Search results for "Mono"

Über die polymerisation von acrylsäurechlorid

1960

Monomeres Acrylsaurechlorid wird mittels Azodiisobuttersaurenitril in Dioxan bei 50°C polymerisiert. Bei Ausschlus von Feuchtigkeit und Sauerstoff entstehen bis zu 90% Umsatz unvernetzte Polymere. Durch Reaktion mit flussigem Ammoniak wurden Polyacrylamide erhalten, die zur viskosimetrischen Molgewichtsbestimmung dienten. Monomeric acrylyl chloride was polymerized in dioxane at 50°C by azo-bis-isobutyronitrile. With the exclusion of moisture and oxygen, a non-cross-linked polymer with a 90% yield was obtained. Polyacrylamides were formed by the reaction of polyacrylyl chloride with liquid ammonia. These products were used for viscosimetric molecular weight determinations.

Synthesis of Photoreactive Block Copolymers Based on 1-Iminopyridinium Ylides

2010

Two photoreactive pyridinium ylide containing monomers, {[2-(metacryloyloxy)ethoxy]carbonyl}(pyridinium-1-yl)azanide (M1) and pyridinium-1-yl-(4-vinylbenzoyl)azanide (M2), were synthesized. Both monomers were polymerized under controlled radical polymerization conditions, i.e. reversible addition–fragmentation chain transfer polymerization (M1 and M2) and nitroxide-mediated polymerization (M2). Further block copolymers PMMA-b-PM1 and PS-b-PM2 were successfully synthesized and their molecular weight, Mn, and block ratio could be determined by 1H NMR analysis, thereby opening the synthetic possibilities of photoreactive ylides in block copolymer syntheses.

Über die polymerisation bei der sublimation des trioxans. 17. Mitt. Über polyoxymethylene

1962

Bei der Sublimation von gereinigtem Trioxan und bei seiner Kristallisation aus der Schmelze erfolgt in der kristallinen Phase eine langsame Polymerisation zu hochmolekularem Polyoxymethylen. Die Ausbeuten an Polymeren sind um so hoher, je trockener das Trioxan ist und je geringer der Fremdgasdruck bei der Sublimation ist. Es wurde festgestellt, das diese Polymerisation durch Spuren von monomerem Formaldehyd ausgelost wird; wenn letzterer durch Silberoxyd zerstort wird, kann Trioxan unverandert sublimiert und kristallisiert werden. Wahrend der Polymerisation wird monomerer Formaldehyd von den wachsenden Polyoxymethylenketten abgespalten und so der Polymerisationskatalysator regeneriert. Desh…

1986

Cinnamic acid moieties were incorporated into amphiphilic compounds containing one and two alkyl chains. These lipid-like compounds with photoreactive units undergo self-organization to form monolayers at the gas-water interface and bilayer structures (vesicles) in aqueous solutions. The photoreaction of the cinnamic acid moiety induced by 254 nm UV light was investigated in the crystalline state, in monolayers, in vesicles and in solution in organic solvents. The single-chain amphiphiles undergo dimerization to yield photoproducts with twice the molecular weight of the corresponding monomers in organized systems. The photoreaction of amphiphiles containing two cinnamic acid groups occurs v…

Structure and properties of pharmacologically active polymers

1975

Although the concept of using pharmacologically active macromolecular compounds as drugs is still regarded with much skepticism for both theoretical and practical reasons, interest in this field has grown in recent years because of the opportunity to take advantage of the specific properties of polymeric materials. For low molecular weight drugs, changes in structure often lead to a loss of specific activity. On the other hand, the properties of macromolecular drugs depend on the structure of the polymer used and this can be varied over a wide range by the incorporation of comonomer units, by the application of polymer-analogous reactions, or by related structural changes. A new model is pr…

Tuneable pH-regulated supramolecular copolymerisation by mixing mismatched dendritic peptide comonomers

2015

Charged phenylalanine-rich dendritic peptides form highly stable and pH-switchable rod-like supramolecular copolymers, when co-assembled with a matching oppositely charged dendritic comonomer. Here, we demonstrate that by mismatching a strong with a weak β-sheet encoded comonomer, both the stability and the pH-triggered disassembly of the copolymers shifts drastically from pH 4.2 to biologically relevant pH 5.8.

Lichtstreuungsmessungen an oligomeren; lösungsverhalten von polypropylenglykol

1967

Es wird uber Lichtstreuungsmessungen an Polypropylenglykolen mit Molekulargewichten von M = 400 bis 4000, an monomerem und dimerem Propylenglykol, an Diphenyl, Tristearin und Pentaerythrittetrastearat in Losung berichtet. Die molekulareinheitlichen Substanzen dienten zur Untersuchung der Leistungsfahigkeit der Lichtstreuungstechnik im Bereich niedriger Molekulargewichte. Fur den CABANNES-Faktor und das Brechungsinkrement wurde eine Abhangigkeit von Molekulargewicht und Konzentration gefunden. Die Streulichtmessungen an den polymerhomologen Propylenglykolen in Verbindung mit Viskositatsmessungen in Aceton und Benzol wurden zur Charakterisierung des Losungsverhaltens verwendet. Es ergab sich,…

Carbohydrates as Polyfunctional Scaffolds in Combinatorial Synthesis

2006

Carbohydrates are inexpensive, polyfunctional molecules which contain a high density of stereogenic centers. Taking advantage of these particular properties monosaccharides like glucose or mannose have been used for the construction of peptidomimetics which simulate recognition sites of somatostatin or RGD ligands of integrins. Due to their poly functionality, carbohydrates are considered promising scaffolds for combinatorial syntheses either in solution or on solid phase. The application of carbohydrate scaffolds, however, requires sets of orthogonally stable, selectively removable protecting groups, and the challenge in this combinatorial strategy increases with increasing number of hydro…

<title>Optically induced switching of dicyclohexylamino substituted azobenzene derivatives in thin ordered films</title>

2005

During the last years, there has been an increasing interest in the photoinduced switching effects. Among the objects of concern azobenzene derivatives, isomerizing under UV and visible light, occupy a prominent position. To understand the photoresponse of these materials in the condensed phase, their spectroscopic and electrical properties are studied. It is shown that the photoresponse depends on the orientation of the molecules and their packing. A number of novel azobenzene derivatives containing a N,N-dicyclohexyl sulfonamide moiety is synthesized. The derivatives differ in the length of alkyl chains between the azobenzene moiety and SH or COOH groups. The morphology and the photoinduc…

Theoretical Study of the Elimination Kinetics of Carboxylic Acid Derivatives in the Gas Phase. Decomposition of 2-Chloropropionic Acid

1997

The reaction mechanism for the decomposition of 2-chloropropionic acid in the gas phase to form hydrogen chloride, carbon monoxide, and acetaldehyde has been theoretically characterized. Analytical gradients have been used by means of AM1 and PM3 semiempirical procedures and ab initio methods at HF and DFT (BLYP) levels with the 6-31G** basis set. The correlation effects were also included by using the perturbational approach at the MP2 level with the 6-31G** and 6-31++G** basis sets and the variational approach at the CISD/6-31G** level and by means of MCSCF wave functions with a (6,6) complete active space and the 6-31G** basis set. The global potential energy surface has been studied, an…