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Tsutomu Takeichi - One of the best experts on this subject based on the ideXlab platform.
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High performance poly(urethane-imide) prepared by introducing imide blocks into the polyurethane backbone
Polymer, 2005Co-Authors: Tsutomu Takeichi, Koichi Ujiie, Kazuto InoueAbstract:Abstract A series of novel linear poly(urethane-imide)s were synthesized by the reaction between isocyanate-terminated polyurethane (PU) prepolymer and amine- or anhydride-terminated oligoimide. PU prepolymer was synthesized by reacting polyethylene adipatediol of molecular weight 1000 with tolylene-2,4-diisocyanate at the molar ratio of 2:3 or 1:2. Oligoimide was synthesized from the reaction of 4,4′-(hexafluoroisopropylidene)diphthalic acid with 4,4′-oxydianiline at various molar ratios. Equimolar amounts of PU prepolymer and oligoimide were reacted in N-methyl-2-pyrrolidone, followed by casting on glass plates and heat treatment at 100 and 150 °C for 1 h each to give linear poly(urethane-imide)s as transparent yellowish brown films. Poly(urethane-imide) films with less of 30% of imide component became elastomer, and films with more than 36% imide component became plastic. The effects of end-groups of oligoimide, molecular weight of oligoimide, and molecular weight of PU prepolymer on the solvent resistance, the tensile properties, viscoelastic properties, and thermogravimetric properties of poly(urethane-imide) films were systematically examined. Solvent resistance and tensile modulus of poly(urethane-imide) films from amine-terminated oligoimides were better than those from anhydride-terminated oligoimides. On the other hand, thermal stability and elongation at break for the poly(urethane-imide) films from anhydride-terminated oligoimides were higher than those from amine-terminated oligoimides.
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Novel Poly(urethane-amide) s from Polyurethane Prepolymer and Reactive Polyamide. Preparation and Properties.
Polymer Journal, 2002Co-Authors: Tsutomu Takeichi, Kyoko Suefuji, Kazuto InoueAbstract:Novel Poly(urethane-amide)s from Polyurethane Prepolymer and Reactive Polyamide. Preparation and Properties
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Morphology of Elastic and Plastic Poly(Urethane-Imide) Films Observed with TEM and FE-SEM:
High Performance Polymers, 2001Co-Authors: Tsutomu Takeichi, Takeshi Kawai, Hajime TsuchiyaAbstract:Direct observation of the morphology of poly(urethane-imide) films, prepared by the reaction of a polyurethane prepolymer and poly(amide acid) as a precursor of polyimide, was performed using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM). The poly(urethane-imide) films were plastic or elastic depending on the ratio of the two components. In the plastic films, TEM and FE-SEM analyses clearly showed the presence of urethane-rich domains in the imide-rich continuous phase. Under the higher magnification of TEM, a lamella structure was clearly observed inside the urethane-rich domains. The size and the number of the urethane-rich domains varied with the chemical structure and the ratio of the two components. It was confirmed that the size of the urethane-rich domains in the poly(urethane-imide) films observed with TEM and FE-SEM was almost the same as that of the pores in the porous polyimide films obtained by pyrolyzing the poly(urethane-imide) films at 300–4...
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synthesis and characterization of poly urethane benzoxazine films as novel type of polyurethane phenolic resin composites
Journal of Polymer Science Part A, 2000Co-Authors: Tsutomu Takeichi, Tarek AgagAbstract:Poly(urethane-benzoxazine) films as novel polyurethane (PU)/phenolic resin composites were prepared by blending a benzoxazine monomer (Ba) and PU prepolymer that was synthesized from 2,4-tolylene diisocyanate (TDI) and polyethylene adipate polyol (MW ca. 1000) in 2 : 1 molar ratio. DSC of PU/Ba blend showed an exotherm with maximum at ca. 246 °C due to the ring-opening polymerization of Ba, giving phenolic OH functionalities that react with isocyanate groups in the PU prepolymer. The poly(urethane-benzoxazine) films obtained by thermal cure were transparent, with color ranging from yellow to pale wine with increase of Ba content. All the films have only one glass transition temperature (Tg ) from viscoelastic measurements, indicating no phase separation in poly(urethane-benzoxazine) due to in situ polymerization. The Tg increased with the increase of Ba content. The films containing 10 and 15% of Ba have characteristics of an elastomer, with elongation at break at 244 and 182%, respectively. These elastic films exhibit good resilience with excellent reinstating behavior. The films containing more than 20% of Ba have characteristics of plastics. The poly(urethane-benzoxazine) films showed excellent resistance to the solvents such as tetrahydrofuran, N,N-dimethyl formamide, and N-methyl-2-pyrrolidinone that easily dissolve PUs. Thermal stability of PU was greatly enhanced even with the incorporation of a small amount of Ba. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4165–4176, 2000
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Synthesis and characterization of poly(urethane‐benzoxazine) films as novel type of polyurethane/phenolic resin composites
Journal of Polymer Science Part A, 2000Co-Authors: Tsutomu Takeichi, Tarek AgagAbstract:Poly(urethane-benzoxazine) films as novel polyurethane (PU)/phenolic resin composites were prepared by blending a benzoxazine monomer (Ba) and PU prepolymer that was synthesized from 2,4-tolylene diisocyanate (TDI) and polyethylene adipate polyol (MW ca. 1000) in 2 : 1 molar ratio. DSC of PU/Ba blend showed an exotherm with maximum at ca. 246 °C due to the ring-opening polymerization of Ba, giving phenolic OH functionalities that react with isocyanate groups in the PU prepolymer. The poly(urethane-benzoxazine) films obtained by thermal cure were transparent, with color ranging from yellow to pale wine with increase of Ba content. All the films have only one glass transition temperature (Tg ) from viscoelastic measurements, indicating no phase separation in poly(urethane-benzoxazine) due to in situ polymerization. The Tg increased with the increase of Ba content. The films containing 10 and 15% of Ba have characteristics of an elastomer, with elongation at break at 244 and 182%, respectively. These elastic films exhibit good resilience with excellent reinstating behavior. The films containing more than 20% of Ba have characteristics of plastics. The poly(urethane-benzoxazine) films showed excellent resistance to the solvents such as tetrahydrofuran, N,N-dimethyl formamide, and N-methyl-2-pyrrolidinone that easily dissolve PUs. Thermal stability of PU was greatly enhanced even with the incorporation of a small amount of Ba. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4165–4176, 2000
Tarek Agag - One of the best experts on this subject based on the ideXlab platform.
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poly benzoxazine co urethane s a new concept for phenolic urethane copolymers via one pot method
Polymer, 2011Co-Authors: Mohamed Baqar, Tarek Agag, Hatsuo Ishida, Syed QutubuddinAbstract:Historically, applications for traditional phenolic resin/polyurethane materials are limited due to the inherently weak thermal stability of urethane-phenolic linkage and slow reaction rate. A novel concept has been developed to produce phenolic resin/polyurethane copolymers via benzoxazine chemistry. Through one-pot synthesis, a series of linear poly(benzoxazine-co-urethane) materials has been synthesized via the reaction of a newly developed dimethylol functional benzoxazine monomer with 4,4′-methylene diphenyl diisocyanate and poly(1,4-butyleneadipate). The structure of the copolymers has been characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR). The copolymers in the film forms have been further thermally treated for crosslinking to produce crosslinked poly(benzoxazine-co-urethane) via the ring opening polymerization of cyclic benzoxazine moieties in the main-chain. The tensile properties of the films have been studied and compared with those of traditional high performance materials. The thermal properties of the crosslinked copolymers have also been studied by dynamic mechanical analysis, and thermogravimetric analysis (TGA).
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synthesis and characterization of poly urethane benzoxazine films as novel type of polyurethane phenolic resin composites
Journal of Polymer Science Part A, 2000Co-Authors: Tsutomu Takeichi, Tarek AgagAbstract:Poly(urethane-benzoxazine) films as novel polyurethane (PU)/phenolic resin composites were prepared by blending a benzoxazine monomer (Ba) and PU prepolymer that was synthesized from 2,4-tolylene diisocyanate (TDI) and polyethylene adipate polyol (MW ca. 1000) in 2 : 1 molar ratio. DSC of PU/Ba blend showed an exotherm with maximum at ca. 246 °C due to the ring-opening polymerization of Ba, giving phenolic OH functionalities that react with isocyanate groups in the PU prepolymer. The poly(urethane-benzoxazine) films obtained by thermal cure were transparent, with color ranging from yellow to pale wine with increase of Ba content. All the films have only one glass transition temperature (Tg ) from viscoelastic measurements, indicating no phase separation in poly(urethane-benzoxazine) due to in situ polymerization. The Tg increased with the increase of Ba content. The films containing 10 and 15% of Ba have characteristics of an elastomer, with elongation at break at 244 and 182%, respectively. These elastic films exhibit good resilience with excellent reinstating behavior. The films containing more than 20% of Ba have characteristics of plastics. The poly(urethane-benzoxazine) films showed excellent resistance to the solvents such as tetrahydrofuran, N,N-dimethyl formamide, and N-methyl-2-pyrrolidinone that easily dissolve PUs. Thermal stability of PU was greatly enhanced even with the incorporation of a small amount of Ba. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4165–4176, 2000
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Synthesis and characterization of poly(urethane‐benzoxazine) films as novel type of polyurethane/phenolic resin composites
Journal of Polymer Science Part A, 2000Co-Authors: Tsutomu Takeichi, Tarek AgagAbstract:Poly(urethane-benzoxazine) films as novel polyurethane (PU)/phenolic resin composites were prepared by blending a benzoxazine monomer (Ba) and PU prepolymer that was synthesized from 2,4-tolylene diisocyanate (TDI) and polyethylene adipate polyol (MW ca. 1000) in 2 : 1 molar ratio. DSC of PU/Ba blend showed an exotherm with maximum at ca. 246 °C due to the ring-opening polymerization of Ba, giving phenolic OH functionalities that react with isocyanate groups in the PU prepolymer. The poly(urethane-benzoxazine) films obtained by thermal cure were transparent, with color ranging from yellow to pale wine with increase of Ba content. All the films have only one glass transition temperature (Tg ) from viscoelastic measurements, indicating no phase separation in poly(urethane-benzoxazine) due to in situ polymerization. The Tg increased with the increase of Ba content. The films containing 10 and 15% of Ba have characteristics of an elastomer, with elongation at break at 244 and 182%, respectively. These elastic films exhibit good resilience with excellent reinstating behavior. The films containing more than 20% of Ba have characteristics of plastics. The poly(urethane-benzoxazine) films showed excellent resistance to the solvents such as tetrahydrofuran, N,N-dimethyl formamide, and N-methyl-2-pyrrolidinone that easily dissolve PUs. Thermal stability of PU was greatly enhanced even with the incorporation of a small amount of Ba. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4165–4176, 2000
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Synthesis and characterization of poly(urethane-benzoxazine) films as novel type of polyurethane/phenolic resin composites
Journal of Polymer Science Part A: Polymer Chemistry, 2000Co-Authors: Tsutomu Takeichi, Yong Guo, Tarek AgagAbstract:Poly(urethane-benzoxazine) films as novel polyurethane (PU)/phenolic resin composites were prepared by blending a benzoxazine monomer (Ba) and PU prepolymer that was synthesized from 2,4-tolylene diisocyanate (TDI) and polyethylene adipate polyol (MW ca. 1000) in 2 : 1 molar ratio. DSC of PU/Ba blend showed an exotherm with maximum at ca. 246 degreesC due to the ring-opening polymerization of Ba, giving phenolic OH functionalities that react with isocyanate groups in the PU prepolymer. The poly(urethane-benzoxazine) films obtained by thermal cure were transparent, with color ranging from yellow to pale wine with increase of Ba content. All the films have only one glass transition temperature (T-g) from viscoelastic measurements, indicating no phase separation in poly(urethane-benzoxazine) due to in situ polymerization. The T-g increased with the increase of Ba content. The films containing 10 and 15% of Ba have characteristics of an elastomer, with elongation at break at 244 and 182%, respectively. These elastic films exhibit good resilience with excellent reinstating behavior. The films containing more than 20% of Ba have characteristics of plastics. The poly(urethane-benzoxazine) films showed excellent resistance to the solvents such as tetrahydrofuran, N,N-dimethyl formamide, and N-methyl-2-pyrrolidinone that easily dissolve PUs. Thermal stability of PU was greatly enhanced even with the incorporation of a small amount of Ba. (C) 2000 John Wiley & Sons, Inc.
Anne Hiltner - One of the best experts on this subject based on the ideXlab platform.
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enzymatic degradation of poly ether urethane and poly carbonate urethane by cholesterol esterase
Biomaterials, 2006Co-Authors: Elizabeth M. Christenson, Sachin Patel, James M Anderson, Anne HiltnerAbstract:Abstract This study examined the effect of cholesterol esterase (CE) on the degradation of commercial poly(ether urethane) (PEU) and poly(carbonate urethane) (PCU). Unstrained PEU and PCU films were incubated in 400 U/mL CE solution or a buffer control for 36 days. The study used a concentration of cholesterol esterase that was considerably higher than the estimated physiological level in order to accelerate degradation. However, characterization of treated polyurethane films with SEM, attenuated total reflectance Fourier transform infrared (ATR-FTIR) and GPC analysis revealed only a small loss in surface soft segment content. Comparison with implanted PEU and PCU films led to the conclusion that any effect of enzymatic hydrolysis was confined to the immediate surface, and the magnitude of the effect was too small to contribute significantly to in vivo degradation. The study confirmed that oxidation, rather than enzymatic hydrolysis, is the primary mechanism responsible for the observed biodegradation of PEU and PCU. The oxidative H 2 O 2 /CoCl 2 treatment continues to accurately predict the long-term biostability of polyurethanes.
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Enzymatic degradation of poly(ether urethane) and poly(carbonate urethane) by cholesterol esterase
Biomaterials, 2006Co-Authors: Elizabeth M. Christenson, Sachin Patel, James M Anderson, Anne HiltnerAbstract:This study examined the effect of cholesterol esterase (CE) on the degradation of commercial poly(ether urethane) (PEU) and poly(carbonate urethane) (PCU). Unstrained PEU and PCU films were incubated in 400 U/mL CE solution or a buffer control for 36 days. The study used a concentration of cholesterol esterase that was considerably higher than the estimated physiological level in order to accelerate degradation. However, characterization of treated polyurethane films with SEM, attenuated total reflectance Fourier transform infrared (ATR-FTIR) and GPC analysis revealed only a small loss in surface soft segment content. Comparison with implanted PEU and PCU films led to the conclusion that any effect of enzymatic hydrolysis was confined to the immediate surface, and the magnitude of the effect was too small to contribute significantly to in vivo degradation. The study confirmed that oxidation, rather than enzymatic hydrolysis, is the primary mechanism responsible for the observed biodegradation of PEU and PCU. The oxidative H2O2/CoCl2 treatment continues to accurately predict the long-term biostability of polyurethanes. © 2006 Elsevier Ltd. All rights reserved.
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poly carbonate urethane and poly ether urethane biodegradation in vivo studies
Journal of Biomedical Materials Research Part A, 2004Co-Authors: Elizabeth M. Christenson, James M Anderson, Mahrokh Dadsetan, Michael J Wiggins, Anne HiltnerAbstract:Several strategies have been used to increase the biostability of medical-grade polyurethanes while maintain- ing biocompatibility and mechanical properties. One ap- proach is to chemically modify or replace the susceptible soft segment. Currently, poly(carbonate urethanes) (PCUs) are being evaluated as a replacement of poly(ether urethanes) (PEUs) in medical devices because of the increased oxidative stability of the polycarbonate soft segment. Preliminary in vivo and in vitro studies have reported improved biostability of PCUs over PEUs. Although several studies have reported evidence of in vitro degradation of these new polyurethanes, there has been no evidence of significant in vivo degradation that validates a degradation mechanism. In this study, the effect of soft segment chemistry on the phase morphology, mechanical properties, and in vivo response of commercial- grade PEU and PCU elastomers was examined. Results from dynamic mechanical testing and infrared spectroscopy sug- gested that the phase separation was better in PCU as com- pared with PEU. In addition, the higher modulus and re- duced ultimate elongation of PCU was attributed to the reduced flexibility of the polycarbonate soft segment. Fol- lowing material characterization, the in vivo biostability and biocompatibility of PEU and PCU were studied using a subcutaneous cage implant protocol. The results from the cage implant study and cell culture experiments indicated that monocytes adhere, differentiate, and fuse to form for- eign body giant cells on both polyurethanes. It is now gen- erally accepted that the reactive oxygen species released by these adherent macrophages and foreign body giant cells initiate PEU biodegradation. Attenuated total reflectance- Fourier transform infrared analysis of explanted samples provided evidence of chain scission and crosslinking in both polyurethanes. This indicated that the PCU was also suscep- tible to biodegradation by agents released from adherent cells. These results reinforce the need to evaluate and un- derstand the biodegradation mechanisms of PCUs. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 407- 416, 2004
Jun Li - One of the best experts on this subject based on the ideXlab platform.
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biodegradable thermogelling poly ester urethane s consisting of poly lactic acid thermodynamics of micellization and hydrolytic degradation
Biomaterials, 2008Co-Authors: Ziyun Li, Jun LiAbstract:Multiblock poly(ether ester urethane)s comprising of poly(lactic acid) (PLA), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) segments were synthesized, and their aqueous solutions exhibited thermogelling behavior at critical gelation concentrations (CGC) ranging from 7 to 9 wt%. The chemical structures and molecular characteristics of the copolymers were studied by GPC, 1H NMR, 13C NMR and FTIR. The thermal stability of the poly(PEG/PPG/PLA urethane)s was studied by thermogravimetry analysis (TGA), and the PLA contents were calculated based on the thermal degradation profile. The results were in good agreement with those obtained from the 1H NMR measurements. The critical micellization concentration (CMC) of these water-soluble poly(ether ester urethane)s was determined at different temperatures using a dye solubilization method. The thermodynamic parameters for micelle formation were calculated, indicating that the process is largely entropy-driven. Interestingly, it appears that there exists a requirement for the system to possess a minimum gain in entropy before the thermogelling effect can be observed. Dilute copolymer solutions showed a lower critical solution temperature (LCST) behavior similar to pNIPAM dissolved in aqueous solutions. The thermogels hydrolytically degraded to polymer fragments corresponding to the constituent segment blocks within 3 months.
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poly ester urethane s consisting of poly r 3 hydroxybutyrate and poly ethylene glycol as candidate biomaterials characterization and mechanical property study
Biomacromolecules, 2005Co-Authors: Xu Li, Chaobin He, Ke Wang, Jun LiAbstract:Poly(ester urethane)s with poly[(R)-3-hydroxybutyrate] (PHB) as the hard and hydrophobic segment and poly(ethylene glycol) (PEG) as the soft and hydrophilic segment were synthesized from telechelic hydroxylated PHB (PHB-diol) and PEG using 1,6-hexamethylene diisocyanate as a nontoxic coupling reagent. Their chemical structures and molecular characteristics were studied by gel permeation chromatography, 1H NMR, and Fourier transform infrared spectroscopy. Results of differential scanning calorimetry and X-ray diffraction indicated that the PHB segment and PEG segment in the poly(ester urethane)s formed separate crystalline phases with lower crystallinity and a lower melting point than those of their corresponding precursors, except no PHB crystalline phase was observed in those with a relatively low PHB fraction. Thermogravimetric analysis showed that the poly(ester urethane)s had better thermal stability than their precursors. The segment compositions were calculated from the two-step thermal decompositio...
Zhi Li - One of the best experts on this subject based on the ideXlab platform.
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synthesis and characterization of three arm poly e caprolactone based poly ester urethanes with shape memory effect at body temperature
Macromolecules, 2009Co-Authors: Zhi LiAbstract:Novel biodegradable star poly(ester−urethanes) containing three-arm poly(e-caprolactone) (PCL) as switching segment were prepared as shape-memory polymers (SMPs) with switching temperature (Ts) around body temperature. PCL-triols with molecular weight (Mn) of 2700−4200 g/mol and Tm of 45−47 °C were synthesized in 55−67% yield by Novozym 435-catalyzed ring-opening polymerization of e-caprolactone with glycerol as initiator, and their three-arm structures were confirmed by 1H and 13C NMR analysis. Reaction of the PCL-triols with methylene diphenyl 4,4′-diisocyanate isocynate and 1,6-hexanediol gave three-arm PCL-based poly(ester−urethane)s (tPCL-PUs) in 83−92% yield, with 65−75% soft segment. The structure of tPCL-PUs was confirmed by 1H NMR analysis, and the thermal properties were analyzed by DSC with Ts of 36−39 °C. tPCL-PUs showed excellent shape-memory effects at 38 °C during cyclic thermomechanical tensile tests: shape recovery within 10 s, shape fixity rate of 92%, and shape recovery rate of 99%. The...