Institute For Textilchemie Und Chemiefasern Itcf Denkendorf

Denkendorf, Germany

Institute For Textilchemie Und Chemiefasern Itcf Denkendorf

Denkendorf, Germany
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Schawaller D.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf | Voss M.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf | Bauch V.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf | Frank E.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf | And 2 more authors.
Macromolecular Materials and Engineering | Year: 2014

The construction of electrochromic multilayers on textiles is described. Polyester foils are sputtered with a thin layer of translucent indium tin oxide (ITO). On these ITO layers, WO3 and polyaniline (PANI), respectively, are deposited electrochemically in a continuous process. Both the PANI- and WO3-based materials are equipped with an ion-conductive interface layer composed of lithium poly(styrene sulfonate). Electrochromic elements are made by laminating a PANI- and a WO3-modified substrates together and by fixing the final material on textile substrates. Electrical control is realized by connecting a metallic fabric to each of the two electrochromic parts of the element. The electrochromic behavior of these materials can be switched reversibly within a few minutes. Flexible electrochromic textile materials consisting of interconnected WO3- and PANI-coated ITO are described. The resulting electrochromic elements can be switched reversibly and with good light fastness. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Frank E.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf | Steudle L.M.,University of Stuttgart | Ingildeev D.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf | Sporl J.M.,University of Stuttgart | Buchmeiser M.R.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf
Angewandte Chemie - International Edition | Year: 2014

This Review gives an overview of precursor systems, their processing, and the final precursor-dependent structure of carbon fibers (CFs) including new developments in precursor systems for low-cost CFs. The following CF precursor systems are discussed: poly(acrylonitrile)-based copolymers, pitch, cellulose, lignin, poly(ethylene), and new synthetic polymeric precursors for high-end CFs. In addition, structure-property relationships and the different models for describing both the structure and morphology of CFs will be presented. Strand and deliver: Different precursor systems for the synthesis of carbon fibers, their processing, and the properties of the resulting carbon fibers with respect to the precursor used as well as the latest developments in alternative precursor systems are presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Sandig B.,University of Stuttgart | Michalek L.,University of Stuttgart | Vlahovic S.,University of Stuttgart | Antonovici M.,University of Stuttgart | And 3 more authors.
Chemistry - A European Journal | Year: 2015

Mesoporous monolithic hybrid cellulose-2.5-acetate (CA)/polymer supports were prepared under solvent-induced phase separation conditions using cellulose-2.5-acetate microbeads 8-14μm in diameter, 1,1,1-tris(hydroxymethyl)propane and 4,4′-methylenebis(phenylisocyanate) as monomers as well as THF and n-heptane as porogenic solvents. 4-(Dimethylamino)pyridine and dibutyltin dilaurate (DBTDL), respectively, were used as catalysts. Monolithic hybrid supports were used in transesterification reactions of vinyl butyrate with 1-butanol under continuous, supported ionic liquid-liquid conditions with Candida antarctica lipaseB (CALB) and octylmethylimidazolium tetrafluoroborate ([OMIM+][BF4 -]) immobilized within the CA beads inside the polymeric monolithic framework and methyl tert-butyl ether (MTBE) as the continuous phase. The new hybrid bioreactors were successfully used in dimensions up to 2×30cm (V=94mL). Under continuous biphasic liquid-liquid conditions a constant conversion up to 96% was achieved over a period of 18days, resulting in a productivity of 58μmolmg-1(CALB)min-1. This translates into an unprecedented turnover number (TON) of 3.9×107 within two weeks, which is much higher than the one obtained under standard biphasic conditions using [OMIM+][BF4 -]/MTBE (TON=2.7×106). The continuous liquid-liquid setup based on a hybrid reactor presented here is strongly believed to be applicable to many other enzyme-catalyzed reactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Wang M.,University of Stuttgart | Wang D.,University of Stuttgart | Widmann L.,University of Stuttgart | Frey W.,University of Stuttgart | And 2 more authors.
Polymer Chemistry | Year: 2016

The novel dialkylzirconium complexes L′ZrR2, (R = CH3, Bn = benzyl, CH2SiMe3, L′ = Me2Si{η5-tetramethylcyclopentadienyl}{6-[2-(dimesitylboryl)phenyl]pyrid-2-ylamido}) were synthesized. Upon activation with 1 equiv. of [Ph3C]+[B(C6F5)4]-, both L′Zr(CH3)2 and L′Zr(Bn)2 are quantitatively converted in situ into [L′Zr(CH3)]+[B(C6F5)4]- and [L′Zr(Bn)]+[B(C6F5)4]- while only 28 mol% conversion is observed with L′Zr(CH2SiMe3)2. The aluminum-free cationic catalysts [L′Zr(CH3)]+[B(C6F5)4]-, [L′Zr(Bn)]+[B(C6F5)4]- and [L′Zr(CH2SiMe3)]+[B(C6F5)4]- initiate ring-opening metathesis polymerization (ROMP) of NBE to form predominantly cis-poly(NBE)ROMP. Upon activation with [Ph3C]+[B(C6F5)4]- and AliBu3, L′Zr(CH3)2, L′Zr(Bn)2 and L′Zr(CH2SiMe3)2 also exhibit moderate catalytic activity in the copolymerization of ethylene (E) with NBE. The resulting copolymers do not contain any ROMP-derived poly(NBE), which is in stark contrast to the complexes' homopolymerization propensity for NBE. Upon activation with methylalumoxane (MAO), L′Zr(CH3)2 and L′Zr(Bn)2 produce pure vinyl-insertion polymerization-derived poly(NBE)-co-poly(E) while L′Zr(CH2SiMe3)2 allows for the synthesis of predominantly trans-poly(NBE)ROMP-co-poly(NBE)VIP-co-poly(E)-based copolymers via an α-H+ elimination/addition process. Our findings are discussed on the basis of the instability of the alkylidenes in the presence of E and the blocking effect of aluminum alkyls on ROMP via coordination to the pyridyl-moiety in the cationic complexes. © 2016 The Royal Society of Chemistry.


Wang M.,University of Stuttgart | Xu G.,University of Stuttgart | Wang D.,University of Stuttgart | Zou Y.,University of Stuttgart | And 3 more authors.
Polymer Chemistry | Year: 2015

Three tailored ansa-type Zr(iv)- and Hf(iv)-complexes, Zr-1, Hf-1 and Zr-2, all bridged by a dimethylsilylene group and bearing both a 6-[2-(BR2)phenyl]pyrid-2-yl motif (R = ethyl, mesityl) and an η1/η5-bound ligand with different Lewis base character and steric demand, have been synthesized. Their structures have been determined by single-crystal X-ray diffraction analysis. Upon activation with methylalumoxane (MAO), Zr-1, Hf-1 and Zr-2 are capable of polymerizing norborn-2-ene (NBE) via ring-opening metathesis polymerization (ROMP). In the MAO-activated copolymerization of ethylene (E) with NBE; however, pure vinyl insertion polymerization (VIP)-derived poly(NBE)-co-poly(E) is obtained by Zr-1, Hf-1 and the model pre-catalyst (Zr-3), which does not contain the borylamino motif. In contrast, Zr-2 yields copolymers containing both ROMP- and VIP-derived poly(NBE)ROMP-co-poly(NBE)VIP-co-poly(E) units via an α-H elimination process. Variable-temperature 11B NMR measurements allow for identifying tri- and tetracoordinated borane species. The propensity of catalysts Zr-1, Hf-1, Zr-2 and Zr-3 to switch from VIP to ROMP is discussed on the basis of their structural differences. A detailed NMR study of the reaction of Zr-1, Zr-2, Hf-1 and in particular of dimethylsilylene-bis(6-[2-(diethylboryl)phenyl]pyrid-2-ylamido)ZrCl2 (Zr-4) with MAO and with MAO/NBE clarifies the reaction cascade from VIP to ROMP and allows for establishing a general concept for a tailored switch from VIP to ROMP within the same polymer chain, allowing for tandem VIP-ROMP copolymerization of E with NBE. This journal is © The Royal Society of Chemistry 2015.


Buchmeiser M.R.,University of Stuttgart | Buchmeiser M.R.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf | Marino M.G.,University of Stuttgart
Macromolecular Materials and Engineering | Year: 2012

The cobalt-mediated radical polymerization of acrylonitrile in DMSO using cobalt (II) acetylacetonate [Co(acac) 2] as mediator is studied. Both the evolution of molecular weight and conversion over time under various conditions are monitored. Molecular weights increase sharply at the beginning of the reaction and subsequently grow linearly with conversion. No branching of the polymer is observed by 13C NMR. By a careful design of the reaction parameters, number-average molecular weights >1.2 · 10 5 g · mol -1 with a PDI around 2.4 together with conversions of up to 90% within 24 h are achieved. The copolymerization parameters of acrylonitrile with methyl methacrylate in DMSO at 30 °C are determined using the Kelen-Tüdõs approach giving r AN = 0.33, r MMA = 0.71. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Autenrieth B.,University of Stuttgart | Willig F.,University of Stuttgart | Pursley D.,University of Stuttgart | Naumann S.,University of Stuttgart | And 2 more authors.
ChemCatChem | Year: 2013

The synthesis of the novel ionic Ru-alkylidenes [Ru[(4-CO2)(1-CH3)Py+)]2(IMesH2)(=CH-2-(2-PrO)-C6H4)][OTf-]2 (1, IMesH2=1,3-dimesitylimidazolin-2-ylidene, Py=pyridine, OTf-=triflate) and [RuCl[(4-CO2)(1-CH3)Py+)](IMesH2)(=CH-2-(2-PrO)-C6H4)][OTf-] (2) is reported. Catalysts 1 and 2 were successfully used in various metathesis reactions under biphasic liquid-liquid conditions using 1-butyl-2,3-dimethylimidazolium tetrafluoroborate and heptane as liquid phases. Ruthenium leaching into the heptane phase was very low (<0.4%), translating into Ru contamination of the products between 0.3 and 2.5ppm. Both 1 and 2 exhibited comparable reactivity in organic solvents and under biphasic conditions. Catalyst 1 and 2 were also successfully used in the continuous metathesis of methyl oleate and 1,7-octadiene under supported liquid-liquid conditions. Finally, the disproportionation of the monocarboxylato monochloro substituted Ru-alkylidene 2 was traced by 1HNMR analysis at 40°C, thereby demonstrating the formation of complex 1 and the neutral complex [RuCl2(IMesH2)(=CH-2-(2-PrO)-C6H4)]. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Clauss M.M.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf | Weldin D.L.,University of Stuttgart | Frank E.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf | Giebel E.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf | Buchmeiser M.R.,Institute For Textilchemie Und Chemiefasern Itcf Denkendorf
Macromolecular Chemistry and Physics | Year: 2015

The molar masses of acetylated kraft lignin and organosolv lignin are determined using both dynamic light scattering and size-exclusion chromatography (SEC). Preparative gel fractionation of both lignins is allowed for the further analysis of low-polydispersity lignin fractions. Fundamental information about the aggregation behavior of different molecular weight lignins in different solvent systems is provided. Two different solvent systems are used for SEC. Universal calibration is used for analysis. Applying the Flory-Fox theory, the obtained molecular weights are allowed for determining the maximum glass transition temperature at theoretical infinite molecular weight, Tg ∞, of both acetylated lignins. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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