Search results for "Styrene"

showing 10 items of 561 documents

Optische aktivität bei copolymeren aus (—)-acrylsäure-menthylester und styrol

1965

Die Copolymerisation von (–)-Acrylsaure-menthylester mit Styrol wurde untersucht. Die Copolymerisationsparameter betragen: r1 = 0,28 (Acrylsaurementhylester), r2 = 0,84 (Styrol); hieraus folgt fur Q = 0,45 und e = 0,40. Die spezifische Drehung der Copolymeren erwies sich bei 5 Wellenlangen als lineare Funktion des Acrylsaurementhylestergehaltes. Aus den Drehwerten kann daher die Zusammensetzung bestimmt werden; Ruckschlusse auf die Sequenzlangenverteilung sind aber nicht moglich. The copolymerization of (—)-menthyl acrylate with styrene was investigated. The reactivity ratios and the Q- and e-values were found to be: r1 = 0.28 (menthylacrylate), r2 = 0.84 (styrene); Q = 0.45, e = 0.40. The …

chemistry.chemical_compoundCopolymer compositionchemistryRotatory powerPolymer chemistryCopolymerStyreneDie Makromolekulare Chemie
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ChemInform Abstract: Preparation and Nonlinear Optics of Monodisperse Oligo(1,4-phenyleneethynylene)s.

2010

Oligo(1,4-phenyleneethynylene)s 1a−e, with solubilizing propoxy side chains, were prepared by use of Hagihara−Sonogashira coupling reactions. The synthetic strategy was based on a building block system and on the use of trimethylsilyl and triisopropylsilyl protecting groups that could be cleaved selectively. The extension of the conjugation with an increasing number of repeat units provokes a bathochromic shift of the long wavelength absorption and a superlinear increase of the second hyperpolarizability |γ|. The corresponding third harmonic generation (THG) measurements were performed using polystyrene matrices and variable laser wavelengths. We conclude that the conjugation length is much…

chemistry.chemical_compoundCrystallographyTrimethylsilylchemistryBathochromic shiftDispersitySide chainNonlinear opticsHyperpolarizabilityGeneral MedicinePolystyreneCoupling reactionChemInform
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1977

Deuteron relaxation times T1 of polystyrenes deuterated at the backbone (PS-d3) and the phenyl ring (PS-d5), respectively, have been measured in solutions of benzene and diethyl malonate as a function of concentration and temperature. We conclude that the motion of the phenyl ring is faster than that of the backbone, the difference being smallest at high temperatures around 180°C. The temperatures dependence is discussed in relation to the activation energies in polystyrene.

chemistry.chemical_compoundDeuteriumchemistryRelaxation (NMR)Polymer chemistryMolecular motionPhysical chemistryPolystyreneRing (chemistry)PhotochemistryBenzeneDiethyl malonateDie Makromolekulare Chemie
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1989

By endcapping of living polystyrene with ethylene oxide and subsequent reaction with bromoacetyl bromide a polymer with a bromoacetoxy endgroup was obtained. This was used as a macroinitiator for the living cationic polymerization of 1-azabicyclo[4.2.0]octane. The structure and composition of the so formed two-block copolymer was elucidated by different methods. The ratio of the two block and their lengths were varied within broad limits.

chemistry.chemical_compoundEnd-groupAnionic addition polymerizationchemistryEndcappingPolymer chemistryCopolymerCationic polymerizationOrganic chemistryPolystyreneLiving cationic polymerizationOctaneDie Makromolekulare Chemie
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Über makrozwitterionen, 10. Versuche zur darstellung von makrozwitterionen aus α,ω-bifunktionellem poly(α-methylstyrol)

1975

Verschiedene Moglichkeiten zur Darstellung von Makrozwitterionen ohne polare Gruppen in der Polymerkette werden diskutiert. Unter Verwendung von 3-Dimethylaminopropyllithium als Initiator und Propansulton (2) als Kettenabbruchreagenz wurden α,ω-bifunktionelle Poly(α-methylstyrol)e 4 mit einer tert. Amino- und einer Lithiumsulfonat-Endgruppe (Molekulargewichtsbereich ≈ 103; Bifunktionalitat >90%) dargestellt. Die beiden Endgruppen wurden wie bei den entsprechenden monofunktionellen Polymeren analytisch (N,S) und spektroskopisch (IR und NMR) nachgewiesen. Obwohl die beiden Endgruppen der bifunktionellen Polymeren jeweils unabhangig in die freie Sulfonsaure-Gruppe bzw. in die Trimethylammonium…

chemistry.chemical_compoundEnd-groupBetainechemistryDiazomethanePolymer chemistryAmmoniumBifunctionalWeight rangeAmmonium iodideStyreneDie Makromolekulare Chemie
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1993

A macromonomer was prepared from succinimido methacrylate and poly(N-isopropylacrylamide) (PIPA) with an amino end group. The macronomer (MA-PIPA) obtained shows a temperature-responsive transition phenomenon from coil to globule in water at about 36°C. For the copolymer of MA-PIPA with acrylamide (ratio of monomer residues of N-isopropylacrylamide (IPA) and acrylamide (AAm) 10:3), the transition temperature of the PIPA chain was the same as that of the macromonomer, whereas the transition temperature of a linear copolymer of IPA and AAm (ratio of the monomer residues 10:3) was much higher than that of PIPA (52°C). Microspheres were prepared by emulsion polymerization of the macromonomer an…

chemistry.chemical_compoundEnd-groupMonomerchemistryPolymer chemistryRadical polymerizationCopolymerEmulsion polymerizationMethacrylateMacromonomerStyreneDie Makromolekulare Chemie
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Asymmetric Aldol Reaction with Polystyrene-Supported Proline-Based Catalysts

2009

chemistry.chemical_compoundHajos–Parrish–Eder–Sauer–Wiechert reactionNitroaldol reactionAldol reactionchemistryOrganocatalysisOrganocatalysis proline supported-catalysts aldol reaction proline peptidesOrganic chemistryAldol condensationSettore CHIM/06 - Chimica OrganicaPolystyreneProlineLewis acid catalysisSynfacts
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Asymmetric aldol reaction in water catalyzed by polystyrene-supported proline

2007

chemistry.chemical_compoundHajos–Parrish–Eder–Sauer–Wiechert reactionchemistryAldol reactionOrganocatalysisOrganic chemistryPolystyreneProlineSettore CHIM/06 - Chimica OrganicaSupported organocatalystCatalysis
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Bestimmung des vernetzungsgrades schwach vernetzter, noch löslicher copolymerer aus styrol und bisacrylsäurephenylestern durch hydrolytischen abbau

1970

Aus Styrol und Bisacrylsaurephenylester durch radikalische, vernetzende Polymerisation erhaltene und in Toluol sowie Dioxan noch losliche Copolymere wurden durch alkalische Hydrolyse gezielt in die linear strukturierten Bestandteile zerlegt. Diese enthielten neben sehr vielen Styrolbausteinen wenige aus dem Vernetzer stammende Acrylsaurebausteine. UV-Spektren zeigten, das die Vernetzerreste durch den hydrolytischen Abbau vollstandig abgespalten waren. Von den linearen Baustucken wurden viskosimetrisch, osmometrisch und z. T. colorimetrisch die Molekulargewichte bestimmt. Die Hydrolyseprodukte zeigten eine unerwartet bei 320 mμ auftretende Extinktion, deren Ursache nicht restlos aufgeklart w…

chemistry.chemical_compoundHydrolysischemistryMolecular massPolymerizationCovalent bondPolymer chemistryCopolymerAlkaline hydrolysis (body disposal)StyreneAcrylic acidDie Makromolekulare Chemie
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Opalescent Cholesteric Networks from Chiral Polyisocyanates in Polystyrene

1998

chemistry.chemical_compoundMaterials sciencePolymer sciencechemistryMechanics of MaterialsMechanical EngineeringPolymer chemistryGeneral Materials SciencePolystyreneAdvanced Materials
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