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Monomer Mixture (monomer + mixture)

Distribution by Scientific Domains

Polymers and Materials Science	90%

Selected Abstracts

Formation and Distribution of Silver Nanoparticles in a Functional Plasma Polymer Matrix and Related Ag+ Release Properties

PLASMA PROCESSES AND POLYMERS, Issue 7 2010
Enrico Körner
Abstract Plasma polymer coatings with embedded Ag nanoparticles were deposited in a low pressure RF plasma reactor using an asymmetrical setup with an Ag electrode. The plasma polymer was deposited from a reactive gas/monomer mixture of CO2/C2H4 yielding a functional hydrocarbon matrix. In addition, Ar was simultaneously used to sputter Ag atoms from the Ag electrode, forming nanoparticles within the growing polymer matrix. The influence of the power input, gas ratio and coating thickness on both, the Ag content and the Ag nanoparticle morphology, as well as the distribution in the polymer matrix were investigated. It was found that both increasing the power input and the CO2 ratio result in a higher incorporation of Ag into the matrix. [source]

Synthesis and Characterization of Poly(N -vinylimidazole- co -acrylonitrile) and Determination of Monomer Reactivity Ratios

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 8 2004
Nursel Pekel
Abstract Summary: Radical-initiated solution copolymerization of N -vinylimidazole (VIM) and acrylonitrile (AN) was carried out with 2,2, -azobisisobutyronitrile (AIBN) as an initiator in benzene at 70,°C in nitrogen atmosphere. The structure and composition of synthesized copolymers for a wide range of monomer feeds were determined by FTIR, 1H and 13C NMR spectroscopy with the aid of recorded analytical absorption bands for VIM (667 cm,1, CN of imidazole ring) and AN (2,242 cm,1, CN group), as well as by using the areas of proton and carbon atom signals from corresponding functional groups of monomer units. Monomer reactivity ratios for VIM (M1)-AN (M2) pair were determined by nonlinear regression (NLR), Kelen,Tüdös (KT) and Fineman,Ross (FR) methods. They were found to be r1,=,0.24 and r2,=,0.15 for the NLR method, r1,=,0.22 and r2,=,0.094 for the KT method, and r1,=,0.24 and r2,=,0.12 for the FR method, respectively. The relatively high activity observed of VIM growing macroradical and the results of FTIR and 1H NMR structural analysis of copolymers suggest the formation of complexed linkages between monomers and growing radicals in chain propagation reactions. Similar complexation between monomer,comonomer units in the structure of formed macromolecules showed an increase in isotactic triad fractions in the copolymer. Complex formation between the imidazole ring and nitrile group in both the monomer mixture and chain growing reactions. [source]

Morphology of Polymer/Clay Latex Particles Synthesized by Miniemulsion Polymerization: Modeling and Experimental Results

MACROMOLECULAR REACTION ENGINEERING, Issue 6-7 2010
Matej Mi
Abstract BA/MMA (90:10,wt.-%) were copolymerized in the presence of two different organomodified clays (C30B and CMA16) and 1.6,2.6,wbm.-% surfactants. The effect of the compatibility of the organoclay in the monomer mixture on the morphology of hybrid polymer/clay particles was determined using TEM. The resulting morphologies were compared with the prediction of a Monte-Carlo simulation that determined the equilibrium morphology of monomer/clay hybrid miniemulsion droplets. The model predicted encapsulated morphologies only when the organoclay presented low clay/monomer and high clay/water interfacial tensions. C30B and CMA16 did not fulfill these conditions and provided a preferential surface location of the platelets on the polymer/water interphase as predicted by the model. [source]

Copolymerization of 2-Acrylamido-2-methyl-1-propanesulfonic Acid and 1-Vinylimidazole in Inverse Miniemulsion

MACROMOLECULAR REACTION ENGINEERING, Issue 2 2008
Susann Wiechers
Abstract The copolymerization behavior of the acidic monomer 2-acrylamido-2-methyl-1-propanesulfonic acid (APSA) and 1-vinylimidazole in inverse miniemulsion was studied under various conditions. Initially, different surfactants and surfactant concentrations were investigated. After determining a suitable composition of the miniemulsion, changes in the reaction behavior under different pH values and monomer feed compositions were studied. The highest polymerization rates could be produced under neutral conditions over all monomer feed ratios. The addition of acid or base to change the pH value of the monomer mixture also has influence on the polymers obtained. The thermal stability, rheological stiffness and intrinsic viscosity increase when Na-APSA is incorporated. [source]

Preparation and properties of silicone-containing poly(methyl methacrylate) gels

POLYMER INTERNATIONAL, Issue 11 2005
Hamid Javaherian Naghash
Abstract Poly(methyl methacrylate) (PMMA) gels with varying amounts of silicone and solvent and constant amounts of crosslinker were prepared by solution free radical crosslinking copolymerization of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDM), tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) comonomer systems. They were then studied in benzene at a total monomer concentration of 3.5 mol L,1 and 70 °C. The conversion of monomer, volume swelling ratio, weight fraction and gel point were measured as a function of the reaction time, silicone concentration and benzene content up to the onset of macrogelation. Structural characteristics of the gels were examined by using equilibrium swelling in benzene, gel fraction and Fourier-transform infrared (FTIR) analysis. The morphology of the copolymers was also investigated by SEM. Based on the obtained results, it was concluded that the FTIR data did not have the capacity to show the presence of the VTES or TEOS moiety in these kinds of copolymers. On the other hand, the variation of weight fraction of gel, Wg, and its equilibrium volume swelling ratio in benzene, qv, exhibited the same behaviour as that of MMA/EGDM copolymers. Also, the dilution of the monomer mixture resulted in an increase in the gel point and swelling degree and a decrease in the percent of conversion and gel fraction. Finally, TEOS is not an ideal silicone compound for reaction in the MMA/EGDM copolymerization system, whereas VTES is a suitable silicone comonomer for this system and it has been proved useful. Copyright © 2005 Society of Chemical Industry [source]

Adventures in multivalency, the Harry S. Fischer memorial lecture CMR 2005; Evian, France

CONTRAST MEDIA & MOLECULAR IMAGING, Issue 1 2006
Michael F. Tweedle
Abstract This review discusses multivalency in the context of drug discovery, specifically the discovery of new diagnostic imaging and related agents. The aim is to draw attention to the powerful role that multivalency plays throughout research involving molecular biology, in general, and much of biochemically targeted contrast agent research, in particular. Two examples from the author's laboratory are described. We created small (,5,kDa) peptide ,dimers' composed of two different, chemically linked peptides. The monomer peptides both bound to the same target protein with Kd,,,100,s,nM, while the heterodimers had sub-nM Kd values. Biological activity was evident in the heterodimers where none or very little existed in homodimers, monomers or monomer mixtures. Two different tyrosine kinases (KDR and C-Met) and four peptide families produced consistent results: multivalent heterodimers were uniquely different. The second example begins with making two micron ultrasound bubbles coated with the peptide, TKPPR (a Tuftsin antagonist) as a negative control for bubbles targeted with angiogenesis target-binding peptides. Unexpected binding of a ,negative' control, (TKPPR)-targeted bubble to endothelial cells expressing angiogenesis targets, led to the surprising result that TKPPR, only when multimerized, binds avidly, specifically and actively to neuropilin-1, a VEGF co-receptor. VEGF is the primary stimulator of angiogenesis. Tuftsin is a small peptide (TKPR) derived from IgG that binds to macrophages during inflammation, and has been studied for over 30 years. The receptor has never been cloned. The results led to new conclusions about Tuftsin, neuropilin-1 and the purpose, up to now unknown, of exon 8 in VEGF. Multivalency can be used rationally to solve practical problems in drug discovery. When targeting larger structures, multivalency is frequently unavoidable, and can lead to unpredictable and useful biochemical information, as well as to new drug candidates. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Synthesis of Luminescent ZrO2:Eu3+ Nanoparticles and Their Holographic Sub-Micrometer Patterning in Polymer Composites

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2009
Tsedev Ninjbadgar
Abstract Here, the facile synthesis of fluorescent ZrO2:Eu3+ nanoparticles with luminescence quantum yield of up to 8.7% that can be easily dispersed in organic solvents and utilized for the preparation of organic/inorganic volume holographic gratings is presented. The nanoparticles are prepared through a one-step solvothermal process resulting in spherical particles with a mean size of 4,nm that were highly crystalline directly after the synthesis, without any need for calcination treatment. Detailed luminescence studies of the nanoparticles as a function of Eu3+ content demonstrate that the dopant concentration and its site symmetry play an important role in the emissive properties and lifetime of the luminescent centers. It is shown that the luminescence quantum yield of the colloidal ZrO2:Eu3+ nanoparticles increases with dopant concentration up to a critical concentration of 11 mol% while the luminescence lifetime is shortened from 1.8 to 1.4 ms. Holographic photopolymerization of suitable monomer mixtures containing the luminescent nanoparticles demonstrated the ability to inscribe volume Bragg gratings (refractive index contrast n1 up to 0.011) with light-emissive properties, evidencing the high suitability of this approach for the fabrication of tailored nanomaterials for elaborate and demanding applications. [source]

Free radical and nitroxide mediated polymerization of hydroxy,functional acrylates prepared via lipase,catalyzed transacylation reactions

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2010
Dragos Popescu
Abstract 3-Hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-methyl-3-hydroxypropyl acrylate, 2-hydroxypropyl acrylate, neopentyl glycol acrylate, glyceryl acrylate, and dihydroxyhexyl acrylate were prepared via transacylation reaction of methyl acrylate with diols and triols catalyzed by Candida antarctica lipase B. After removal of the enzyme by filtration and the methyl acrylate by distillation, the monomers were polymerized via free radical polymerization (FRP) with azobisisobutyronitrile as initiator and nitroxide mediated polymerization (NMP) employing BlocbuilderÔ alkoxyamine initiator and SG-1 free nitroxide resulting in hydroxy functional poly(acrylates). The NMP kinetics are discussed in detail. In addition, the polymers obtained by FRP and NMP are compared and the results are related to the amount of bisacrylates that are present in the initial monomer mixtures resulting from the transacylation reactions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2610,2621, 2010 [source]

Comparison of properties of acrylic,polyurethane hybrid emulsions prepared by batch and semibatch processes with monomer emulsion feed

POLYMER INTERNATIONAL, Issue 5 2003
ebenik
Abstract Aqueous acrylic,polyurethane hybrid emulsions were prepared by batch and semibatch polymerization of acrylic monomer mixtures (butyl acrylate, methyl methacrylate and acrylic acid) in the presence of polyurethane dispersion. The acrylic component was introduced in the monomer emulsion feed. The weight ratio between acrylic and polyurethane components was varied to obtain different emulsion properties, microphase structure and mechanical film properties. Scanning electron microscopy, average particle size and molecular weight measurements were performed to characterize the latex systems. Mechanical properties were examined by measuring Koenig hardnesses of dried films. The average particle size increased with the acrylic/polyurethane ratio. Particles of larger than average size and, to some extent, higher than average molecular weights by batch process were formed. Koenig hardnesses decreased with increasing acrylic/polyurethane ratio. Properties of emulsions synthesized by semibatch processes were compared with the results reported for a different polyurethane dispersion. Copyright © 2003 Society of Chemical Industry [source]

Modeling Studies of the Phase Behavior of Monomer/Polymer/Disk Composites

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 6 2008
Francisco Torrens
Abstract The model developed by Balazs et al. to explain the phase behavior of polymer/clay composites is extended to monomer/polymer/clay composites, obtaining an expression for the free energy of a monomer/polymer/thin-disk mixture. By minimizing the free energy and calculating the chemical potentials of the three system components, phase diagrams for the monomer/disk and monomer/polymer/disk mixtures are contructed. Through the evolution and comparison of these diagrams, the effects of nanodisk size, polymer molecular mass and interaction parameters (temperature) on mixture stability and attained morphology are then studied. [source]