Dorota Neugebauer

Influence of substituent on the polymerization of oxiranes by potassium hydride

The polymerization of butoxymethyl-, ethyl-, methyl-, phenoxymethyl-, phenyl- and 2-propen-1-yloxymethyloxirane in the presence of potassium hydride suspension in tetrahydrofuran with 18-crown-6 was studied. The influence of polar and steric effects of substituent on the reaction rate is described. The appropriate correlation equation is derived. The chain transfer reaction to the monomer, found to occur only in the polymerization of methyloxirane, results in lower molecular weight and higher polydispersity of poly(methyloxirane) as compared with other polymers obtained.

ELECTROSPRAY IONIZATION TANDEM MASS SPECTROMETRY FOR POLY(PROPYLENE OXIDE)STARTING AND END GROUP ANALYSIS

Electrospray ionization tandem mass spectrometry was applied to study poly(propylene oxide) obtained in the presence of potassium hydride. It was found that the polyether chains possess different starting groups, i.e. those situated at the beginning of the polymer backbone. These were isopropoxy, hydroxy, methoxy and allyloxy groups when the polymerization was stopped by the addition of methyl iodide. Each macromolecule was terminated by the methoxy group in this case. Copyright 1999 John Wiley & Sons, Ltd.

Structure of poly(propylene oxide) obtained in the presence of K−, K+(15-crown-5)2

Abstract Potassium isopropoxide and potassium tetraethylene glycoxide vinyl ether as well as small amounts of dipotassium tri- and tetraethylene glycoxides are formed in the initiation step of propylene oxide polymerization by K−, K+(15-crown-5)2. Chain transfer reactions occur during the polymerization. Therefore, macromolecules with various starting groups, i.e. with the isopropyl, vinyl, allyl, and propenyl ones, are obtained in the process. The kind of end groups generally depends on the quenching agent used for termination. However, the macromolecules terminated in the chain transfer reactions possess exclusively the hydroxyl end group. The functionality of protonated polymers is equal to about 1.2 as a result of propagation occurring on dipotassium glycoxides.

Analysis of the end groups of poly(methyl methacrylate)

Methyl methacrylate polymerization by potassium hydride results in macromolecules with the methyl starting group. A side-reaction occurs during the process leading to potassium methoxide. It serves as the second initiator of the polymerization and gives macromolecules with the methoxy starting group. All macromolecules possess the methine group at the chain end after protonation. Potassium alkalide K - , K + (15-crown-5) 2 produces various active centres in the initial step of the polymerization. It results in macromolecules with the methyl, ethyl, methoxy and vinyl ether starting groups. However, the majority of macromolecules are formed on the species with two active centres. The termination reaction takes place during the polymerization, therefore, not all chains have the methine end group after protonation.

Study of the structure of poly(methyl methacrylate) obtained in the presence of potassium hydride

Electrospray ionization mass spectrometry (ESI-MS) in positive- and negative-ion mode and multi-step tandem mass spectrometry (ESI-MS ( n) ) were selected for the determination of the structure of poly(methyl methacrylate) obtained using potassium hydride as initiator. Macromolecules with methoxy and methyl starting groups, i. e. those situated at the beginning of the polymer backbone, were observed in this case. No other differences in the chain structure were found in the polymer.

Influence of the kind of crown ether on the heterogeneous polymerization of propylene oxide in the presence of potassium hydride

The influence of 12-crown-4, 15-crown-5, 18-crown-6, dicyclohexano-18-crown-6 and dicyclo-hexano-24-crown-8 on the propylene oxide polymerization with potassium hydride was studied. The highest reaction rate was obtained in the presence of 18-crown-6 or dicyclohexano-18-crown-6. The use of dicyclohexano-18-crown-6 was found to enhance the molecular mass of polymers more than other ligands. The observed effects were related to the heterogeneity of the reaction mixture and the structure of the crown ether complexes with the potassium cation.

Luminescence properties of novel substituted polyethers

New polyethers have been obtained in the anionic polymerization of oxiranes containing carbazole andlor hydrazone groups in the substituent. Excitation and luminescence spectra of the novel polymers were measured in powder and in tetrahydrofuran solution. It allowed to conclude that in the absence of excimer trapping sites, only intermolecular energy migration will be encouraged in dilute solutions of the polymers. Some polyethers and their solutions in tetrahydrofuran showed blue fluorescence. That would have an application to electroluminescent materials, such as electroluminescence polymer diodes.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.