Search results for "Styrene"
showing 10 items of 561 documents
Intrinsic viscosities of polyelectrolytes: specific salt effects and viscometric master curves.
2013
Dilute solutions of the sodium salt of polystyrene sulfonic acid (PSS-Na) were measured viscometrically as a function of composition in aqueous solvents of different salinity, where the extra salt was either NaCl or CaCl2. Such experiments yield {η}, the generalized intrinsic viscosities (hydrodynamic specific volume) of the polyelectrolyte for arbitrary polymer concentrations, c. In the limit of infinite dilution {η} becomes identical to the intrinsic viscosity [η]. For NaCl {η} decreases monotonously with rising c, whereas maxima are passed in the case of CaCl2. Condensing c and the concentration of extra salt in the mixed solvent into a single variable enables the establishment of predic…
Zur verzögernden wirkung aromatischer aldehyde auf die radikalische polymerisation von vinylverbindungen
1972
Die Einwirkung einer Reihe aromatischer Aldehyde auf die mit α.α-′Azobisisobuttersaurenitril gestarteten Polymerisationen von Styrol und Methacrylsauremethylester wurde untersucht (a) durch Vergleich der Polymerausbeuten; (b) durch quantitative Analyse der UV-Spektren der gereinigten Polymeren und (c) durch Vergleich ihrer Mn- und Mn-Werte. Bei der Styrolpolymerisation zeigen 4-Phenyl-benzaldehyd und Indol-3-aldehyd keine Einwirkung. 4-Phenylazo-benzaldehyd, Benzaldehyd, Anthracen-9-aldehyd und m-(2.4-Dinitrophenoxy)-benzaldehyd verzogern die Polymerisation. Bis auf Benzaldehyd wird hierbei ihr kovalenter Einbau in das Polystyrol nachgewiesen. Fur 4-Phenylazo-benzaldehyd konnte eine scheinb…
Treatment of poly(styrene-co-methacrylic acid)/poly(4-vinylpyridine) blends in solution under liquid–liquid phase-separation conditions. A new method…
2006
Phase diagrams are contributed for polymer mixture systems in solution. One polymer has proton-acceptor character and the other has growing proton-donor nature, which is reflected in the phase diagrams. Usually, these diagrams are obtained from size-exclusion chromatographic (SEC) measurements. A totally novel application, which is exposed in this report, is the construction of the phase diagram from the viscometric experiments of polymer mixtures. The evaluated binodal or cloud-point isotherms so built agree well with those from SEC. The results indicate an augmentation in the dimensions of donor polymer B, in the presence of acceptor polymer C, intensifying with the concentration of C, wh…
1983
Poly(ethylene glycol)s grated onto suitably functionalized, crosslinked polystyrenes were introduced as a new class of multidetachably immobilized hydrophilic macromolecular supports for the synthesis of peptides. This new polymeric carrier system facilitates both the homogeneous solvation of the reaction site and the insolubilization of the substrate, which are prerequisites for an efficient multistep synthesis using polymeric supports. In these support systems, a strongly solvated hydrophilic linear chain molecule, poly(ethylene glycol) (PEG)1 , is attached to an insoluble, crosslinked polystyrene through suitable anchoring linkages. At the free chain end of this supported PEG, amino acid…
Functionalization of TiO2Nanoparticles with Semiconducting Polymers Containing a Photocleavable Anchor Group and Separation via Irradiation Afterward
2014
The controlled radical polymerization (RAFT polymerization) of semiconducting polymers based on poly(4,4′-dimethyl-triphenylamine) is described. These polymers are afterward end-functionalized with a photocleavable group and an anchor unit (catechol) for oxidic nanoparticles (NPs). Serving as a reference, polystyrene oligomers with the same end groups are also synthesized. Using these polymers allows functionalization of the TiO2-NPs, leading to an improved solubility and miscibility in organic solvents or polymer matrices. Irradiation in the UV region is used to split the photocleavable group and remove the polymer chains from the NPs, which leads to their aggregation.
Cationic and Zwitterionic Polymerizable SurfactantsQuaternary Ammonium Dialkyl Maleates. 2. Emulsion Polymerization of Styrene and Butyl Acrylate
1998
Polymerizable cationic and zwitterionic dialkyl maleates with different hydrophobic chain lengths (R = C10H21, C12H25, C16H33, C18H37) and different counterions (I, Br, HSO4) for the cationic hydrophilic part, as well as some similar surfactants, dialkyl succinates, were used in batch and seeded emulsion polymerization of styrene and butyl acrylate. All surfactants, when used in emulsion polymerization, provide good stability to the styrene/butyl acrylate latices. A styrene/butyl acrylate latex prepared with sodium dodecyl sulfate (SDS) was used as a reference. Some stability tests for latices were performed, and the glass transition temperatures, as well as the molecular weights of the pol…
Vapor Pressures of Polymer Solutions and the Modeling of Their Composition Dependence
2009
Equilibrium vapor pressures, p, are reported for the systems tetrahydrofuran + poly(vinyl methyl ether) and tetrahydrofuran + polystyrene at 20, 40, and 60 °C. These data plus information from the literature serve to demonstrate that the composition dependence of p can be modeled quantitatively for polymer solutions in thermodynamically very different solvents by means of three, physically meaningful parameters.
1989
Coefficients de diffusion de traceurs dans les melanges de PS avec poly(o-methylstyrene), poly(p-methylstyrene et un copolymere statistique p-m-methylstyrene
Coil overlap in moderately concentrated polyelectrolyte solutions: effects of self-shielding as compared with salt-shielding as a function of chain l…
2016
The generalized intrinsic viscosity {η} (hydrodynamic volume of the solute at arbitrary polymer concentration c) – introduced by analogy to the intrinsic viscosity [η] – provides access to the degree of coil overlap Ω for polyelectrolyte solutions in pure water or in saline water. The experimental basis of this investigation consists in viscosity measurements as a function of c for a large number of sodium polystyrene sulfonate (Na-PSS) samples covering the molecular weight range from 0.91 to 1000 kg mol−1. The accurate modeling of these dependencies with a maximum of three parameters yields detailed information on Ω as a function of (c[η]) in the absence and in the presence of extra salt. …