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Holger Frey - One of the best experts on this subject based on the ideXlab platform.
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thioether bearing hyperbranched polyether polyols with methionine like side chains a versatile platform for orthogonal functionalization
Macromolecular Rapid Communications, 2017Co-Authors: Jan Seiwert, Jana Herzberger, Daniel Leibig, Holger FreyAbstract:The synthesis of thioether-bearing hyperbranched polyether polyols based on an AB/AB2 type copolymerization (cyclic latent monomers) is introduced. The polymers are prepared by anionic ring-opening multibranching copolymerization of Glycidol and 2-(methylthio)ethyl glycidyl ether (MTEGE), which is conveniently accessible in a single etherification step. Slow monomer addition provides control over molecular weights. Moderate dispersities (Đ = 1.48–1.85) are obtained, given the hyperbranched structure. In situ 1H NMR copolymerization kinetics reveal reactivity ratios of rG = 3.7 and rMTEGE = 0.27. Using slow monomer addition, copolymer composition can be systematically varied, allowing for the adjustment of the hydroxyl/thioether ratio, the degree of branching (DB = 0.36–0.48), thermal properties, and cloud point temperatures in aqueous solution in the range of 29–75 °C. Thioether oxidation to sulfoxides enables to tailor the copolymers' solubility profile. Use of these copolymers as a versatile, multifunctional platform for orthogonal modification is highlighted. The methyl sulfide groups can be selectively alkoxylated, using propylene oxide, allyl glycidyl ether, or furfuryl glycidyl ether, resulting in functional hyperbranched polyelectrolytes. Reaction of the alcohol groups with benzyl isocyanate demonstrates successful orthogonal functionalization.
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copolymerization kinetics of Glycidol and ethylene oxide propylene oxide and 1 2 butylene oxide from hyperbranched to multiarm star topology
Macromolecules, 2016Co-Authors: Daniel Leibig, Jan Seiwert, Johannes C Liermann, Holger FreyAbstract:Copolymerization of established epoxide monomers with Glycidol (G) is a key reaction to prepare branched or hyperbranched polyethers. The kinetics of the multibranching anionic ring-opening copolymerization of Glycidol (a cyclic latent AB2 monomer) with ethylene oxide (EO), propylene oxide (PO), and 1,2-butylene oxide (BO; cyclic latent AB monomers), respectively, in dimethyl sulfoxide was studied. Online 1H NMR spectroscopy was employed for in situ monitoring of the individual monomer consumption during the entire course of the statistical copolymerization. Varying the counterion, both the cesium alkoxide and potassium alkoxide initiated copolymerization were studied and compared. From the individual monomer consumption, reactivity ratios were calculated. The reactivity ratio of the alkylene oxides decreases from 0.44 to 0.11 with increasing alkyl chain length on going from EO to BO. Unexpectedly, Glycidol was found to exhibit a higher reactivity ratio in each copolymerization, with reactivity ratios ran...
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catechol acetonide glycidyl ether cage a functional epoxide monomer for linear and hyperbranched multi catechol functional polyether architectures
Macromolecules, 2016Co-Authors: Kerstin Niederer, Daniel Leibig, Christoph Schull, Tobias Johann, Holger FreyAbstract:A protected catechol-containing epoxide monomer, catechol acetonide glycidyl ether (CAGE), is introduced. CAGE is conveniently obtained in three steps and enables the incorporation of surface-active catechol moieties into a broad variety of hydrophilic and biocompatible polyether architectures by copolymerization. Via acidic cleavage of the acetal protecting groups, the polymer-attached catechol functionalities are liberated and available for surface attachment or metal complexation. CAGE has been copolymerized with ethylene oxide and Glycidol to obtain both linear poly(ethylene glycol) and hyperbranched polyglycerol copolymers, respectively, with multiple surface-adhesive catechol moieties. The CAGE content in the copolymers was varied from 1 to 16%, and all polymers exhibit moderate polydispersity (linear: Mw/Mn = 1.05–1.33; hyperbranched: Mw/Mn = 1.44–1.86). In situ kinetic studies of the simultaneous copolymerization of EO and CAGE via NMR spectroscopy have been performed to determine the microstructu...
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hyperbranched polyols via copolymerization of 1 2 butylene oxide and Glycidol comparison of batch synthesis and slow monomer addition
Macromolecules, 2016Co-Authors: Jan Seiwert, Daniel Leibig, Ulrike Kemmerjonas, Marius Bauer, Igor Perevyazko, Jasmin Preis, Holger FreyAbstract:Hyperbranched poly(butylene oxide) polyols have been synthesized by multibranching anionic ring-opening copolymerization of 1,2-butylene oxide and Glycidol. Systematic variation of the composition from 24 to 74% Glycidol content resulted in a series of moderately distributed copolymers (Đ = 1.41–1.65, SEC), albeit with limited molecular weights in the solvent-free batch process in the range of 900–1300 g mol–1 (apparent Mn determined by SEC with PEG standards). In situ monitoring of the copolymerization kinetics by 1H NMR showed a pronounced compositional drift with respect to the monomer feed, indicating a strongly tapered microstructure caused by the higher reactivity of Glycidol. In the case of slow monomer addition considerably higher apparent molecular weights up to 8500 g mol–1 were obtained (SEC). By alteration of the comonomer ratio, aqueous solubility of the hyperbranched copolymers could be tailored, resulting in well-defined cloud points between 20 and 84 °C. Glass transition temperatures betwe...
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Catechol Acetonide Glycidyl Ether (CAGE): A Functional Epoxide Monomer for Linear and Hyperbranched Multi-Catechol Functional Polyether Architectures
2016Co-Authors: Kerstin Niederer, Daniel Leibig, Tobias Johann, Christoph Schüll, Holger FreyAbstract:A protected catechol-containing epoxide monomer, catechol acetonide glycidyl ether (CAGE), is introduced. CAGE is conveniently obtained in three steps and enables the incorporation of surface-active catechol moieties into a broad variety of hydrophilic and biocompatible polyether architectures by copolymerization. Via acidic cleavage of the acetal protecting groups, the polymer-attached catechol functionalities are liberated and available for surface attachment or metal complexation. CAGE has been copolymerized with ethylene oxide and Glycidol to obtain both linear poly(ethylene glycol) and hyperbranched polyglycerol copolymers, respectively, with multiple surface-adhesive catechol moieties. The CAGE content in the copolymers was varied from 1 to 16%, and all polymers exhibit moderate polydispersity (linear: Mw/Mn = 1.05–1.33; hyperbranched: Mw/Mn = 1.44–1.86). In situ kinetic studies of the simultaneous copolymerization of EO and CAGE via NMR spectroscopy have been performed to determine the microstructure of the linear poly(ethylene oxide-co-catechol acetonide glycidyl ether), P(EO-co-CAGE), copolymers. EO shows slightly higher reactivity than CAGE (rEO = 1.14, rCAGE = 0.88), leading to an almost ideally random copolymerization. Because of the catechol units, the copolymers form pH-induced cross-linked networks through metal–ligand interactions. ABA triblock copolymers of the type PCAGE-b-PEG-b-PCAGE formed highly swellable hydrogels upon addition of FeCl3. Furthermore, static water contact angle measurements demonstrate an increase in the hydrophilicity of iron, PTFE, and PVC surfaces after coating with catechol-functional mf-PEGs
Daniel Leibig - One of the best experts on this subject based on the ideXlab platform.
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thioether bearing hyperbranched polyether polyols with methionine like side chains a versatile platform for orthogonal functionalization
Macromolecular Rapid Communications, 2017Co-Authors: Jan Seiwert, Jana Herzberger, Daniel Leibig, Holger FreyAbstract:The synthesis of thioether-bearing hyperbranched polyether polyols based on an AB/AB2 type copolymerization (cyclic latent monomers) is introduced. The polymers are prepared by anionic ring-opening multibranching copolymerization of Glycidol and 2-(methylthio)ethyl glycidyl ether (MTEGE), which is conveniently accessible in a single etherification step. Slow monomer addition provides control over molecular weights. Moderate dispersities (Đ = 1.48–1.85) are obtained, given the hyperbranched structure. In situ 1H NMR copolymerization kinetics reveal reactivity ratios of rG = 3.7 and rMTEGE = 0.27. Using slow monomer addition, copolymer composition can be systematically varied, allowing for the adjustment of the hydroxyl/thioether ratio, the degree of branching (DB = 0.36–0.48), thermal properties, and cloud point temperatures in aqueous solution in the range of 29–75 °C. Thioether oxidation to sulfoxides enables to tailor the copolymers' solubility profile. Use of these copolymers as a versatile, multifunctional platform for orthogonal modification is highlighted. The methyl sulfide groups can be selectively alkoxylated, using propylene oxide, allyl glycidyl ether, or furfuryl glycidyl ether, resulting in functional hyperbranched polyelectrolytes. Reaction of the alcohol groups with benzyl isocyanate demonstrates successful orthogonal functionalization.
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copolymerization kinetics of Glycidol and ethylene oxide propylene oxide and 1 2 butylene oxide from hyperbranched to multiarm star topology
Macromolecules, 2016Co-Authors: Daniel Leibig, Jan Seiwert, Johannes C Liermann, Holger FreyAbstract:Copolymerization of established epoxide monomers with Glycidol (G) is a key reaction to prepare branched or hyperbranched polyethers. The kinetics of the multibranching anionic ring-opening copolymerization of Glycidol (a cyclic latent AB2 monomer) with ethylene oxide (EO), propylene oxide (PO), and 1,2-butylene oxide (BO; cyclic latent AB monomers), respectively, in dimethyl sulfoxide was studied. Online 1H NMR spectroscopy was employed for in situ monitoring of the individual monomer consumption during the entire course of the statistical copolymerization. Varying the counterion, both the cesium alkoxide and potassium alkoxide initiated copolymerization were studied and compared. From the individual monomer consumption, reactivity ratios were calculated. The reactivity ratio of the alkylene oxides decreases from 0.44 to 0.11 with increasing alkyl chain length on going from EO to BO. Unexpectedly, Glycidol was found to exhibit a higher reactivity ratio in each copolymerization, with reactivity ratios ran...
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catechol acetonide glycidyl ether cage a functional epoxide monomer for linear and hyperbranched multi catechol functional polyether architectures
Macromolecules, 2016Co-Authors: Kerstin Niederer, Daniel Leibig, Christoph Schull, Tobias Johann, Holger FreyAbstract:A protected catechol-containing epoxide monomer, catechol acetonide glycidyl ether (CAGE), is introduced. CAGE is conveniently obtained in three steps and enables the incorporation of surface-active catechol moieties into a broad variety of hydrophilic and biocompatible polyether architectures by copolymerization. Via acidic cleavage of the acetal protecting groups, the polymer-attached catechol functionalities are liberated and available for surface attachment or metal complexation. CAGE has been copolymerized with ethylene oxide and Glycidol to obtain both linear poly(ethylene glycol) and hyperbranched polyglycerol copolymers, respectively, with multiple surface-adhesive catechol moieties. The CAGE content in the copolymers was varied from 1 to 16%, and all polymers exhibit moderate polydispersity (linear: Mw/Mn = 1.05–1.33; hyperbranched: Mw/Mn = 1.44–1.86). In situ kinetic studies of the simultaneous copolymerization of EO and CAGE via NMR spectroscopy have been performed to determine the microstructu...
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hyperbranched polyols via copolymerization of 1 2 butylene oxide and Glycidol comparison of batch synthesis and slow monomer addition
Macromolecules, 2016Co-Authors: Jan Seiwert, Daniel Leibig, Ulrike Kemmerjonas, Marius Bauer, Igor Perevyazko, Jasmin Preis, Holger FreyAbstract:Hyperbranched poly(butylene oxide) polyols have been synthesized by multibranching anionic ring-opening copolymerization of 1,2-butylene oxide and Glycidol. Systematic variation of the composition from 24 to 74% Glycidol content resulted in a series of moderately distributed copolymers (Đ = 1.41–1.65, SEC), albeit with limited molecular weights in the solvent-free batch process in the range of 900–1300 g mol–1 (apparent Mn determined by SEC with PEG standards). In situ monitoring of the copolymerization kinetics by 1H NMR showed a pronounced compositional drift with respect to the monomer feed, indicating a strongly tapered microstructure caused by the higher reactivity of Glycidol. In the case of slow monomer addition considerably higher apparent molecular weights up to 8500 g mol–1 were obtained (SEC). By alteration of the comonomer ratio, aqueous solubility of the hyperbranched copolymers could be tailored, resulting in well-defined cloud points between 20 and 84 °C. Glass transition temperatures betwe...
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Catechol Acetonide Glycidyl Ether (CAGE): A Functional Epoxide Monomer for Linear and Hyperbranched Multi-Catechol Functional Polyether Architectures
2016Co-Authors: Kerstin Niederer, Daniel Leibig, Tobias Johann, Christoph Schüll, Holger FreyAbstract:A protected catechol-containing epoxide monomer, catechol acetonide glycidyl ether (CAGE), is introduced. CAGE is conveniently obtained in three steps and enables the incorporation of surface-active catechol moieties into a broad variety of hydrophilic and biocompatible polyether architectures by copolymerization. Via acidic cleavage of the acetal protecting groups, the polymer-attached catechol functionalities are liberated and available for surface attachment or metal complexation. CAGE has been copolymerized with ethylene oxide and Glycidol to obtain both linear poly(ethylene glycol) and hyperbranched polyglycerol copolymers, respectively, with multiple surface-adhesive catechol moieties. The CAGE content in the copolymers was varied from 1 to 16%, and all polymers exhibit moderate polydispersity (linear: Mw/Mn = 1.05–1.33; hyperbranched: Mw/Mn = 1.44–1.86). In situ kinetic studies of the simultaneous copolymerization of EO and CAGE via NMR spectroscopy have been performed to determine the microstructure of the linear poly(ethylene oxide-co-catechol acetonide glycidyl ether), P(EO-co-CAGE), copolymers. EO shows slightly higher reactivity than CAGE (rEO = 1.14, rCAGE = 0.88), leading to an almost ideally random copolymerization. Because of the catechol units, the copolymers form pH-induced cross-linked networks through metal–ligand interactions. ABA triblock copolymers of the type PCAGE-b-PEG-b-PCAGE formed highly swellable hydrogels upon addition of FeCl3. Furthermore, static water contact angle measurements demonstrate an increase in the hydrophilicity of iron, PTFE, and PVC surfaces after coating with catechol-functional mf-PEGs
Kerstin Niederer - One of the best experts on this subject based on the ideXlab platform.
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catechol acetonide glycidyl ether cage a functional epoxide monomer for linear and hyperbranched multi catechol functional polyether architectures
Macromolecules, 2016Co-Authors: Kerstin Niederer, Daniel Leibig, Christoph Schull, Tobias Johann, Holger FreyAbstract:A protected catechol-containing epoxide monomer, catechol acetonide glycidyl ether (CAGE), is introduced. CAGE is conveniently obtained in three steps and enables the incorporation of surface-active catechol moieties into a broad variety of hydrophilic and biocompatible polyether architectures by copolymerization. Via acidic cleavage of the acetal protecting groups, the polymer-attached catechol functionalities are liberated and available for surface attachment or metal complexation. CAGE has been copolymerized with ethylene oxide and Glycidol to obtain both linear poly(ethylene glycol) and hyperbranched polyglycerol copolymers, respectively, with multiple surface-adhesive catechol moieties. The CAGE content in the copolymers was varied from 1 to 16%, and all polymers exhibit moderate polydispersity (linear: Mw/Mn = 1.05–1.33; hyperbranched: Mw/Mn = 1.44–1.86). In situ kinetic studies of the simultaneous copolymerization of EO and CAGE via NMR spectroscopy have been performed to determine the microstructu...
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Catechol Acetonide Glycidyl Ether (CAGE): A Functional Epoxide Monomer for Linear and Hyperbranched Multi-Catechol Functional Polyether Architectures
2016Co-Authors: Kerstin Niederer, Daniel Leibig, Tobias Johann, Christoph Schüll, Holger FreyAbstract:A protected catechol-containing epoxide monomer, catechol acetonide glycidyl ether (CAGE), is introduced. CAGE is conveniently obtained in three steps and enables the incorporation of surface-active catechol moieties into a broad variety of hydrophilic and biocompatible polyether architectures by copolymerization. Via acidic cleavage of the acetal protecting groups, the polymer-attached catechol functionalities are liberated and available for surface attachment or metal complexation. CAGE has been copolymerized with ethylene oxide and Glycidol to obtain both linear poly(ethylene glycol) and hyperbranched polyglycerol copolymers, respectively, with multiple surface-adhesive catechol moieties. The CAGE content in the copolymers was varied from 1 to 16%, and all polymers exhibit moderate polydispersity (linear: Mw/Mn = 1.05–1.33; hyperbranched: Mw/Mn = 1.44–1.86). In situ kinetic studies of the simultaneous copolymerization of EO and CAGE via NMR spectroscopy have been performed to determine the microstructure of the linear poly(ethylene oxide-co-catechol acetonide glycidyl ether), P(EO-co-CAGE), copolymers. EO shows slightly higher reactivity than CAGE (rEO = 1.14, rCAGE = 0.88), leading to an almost ideally random copolymerization. Because of the catechol units, the copolymers form pH-induced cross-linked networks through metal–ligand interactions. ABA triblock copolymers of the type PCAGE-b-PEG-b-PCAGE formed highly swellable hydrogels upon addition of FeCl3. Furthermore, static water contact angle measurements demonstrate an increase in the hydrophilicity of iron, PTFE, and PVC surfaces after coating with catechol-functional mf-PEGs
JOHANNIS ADRIAAN DUINE - One of the best experts on this subject based on the ideXlab platform.
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enzymes involved in the glycidaldehyde 2 3 epoxy propanal oxidation step in the kinetic resolution of racemic Glycidol 2 3 epoxy 1 propanol by acetobacter pasteurianus
Enzyme and Microbial Technology, 2001Co-Authors: U. Wandel, Salgueiro S Machado, Jaap A Jongejan, JOHANNIS ADRIAAN DUINEAbstract:It is already known that kinetic resolution of racemic Glycidol (2,3-epoxy-1-propanol) takes place when Acetobacter pasteurianus oxidizes the compound to glycidic acid (2,3-epoxy-propionic acid) with glycidaldehyde (2,3-epoxy-propanal) proposed to be the transient seen in this conversion. Since inhibition affects the feasibility of a process based on this conversion in a negative sense, and the chemical reactivity of glycidaldehyde predicts that it could be the cause for the phenomena observed, it is important to know which enzyme(s) oxidise(s) this compound. To study this, rac.- as well as (R)-glycidaldehyde were prepared by chemical synthesis and analytical methods developed for their determination. It appears that purified quinohemoprotein alcohol dehydrogenase (QH-ADH type II), the enzyme responsible for the kinetic resolution of rac.-Glycidol, also catalyses the oxidation of glycidaldehyde. In addition, a preparation exhibiting dye-linked aldehyde dehydrogenase activity for acetaldehyde, most probably originating from molybdohemoprotein aldehyde dehydrogenase (ALDH), which has been described for other Acetic acid bacteria, oxidised glycidaldehyde as well with a preference for the (R)-enantiomer, the selectivity quantified by an enantiomeric ratio (E) value of 7. From a comparison of the apparent kinetic parameter values of QH-ADH and ALDH, it is concluded that ALDH is mainly responsible for the removal of glycidaldehyde in conversions of Glycidol catalysed by A. pasteurianus cells. It is shown that the transient observed in rac.-Glycidol conversion by whole cells, is indeed (R)-glycidaldehyde. Since both QH-ADH and ALDH are responsible for vinegar production from ethanol by Acetobacters, growth and induction conditions optimal for this process seem also suited to yield cells with high catalytic performance with respect to kinetic resolution of Glycidol and prevention of formation of inhibitory concentrations glycidaldehyde.
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factors relevant to the production of r Glycidol 2 3 epoxy 1 propanol from racemic Glycidol by enantioselective oxidation with acetobacter pasteurianus atcc 12874
Enzyme and Microbial Technology, 1994Co-Authors: Arie Geerlof, Jaap A Jongejan, Thei J.g.m. Van Dooren, Will J. J. Van Den Tweel, Petronella Catharina Raemakersfranken, JOHANNIS ADRIAAN DUINEAbstract:Abstract Acetobacter pasteurianus oxidizes Glycidol with high activity, comparable to the oxidation of ethanol. The organism has a preference for the S -enantiomer, and the kinetic resolution process obeys a simple relationship, indicating an enantiomeric ratio (E) of 19. The compound is converted into glycidic acid, although a transient accumulation of glycidaldehyde occurs initially. Determination of other parameters revealed a temperature optimum of 50°C, long-term stability (cells in the resting state), and a pH optimum compatible with the chemical stability of Glycidol. However, it was also noted that respiration rates decrease at concentrations of Glycidol above 1 m . This is most likely caused by substrate inhibition of the Glycidol-oxidizing enzyme, the quinohemoprotein ethanol dehydrogenase. Comparison with existing methods for enantiomerically pure Glycidol production indicated a number of attractive points for the method described here, although definitive evaluation must await further studies on the long-term stability under process conditions, reusability of the cells, and the mechanism of Glycidol inhibition.
Stephane Carlotti - One of the best experts on this subject based on the ideXlab platform.
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selective ring opening polymerization of glycidyl methacrylate toward the synthesis of cross linked co polyethers with thermoresponsive properties
Macromolecules, 2011Co-Authors: Amelie Labbe, Annelaure Brocas, Alain Deffieux, Emmanuel Ibarboure, Takashi Ishizone, Akira Hirao, Stephane CarlottiAbstract:Selective polymerization of glycidyl methacrylate (GMA), which has two polymerizable functional groups such as epoxide and methacrylate, was achieved by the monomer-activated anionic approach using tetraoctylammonium bromide/triisobutylaluminum initiating system in toluene at 20 °C. Quantitative and controlled synthesis of poly(glycidyl methacrylate ether), up to about 20 000 g/mol, with pendant methacrylate functions, was obtained by ring-opening of the epoxide. The copolymerization of glycidyl methacrylate with glycidyl methyl ether (GME) in similar conditions, the resulting copolyether structures, and their properties were investigated as a function of feed composition. Reactive poly(glycidyl methyl ether-co-glycidyl methacrylate ether)s P(GME-co-GMA) with lower critical solubility temperature depending on the ratio [GME]/[GMA] were prepared and analyzed by NMR spectroscopy and differential scanning calorimetry. Postpolymerization cross-linking reactions of PGMA and random P(GME-co-GMA) copolymers were...
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synthesis of linear high molar mass Glycidol based polymers by monomer activated anionic polymerization
Macromolecules, 2010Co-Authors: Matthieu Gervais, Annelaure Brocas, Gabriel Cendejas, Alain Deffieux, Stephane CarlottiAbstract:Linear polyGlycidols of high molar masses were prepared by the monomer-activated anionic polymerization of the corresponding protected monomers, ethoxyethyl glycidyl ether and tert-butyl glycidyl ether, using a system composed of tetraoctylammonium bromide as initiator and triisobutylaluminum as monomer activator. The aluminic compound was used in 1.5−5-fold excess compared to the initiator. Linear poly(ethoxyethyl glycidyl ether) and poly(tert-butyl glycidyl ether), with narrow chain dispersity and controlled high molar masses, up to 85 000 g/mol, were prepared at 0 °C in a few hours. Deprotection of hydroxyl functions by acidic treatment of the polymers was shown to proceed quantitatively and cleanly affording the corresponding linear polyglycerol and validating the use of these protecting groups. The copolymerization of protected Glycidols with propylene oxide and butene oxide was also investigated with the goal to broaden the scope of this synthetic approach to various polyethers and copolyethers.