Search results for "polymerization"
showing 10 items of 1689 documents
UV-photometrisch bestimmte relative molare massen von anionisch erzeugten polyäthylenoxiden mit unterschiedlichen endgruppen
1976
Athylenoxid wurde mit Kalium-4-(phenylazo)benzylalkoholat (1f) polymerisiert, die gereinigten Produkte fraktioniert und anschliesend acyliert. Die UV-photometrische Bestimmung der Endgruppen ergab, das HO-Endgruppen, verglichen mit den Starterendgruppen, in grosem Uberschus vorhanden waren. Aus den Endgruppenwerten liesen sich Zahlenmittel des Molekulargewichts (Mn) ableiten. Sie wurden mit osmotisch bestimmten Mn-Werten und Viskositatsmittel (Mη)-verglichen und bestatigten die angenommene Struktur der Polyathylenoxide. Ethylene oxide was polymerized with potassium 4-(phenylazo)benzylalcoholate (1f). The purified and fractionated products were acylated. The ultra-violet measurement of the e…
Poly(THF-co-cyano ethylene oxide): Cyano Ethylene Oxide (CEO) Copolymerization with THF Leading to Multifunctional and Water-Soluble PolyTHF Polyelec…
2016
Cyano-functional polyether copolymers based on THF were prepared via cationic ring-opening copolymerization of THF with cyano ethylene oxide (CEO). The CEO content of poly(tetrahydrofuran) (polyTHF) based copolymers varied from 3.3 to 29.3%, and molecular weights ranged from 5100 to 31900 g·mol–1 with Mw/Mn in the range of 1.31 to 1.74 (SEC in THF, PS standards). The polymerization was conducted with methyl trifluoromethanesulfonate (MeOTf) as an initiator. Kinetic studies concerning incorporation of both monomers were performed via NMR spectroscopy. The cyano groups at the poly(THF-co-CEO) copolymers enable direct access to amino (polyTHF–NH2) and carboxyl groups (polyTHF–COOH) in facile o…
Synthesis and properties of amphiphilic “dumbbell”-shaped grafted block copolymers, 1. Anionic synthesis via a polyfunctional initiator
1994
Two poly(ethylene oxide) stars linked by a long polystyrene chain represent a novel amphiphilic architecture (dumbbell), which is available by anionic grafting of ethylene oxide from a hydroxylated polybutadiene-block-polystyrene-block-polybutadiene triblock copolymer. The short butadiene end-blocks (DPB = 36) of a BSB triblock copolymer with a long styrene middle block (DPS = 650) was first modified by hydroboration and oxidation. A multifunctional alkoxide initiator is thus prepared by titration of the hydroxyl groups of the “polybutadiene” end-block with cumylpotassium. Gelation and precipitation of the polyfunctional initiator in THF could be avoided by complexing the cation (K+) with a…
Maleimide Glycidyl Ether: A Bifunctional Monomer for Orthogonal Cationic and Radical Polymerizations.
2015
A novel bifunctional monomer, namely maleimide glycidyl ether (MalGE), prepared in a four-step reaction sequence is introduced. This monomer allows for selective (co)polymerization of the epoxide group via cationic ring-opening polymerization, preserving the maleimide functionality. On the other hand, the maleimide functionality can be copolymerized via radical techniques, preserving the epoxide moiety. Cationic ring-opening multibranching copolymerization of MalGE with glycidol was performed, and a MalGE content of up to 24 mol% could be incorporated into the hyperbranched polymer backbone (Mn = 1000-3000 g mol(-1)). Preservation of the maleimide functionality during cationic copolymerizat…
Water sorption isotherms of molecularly imprinted polymers. Relation between water binding and iprodione binding capacity
2017
International audience; Molecularly imprinted polymers are often used in aqueous medium in order to recognize specifically a target molecule. The molecular recognition is usually based on hydrogen bonding. In this case, water molecule presents a serious competition towards the target molecule. In this study, the water sorption by molecularly imprinted polymers was studied in aqueous medium. The molecularly imprinted polymers were specific for iprodione fungicide and were prepared using a 24 full factorial experimental design. They were synthesized using EGDMA or TRIM as crosslinker, methacrylamide or styrene as functional monomer and using bulk or precipitation polymerization. The water sor…
Polymerizable ring-shaped molecules containing aspartic acid: synthesis and free radical polymerization of a macrocycle derived from (N'-methacryloyl…
1999
A novel polymerizable macrocycle, 6, was prepared using high dilution techniques. Starting from N-(N'-methacryloyl-11-aminoundecanoyl)-L-aspartic acid dimethyl ester (2), N-(N'methacryloyl-11-aminoundecanoyl)-α,β-bis( 4,9-dioxadodecane-1,12-diamine)-L-aspartic acid amide (4) was obtained via amino-lysis with the bifunctional amine 4,9-dioxadodecane-1,12-diamine (3) in high excess. Addition of the free amino groups to toluene-2,4-diisocyanate (5) under high dilution provided macrocycle 6. The existence and purity of 6 were confirmed by mass spectrometry, NMR and IR spectroscopy, and HPLC. The methacrylic function was used to build up oligomers by free radical polymerization, using AIBN as an…
Poly(methyl ethylene phosphate) hydrogels
2020
Abstract A degradable and water-soluble polyphosphoester (PPE), namely poly(methyl ethylene phosphate)-dimethacrylate (PMEP-DMA), was synthesized and crosslinked by UV irradiation to prepare PPE-hydrogels. Hydrogels with 10 and 15 wt% of PMEP were prepared after UV-irradiation with an additional 0.2 wt% of photoinitiator. The colorless and transparent PPE hydrogels were studied for their swelling and water uptake. The rheological analysis demonstrated their viscoelastic behavior. The PPE hydrogels were compared to poly(ethylene glycol) (PEG) hydrogels prepared from PEG-macromonomers of similar degrees of polymerization. Hydrolysis experiments proved a successful disintegration of the PPE hy…
Effect of hydrogen on the ethylene polymerization process over Ziegler-Natta catalysts supported on MgCl2(THF)2. II. Kinetic studies
2000
This article reports on a study of the effects of hydrogen on the activity of vanadium and titanium catalysts supported on MgCl 2 (THF) 2 in ethylene polymerization. It was found that hydrogen did not change the stable nature of the active sites and the polydispersity index of the polyethylene obtained. The propagation rate, expressed as k p , was found to be independent of the presence and concentration of hydrogen, indicating that this reacting agent does not modify the reactivity of the active sites. However, the presence of hydrogen in the polymerization medium is responsible for partial deactivation of the active sites just before polymerization is initiated.
Olefin polymerization and copolymerization by complexes bearing [ONNO]-Type salan ligands: Effect of ligand structure and metal type (titanium, zirco…
2014
A series of novel titanium(IV) complexes bearing tetradentate [ONNO] salan type ligands: [Ti{2,2′-(OC6H3-5-t-Bu)2-NHRNH}Cl2] (Lig1TiCl2: R = C2H4; Lig2TiCl2: R = C4H8; Lig3TiCl2: R = C6H12) and [Ti{2,2′-(OC6H2-3,5-di-t-Bu)2-NHC6H12NH}Cl2] (Lig4TiCl2) were synthesized and used in the (co)polymerization of olefins. Vanadium and zirconium complexes: [M{2,2′-(OC6H3-3,5-di-t-Bu)2-NHC6H12NH}Cl2] (Lig4VCl2: M = V; Lig4ZrCl2: M = Zr) were also synthesized for comparative investigations. All the complexes turned out active in 1-octene polymerization after activation by MAO and/or Al(i-Bu)3/[Ph3C][B(C6F5)4]. The catalytic performance of titanium complexes was strictly dependent on their structures an…
Synthesis and characterization of amphiphilic comb-polymers via ring-opening metathesis polymerization of exo,exo-5,6-bis(alkoxymethyl)-7-oxabicyclo[…
1994
A number of exo,exo-5,6-bis(alkoxymethyl)-7-oxabicyclo[2.2.1]hept-2-enes (exo,exo-5,6-bis(alkoxymethyl)-7-oxanorbornenes) with long alkyl chains were prepared by reduction of the Diels-Alder adduct of furan and maleic anhydride, followed by alkylation with a series of different n-alkylbromides. These monomers were polymerized via ring-opening metathesis polymerization (ROMP) catalyzed by ruthenium trichloride in ethanolic solution. Contrary to a helical conformation as it was predicted by a previous molecular model study the poly(7-oxanorbornenes) adopt a coil conformation in solution. In bulk the materials show side chain crystallization.