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Divinyl Benzene (divinyl + benzene)
Selected AbstractsSynthesis of charged ultrafiltration poly(styrene- co -divinyl benzene) composite membraneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Sonny Sachdeva Abstract A ceramic supported crosslinked polystyrene composite membrane has been prepared from its monomers using a dual initiator system. The nonionic hydrophobic membrane so prepared has been chemically modified by a low temperature (50°C), single step reaction with chloroacetic acid. The carboxylated membrane has acid functional groups on its surface making it negatively charged and highly hydrophilic in nature. The membranes (unmodified and carboxylated) have been used for the separation of hazardous chromium (VI) salt solution where observed and intrinsic rejection has been studied as a function of pressure and concentration of the feed solution. The intrinsic rejection has been determined by calculating the concentration at the membrane surface (Cm) using Speigler-Kedam model and osmotic pressure model. The observed rejection for the chemically modified membrane decreases with increasing pressure but the intrinsic rejection is found to be more than 80% for all concentrations in the range of study. The experimental results have been fitted using Space-Charge model to obtain the membrane wall potential and the membrane surface concentration which are difficult to measure directly. The transport through the membrane capillaries has been described by the two dimensional model using Nernst-Planck equation for ion transport, Navier-Stokes equation and Poisson-Boltzmann equation for the radial distribution of potential. We have then presented a semianalytical series solution to the highly nonlinear Poisson-Boltzmann equation to reduce the computational time required to solve the set of coupled differential equations. The effective wall potential of the carboxylated membrane was found to be ,28.07 mV. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Characterization of anion-exchange membranes containing pyridinium groupsAICHE JOURNAL, Issue 12 2003Moon-Sung Kang A poly(vinyl chloride) (PVC)/glycidyl methacrylate (GMA)-divinyl benzene (DVB)-based membrane was prepared via monomer sorption, and then pyridium or its derivates (that is, 4-ethyl pyridium, 4-tetrabutyl pyridium) were introduced into the PVC/poly(GMA-DVB) base membrane. The effects of pyridinium anion-exchangeable sites on the water splitting and the electrochemical properties of the membrane were investigated. The electrochemical properties and the water splitting on the anion-exchange membranes were compared with selected commercial membranes containing quaternary ammonium groups. The pyridium membranes showed good electrochemical properties, comparable to those of the commercial membranes, with electrical resistances of less than 3.0 × 10,4 ,·m2 in 0.5 mol dm,3 NaCl and high ionic permselectivities (the transport number of Cl, ions being 0.96). Moreover, water splitting indicated by the proton transport numbers of the membranes containing pyridinium or its derivates, were about two or three orders of magnitude lower than those of the commercial membranes (such as AM-1) at the same current density because the resonance effect in the quaternary pyridinium groups contributed to their molecular stability. [source] Star polymers by cross-linking of linear poly(benzyl- L -glutamate) macromonomers via free-radical and RAFT polymerization.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2010A simple route toward peptide-stabilized nanoparticles Abstract Poly(benzyl- L -glutamate) (PBLG) macromonomers were synthesized by N -carboxyanhydride (NCA) polymerization initiated with 4-vinyl benzylamine. MALDI-ToF analysis confirmed the presence of styrenic end-groups in the PBLG. Free-radical and RAFT polymerization of the macromonomer in the presence of divinyl benzene produced star polymers of various molecular weights, polydispersity, and yield depending on the reaction conditions applied. The highest molecular weight (Mw) of 10,170,000 g/mol was obtained in a free-radical multibatch approach. It was shown that the PBLG star polymers can be deprotected to obtain poly(glutamic acid) star polymers, which form water soluble pH responsive nanoparticles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 [source] Highly porous elastomer-silsesquioxane nanocomposites synthesized within high internal phase emulsionsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2008Jenny Normatov Abstract Highly porous elastomeric nanocomposites were successfully synthesized through copolymerization of 2-ethylhexyl acrylate (EHA), divinyl benzene (DVB), and up to 9 mol % of a polyhedral oligomeric silsesquioxane bearing one propylmethacryl group and seven cyclohexyl groups (MACH-POSS) within the external phase of high internal phase emulsions (HIPE). The chemical structures, morphologies, thermal properties, and mechanical properties of the polyHIPE were investigated. The mechanical loss peak temperature and full width at half maximum increased with increasing MACH-POSS content. These changes indicate that copolymerization with MACH-POSS limits segmental mobility and produces compositional distributions on the nanometer scale. At 9 mol % MACH-POSS, the reduction in segmental mobility produced a glass transition temperature above room temperature and a significant increase in modulus that can be ascribed to the relatively glassy nature of the polymer. Inorganic monoliths with porosities of around 86%, O/Si of about 1.6, and less than 10% carbon were produced on pyrolysis of the nanocomposite polyHIPE. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2357,2366, 2008 [source] Highly magnetic latexes from submicrometer oil in water ferrofluid emulsionsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2006Franck Montagne Abstract The synthesis of functionalized submicrometer magnetic latex particles is described as obtained from a preformed magnetic emulsion composed of organic ferrofluid droplets dispersed in water. Composite (polystyrene/,-Fe2O3) particles were prepared according to a two-step procedure including the swelling of ferrofluid droplets with styrene and a crosslinking agent (divinyl benzene) followed by seeded emulsion polymerization with either an oil-soluble [2,2,-azobis(2-isobutyronitrile)] or water-soluble (potassium persulfate) initiator. Depending on the polymerization conditions, various particle morphologies were obtained, ranging from asymmetric structures, for which the polymer phase was separated from the inorganic magnetic phase, to regular core,shell morphologies showing a homogeneous encapsulation of the magnetic pigment by a crosslinked polymeric shell. The magnetic latexes were extensively characterized to determine their colloidal and magnetic properties. The desired core,shell structure was efficiently achieved with a given styrene/divinyl benzene ratio, potassium persulfate as the initiator, and an amphiphilic functional copolymer as the ferrofluid droplet stabilizer. Under these conditions, ferrofluid droplets were successfully turned into superparamagnetic polystyrene latex particles, about 200 nm in size, containing a large amount of iron oxide (60 wt %) and bearing carboxylic surface charges. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2642,2656, 2006 [source] PVC modification through polymerization of a monomer absorbed in porous suspension-type PVC particlesJOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 3 2004M. Narkis In-situ polymerization is the polymerization of one monomer in the presence of another polymer. It can be performed by sequential emulsion polymerization, or by reactions in the melt, in the solid phase, or in solution. The current report describes two methods to obtain poly(vinyl chloride) (PVC) modification through polymerization of a monomer absorbed in commercial porous suspension-type PVC particles. The generated modified PVC products differ significantly in their structure and properties. The first approach includes absorption of a monomer/peroxide solution within porous suspension-type PVC particles, followed by polymerization/crosslinking in the solid state at 80°C in an aqueous stabilizer-free dispersion. The monomer/crosslinker pairs selected are styrene/DVB (divinyl benzene), methylmethacrylate/EGDMA (ethylene glycol dimethacrylate), butyl acrylate/EGDMA, and ethylhexyl acrylate/EGDMA. The influence of composition and nature of the polymerizing/crosslinking constituents on the modified PVC particle structure was studied by microscopy methods, porosity measurements, and dynamic mechanical behavior (DMTA). The level of molecular grafting between PVC and the modifying polymer was determined by solvent extraction experiments. This work shows that the different monomers used represent distinct courses of monomer transport through the PVC particles. The characteristics of the modified PVC particle indicate that the polymerization/crosslinking process occurs in both the PVC bulk, i.e., within the walls constituting a particle, and in the PVC pores. No indication of chemical intermolecular interaction within the modified PVC particles was found. In the second approach, a solution of monomer, initiator, and a crosslinking agent is absorbed in commercial suspension-type porous PVC particles, thus forming a dry blend. This dry blend is subsequently reactively polymerized in a twin-screw extruder at an elevated temperature, 180°C, in the molten state. The properties of the reactively extruded PVC/PMMA blends are compared with those of physical blends at similar compositions. Owing to the high polymerization temperature, short-chain polymers are formed in the reactive polymerization process. Reactively extruded PVC/PMMA blends are transparent, form single-phase morphology, have a single Tg, and show mechanical properties comparable with those of the neat PVC. The resulting reactively extruded PVC/PMMA blends have high compatibility. J. Vinyl Addit. Technol. 10:109,120, 2004. © 2004 Society of Plastics Engineers. [source] Facile Synthesis of Spherical Polyelectrolyte Brushes as Carriers for Conducting Polymers to be Used in Plastic ElectronicsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 18 2009Jianjun Wang Abstract A two-step method for the preparation of spherical polyelectrolyte brushes (SPBs) has been developed. Copolymerization of styrene and divinyl benzene at the particle surface resulted in a large number of accessible vinyl groups. These vinyl groups reacted with sodium styrene sulfonate to give SPBs. The SPBs were used as carriers for conducting polymers resulting in redispersible conducting inks with good film forming properties. Direct current (DC) conductivity of the polypyrrole (PPy) loaded samples showed a percolating behavior as probed by impedance spectroscopy. Finally, device performance of organic light-emitting diodes based on the conducting thin films assembled from the PPy loaded particles was tested. [source] Encapsulation of a Single Metal Nanoparticle with Tunable Size in a Monodisperse Polymer MicrocapsuleMACROMOLECULAR RAPID COMMUNICATIONS, Issue 3 2009Haiqing Li Abstract A versatile approach to fabricate monodisperse poly[styrene- co -(divinyl benzene)] (PS- co -DVB) microcapsules that contain a single gold nanoparticle (AuNP) has been demonstrated. Using the PS- co -DVB microcapsule as a microreactor, aqueous HAuCl4 and NaBH4 solutions are subsequently infiltrated. The size of the resulting AuNP inside of the PS- co -DVB microcapsules is easily tunable by controlling the repeated infiltration cycles of aqueous HAuCl4 and NaBH4. PS- co -DVB microcapsules that contain a single silver and palladium nanoparticle are also obtained by following a similar protocol. [source] Modified suspension-PVC particles as absorbents of ortho -dichlorobenzene from waterPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2 2003M. Shach-Caplan Abstract Modified porous PVC particles are studied as absorbents of o-dichlorobenzene (DCB), from water. The modified particles were produced by an in-situ stabilizer-free polymerization/crosslinking of a monomer/crosslinker/peroxide solution absorbed within commercial porous suspension-type PVC particles. The modifying monomers used include styrene with divinyl benzene (DVB) as a crosslinking comonomer, methyl methacrylate (MMA), butyl acrylate (BA), or ethylhexyl acrylate (EHA) with ethylene glycol dimethacrylate (EGDMA) as a crosslinking comonomer. The effect of the nature of the monomers, morphology, porosity, surface area and composition of the modified PVC particles on DCB absorption was studied. Batch experiments (absorption rate and isotherms) were used to screen the PVC absorbents on the basis of absorption rate and absorption capacity. Continuous absorption column experiments were conducted to study the parameters characterizing the absorption process. Both the unmodified and modified PVC particles absorb DCB from water. The PBA and PEHA-modified PVC particles approach equilibrium capacity faster and have greater absorption capacity than neat PVC, PS-modified PVC and PMMA-modified PVC particles. The absorption characteristics are influenced by the modifying polymer's Tg. The rubbery nature of PBA and PEHA yields better absorption in spite of the significantly lower surface area and porosity obtained in the modified PVC particles. Thus, indicating that fast adsorption followed by bulk absorption of DCB is taking place. A clear influence of the crosslinking effect was not established. The continuous absorption experiments were found more efficient than the batch absorption experiments. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||