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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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Multiarm Polycarbonate Star Polymers with a Hyperbranched Polyether Core from CO2 and Common Epoxides
2017Co-Authors: Markus Scharfenberg, Jan Seiwert, Maximilian Scherger, Jasmin Preis, Moritz Susewind, Holger FreyAbstract:Multiarm star copolymers, consisting of hyperbranched poly(ethylene oxide) (hbPEO) or poly(butylene oxide) (hbPBO) Polyether copolymers with glycerol branching points as a core, and linear aliphatic polycarbonate arms generated from carbon dioxide (CO2) and epoxide monomers, were synthesized via a “core-first” approach in two steps. First, hyperbranched Polyether Polyols were prepared by anionic copolymerization of ethylene oxide or 1,2-butylene oxide with 8–35% glycidol with molecular weights between 800 and 389,000 g·mol–1. Second, multiple arms were grown via immortal copolymerization of CO2 with propylene oxide or 1,2-butylene oxide using the Polyether Polyols as macroinitiators and (R,R)-(salcy)-CoCl as a catalyst in a solvent-free procedure. Molecular weights up to 812,000 g·mol–1 were obtained for the resulting multiarm polycarbonates, determined by online viscometry with universal calibration and 1H NMR. Comparing the synthesis of different multiarm star polycarbonates, a combination of a highly reactive macroinitiator with a less reactive epoxide monomer was found to be most suitable to obtain well-defined structures containing up to 88 mol% polycarbonate. The multiarm star copolymers were investigated with respect to their thermal properties, intrinsic viscosity, and potential application as Polyols for polyurethane synthesis. Glass transition temperatures in the range from −41 to +25 °C were observed. The intrinsic viscosity could be adjusted between 5.4 and 17.3 cm3·g–1 by varying the ratio of Polyether units and polycarbonate units
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cationic copolymerization of 3 3 bis hydroxymethyl oxetane and glycidol biocompatible hyperbranched Polyether Polyols with high content of primary hydroxyl groups
Biomacromolecules, 2015Co-Authors: Evamaria Christ, Dominika Hobernik, Matthias Bros, Manfred Wagner, Holger FreyAbstract:The cationic ring-opening copolymerization of 3,3-bis(hydroxymethyl)oxetane (BHMO) with glycidol using different comonomer ratios (BHMO content from 25 to 90%) and BF3OEt2 as an initiator has been studied. Apparent molecular weights of the resulting hyperbranched Polyether copolymers ranged from 1400 to 3300 g mol–1 (PDI: 1.21–1.48; method: SEC, linear PEG standards). Incorporation of both comonomers is evidenced by MALDI-TOF mass spectroscopy. All hyperbranched Polyether Polyols with high content of primary hydroxyl groups portray good solubility in water, which correlates with an increasing content of glycerol units. Detailed NMR characterization was employed to elucidate the copolymer microstructures. Kinetic studies via FTIR demonstrated a weak gradient-type character of the copolymers. MTT assays of the copolymers (up to 100 μg mL–1) on HEK and fibroblast cell lines (3T3, L929, WEHI) as well as viability tests on the fibroblast cells were carried out to assess the biocompatibility of the materials, c...
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Cationic Copolymerization of 3,3-Bis(hydroxymethyl)oxetane and Glycidol: Biocompatible Hyperbranched Polyether Polyols with High Content of Primary Hydroxyl Groups
2015Co-Authors: Evamaria Christ, Dominika Hobernik, Matthias Bros, Manfred Wagner, Holger FreyAbstract:The cationic ring-opening copolymerization of 3,3-bis(hydroxymethyl)oxetane (BHMO) with glycidol using different comonomer ratios (BHMO content from 25 to 90%) and BF3OEt2 as an initiator has been studied. Apparent molecular weights of the resulting hyperbranched Polyether copolymers ranged from 1400 to 3300 g mol–1 (PDI: 1.21–1.48; method: SEC, linear PEG standards). Incorporation of both comonomers is evidenced by MALDI-TOF mass spectroscopy. All hyperbranched Polyether Polyols with high content of primary hydroxyl groups portray good solubility in water, which correlates with an increasing content of glycerol units. Detailed NMR characterization was employed to elucidate the copolymer microstructures. Kinetic studies via FTIR demonstrated a weak gradient-type character of the copolymers. MTT assays of the copolymers (up to 100 μg mL–1) on HEK and fibroblast cell lines (3T3, L929, WEHI) as well as viability tests on the fibroblast cells were carried out to assess the biocompatibility of the materials, confirming excellent biocompatibility. Transfection efficiency characterization by flow cytometry and confocal laser microscopy demonstrated cellular uptake of the copolymers. Antiadhesive properties of the materials on surfaces were assessed by adhesion assays with fibroblast cells
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Hyperbranched aliphatic Polyether Polyols
Journal of Polymer Science Part A, 2012Co-Authors: Martina Schömer, Christoph Schüll, Holger FreyAbstract:Hyperbranched polymers, dendritic macromolecules with branch-on-branch structures, have become an important polymer class since the early 1990s. They combine several advantages of the perfectly branched dendrimers with easy accessibility, typically in a one-step synthesis. Hyperbranched Polyethers are a particularly interesting class of chemically stable and often biocompatible materials. Multifunctional hyperbranched Polyethers with controllable molar mass and comparably low polydispersities can been prepared using hydroxyl-functional epoxides or oxetanes for polymerization via anionic and cationic polymerization mechanisms. Here, we review the progress in the preparation, characterization, and application of these uniquely versatile aliphatic Polyether Polyols. Their unusual mechanical, thermal, and solution properties render them useful for a variety of applications, for example, as building blocks for various complex macromolecular architectures or in biomedical applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Juan F. Rodríguez - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of trifunctional graft polymer Polyether Polyols employing a silica based gel as non-aqueous dispersant
European Polymer Journal, 2019Co-Authors: Irene Izarra, Juan F. Rodríguez, D. Simón, M. Molina, Manuel CarmonaAbstract:Abstract Currently, the PU industry is developing new products with enhanced physical, mechanical and structural properties. One of the specialties that is attracting more and more attention from managers and enterprises all over the world are the PUs based on polymer Polyether Polyols (graft Polyols). In this work, the synthesis of graft Polyols was developed employing a non-aqueous dispersant (NAD) based on silica gel, which contains in its chemical structure segments with a great affinity for the solid polymeric particles and other segment having a strong affinity for the hydroxyl groups of the liquid polyol. The combination of both polar and non-polar characteristics ensures the stability of the resulting polymer dispersion and prevent the sedimentation and the coalescence of the polymer particles. By using this NAD it was possible to synthesize trifunctional polymer Polyether polyol (PPP) from Styrene and containing up to 38.69 wt% of solids. The optimal reaction conditions have been stablished using a concentration of 1.5 wt% NAD, 4 wt% of initiator respect to the monomer amount and a polymerization temperature of 80 °C. The viscosity of the optimal PPP (1930 mPa·s) and the particle size (dv0.5 of 5.427 μm and dn0.5 of 1.711 μm) were in the range of graft Polyols available in the market for similar solids content, with the additional advantage of employing a lower quantity of NAD and a softer reaction temperature than those employed in the industrial process (110 °C).
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Synthesis of Polyether Polyols using Glycerol Phosphate Disodium Salt as Initiator
Journal of Macromolecular Science Part A, 2013Co-Authors: María M. Velencoso, A Lucas, María Jesús Ramos, Joaquín C. García-martínez, Juan F. RodríguezAbstract:The employment of glycerol phosphate as initiator for the synthesis of Polyether Polyols is explored in order to open the possibility of preparing a new range of products with enhanced flame retardant properties. For this purpose, glycerol phosphate disodium salt was employed as initiator, caesium hydroxide was selected as catalyst and dimethyl sulfoxide as the aprotic solvent. The influence of the operative conditions on the polymerization rate and the product properties was studied. This study revealed that the employment of dimethyl sulfoxide allows the activation of the initiator and the start-up of the propylene oxide incorporation to the polyol chain. The optimal ratio between the catalyst and the initiator resulted to be 1:6 using CsOH. MALDI-TOF MS, 1H-NMR and 31P-NMR results confirmed that the phosphate was incorporated into the polymer chain. Finally, the thermal stability of the phosphorylated Polyols was confirmed by thermogravimetric analysis.
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click ligation of coumarin to Polyether Polyols for polyurethane foams
Polymer International, 2013Co-Authors: María M. Velencoso, María Jesús Ramos, Antonio De Lucas, Agustin S B Gonzalez, Joaquin C Garciamartinez, Juan F. RodríguezAbstract:A simple strategy for the synthesis and functionalization of polyurethanes is described. Anionic ring-opening polymerization was combined with ‘click’ chemistry to synthesize Polyols with fluorescent properties. This route allows the incorporation of a wide range of functionalities in the Polyols with an easy, clean and highly selective process compatible with several types of functional groups. The proposed strategy opens the way to the production, in a cost-effective way, of ‘smart’ polyurethanes with non-conventional properties like fire retardancy, antimite properties, antibacterial properties, etc. Alkynyl groups were introduced into the polyol chains by the controlled addition of glycidyl propargyl ether as co-monomer during a conventional anionic ring-opening copolymerization with propylene oxide. Subsequently 4-azidomethyl-7-methoxycoumarin molecules were introduced onto the alkynyl-Polyether Polyols by copper-catalysed cycloaddition reactions to produce end-functionalized Polyols. The chemical structure of the novel Polyols was characterized using infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography with triple detection and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy. These characterization techniques confirmed the presence of a considerable amount of functional groups in the structure of the Polyols. Finally, various fluorescent rigid foams, based on the functionalized Polyols, were synthesized. Copyright © 2012 Society of Chemical Industry
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Production of Polyether Polyols Using Phosphate Calcium Salt
Journal of Macromolecular Science Part A, 2011Co-Authors: María M. Velencoso, A Lucas, Cristina Gutiérrez, María Jesús Ramos, Joaquín C. García-martínez, Juan F. RodríguezAbstract:The synthesis of bifunctional Polyols using glycerol phosphate calcium salt hydrate as initiator and caesium hydroxide and potassium tert-butoxide as catalyst by means of anionic polymerization was achieved. If a phosphate salt is used as initiator, this reaction allows us to obtain Polyols with phosphate groups in its structure not previously described. The relationship to catalyst type was also studied. The kinetic studies revealed that there was a linear relationship between the propylene oxide consumption and time. Both the polydispersity indexes of the polyol and the reaction time decreased using caesium hydroxide instead of potassium tert-butoxide under the same synthesis conditions. The incorporation of phosphorus in the polyol chain was confirmed by MALDI-TOF spectra and 31P-NMR spectra. GPC analyses showed an additional small peak in the product, attributed to the allyl adduct. The purification procedure of Polyether Polyols was also studied by means of liquid-liquid extraction, desorption and io...
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Purification by Liquid Extraction of Recovered Polyols
Solvent Extraction and Ion Exchange, 2006Co-Authors: Carolina Molero, A Lucas, Juan F. RodríguezAbstract:Abstract Polyether Polyols can be recovered from polyurethane wastes by chemical recycling. After a two–phase glycolysis, a polyol rich product is obtained, but to be applied in the same use of a raw polyol, it has to be purified. Liquid extraction is a non‐aggressive technique suitable for the polymer purification. Therefore, a study has been conducted dealing with the effect of extraction conditions with aqueous solutions on the purification of polyol. Temperature, mass ratio of solvent used, and pH of the solution were modified to achieve the maximum polyol purity. Due to the rheological properties of the polyol, the requirement of mechanical aid to provide proper phase separation has been also studied.
María M. Velencoso - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Polyether Polyols using Glycerol Phosphate Disodium Salt as Initiator
Journal of Macromolecular Science Part A, 2013Co-Authors: María M. Velencoso, A Lucas, María Jesús Ramos, Joaquín C. García-martínez, Juan F. RodríguezAbstract:The employment of glycerol phosphate as initiator for the synthesis of Polyether Polyols is explored in order to open the possibility of preparing a new range of products with enhanced flame retardant properties. For this purpose, glycerol phosphate disodium salt was employed as initiator, caesium hydroxide was selected as catalyst and dimethyl sulfoxide as the aprotic solvent. The influence of the operative conditions on the polymerization rate and the product properties was studied. This study revealed that the employment of dimethyl sulfoxide allows the activation of the initiator and the start-up of the propylene oxide incorporation to the polyol chain. The optimal ratio between the catalyst and the initiator resulted to be 1:6 using CsOH. MALDI-TOF MS, 1H-NMR and 31P-NMR results confirmed that the phosphate was incorporated into the polymer chain. Finally, the thermal stability of the phosphorylated Polyols was confirmed by thermogravimetric analysis.
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click ligation of coumarin to Polyether Polyols for polyurethane foams
Polymer International, 2013Co-Authors: María M. Velencoso, María Jesús Ramos, Antonio De Lucas, Agustin S B Gonzalez, Joaquin C Garciamartinez, Juan F. RodríguezAbstract:A simple strategy for the synthesis and functionalization of polyurethanes is described. Anionic ring-opening polymerization was combined with ‘click’ chemistry to synthesize Polyols with fluorescent properties. This route allows the incorporation of a wide range of functionalities in the Polyols with an easy, clean and highly selective process compatible with several types of functional groups. The proposed strategy opens the way to the production, in a cost-effective way, of ‘smart’ polyurethanes with non-conventional properties like fire retardancy, antimite properties, antibacterial properties, etc. Alkynyl groups were introduced into the polyol chains by the controlled addition of glycidyl propargyl ether as co-monomer during a conventional anionic ring-opening copolymerization with propylene oxide. Subsequently 4-azidomethyl-7-methoxycoumarin molecules were introduced onto the alkynyl-Polyether Polyols by copper-catalysed cycloaddition reactions to produce end-functionalized Polyols. The chemical structure of the novel Polyols was characterized using infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography with triple detection and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy. These characterization techniques confirmed the presence of a considerable amount of functional groups in the structure of the Polyols. Finally, various fluorescent rigid foams, based on the functionalized Polyols, were synthesized. Copyright © 2012 Society of Chemical Industry
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Production of Polyether Polyols Using Phosphate Calcium Salt
Journal of Macromolecular Science Part A, 2011Co-Authors: María M. Velencoso, A Lucas, Cristina Gutiérrez, María Jesús Ramos, Joaquín C. García-martínez, Juan F. RodríguezAbstract:The synthesis of bifunctional Polyols using glycerol phosphate calcium salt hydrate as initiator and caesium hydroxide and potassium tert-butoxide as catalyst by means of anionic polymerization was achieved. If a phosphate salt is used as initiator, this reaction allows us to obtain Polyols with phosphate groups in its structure not previously described. The relationship to catalyst type was also studied. The kinetic studies revealed that there was a linear relationship between the propylene oxide consumption and time. Both the polydispersity indexes of the polyol and the reaction time decreased using caesium hydroxide instead of potassium tert-butoxide under the same synthesis conditions. The incorporation of phosphorus in the polyol chain was confirmed by MALDI-TOF spectra and 31P-NMR spectra. GPC analyses showed an additional small peak in the product, attributed to the allyl adduct. The purification procedure of Polyether Polyols was also studied by means of liquid-liquid extraction, desorption and io...
Wei Jianhui - One of the best experts on this subject based on the ideXlab platform.
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Influence of Structural Flame Retardant Polyether Polyols on Flame Retardant Performance of Rigid Polyurethane Foam
Chemical Propellants & Polymeric Materials, 2013Co-Authors: Wei JianhuiAbstract:The rigid polyurethane foams were prepared by using structural flame retardant Polyether Polyols containing phosphorus and nitrogen elements.The influence of the structural flame retardant Polyether amounts on the physical and flame retardant performance of the foams was investigated.The results show that the compression strength,size stability and oxygen index of the foams significantly increase by adding the structural flame retardant Polyether.When the mass of the structural flame retardant Polyether in the total mass of the Polyether is 30%,and the additive amount of the mixed flame retardant is appropriate,its oxygen index reaches more than 32%.In addition,the additive amount of the flame retardant in the structural flame retardant foam articles under the same flame retardant specifications significantly decreases,but various properties of the foams obviously increase.
Antonio De Lucas - One of the best experts on this subject based on the ideXlab platform.
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click ligation of coumarin to Polyether Polyols for polyurethane foams
Polymer International, 2013Co-Authors: María M. Velencoso, María Jesús Ramos, Antonio De Lucas, Agustin S B Gonzalez, Joaquin C Garciamartinez, Juan F. RodríguezAbstract:A simple strategy for the synthesis and functionalization of polyurethanes is described. Anionic ring-opening polymerization was combined with ‘click’ chemistry to synthesize Polyols with fluorescent properties. This route allows the incorporation of a wide range of functionalities in the Polyols with an easy, clean and highly selective process compatible with several types of functional groups. The proposed strategy opens the way to the production, in a cost-effective way, of ‘smart’ polyurethanes with non-conventional properties like fire retardancy, antimite properties, antibacterial properties, etc. Alkynyl groups were introduced into the polyol chains by the controlled addition of glycidyl propargyl ether as co-monomer during a conventional anionic ring-opening copolymerization with propylene oxide. Subsequently 4-azidomethyl-7-methoxycoumarin molecules were introduced onto the alkynyl-Polyether Polyols by copper-catalysed cycloaddition reactions to produce end-functionalized Polyols. The chemical structure of the novel Polyols was characterized using infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography with triple detection and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy. These characterization techniques confirmed the presence of a considerable amount of functional groups in the structure of the Polyols. Finally, various fluorescent rigid foams, based on the functionalized Polyols, were synthesized. Copyright © 2012 Society of Chemical Industry
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production of Polyether Polyols using caesium as catalyst
Polymer International, 2002Co-Authors: Antonio De Lucas, Lourdes Rodriguez, Mario Perezcollado, Paula SanchezAbstract:An alternative catalyst to the traditional KOH was studied for preparation of Polyols, having high molecular weight (about 6000 g mol -1 ) and low unsaturation content. KOH catalyst is useful until the equivalent weight of the polyol reaches about 1 000 g mol -1 , at which point an excess of allylic terminal unsaturation starts to develop. Polyols were synthesised using caesium and potassium hydroxide, at different temperatures and catalyst concentrations. Both the unsaturation content of the final polyol and the synthesis time decreased using caesium hydroxide instead of potassium hydroxide under the same synthesis conditions. The relationship to temperature and catalyst concentration was also studied. GPC analyses showed an additional small peak in the product, attributed to the allyl adduct, whose intensity was greater when potassium hydroxide was used as catalyst.
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An Improved Method for the Purification of Polyether−Polyols Using Phosphoric Acid as Neutralization Agent
Organic Process Research & Development, 1999Co-Authors: Antonio De Lucas, Ángel Pérez, Pablo Cañizares, And Maria J. Gomez, Juan F. RodríguezAbstract:The aim of this study was to develop a crystallization process for the removal of the alkaline catalyst (potassium hydroxide) from crude Polyether−Polyols. The process involves a first step of neutralization with an aqueous solution of phosphoric acid and subsequently the removal of water to reach supersaturation and crystal growth. Finally, the crystals formed are removed by filtration. Different amounts of phosphoric acid and water were investigated in order to establish a suitable recipe for this process. Different depressurization vs time profiles for the water evaporation were used to produce an uniform and narrow crystal size distribution with a large mean crystal size in this kind of experimental device.