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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. Source


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. Source


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. Source


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. Source


Ciftci M.,Technical University of Istanbul | Batat P.,Koc University | Demirel A.L.,Koc 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. Source

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