEP) and (1-methacryloxy-3-ethoxymethacryloxy-2-hydroxy)propane (MEHP) for use as the monomer phase in dental composites are reported. The monomers were prepared by the reaction of 2-hydroxyethyl methacrylate (HEMA) with diglycidyl-ether of bisphenol A (DGEBA) and with glycidyl methacrylate (GMA), respectively. The progress of the reaction was followed by measuring the disappearance of the epoxide group peak using FTIR and the structure of the monomers was characterized by 1H-NMR. BHEP and MEHP have lower viscosity because of the presence of long aliphatic spacer on both sides of the aromatic ring in BHEP and the absence of aromatic rings and the presence of only one hydroxyl group in each molecule of MEHP. Thermal curing of the monomers was conducted in a DSC using benzoyl peroxide as an initiator. Photopolymerization of the monomers was also conducted with the visible light using camphorquinone and N,N -dimethylaminoethyl methacrylate as the photoinitiating system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] A Novel Route to Multiphase Polymer Systems Containing Nano-Droplets: Radical Polymerization of Vinylic Monomers in Gelled Water-in-Oil MiniemulsionsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2005Christian Holtze Abstract Summary: A new strategy for the synthesis of composite polymers with larger volume fraction of aqueous inclusions less than 1 µm in diameter is presented. A water-in-oil miniemulsion of aqueous droplets in a continuous, cross-linkable monomer phase is prepared. The addition of an organo-gelator allows the immobilization of the droplets in a solid gel, thus avoiding the usual demixing upon polymerization of the continuous phase. This pregelled system is then converted into a composite polymer by photoinitiated free radical polymerization. Such coatings may be used for an improved climate control of buildings or as a deposit for the controlled release of actives from polar nano-droplets. SEM image of a cross-linked composite polymer showing controlled droplet inclusions with a maximal diameter of 500 nm. [source] Ultrasonically initiated miniemulsion polymerization of styrene in the presence of Fe3O4 nanoparticlesPOLYMER INTERNATIONAL, Issue 3 2006Guihua Qiu Abstract Ultrasonically initiated miniemulsion polymerization of styrene was conducted in the presence of Fe3O4 nanoparticles. Stable polystyrene (PS)/Fe3O4 nanocomposite emulsions were prepared and magnetic PS/Fe3O4 composite particles were obtained through magnetic separation. The whole procedure comprised two steps. First, Fe3O4 nanoparticles were dispersed in the monomer phase with the aid of stabilizer Span-80. Second, miniemulsion polymerization of styrene in the presence of Fe3O4 nanoparticles was carried out under an ultrasonic field in the absence of a chemical initiator. The affecting factors, including stabilizer concentration, surfactant concentration, hexadecane concentration and the amount of Fe3O4, were systematically studied. Stabilizer concentration, surfactant concentration and hexadecane concentration strongly affected the formation of the coagulation. The least amount of coagulation was formed at 2.5 wt% Span-80 concentration. The addition of Fe3O4 nanoparticles drastically increased the polymerization rate owing to the fact that Fe3O4 nanoparticles increased the acoustic intensity and Fe2+ reacted with H2O2 to produce hydroxyl radicals and increase the number of radicals. The increase in cosurfactant concentration and power output also increased the polymerization rate. Copyright © 2005 Society of Chemical Industry [source] Mechanism of emulsion polymerization of styrene using a reactive surfactantJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2001X. Wang Abstract The emulsion polymerization of styrene using the reactive surfactant sodium dodecyl allyl sulfosuccinate (TREM LF-40) was studied. The polymerization kinetics were found to be unusual in that Rp was not directly proportional to Np (Rp , Np0.67). Several reasons are stated to explain the unusual kinetics, including chain transfer to TREM LF-40, copolymerization of styrene with TREM LF-40, and the influence of the homopolymer of TREM LF-40 [poly(TREM)] and/or the copolymer [poly(TREM- co -styrene)] on the entry and exit rates of free radicals. The possibility of both chain transfer and copolymerization exists primarily at the oil/water interface, whereas both can also occur in the aqueous and monomer phases. Bulk polymerizations of styrene in the presence of TREM LF-40 and poly(TREM) were conducted, and the results show that the reaction rate decreased for the styrene/TREM LF-40 system. Latex characterization by serum replacement and titration measurements provided evidence for the chemical bonding of TREM LF-40 to the polymer particles. The fraction of chemically bound reactive surfactant decreased with increasing surfactant concentration and increased with increasing initiator concentration. Relatively high contact angles of water on films cast from the latexes showed that TREM LF-40 did not migrate significantly to the surface of the film, which was consistent with the latex-surface characterization results. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3093,3105, 2001 [source] | ||||||||||