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Takeshi Endo - One of the best experts on this subject based on the ideXlab platform.
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synthesis and cationic ring opening polymerization of oxetane monomer containing five membered Cyclic Carbonate moiety via highly chemoselective addition of co2
Journal of Polymer Science Part A, 2019Co-Authors: Naoto Aoyagi, Takeshi EndoAbstract:The biCyclic amidinium iodide effectively catalyzed the reaction of carbon dioxide and the epoxy‐containing oxetane under ordinary pressure and mild conditions with high chemoselectivity to give the corresponding oxetane monomer containing five‐membered Cyclic Carbonate quantitatively. The cationic ring‐opening polymerization of the obtained monomer by boron trifluoride diethyl ether proceeded to give linear polyoxetane bearing five‐membered Cyclic Carbonate pendant group in high yield. The molecular weight of the polyoxetane was higher than that of polyepoxide obtained by the cationic ring‐opening polymerization of epoxide monomer containing five‐membered Cyclic Carbonate. The Cyclic Carbonate functional crosslinked polyoxetanes were also synthesized by the cationic ring‐opening copolymerization of Cyclic Carbonate having oxetane and commercially available bisoxetane monomers. Analyses of the resulting polyoxetanes were performed by proton nuclear magnetic resonance, size exclusion chromatography, thermogravimetric analysis, and differential scanning calorimetry. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2606–2615
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salt effect on polyaddition of bifunctional Cyclic Carbonate and diamine
Journal of Polymer Science Part A, 2005Co-Authors: Bungo Ochiai, Shoko Inoue, Takeshi EndoAbstract:The effect of various additives was examined for polyaddition of bifunctional Cyclic Carbonate and diamine giving poly(hydroxyurethane). Lithium chloride and lithium fluoride especially proved to be effective for the acceleration that resulted in giving polymers with higher molecular weights without coloration. The IR spectroscopic analysis of the mixtures of the additives and the Carbonate monomer suggested that the acceleration with the lithium salts depends on the activation of the carbonyl group to enhance its electrophilicity. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6282–6286, 2005
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efficient gas solid phase reaction of atmospheric carbon dioxide into copolymers with pendent oxirane groups effect of comonomer component and catalyst on incorporation behavior
Macromolecules, 2005Co-Authors: Bungo Ochiai, Tokinori Iwamoto, Koji Miyazaki, Takeshi EndoAbstract:The appropriate choice of catalysts and comonomers improved the selectivity of the gas−solid-phase reaction of carbon dioxide into copolymers from glycidyl methacrylate (GMA), which transforms the pendent oxirane moieties to Cyclic Carbonate moieties. Benzyltributylammonium chloride (BnBu3NCl) exhibited good and selective catalytic behavior owing to its appropriate mobility in the copolymer film and moderate catalytic activity. n-Butyl methacrylate proved to be an effective comonomer, resulting in higher incorporation efficiency and better selectivity by preventing the cross-linking reaction, allowing one to obtain soluble polymers bearing Cyclic Carbonate structure.
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cationic copolymerization behavior of glycidyl phenyl ether with seven membered Cyclic Carbonate
Macromolecular Chemistry and Physics, 2005Co-Authors: Hiroshi Morikawa, Takeshi Endo, Atsushi Sudo, Haruo NishidaAbstract:Summary: To clarify the cationic copolymerization behavior of epoxide and Cyclic Carbonate, the copolymerization behavior of glycidyl phenyl ether (GPE) with seven-membered Cyclic Carbonate (7CC) was carried out using methyl trifluoromethanesulfonate (MeOTf) as a cationic initiator. The addition of 7CC accelerated the consumption rate of GPE, and the resulting copolymers were richer in 7CC-derived unit compared to the feed ratio of 7CC. During the copolymerization, a large amount of five-membered Cyclic Carbonate having a phenoxymethyl group (PM-5CC) was produced as a by-product, which suggests the corresponding spiroorthoCarbonate was formed as an intermediate and that residual oxytetramethylene (OTM) unit was incorporated into the copolymer sequence. From 1H NMR analysis, it was found that the copolymers had a statistically random sequence consisting of GPE, 7CC, and OTM units.
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model reaction for the synthesis of polyhydroxyurethanes from Cyclic Carbonates with amines substituent effect on the reactivity and selectivity of ring opening direction in the reaction of five membered Cyclic Carbonates with amine
Journal of Polymer Science Part A, 2001Co-Authors: Hidetoshi Tomita, Fumio Sanda, Takeshi EndoAbstract:This article focuses on the substituent effect on the reactivity and selectivity of the ring-opening direction in the reaction of five-membered Cyclic Carbonates with n-hexylamine. The reactivity of the Cyclic Carbonate and the formation selectivity of the adduct with a secondary hydroxyl group increased as a stronger electron-withdrawing group was introduced at the α-methylene of the Cyclic Carbonate. These results are discussed on the basis of the stability of intermediates, primary and secondary alcoholate anions, Mulliken charges on carbonyl carbon, and the bond lengths and orders of the OCO single bond. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3678–3685, 2001
John M Torkelson - One of the best experts on this subject based on the ideXlab platform.
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reprocessable polyhydroxyurethane networks exhibiting full property recovery and concurrent associative and dissociative dynamic chemistry via transcarbamoylation and reversible Cyclic Carbonate aminolysis
Polymer Chemistry, 2017Co-Authors: Xi Chen, Lingqiao Li, John M TorkelsonAbstract:We discovered that polyhydroxyurethane (PHU) networks synthesized in the presence of a catalyst from five-membered Cyclic Carbonates are intrinsically reprocessable with full property recovery via transcarbamoylation exchange reactions and reversible Cyclic Carbonate aminolysis. Through a judicious choice of monomers, we demonstrated that PHU networks can be recycled multiple times with full property retention. The presence of reversible reactions in addition to exchange reactions in PHU network reprocessing should spur reconsideration of the underlying reprocessing chemistries associated with some dynamic covalent polymer networks which have been ascribed solely to exchange reactions. With excellent reprocessability, this synthetic framework also serves as a sustainable non-isocyanate-based alternative to traditional polyurethane (PU) networks.
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nonisocyanate thermoplastic polyhydroxyurethane elastomers via Cyclic Carbonate aminolysis critical role of hydroxyl groups in controlling nanophase separation
ACS Macro Letters, 2016Co-Authors: Emily K Leitsch, William H Heath, Karl A Scheidt, Goliath Beniah, John M TorkelsonAbstract:Thermoplastic polyhydroxyurethanes (PHUs) were synthesized from Cyclic Carbonate aminolysis. Because of the hydroxyl groups in PHU, the choice of soft segment has a dramatic influence on nanophase separation in polyether-based PHUs. Use of a polyethylene glycol-based soft segment, which results in nanophase-separated thermoplastic polyurethane elastomers (TPUs), leads to single-phase PHUs that flow under the force of gravity. This PHU behavior is due to major phase mixing caused by hydrogen bonding of hard-segment hydroxyl groups to the soft-segment ether oxygen atoms. This hydrogen bonding can be suppressed by using polypropylene glycol-based or polytetramethylene oxide (PTMO)-based soft segments, which reduce hydrogen bonding by steric hindrance and dilution of oxygen atom content and result in nanophase-separated PHUs with robust, tunable mechanical properties. The PTMO-based PHUs exhibit reversible elastomeric response with hysteresis, like that of conventional TPUs. Because of nanophase separation wi...
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Nonisocyanate Thermoplastic Polyhydroxyurethane Elastomers via Cyclic Carbonate Aminolysis: Critical Role of Hydroxyl Groups in Controlling Nanophase Separation
2016Co-Authors: Emily K. Leitsch, William H Heath, Karl A Scheidt, Goliath Beniah, Kun Liu, Tian Lan, John M TorkelsonAbstract:Thermoplastic polyhydroxyurethanes (PHUs) were synthesized from Cyclic Carbonate aminolysis. Because of the hydroxyl groups in PHU, the choice of soft segment has a dramatic influence on nanophase separation in polyether-based PHUs. Use of a polyethylene glycol-based soft segment, which results in nanophase-separated thermoplastic polyurethane elastomers (TPUs), leads to single-phase PHUs that flow under the force of gravity. This PHU behavior is due to major phase mixing caused by hydrogen bonding of hard-segment hydroxyl groups to the soft-segment ether oxygen atoms. This hydrogen bonding can be suppressed by using polypropylene glycol-based or polytetramethylene oxide (PTMO)-based soft segments, which reduce hydrogen bonding by steric hindrance and dilution of oxygen atom content and result in nanophase-separated PHUs with robust, tunable mechanical properties. The PTMO-based PHUs exhibit reversible elastomeric response with hysteresis, like that of conventional TPUs. Because of nanophase separation with broad interphase regions possessing a wide range of local composition, the PTMO-based PHUs also demonstrate potential as novel broad-temperature-range acoustic and vibration damping materials, a function not observed with TPUs
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cooperative catalysis of Cyclic Carbonate ring opening application towards non isocyanate polyurethane materials
European Journal of Organic Chemistry, 2015Co-Authors: Vince M Lombardo, Elizabeth A Dhulst, Emily K Leitsch, Nathan Wilmot, William H Heath, Anthony P Gies, Matthew Miller, John M Torkelson, Karl A ScheidtAbstract:The reaction between Cyclic Carbonates and amines to produce hydroxyurethanes is an important alternative to current urethane chemistry. In order to address the issue of slow reaction rates, an efficient ring opening of Cyclic Carbonates with amines has been achieved utilizing cooperative catalysis. A new Lewis acid/Lewis base combination substantially decreases the reaction times for small molecule systems to reach complete conversion. Although triazabicyclodecene (TBD) has a substantial impact on the reaction rate, the addition of lithium triflate (LiOTf) as a co-catalyst allows for the fastest ring opening reported in the current literature. Cooperative catalysis is also applied to the synthesis of polymers containing hydroxyurethane linkages and is able to achieve rapid conversion of the bis-Cyclic Carbonate and diamine precursors when compared with the uncatalyzed reaction.
James L Hedrick - One of the best experts on this subject based on the ideXlab platform.
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2 amino 1 3 propane diols a versatile platform for the synthesis of aliphatic Cyclic Carbonate monomers
Polymer Chemistry, 2013Co-Authors: Shrinivas Venkataraman, James L Hedrick, Natalia Veronica, Zhi Xiang Voo, Yi Yan YangAbstract:Starting from commercially available 2-amino-1,3-propane diols, a variety of functional Cyclic Carbonate monomers were synthesized through a general two-step strategy. First the amino group was chemo-selectively reacted with a diverse set of electrophiles to result in functional diol intermediates (1), which were then cyclized in an intramolecular fashion to generate a series of functional aliphatic six-membered Cyclic Carbonate monomers (2). The unique feature of this approach is its ability to install concurrently two different functional groups. This includes a specific tethered functional group and a second functional group, which are installed in the monomer-forming reactions. Selected monomers were subjected to organo-catalytic ring opening polymerization to produce well-defined homopolymers and copolymers (ĐM ≥ 1.5) with controlled composition. Primary amine containing polymers were also readily accessed via post-polymerization acidolysis of a tBoc-derived monomer (2k). This approach will provide direct access to functional biodegradable polymers and impact the development of next-generation materials for biomedical and environmentally friendly products.
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tagging alcohols with Cyclic Carbonate a versatile equivalent of meth acrylate for ring opening polymerization
Chemical Communications, 2008Co-Authors: Russell C Pratt, Fredrik Nederberg, Robert M Waymouth, James L HedrickAbstract:Cyclic Carbonate monomers based on a single biocompatible scaffold allow for incorporation of a wide range of functional groups into macromolecules via ring-opening polymerization.
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new ground for organic catalysis a ring opening polymerization approach to hydrogels
Biomacromolecules, 2007Co-Authors: Fredrik Nederberg, Russell C Pratt, Robert M Waymouth, Vivian Trang, Andrew F Mason, Curtis W Frank, James L HedrickAbstract:Herein, we describe an organocatalytic living polymerization approach to network and subsequent hydrogel formation. Cyclic Carbonate-functionalized macromolecules were ring-opened using an alcoholic initiator in the presence of an organic catalyst, amidine 1,8-diazabicyclo[5.4.0]undec-7-ene. A model reaction for the cross-linking identified monomer concentration-dependent reaction regimes, and enhanced kinetic control was demonstrated by introducing a co-monomer, trimethylene Carbonate. The addition of the co-monomer facilitated near-quantitative conversion of monomer to polymer (>96%). Resulting poly(ethylene glycol) networks swell significantly in water, and an open co-continuous (water-gel) porous structure was observed by scanning electron microscopy. The organocatalytic ring-opening polymerization of Cyclic Carbonate functional macromonomers using alcoholic initiators provides a simple, efficient, and versatile approach to hydrogel networks.
Karl A Scheidt - One of the best experts on this subject based on the ideXlab platform.
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nonisocyanate thermoplastic polyhydroxyurethane elastomers via Cyclic Carbonate aminolysis critical role of hydroxyl groups in controlling nanophase separation
ACS Macro Letters, 2016Co-Authors: Emily K Leitsch, William H Heath, Karl A Scheidt, Goliath Beniah, John M TorkelsonAbstract:Thermoplastic polyhydroxyurethanes (PHUs) were synthesized from Cyclic Carbonate aminolysis. Because of the hydroxyl groups in PHU, the choice of soft segment has a dramatic influence on nanophase separation in polyether-based PHUs. Use of a polyethylene glycol-based soft segment, which results in nanophase-separated thermoplastic polyurethane elastomers (TPUs), leads to single-phase PHUs that flow under the force of gravity. This PHU behavior is due to major phase mixing caused by hydrogen bonding of hard-segment hydroxyl groups to the soft-segment ether oxygen atoms. This hydrogen bonding can be suppressed by using polypropylene glycol-based or polytetramethylene oxide (PTMO)-based soft segments, which reduce hydrogen bonding by steric hindrance and dilution of oxygen atom content and result in nanophase-separated PHUs with robust, tunable mechanical properties. The PTMO-based PHUs exhibit reversible elastomeric response with hysteresis, like that of conventional TPUs. Because of nanophase separation wi...
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Nonisocyanate Thermoplastic Polyhydroxyurethane Elastomers via Cyclic Carbonate Aminolysis: Critical Role of Hydroxyl Groups in Controlling Nanophase Separation
2016Co-Authors: Emily K. Leitsch, William H Heath, Karl A Scheidt, Goliath Beniah, Kun Liu, Tian Lan, John M TorkelsonAbstract:Thermoplastic polyhydroxyurethanes (PHUs) were synthesized from Cyclic Carbonate aminolysis. Because of the hydroxyl groups in PHU, the choice of soft segment has a dramatic influence on nanophase separation in polyether-based PHUs. Use of a polyethylene glycol-based soft segment, which results in nanophase-separated thermoplastic polyurethane elastomers (TPUs), leads to single-phase PHUs that flow under the force of gravity. This PHU behavior is due to major phase mixing caused by hydrogen bonding of hard-segment hydroxyl groups to the soft-segment ether oxygen atoms. This hydrogen bonding can be suppressed by using polypropylene glycol-based or polytetramethylene oxide (PTMO)-based soft segments, which reduce hydrogen bonding by steric hindrance and dilution of oxygen atom content and result in nanophase-separated PHUs with robust, tunable mechanical properties. The PTMO-based PHUs exhibit reversible elastomeric response with hysteresis, like that of conventional TPUs. Because of nanophase separation with broad interphase regions possessing a wide range of local composition, the PTMO-based PHUs also demonstrate potential as novel broad-temperature-range acoustic and vibration damping materials, a function not observed with TPUs
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cooperative catalysis of Cyclic Carbonate ring opening application towards non isocyanate polyurethane materials
European Journal of Organic Chemistry, 2015Co-Authors: Vince M Lombardo, Elizabeth A Dhulst, Emily K Leitsch, Nathan Wilmot, William H Heath, Anthony P Gies, Matthew Miller, John M Torkelson, Karl A ScheidtAbstract:The reaction between Cyclic Carbonates and amines to produce hydroxyurethanes is an important alternative to current urethane chemistry. In order to address the issue of slow reaction rates, an efficient ring opening of Cyclic Carbonates with amines has been achieved utilizing cooperative catalysis. A new Lewis acid/Lewis base combination substantially decreases the reaction times for small molecule systems to reach complete conversion. Although triazabicyclodecene (TBD) has a substantial impact on the reaction rate, the addition of lithium triflate (LiOTf) as a co-catalyst allows for the fastest ring opening reported in the current literature. Cooperative catalysis is also applied to the synthesis of polymers containing hydroxyurethane linkages and is able to achieve rapid conversion of the bis-Cyclic Carbonate and diamine precursors when compared with the uncatalyzed reaction.
Fredrik Nederberg - One of the best experts on this subject based on the ideXlab platform.
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tagging alcohols with Cyclic Carbonate a versatile equivalent of meth acrylate for ring opening polymerization
Chemical Communications, 2008Co-Authors: Russell C Pratt, Fredrik Nederberg, Robert M Waymouth, James L HedrickAbstract:Cyclic Carbonate monomers based on a single biocompatible scaffold allow for incorporation of a wide range of functional groups into macromolecules via ring-opening polymerization.
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new ground for organic catalysis a ring opening polymerization approach to hydrogels
Biomacromolecules, 2007Co-Authors: Fredrik Nederberg, Russell C Pratt, Robert M Waymouth, Vivian Trang, Andrew F Mason, Curtis W Frank, James L HedrickAbstract:Herein, we describe an organocatalytic living polymerization approach to network and subsequent hydrogel formation. Cyclic Carbonate-functionalized macromolecules were ring-opened using an alcoholic initiator in the presence of an organic catalyst, amidine 1,8-diazabicyclo[5.4.0]undec-7-ene. A model reaction for the cross-linking identified monomer concentration-dependent reaction regimes, and enhanced kinetic control was demonstrated by introducing a co-monomer, trimethylene Carbonate. The addition of the co-monomer facilitated near-quantitative conversion of monomer to polymer (>96%). Resulting poly(ethylene glycol) networks swell significantly in water, and an open co-continuous (water-gel) porous structure was observed by scanning electron microscopy. The organocatalytic ring-opening polymerization of Cyclic Carbonate functional macromonomers using alcoholic initiators provides a simple, efficient, and versatile approach to hydrogel networks.
