Search results for "polymerization"
showing 10 items of 1689 documents
Synthesis of pentafluorophenyl(meth)acrylate polymers: New precursor polymers for the synthesis of multifunctional materials
2005
Pentafluorophenyl acrylate and -methacrylate were polymerized using AIBN as a thermal initiator. The obtained polymers were soluble polymeric active esters that could be used for the preparation of multifunctional polymers. The reactivity of poly(pentafluorophenylacrylate) and poly(pentafluorophenylmethacrylate) towards primary and secondary amines, as well as alcohols was investigated in a quantitative way. Both poly(active esters) reacted satisfactorily with aliphatic primary and secondary amines but only low conversion was found in the case of aromatic amines. Conversions of only 30% were reached when poly(pentafluorophenylacrylate) was treated with one equivalent of alcohol under base c…
Transfer to Polymer and Long-Chain Branching in PLP-SEC of Acrylates
2009
Pulsed laser polymerization (PLP) combined with size exclusion chromatography (SEC) is the method of choice for determining propagation rate coefficients. The influence of the long-chain branching in PLP-SEC is investigated using multiple-detection SEC and a recently developed method to detect long-chain branching [P. Castignolles, R. Grab, M. Parkinson, M. Wilhelm, M. Gaborieau, Polymer 2009, 50, 2373.] While little or no long-chain branching is detected in poly(n-butyl acrylate), the error in relevant molecular weights of poly(2-ethylhexyl acrylate) is large (30-100%) due to long-chain branching. Possible variations of propagation rate coefficient with alkyl groups in alkyl acrylates or w…
Synthesis of CO2-responsive polymers by post-polymerization modification
2014
Abstract We describe a general method to synthesize a double responsive polymer, exhibiting a temperature and CO 2 responsive behavior. The polymer derived from a controlled radical polymerization technique of pentafluorophenyl acrylate (PFPA), followed by a sequential post-polymerization modification of a CO 2 responsive- and thermo-responsive amines. Utilizing this approach three double responsive copolymers were synthesized, poly(3- N′,N′ -dimethylaminopropyl acrylamide- co - N -isopropyl acrylamide) (poly(DMPA- co -NIPAM)), poly( L -Arginine methyl ester acrylamide- co - N -isopropyl acrylamide) (poly(AME- co -NIPAM)) and poly( L -Arginine methyl ester acrylamide- co - N -cyclopropyl ac…
Versatile Responsive Surfaces via Hybrid Polymers Containing Acetal Side Groups
2009
Two hybrid polymers, poly(methylsilsesquioxane)-poly(2,2-diethoxyethyl acrylate) and poly-(methylsilsesquioxane)-poly(1,3-dioxolan-2-ylmethyl acrylate), were synthesized and used for preparation of stable surface coatings. Their acetal side groups could be functionalized via solution-dipping with different primary amines and hydroxylamines after acidic deprotection and thus allowed for flexible modification of the surface hydrophilicity. Functionalization with a thermo-responsive polymer resulted in a thermo-responsive surface with temperature-dependent contact angles. Further, the two types of acetals showed different stability toward acidic treatment and could be addressed independently.
Anionic Polymerization of (Meth)acrylates in the Presence of Tetraalkylammonium Halide−Trialkyl Aluminum Complexes in Toluene. 3. Kinetic Investigati…
2001
The polymerization of n-butyl acrylate initiated by ester enolates in the presence of tetraalkylammonium halide−trialkylaluminum complexes, R4N[AlnR‘3nX] (n = 1, 2), in toluene has a controlled character at −78 °C only for selected combinations of the complex. Quantitative monomer conversions are usually reached with Me4N[AlnBui3nCl] leading to polymers with narrow molecular weight distributions (Mw/Mn < 1.2). Kinetic investigations show a complex mechanism of the polymerization, implying an equilibrium between at least two active species. Besides, various acrylate homopolymers and block copolymers (PMMA-b-polyacrylate) can be synthesized with this new initiating system.
Synthesis of hyperbranched poly(tert-butyl acrylate) by self-condensing atom transfer radical polymerization of a macroinimer
2000
Using 2-hydroxyethyl α-bromoisobuty-rate as initiator, atom transfer radical polymerization (ATRP) of tert-butyl acrylate leads to poly(tert-butyl acrylate) (PtBA) with a hydroxyl group at one and a bromine atom at the other end. Esterification of the hydroxyl group of these heterotelechelic polymers with acryloyl chloride yields PtBA (M n = 3060) with a polymerizable double bond at one end and a bromine atom at the other end which can act as an initiator in ATRP (macroinimer). Self-condensing ATRP of such a macroinimer leads to hyperbranched or highly branched PtBA. The polymer was characterized by GPC viscosity measurements. Even at M w = 78800, a rather low polydispersity index of M w M …
Strukturaufklärung der bei der Addition von 2-Cyano-2-propylradikalen an p-Tolyl- und 4-Cyclohexylphenyl-methacrylat entstehenden Produkte mittels 1H…
1978
The chromatographically pure products, gained on the suppression of polymerisation of p-tolyl or 4-cyclohexylphenyl methacrylates (1, 2) by a great excess of 2-cyano-2-propyl radicals, could be isolated in a total yield of 95 to 100%. The structure of these products was established by 1H NMR and mass spectroscopy. There are p-tolyl or 4-cyclohexylphenyl 4-cyano-2-(2-cyano-2-propyl)-2,4-dimethylvalerate (1a, 2a), p-tolyl or 4-cyclohexylphenyl 2-(2-cyano-2-methylpropyl)acrylate (1b, 2b), p-tolyl or 4-cyclohexylphenyl 4-cyano-4-methyl-2-(2-cyano-2-methylpropyl)valerate (1c, 2c), p-tolyl or 4-cyclohexylphenyl 4-cyano-2,4-dimethylvalerate (1d, 2d), and p-tolyl or 4-cyclohexylphenyl 4-cyano-2,4-d…
Endgruppenuntersuchungen an isotaktischen Polystyrolen. VII. Mitt. über die stereospezifische Polymerisation von Styrol mit alkaliorganischen Verbind…
1963
Durch Polymerisation von Styrol mit optisch aktivem 2-Methylbutylnatrium oder -lithium konnen Polystyrole hergestellt werden, welche die Ebene des polarisierten Lichtes drehen; der gemessene Drehwert entspricht bei nicht zu hochmolekularen Polymeren einer 2-Methylbutylgruppe pro Makromolekul. Bei der Suche nach einer ungesattigten Endgruppe konnten weder mit einer infrarotspektroskopischen Kompensationsmethode noch durch eine Anlagerungsreaktion eines Siloxanmonohydrids Doppelbindungen in mit 2-Methylbutylnatrium hergestellten Polystyrolen nachgewiesen werden. Aus der Bestimmung der wachsenden Polystyrolmolekule mit Hilfe von MICHLERS Keton als Abbruchsreagenz ergibt sich, das der groste Te…
Reactions of α-diimino ligands with the chloro-bridged dimer [RhCl(COD)]2(COD=1,5-cyclooctadiene)
1988
Abstract The reactions of α-diimino ligands N - N ′ [ N - N ′= 2,2′-bipyridine (bipy), C 5 H 4 N2CHNR (R= C 6 H 4 OMe- p , PyCa), RNCHCHNR (R=C 6 H 4 - OMe- p , DAB)] with [RhCl(COD)] 2 give rise to stoichiometry, solvent, ligand, and temperature dependent equilibria. In general, the 1/1 ligand/dimer reaction yields the ionic product [Rh(COD)( N - N ′)] [RhCl 2 (COD)], at room temperature. For N - N ′=DAB, the ionic form is in equilibrium with the binuclear compound [{RhCl(COD)} (μ-DAB){RhCl(COD)}] (containing a σ σ,'- N , N ′ bridging α-diimine), which becomes the predominant species at low temperatures. In [Rh(COD)( N - N ′)] [RhCl 2 (COD)], a fast exchange of the Rh(COD) unit betwe…
Transport mechanism of peptides through supported liquid membranes
2007
Abstract The transport of selected dipeptides through supported liquid membranes impregnated with di(2-ethylhexyl) phosphoric acid in n-dihexylether has been investigated. The fluxes depend on the side chain of amino acids, presence in the peptide structure. The highest fluxes were obtained for the peptides extracted with the highest efficiency. It has been found that the hydrophobicity of investigated peptides, was not the major factor, influences their SLM permeation. In the conditions studied, it has been observed that the transport of peptide–carrier complex was depending on the acidic–basic properties of the analyte. The linearly least-square fittings of log {K1 + [H+]D} and log[(HR)2]…