Search results for "TYR"

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.

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.

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…

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…

1978

The synthesis and polymerization of 2-cyanoethyl N-vinylcarbamate (3b) and of the corresponding 2-trimethylsilylethyl isomer 3c are reported. The homopolymers 4b and 4c, derived from 3b and 3c, could be deblocked under mild conditions (ethanolamine for 4b and trifluoroacetic acid or tetraethylammonium fluoride for 4c) with essentially 100% unmasking of the amino function. Treatment of such unmasked amino groups in a copolymer derived from N-vinyl-2-pyrrolidone and 3b with 4-{4-[bis(2-chloroethyl)amino]phenyl}butyryl chloride (13) (chlorambucil chloride) gave the corresponding amide, a potential antitumor agent. Kinetic studies showed that fluoride ion cleavage of poly(2-trimethylsilylethyl …

Asymmetric Aldol Reaction with Polystyrene-Supported Proline-Based Catalysts

2009

Asymmetric aldol reaction in water catalyzed by polystyrene-supported proline

2007

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…

Opalescent Cholesteric Networks from Chiral Polyisocyanates in Polystyrene

1998

Hemiesters and hemiamides of maleic and succinic acid: synthesis and application of surfactants in emulsion polymerization with styrene and butyl acr…

1999

Hemiesters and hemiamides of maleic acid with different chain lengths of the hydrophobic alkyl group (R = C8H17, C10H21, C12H25, C16H33) have been synthesized and used as surfactants in the emulsion polymerization of styrene and butyl acrylate. The same polymerization experiments were also carried out using nonreactive surfactants with an analogous succinic structure. The chemical structure of the surfactants was confirmed by 1H nuclear magnetic resonance. The melting point and critical micelle concentration of the reactive surfactants described herein were measured. All of the surfactants studied provided good stability of styrene/butyl acrylate latexes, when compared with a reference late…