Search results for "Ionic polymerization"

1983

Synthese a partir de l'hexahydro-1,5,5a,6,9,9a benzodioxepinne-2,4. Polymerisation en masse en un produit incolore, cireux (Tg=−11°C)

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.

Synthesis of Macromolecular Substances by Condensation Polymerization and Stepwise Addition Polymerization

2001

Condensation polymerizations (polycondensations) are stepwise reactions between bifunctional or polyfunctional components, with elimination of simple molecules such as water or alcohol and the formation of macromolecular substances. For the preparation of linear condensation polymers from bifunctional compounds (the same considerations apply to polyfunctional compounds which then lead to branched or crosslinked condensation polymers) there are basically two possibilities. One either starts from a monomer which has two unlike groups suitable for polycondensation (AB type), or one starts from two different monomers, each possessing a pair of identical reactive groups that can react with each …

Fluorimetric determination of binding constants between micelles and chemical systems

1991

Abstract A fluorimetric method is adapted to determine the binding constants (K) between different systems and micelles. The method is based on the variation of the fluorescence of the system in the presence of increasing amounts of a surfactant agent. This method permits the determination of binding constants in strong acid or alkaline media. The binding constants of 1-naphthol and 2-(4-alkylamino-2 hydroxyphenyl)benzo-X azoles (X being an O or an S atom, PAS-O and PAS-S) with cationic, anionic, and nonionic surfactants have been determined by the proposed method. Values from 49,100 M−1 for the interaction between PAS-S and CTAB in basic medium to 10 M−1 for the interaction of 1-naphthol w…

1963

Es wird gezeigt, das sich e-Caprolactam mit wasserfreiem Bromwasserstoff kationisch polymerisieren last und die dabei gebildeten Polymeren die Struktur von N-(Poly-e-aminocaproyl)-caprolactamen besitzen. Die charakteristische Diacylimidstruktur wird IR-spektroskopisch, durch die Hydroxamsaurereaktion und durch alkoholytische Abspaltung des C-terminalen Lactamringes nachgewiesen. Oligomerengemische, die durch kurzzeitige Umsetzung molarer Mengen an Caprolactam und Initiator bei 175–200°C erhalten werden, konnen durch Hochspannungspapierelektrophorese in einheitliche Individuen aufgetrennt werden. Die Umsetzung mit Hydroxylamin fuhrt zu Oligo-e-aminocapronhydroxamsauren, die sich mit Hilfe au…

1991

Polyfunctional chloroformates were applied to the polymerization of 2-phenyl-2-oxazoline and 2-methyl-2-oxazoline. The use of a trifunctional initiator, viz. the chloroformate of 2,2-bis(hydroxymethyl)-1-butanol, led to three-arm star polymers of 2-oxazolines. Two macromolecular initiators, viz. poly(ethylene oxide) with two chloroformate end groups (α-chloroformyl-ω-chloroformyloxypoly(oxyethylene)) with number-average molar masses 350 g/mol ≤ Mn ≤ 6000 g/mol and α-chloroformyl-ω-methoxypoly(oxyethylene) with Mn = 350 and 750 g/mol were applied for the synthesis of poly(2-oxazoline)-block-poly(ethylene oxide)-block-poly(2-oxazoline) and poly(2-oxazoline)-block-poly(ethylene oxide) copolyme…

1977

The solution polymerization of styrene in methylene dichloride catalysed by trifluoromethanesulfonic acid takes place at a high rate even at low catalyst concentration. The S-shaped course of the conversion curves is explained by a reaction mechanism, in which the catalyst rapidly forms an inactive complex with one monomer molecule, and this monomer-acid complex is in equilibrium with the free catalyst molecule from which the propagating species are formed. Therefore, the formation of active initiating species becomes a slow process which depends also on the change of monomer concentration during polymerization. It is assumed that the active initiating species are formed from two or three m…

1975

In the polymerization of isobutene catalyzed by aluminium tribromide and in the polymerization of styrene catalyzed by trifluoromethanesulphonic acid it is supposed that an inactive catalyst monomer complex is formed which is in equilibrium with other active species. The monomer complexation of the catalyst explains the S-shaped conversion curves and the complex kinetics of the polymerization. The value of the equilibrium constant Km (complexation constant) expresses what part of the catalyst may take part in the polymerization process as an active initiating species. For the system isobutene/AlBr3, Km was found to be 0,62 1/mol. In the system styrene/CF3SO3H, the high value of the complexa…

Über die polymerisation von styrol in flüssigem schwefeldioxyd

1963

In uberschussigem flussigem Schwefeldioxyd gelostes Styrol kann durch Zugabe von Hydroperoxyden oder Persaren polymerisiert werden. Innerhalb weniger Minuten entstehen in hohen Ausbeuten nach einem kationischen Mechanismus hochmolekulare Polystyrole. Der Einflus der Monomeren-Konzentration, der Temperatur, der Losungsmittel und sonstiger Zusatze wird studiert. Bei Anwesenheit bestimmter Losungsmittel entstehen mit den gleichen Katalysatoren bei stark verminderter Reaktionsgeschwindigkeit durch radikalische Copolymerisation Polystyrolsulfone. Styrene, dissolved in excess liquid SO2 can be polymerized by addition of hydroperoxides or peracids. In a few minutes high yields of high molecular po…

Anorganische verbindungen als lösungsmittel für polymere und monomere. Polymerisationen in phosphoroxychlorid und thionylchlorid

1966

Die Loslichkeit verschiedener Monomerer, Polymerer und Polymerisationskatalasatoren in anorganischen Verbindungen wurde untersucht. Chloride und Oxychloride des Phosphors und Schwefels zeigten gute Losungseigenschaften. Thionylchlorid und Phosphoroxychlorid wurden als Losungsmittel bei der kationischen Polymerisation von Styrol, Isobutylvinylather, 3,3-Bis-(chlormethyl)-oxetan, Tetrahydrofuran und Epichlorhydrin eingeaetzt. Als geeignete Katalysatoren erwiesen sich hierbei Aluminiumchlorid und Eisentrichlorid. In Phosphoroxychlorid konnten Acrylnitril und Vinylchlorid radikalisch polymerisiert werden. The solubility of a series of monomers, polymers, and initiators in inorganic compounds wa…