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Shadpour Mallakpour - One of the best experts on this subject based on the ideXlab platform.
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polycondensation of new optically active diacid with Diisocyanates in the presence of tetrabutylammonium bromide as a green media under microwave heating
Reactive & Functional Polymers, 2008Co-Authors: Shadpour Mallakpour, Saghi SepehriAbstract:Abstract Ionic liquids ( IL )s have been recognized as ‘green’ alternatives to the organic solvents in a range of synthesis, catalysis and electrochemistry due to their unique chemical and physical properties. In this investigation, (2S)-5-(3-phenyl-2-phthalimidylpropanoylamino)isophthalic acid was prepared in three steps. The step-growth polymerization reaction of this novel diacid with various aromatic and aliphatic Diisocyanates such as 4,4′-methylene bis(4-phenylisocyanate) ( 8a ), toluylene-2,4-diisocyanate ( 8b ), hexamethylene diisocyanate ( 8c ) and isophorone diisocyanate ( 8d ) were carried out in the presence of tetrabutylammonium bromide (TBAB) as a molten ionic liquid under microwave irradiation conditions and was compared with polymerization in traditional solvent like N -methyl-2-pyrrolidone (NMP). This process is safe and green since toxic and volatile organic solvent such as NMP was eliminated. The resulting new polymers were obtained in good yields with inherent viscosities ranging between 0.25 and 0.46 dL g −1 and were characterized with FT-IR, 1 H-NMR, elemental and thermogravimetric analysis techniques.
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Solid-State Polymerization of 4-(4-Dimethylaminophenyl)-urazole with Diisocyanates
Polymer Bulletin, 2008Co-Authors: Shadpour Mallakpour, Zahra RafieeAbstract:In the present study, the solid-state thermal polymerization of 4-(4-dimethylaminophenyl)-1,2,4-triazolidine-3,5-dione (DAPTD) with Diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate and toluylene-2,4-diisocyanate as a new method for synthesis of polyureas are described. The influence of reaction parameters, such as presence of catalyst in the starting material and ratio of DAPTD to diisocyanate were investigated. Polycondensation was successfully preceded without any solvent, which is used in conventional method. The resulting polyureas were obtained in high yields with inherent viscosities ranging from 0.14 to 0.25 dL/g. This method was also compared with two other polycondensation methods for the polymerization reactions which were reported before: conventional solution method and a method using tetrabutylammonium bromide as a molten ionic liquid media.
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a facile microwave assisted synthesis of novel optically active polyamides derived from 5 3 methyl 2 phthalimidylpentanoylamino isophthalic acid and different Diisocyanates
European Polymer Journal, 2008Co-Authors: Shadpour Mallakpour, Mehdi TaghaviAbstract:Abstract 5-(3-Methyl-2-phthalimidylpentanoylamino)isophthalic acid as a novel aromatic diacid monomer was prepared in three steps. In the first step, phthalic anhydride was reacted with l -isoleucine in acetic acid solution, and the resulting imide acid was obtained in high yield. In the second step, treatment of this imide acid with excess thionyl chloride gave aliphatic acid chloride in good yield. In the last step, this acid chloride was reacted with 5-aminoisophthalic acid to provide novel bulky chiral aromatic diacid monomer. The direct polycondensation reactions of this diacid with several aromatic and aliphatic Diisocyanates such as 4,4′-methylenebis(phenyl isocyanate), toluylene-2,4-diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate were carried out under microwave irradiation. In order to compare this method with classical heating, the polymerization reactions were also performed under solution polycondensation conditions. The polymerization reactions occurred rapidly under microwave conditions and produced a series of novel optically active polyamides (PA)s containing pendent phthalimide group, with good yields and moderate inherent viscosities of 0.17–0.60 dL/g. Some of the new PAs showed good solubility and are readily soluble in organic solvents. The resulting macromolecules were characterized by FT-IR, specific rotation, and representative ones by 1 H NMR, elemental and thermogravimetric analyses (TGA).
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Novel Optically Active Poly(amide-imide)s Derived from N-Trimellitylimido-L-Isoleucine and Different Diisocyanates
Polymer Bulletin, 2007Co-Authors: Shadpour Mallakpour, Marziyeh KhaniAbstract:A new class of optically active poly(amide-imide)s was synthesized via direct solution polycondensation of different aliphatic and aromatic Diisocyanates with a chiral diacid monomer. The polymerization of N -trimellitylimido- L -isoleucine (TMIIL) (1) as an aromatic-aliphatic diacid monomer with 4,4’-methylenebis(phenyl isocyanate) (MDI) (2) was carried out by graduate heating as well as refluxing method in the presence of pyridine (Py) , dibutyltin dilaurate (DBTDL) , triethylamine (TEA) as a catalyst and without catalyst, respectively. In these solution polycondensations we used amino acids as chiral inducing agents. The optimized polymerization conditions of MDI were used for the polymerization of isophorone diisocyanate (IPDI) (3), tolylene-2,4-diisocyanate (TDI) (4) , and hexamethylene diisocyanate (HDI) (5) . The resulting polymers have inherent viscosities in a range of 0.17–0.48 dL/g. These polymers are optically active, thermally stable and soluble in amide type solvents.
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microwave assisted and classical heating polycondensation reaction of bis p amido benzoic acid n trimellitylimido l leucine with Diisocyanates as a new method for preparation of optically active poly amide imide s
Journal of Applied Polymer Science, 2004Co-Authors: Shadpour Mallakpour, Fatemeh RafiemanzelatAbstract:A new class of optically active poly(amide imide)s were synthesized via direct polycondensation reaction of Diisocyanates with a chiral diacid monomer. The step-growth polymerization reactions of monomer bis(p-amido benzoic acid)-N-trimellitylimido-L-leucine (BPABTL) (5) as a diacid monomer with 4,4′-methylene bis(4-phenylisocyanate) (MDI) (6) was performed under microwave irradiation, solution polymerization under gradual heating and reflux condition in the presence of pyridine (Py), dibuthyltin dilurate (DBTDL), and triethylamine (TEA) as a catalyst and without a catalyst, respectively. The optimized polymerization conditions according to solvent and catalyst for each method were performed with tolylene-2,4-diisocyanate (TDI) (7), hexamethylene diisocyanate (HDI) (8), and isophorone diisocyanate (IPDI) (9) to produce optically active poly(amide imide)s by the diisocyanate route. The resulting polymers have inherent viscosities in the range of 0.09–1.10 dL/g. These polymers are optically active, thermally stable, and soluble in amide type solvents. All of the above polymers were fully characterized by IR spectroscopy, 1H NMR spectroscopy, elemental analyses, specific rotation, and thermal analyses methods. Some structural characterization and physical properties of this new optically active poly(amide imide)s are reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1647–1659, 2004
Carrie A. Redlich - One of the best experts on this subject based on the ideXlab platform.
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Mouse Models of Diisocyanate Asthma
American Journal of Respiratory Cell and Molecular Biology, 2002Co-Authors: Carrie A. Redlich, Adam V Wisnewski, Terry GordonAbstract:Occupational asthma is the most commonly reported ocpriate forms and concentrations of Diisocyanates for use in animal models and in vitro studies. cupational lung disease in many industrialized countries. Diisocyanates, highly reactive low molecular weight comClinical Presentation of Diisocyanate Asthma pounds used to make polyurethanes, are the most commonly identified cause of occupational asthma (1). Animal Clinically, the presentation of diisocyanate asthma can be and clinical studies of diisocyanate asthma have been more variable and difficult to distinguish from adult onset asthma limited compared with atopic asthma, and our understanddue to other causes. There is a latency period between ing of diisocyanate pathogenesis is less clear. Unlike typical exposure and onset of symptoms; patients develop respiraallergens that cause asthma, Diisocyanates are extremely tory symptoms after recurrent exposures over months to a reactive compounds, creating great uncertainty regarding few years. Once sensitized, individuals can develop early, the carrier proteins for these chemical haptens in vivo. Redelayed, or dual asthmatic attacks in response to very low search on diisocyanate asthma has been hampered by this levels of exposure, making control difficult. Disease can uncertainty, as well as the lack of mouse models that replipersist away from exposure, emphasizing the importance cate the human disease. Recent studies have made signifiof early diagnosis (6, 7). It is estimated that 5%–15% of cant progress tackling both of these difficult problems. In exposed workers develop asthma (8, 9). However, exposure the present issue of AJRCMB, Matheson and colleagues and host risk factors are not well understood. Unlike many (2) investigate the role of tumor necrosis factor (TNF)types of asthma, atopy is not a risk factor for diisocyanatein a mouse model of toluene diisocyanate (TDI) asthma. induced disease. Certain human leukocyte antigen alleles This Perspective will discuss these findings and address key and glutathione S-transferase haplotypes have been associissues that have hindered progress in understanding diisocyated with diisocyanate asthma, but this has not been conanate asthma and in developing better diagnostic tools. firmed (10–12). Several other recent promising mouse models that should The diagnosis of diisocyanate asthma remains quite facilitate future research are also discussed. problematic and a challenge for physicians. Clinical history, The major Diisocyanates currently in use are diphenylquestionnaires, and physiologic studies frequently are not definitive (13, 14). Immunologic tests, although of great methane diisocyanate, toluene diisocyanate, and hexamethinterest, have shown variable correlation with disease. The ylene diisocyanate (HDI) (Figure 1). The characteristics of prevalence of diisocyanate-specific IgG and IgE antibodies diisocyanate exposure that determine risk are unclear. Both among individuals with diisocyanate asthma is variable and the respiratory tract and skin are considered important not closely associated with disease (13–18). Diisocyanateroutes of exposure and sensitization (3, 4). Depending on specific lymphocyte proliferation or cytokine enhancement the specific diisocyanate, exposures can occur as an aerosol have also been investigated, but correlation with disease and/or as a vapor, as well as different monomeric and polyhas been variable (19–21). A promising study by Bernstein meric species, making airborne monitoring difficult (5). This and colleagues recently reported that monocyte chemoatcomplexity of exposure, along with the marked chemical tractant protein-1 (MCP-1) in vitro production had a sensireactivity, greatly adds to the difficulty of generating approtivity and specificity of 79% and 91% in diagnosing diisocyanate asthma (16). Specific inhalation challenge is considered the “gold standard” for diagnosis. However, such testing is (Received in original form August 26, 2002) neither 100% sensitive nor specific, nor is it readily available
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a novel mouse model of diisocyanate induced asthma showing allergic type inflammation in the lung after inhaled antigen challenge
The Journal of Allergy and Clinical Immunology, 2002Co-Authors: Christina A Herrick, Adam V Wisnewski, Carrie A. Redlich, Lan Xu, Kim BottomlyAbstract:Abstract Background: Exposure to Diisocyanates, a group of highly reactive, low-molecular-weight compounds, is a major cause of occupational asthma. In contrast to mouse models of atopic asthma, previous mouse models of diisocyanate-induced asthma have failed to show lung inflammation with characteristics of human disease. Objective : Our goal was to establish a novel mouse model of diisocyanate-induced asthma in which lung inflammation reminiscent of that seen in human asthma is generated after inhaled antigen challenge. Methods : BALB/c mice were epicutaneously sensitized to hexamethylene diisocyanate (HDI) and then challenged with an HDI-protein conjugate administered by means of an intranasal droplet. Results : HDI sensitization resulted in development of contact hypersensitivity and HDI-specific antibody production. Most importantly, however, vigorous inflammatory responses with characteristics of human asthma were generated in the lung after inhaled HDI challenge. Challenge of sensitized, but not unsensitized, mice resulted in airway eosinophilia, mucus hypersecretion, and production of T H 1-type (IFN-γ) and T H 2-type (IL-4, IL-5, and IL-13) cytokines by lung inflammatory cells. Despite the mixed T H 1/T H 2 response induced by HDI sensitization, use of cytokine-deficient mice revealed that airway eosinophilia was mediated by T H 2 cytokines and not by IFN-γ. Conclusion : We report a novel mouse model of diisocyanate-induced asthma that, in contrast to previous models, demonstrates antigen-induced lung inflammation with characteristics of human disease. This model will allow investigation of the immunopathogenesis of diisocyanate-induced asthma and should provide insight into this common form of occupational disease. (J Allergy Clin Immunol 2002;109:873–8.)
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diisocyanate asthma clinical aspects and immunopathogenesis
International Immunopharmacology, 2002Co-Authors: Carrie A. Redlich, Meryl H. KarolAbstract:Diisocyanates, highly reactive chemicals used in the production of polyurethanes, are currently the most frequently reported cause of chemically induced occupational asthma and their use continues to rise. The prevalence of diisocyanate asthma among exposed workers is estimated to range from 5% to 15%. Routes of exposure include the respiratory tract and skin. Workplace exposures are difficult to quantify and control, and there is no simple diagnostic test for the disease. This review considers recent concepts in exposure, clinical aspects and pathogenesis of the disease. The pathogenesis of diisocyanate asthma remains unclear, with evidence supporting both immunological and nonimmunological mechanisms. Knowledge of the chemical reactivity of Diisocyanates, the target biomolecules, and the cellular sites of reaction are fundamental to understanding diisocyanate toxicity and disease. Recent findings of chemical interactions with biological nucleophiles will be described. The importance of diisocyanate-adducted biomolecules will be emphasized and their potential contributions to pathogenesis discussed. It is anticipated that greater understanding of the immunopathogenesis of diisocyanate asthma, including the initial cell/diisocyanate reactions, should lead to clinically useful markers of exposure and early disease.
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identification of human lung and skin proteins conjugated with hexamethylene diisocyanate in vitro and in vivo
American Journal of Respiratory and Critical Care Medicine, 2000Co-Authors: Adam V Wisnewski, Ranjana Srivastava, Christina Herick, Ranulfo Lemus, Hilary Cain, Nadine Magoski, Kim Bottomly, Meryl H. Karol, Lan Xu, Carrie A. RedlichAbstract:Diiisocyanates are asthma-causing chemicals used in the commercial production of polyurethane. We have previously shown that human lung epithelial cell proteins can become conjugated with hexamethylene diisocyanate (HDI) and may be biologically important in diisocyanate-induced asthma. The objective of this study was to identify specific human lung and skin proteins that become conjugated with diisocyanate after in vitro and in vivo exposure. Following in vitro exposure of human airway epithelial cells (A549), keratin 18, the 78-kD glucose-regulated protein, trans-1,2-dihyrobenzene-1,2-diol dehydrogenase, and actin were identified as prominent diisocyanate-conjugated proteins through use of a combination of immunocytochemical and mass spectrometric techniques. Following in vivo inhalation of an HDI aerosol, keratin 18 was also identified as the predominant diisocyanate-conjugated protein in human endobronchial biopsy samples, whereas albumin was the predominant diisocyanate-conjugated protein in bronchoal...
Meryl H. Karol - One of the best experts on this subject based on the ideXlab platform.
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diisocyanate asthma clinical aspects and immunopathogenesis
International Immunopharmacology, 2002Co-Authors: Carrie A. Redlich, Meryl H. KarolAbstract:Diisocyanates, highly reactive chemicals used in the production of polyurethanes, are currently the most frequently reported cause of chemically induced occupational asthma and their use continues to rise. The prevalence of diisocyanate asthma among exposed workers is estimated to range from 5% to 15%. Routes of exposure include the respiratory tract and skin. Workplace exposures are difficult to quantify and control, and there is no simple diagnostic test for the disease. This review considers recent concepts in exposure, clinical aspects and pathogenesis of the disease. The pathogenesis of diisocyanate asthma remains unclear, with evidence supporting both immunological and nonimmunological mechanisms. Knowledge of the chemical reactivity of Diisocyanates, the target biomolecules, and the cellular sites of reaction are fundamental to understanding diisocyanate toxicity and disease. Recent findings of chemical interactions with biological nucleophiles will be described. The importance of diisocyanate-adducted biomolecules will be emphasized and their potential contributions to pathogenesis discussed. It is anticipated that greater understanding of the immunopathogenesis of diisocyanate asthma, including the initial cell/diisocyanate reactions, should lead to clinically useful markers of exposure and early disease.
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identification of human lung and skin proteins conjugated with hexamethylene diisocyanate in vitro and in vivo
American Journal of Respiratory and Critical Care Medicine, 2000Co-Authors: Adam V Wisnewski, Ranjana Srivastava, Christina Herick, Ranulfo Lemus, Hilary Cain, Nadine Magoski, Kim Bottomly, Meryl H. Karol, Lan Xu, Carrie A. RedlichAbstract:Diiisocyanates are asthma-causing chemicals used in the commercial production of polyurethane. We have previously shown that human lung epithelial cell proteins can become conjugated with hexamethylene diisocyanate (HDI) and may be biologically important in diisocyanate-induced asthma. The objective of this study was to identify specific human lung and skin proteins that become conjugated with diisocyanate after in vitro and in vivo exposure. Following in vitro exposure of human airway epithelial cells (A549), keratin 18, the 78-kD glucose-regulated protein, trans-1,2-dihyrobenzene-1,2-diol dehydrogenase, and actin were identified as prominent diisocyanate-conjugated proteins through use of a combination of immunocytochemical and mass spectrometric techniques. Following in vivo inhalation of an HDI aerosol, keratin 18 was also identified as the predominant diisocyanate-conjugated protein in human endobronchial biopsy samples, whereas albumin was the predominant diisocyanate-conjugated protein in bronchoal...
Mohsen Miraftab - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and characterization of polyurethane-based shape-memory polymers for tailored Tgaround body temperature for medical applications
Macromolecular Chemistry and Physics, 2011Co-Authors: Manzoor Ahmad, Peter James King, Hendra Purnawali, Wei Min Huang, Jikui Luo, Yong Qing Fu, Paul R. Chalker, Bin Xu, Mohsen MiraftabAbstract:Various polyurethane-based SMPUs were synthesized using five types of polyols as soft segments and two different Diisocyanates as hard segments. The effects of diisocyanate concentration on material properties such as crystallinity, transition temperature, shape-memory effect and tensile strength were investigated. SMPUs with a maximum strain near 1000%, recovery rate up to â98%, fixity up to â90% and Tgs of 35-45°C were obtained. A high MDI content results in SMPUs with better shape-memory effect, whereas increasing IPDI content leads to a weaker shape-memory effect. High IPDI concentration seems to prevent or restrict chemical reactions and crosslinks between the polyols and the hard segments, leading to large phase separation and coexistence of soft and hard segments in the macrophases. The properties of polyurethane-based SMPUs are studied systematically using five types of soft segment polyols and two different diisocyanate hard segments. By varying the concentration of the Diisocyanates and the ratio of MDI to IPDI, it was found that crystallinity, transition temperature, shape-memory effect, and tensile strength can be tailored. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Fernanda M B Coutinho - One of the best experts on this subject based on the ideXlab platform.
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degradation profiles of cast films of polyurethane and poly urethane urea aqueous dispersions based on hydroxy terminated polybutadiene and different Diisocyanates
Polymer Degradation and Stability, 2003Co-Authors: Fernanda M B Coutinho, Marcia C Delpech, Thais L Alves, Antonio A FerreiraAbstract:Abstract New formulations of waterborne polyurethanes (wPU) and poly(urethane-urea)s (wPUU) were produced based on hydroxy-terminated polybutadiene (HTPB), poly(propylene glycol) (PPG), dimethylolpropionic acid (DMPA), and three different types of aliphatic Diisocyanates—isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (HMDI) and hexamethylene diisocyanate (HDI)—and the aromatic tolylene diisocyanate (TDI). Three types of chain extender were used in some of the formulations: ethylene glycol (EG), forming polyurethanes, and hydrazine (HYD) or ethylenediamine (EDA), resulting in poly(urethane-urea)s. In the formulations, HTPB content and NCO/OH ratio were varied. The thermal stability of the materials, obtained as cast films prepared from aqueous dispersions was evaluated by thermogravimetry (TG). It was observed that initial degradation temperatures were above 200 °C, with two- or three-step degradation profiles. An increase in HTPB content, the presence of urea linkages, and HMDI as diisocyanate in the formulations led to materials with higher thermal stability. DTG curves exhibited stages not perceptible in the curves of weight loss, which were mainly influenced by the differences in the formulations.