Institute of Textile Chemistry and Chemical Fibers

Denkendorf, Germany

Institute of Textile Chemistry and Chemical Fibers

Denkendorf, Germany

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Xu G.,University of Stuttgart | Wang D.,University of Stuttgart | Buchmeiser M.R.,University of Stuttgart | Buchmeiser M.R.,Institute of Textile Chemistry and Chemical Fibers
Macromolecular Rapid Communications | Year: 2012

Poly(cis-cyclooctene) is synthesized via ring-opening metathesis polymerization in the presence of a chain-transfer agent and quantitatively hydrobrominated. Subsequent graft polymerization of tert-butyl acrylate (tBA) via Cu-catalyzed atom transfer radical polymerization (ATRP) from the non-activated secondary alkyl bromide moieties finally results in PE-g-PtBA copolymer brushes. By varying the reaction conditions, a series of well-defined graft copolymers with different graft densities and graft lengths are prepared. The maximum extent of grafting in terms of bromoalkyl groups involved is approximately 80 mol%. DSC measurements on the obtained graft copolymers reveal a decrease in T m with increasing grafting density. The Cu-catalyzed atom transfer radical graft polymerization of tert-butyl acrylate from polyhydrobrominated ring-opening metathesis polymerization-derived poly(cis-cyclooctene), which structurally corresponds to polybrominated poly(ethylene), is reported. Up to 80 mol-% of the non-activated bromo-groups present in the polymer can be addressed offering unique and unprecedented access to functional polyolefins. Melting points of the graft copolymers correlate with the degree of grafting. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Bandari R.,University of Stuttgart | Buchmeiser M.R.,University of Stuttgart | Buchmeiser M.R.,Institute of Textile Chemistry and Chemical Fibers
Macromolecular Rapid Communications | Year: 2012

Monolithic polymeric materials are prepared via ring-opening metathesis copolymerization of norborn-2-ene with 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo- dimethanonaphthalene in the presence of macro- and microporogens, that is, of n-hexane and 1,2-dichloroethane, using the Schrock catalyst Mo(N-2,6-(2-Pr) 2-C6H3)(CHCMe2Ph)(OCMe 3)2. Functionalization of the monolithic materials is accomplished by either terminating the living metal alkylidenes with various functional aldehydes or by post-synthesis grafting with norborn-5-en-2-ylmethyl- 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate. Finally, boronate-grafted monolithic columns (100 × 3 mm i.d.) are successfully applied to the affinity chromatographic separation of cis-diol-based biomolecules. Polymeric monoliths were prepared via Schrock catalyst-triggered ring-opening metathesis polymerization. Functionalization is accomplished by terminating the metal alkylidenes with various aldehydes. Alternatively, a dioxoborolanyl-substituted norborn-2-ene is grafted onto the monolith. Boronate grafted-monolithic columns are successfully applied to the affinity chromatographic separation of cis-diol-based biomolecules. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Imbrich D.A.,University of Stuttgart | Frey W.,University of Stuttgart | Naumann S.,University of Stuttgart | Buchmeiser M.R.,University of Stuttgart | Buchmeiser M.R.,Institute of Textile Chemistry and Chemical Fibers
Chemical Communications | Year: 2016

The synthesis, single crystal X-ray structure and activity in olefin metathesis of novel anionic tungsten imido alkylidene complexes [1,3-bis-(2,4,6-trimethylphenyl)imidazolinium]+ [W(N-2,6-iPr2C6H3)(CHCMe2Ph)(2,5-Me2Pyr)2Cl]-, [1,3-bis-(2,4,6-trimethylphenyl)imidazolinium]+ [W(N-2,6-iPr2C6H3)(CHCMe2Ph)(2,5Me2Pyr)2(OC6F5)]-, and [1,3-bis-(2,6-diisopropylphenyl)imidazolinium]+ [W(N-2,6-iPr2C6H3)(CHCMe2Ph)(2,5-Me2Pyr)Cl2]- are reported. Additionally, the first example of a bis(N-heterocyclic olefinium) alkylidene tungstate, W(N-2,6-iPr2C6H3)(CHCMe2Ph)(2-methylene-1,3,4,5-tetramethyl-imidazoline)2(OTf)2, is described, including preparation, crystal structure and catalytic activity. © 2016 The Royal Society of Chemistry.


Ciftci M.,Technical University of Istanbul | Batat P.,Koç University | Demirel A.L.,Koç University | Xu G.,University of Stuttgart | And 4 more authors.
Macromolecules | Year: 2013

Polyethylene-graft-poly(tert-butylacrylate) (PE-g-PtBA) copolymers were prepared by using a combination of ring-opening metathesis polymerization (ROMP), hydrobromination, and visible light-induced free radical polymerization. First, cis-cyclooctene was polymerized via ROMP in the presence of a chain transfer agent and quantitatively hydrobrominated. Poly(tert-butyl acrylate) (PtBA) chains were then grown via a grafting from approach from the Br-substituted linear poly(ethylene) (PE) backbone using dimanganese decacarbonyl (Mn2(CO)10) under visible light. The effect of Mn2(CO)10 concentration and irradiation time on the grafting density and efficiency was evaluated. The tert-butyl acrylate (tBA) esters of the graft copolymers were hydrolyzed into acrylic acid functionalities by acidolysis to obtain hydrophilic polyolefins. The precursor polymer, graft copolymer, and hydrolyzed polymer were characterized by 1H and 13C NMR, Fourier transform infrared, atomic force microscopy, and contact angle measurements. © 2013 American Chemical Society.


Naumann S.,University of Stuttgart | Speiser M.,University of Stuttgart | Schowner R.,University of Stuttgart | Giebel E.,Institute of Textile Chemistry and Chemical Fibers | And 2 more authors.
Macromolecules | Year: 2014

Bisphenol A diglycidyl ether (BADGE) is cured thermally using phthalic acid anhydride (PhA) or hexahydrophthalic anhydride (HHPA) as hardener in the presence of different protected N-heterocyclic carbenes (NHCs), from which the catalytically active NHCs are generated in situ upon heating. It is found that the curing reactions proceed in a well-defined manner, delivering highly cross-linked, high-Tg-thermosets using low catalyst loadings (0.1-1 mol % of NHC precursor). The polymerizations can be conducted under air without loss of activity, employing mild curing temperatures (120-160 °C) and short reaction times. By contrast, at room temperature, polymerizations proceed only very slowly and the mixtures remain processable for weeks, enabling formation of a true single-component composition suitable for applications where large processing windows or storage are required. The curing process was followed in situ by DSC as well as by rheological measurements. On the basis of these observations, the structure of the NHC precursor is correlated with its polymerization activity with regard to latency, temperature profile and polymerization kinetics. The robust and fully homogeneous system consisting of the protected NHC, BADGE, and HHPA was successfully tuned both in terms of activity and pot life by choosing the appropriate protected NHC out of 12 different precatalysts. The most rapid polymerization was effected by N,N′-bis(2,4-dimethoxyphenyl-)tetrahydropyrimidinium-2-carboxylate (6-OMe-CO2), while a dimeric zinc-based NHC-complex (6-Mes-ZnCl 2) displayed the longest pot times. © 2014 American Chemical Society.


Naumann S.,University of Stuttgart | Epple S.,University of Stuttgart | Bonten C.,University of Stuttgart | Buchmeiser M.R.,University of Stuttgart | Buchmeiser M.R.,Institute of Textile Chemistry and Chemical Fibers
ACS Macro Letters | Year: 2013

The cyclic amide ε-caprolactam (ε-CLA) is efficiently polymerized by thermally latent C-2-protected N-heterocyclic carbenes (NHCs) to give the corresponding polyamide (PA 6). Carbon dioxide- and metal salt-protected NHCs were used as precatalysts, out of which the free carbenes were generated thermally. This way, a premixing of the corresponding initiator with ε-CLA was possible to yield a storable and directly polymerizable mixture. The screening of a variety of differently constituted carbenes showed the importance of basicity of the active species, thereby revealing N-alkyl-bearing tetrahydropyrimidinium-based carbenes as the most active ones. Rapid production of PA 6 in high yields was possible in bulk polymerization at 180 C, the best activity displayed by 1,3-dicyclohexyltetrahydropyrimidinium-2-carboxylate (6-Cy-CO2). In situ rheology during polymerization showed the characteristics typical for the anionic polymerization of ε-CLA. © 2013 American Chemical Society.


Buchmeiser M.R.,University of Stuttgart | Buchmeiser M.R.,Institute of Textile Chemistry and Chemical Fibers
Current Organic Chemistry | Year: 2013

The concept for preparing functional, high molecular weight poly(olefin)s via tandem ring-opening metathesis / vinyl insertion polymerization is reviewed. It is based on a reversible α-H-addition/ α-H-elimination process occurring in tailor-made catalysts. Copolymerization of ethylene with cyclic olefins with these catalysts yields poly(olefin)s with double bonds in the main chain. These can then be converted into various functional groups. First accomplishments are reported. Particular attention is devoted to the current status of this approach, its limitations and to approaches to overcome these. © 2013 Bentham Science Publishers.


Unold J.,University of Stuttgart | Wang D.,University of Stuttgart | Frey W.,University of Stuttgart | Buchmeiser M.R.,University of Stuttgart | Buchmeiser M.R.,Institute of Textile Chemistry and Chemical Fibers
Polymer Chemistry | Year: 2013

A series of diastereomeric 4,5-diethoxycarbonyl-1,7-octadiynes were synthesized from which the pure diastereomers were obtained by selective Soxhlet extraction in CHCl3. The concept of "small alkoxides" was used with varying size of the alkoxide ligands and all the monomers were cyclopolymerized with two different Schrock-type initiators. As a result, poly(1,7-octadiyne)s consisting virtually solely of six membered repeat units were obtained via regioselective α-insertion. The structure of the polymers and the regioselectivity of insertion were further confirmed by comparing the 13C NMR shifts of model compounds with those of the corresponding polymers. The living character of the polymerization was demonstrated by kinetic studies and end group analysis via MALDI-ToF MS; diblock copolymers were successfully prepared from 1,7-octadiynes and 1,6-heptadiynes. Finally, the tacticity of the cyclopolymers was elucidated from NMR of poly(1,7-octadiyne) synthesized from 1,7-octadiyne-4,4-dicarboxylic esters containing enantiomerically pure menthyl ester groups. These investigations revealed the formation of highly tactic polymers (>86%) with at least predominantly trans-configured exocyclic double bonds. This journal is © 2013 The Royal Society of Chemistry.


Naumann S.,University of Stuttgart | Schmidt F.G.,Evonik Industries | Schowner R.,University of Stuttgart | Frey W.,University of Stuttgart | And 2 more authors.
Polymer Chemistry | Year: 2013

Various carbon dioxide-protected N-heterocyclic carbenes (NHCs) have been investigated with regard to their ability to act as thermally latent initiators for the polymerization of methyl methacrylate (MMA). Such CO2- protected NHCs, while completely inactive at room temperature, deliver poly(methyl methacrylate) (PMMA) in high yields upon heating and thus represent truly latent pre-catalysts. Polymerizations were conducted in the bulk, semi-bulk and in solution. Especially tetrahydropyrimidinium-2-carboxylates as well as 1,3-di(tert-butyl)imidazolium-2-carboxylate, both in combination with dimethylsulfoxide (DMSO), were identified as suitable pre-catalysts for the polymerization of MMA. With 1,3-di(tert-butyl)imidazolium-2-carboxylate in toluene, polydispersity indices (PDIs) as low as 1.3 and number-average molecular weights (Mn) of 500000 g mol-1 could be realized. Tetrahydropyrimidinium-2-carboxylates in conjunction with DMSO resulted in lower molecular weights. Notably, isolated polymer yields up to 96% were possible in some cases, though yields proved to be sensitive to the structure of the initiators used. In principle, at least two different polymerization mechanisms are active. In the presence of DMF or DMSO, the formation of a solvent anion (e.g., DMSO-), which then reacts with the monomer, is proposed. What follows is that only highly basic NHCs work well under these conditions. In contrast, the polymerization of MMA in toluene or in the bulk is probably governed by the nucleophilicity of the NHC, rendering unsaturated, less basic NHCs more applicable. Both mechanisms are discussed. © 2013 The Royal Society of Chemistry.


Fanous J.,University of Stuttgart | Schweizer M.,Institute of Textile Chemistry and Chemical Fibers | Schawaller D.,Institute of Textile Chemistry and Chemical Fibers | Buchmeiser M.R.,University of Stuttgart
Macromolecular Materials and Engineering | Year: 2012

Intrinsically conducting polymer fibers are prepared from P3HT by melt spinning. High crystallinity is achieved by drawing the fibers after the spinning process, applying a draw ratio of 1:2. DSC and XRD measurements confirm the continuous increase of crystalline phases with drawing. For comparison, poly(ethylene terephthalate) fibers are coated with P3HT and drawn as well. Again, the drawing of the coated fiber results in a significant increase in crystallinity of the P3HT coating. The high amount of crystalline phases is associated with a dramatic increase in conductivity (350 SA·cm -1) after doping with FeCl 3 in nitromethane. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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