Journal articles: 'Urethane A'

1

Tennebroek, R., J. Geurts, A. Overbeek, and A. Harmsen. "Self crosslinkable urethanes and urethane-acrylics." Surface Coatings International 83, no. 1 (January 2000): 13–19. http://dx.doi.org/10.1007/bf02692682.

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Field, K. J., and C. M. Lang. "Hazards of urethane (ethyl carbamate): a review of the literature." Laboratory Animals 22, no. 3 (July 1, 1988): 255–62. http://dx.doi.org/10.1258/002367788780746331.

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Urethane (ethyl carbamate) is used alone or in combination with other drugs to produce anaesthesia in laboratory animals. Although originally studied as a potential phytocide, urethane demonstrated antineoplastic properties when administered to rats with the Walker rat carcinoma 256. Subsequent trials in humans led to its use as a chemotherapeutic agent for various leukaemias. Mice develop pulmonary adenomas earlier in life and at a higher incidence following urethane administration. Urethane's carcinogenic influence is greater in neonatal mice; it also has a transplacental influence in mice. In rats, urethane increases the incidence of pulmonary adenomas, Zymbal Gland tumours, and a variety of other neoplasms. Urethane is absorbed sufficiently from the skin of laboratory animals to produce a transient narcosis. The carcinogenic effect appears to be due to an undefined oncogenic intermediate formed in the blood. Considering the properties urethane demonstrates in animals, the safety of its use by laboratory personnel is in question. However, if appropriate guidelines are followed, urethane should continue to be a useful anaesthetic agent for laboratory animals.

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Jalali, Shakeeba. "APPLICATION OF DYNAMIC MECHANICAL ANALYSIS FOR UV-CURED COATINGS." Chemistry & Material Sciences Research Journal 2, no. 2 (June 23, 2020): 55–59. http://dx.doi.org/10.51594/cmsrj.v2i2.138.

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The present study is about soya epoxy ester which was made by epoxy resin and fatty acid. Oleochemical polyols were prepared after the soya epoxy ester reacted with various hydroxyl and cellulose based derivatives. These oleochemical polyols were changed to urethanes prepolymers by reacting NCO groups of TDI and IPDI. By utilizing the reaction of NCO end group of urethane with HEMA, these urethanes were transformed in to urethane acrylate oligomer. By mixing the oligomers with various reactive diluents, UV curable coating compositions were derived. The methodology was based on dynamic mechanical analysis. The UV cured samples from cellulose based oleochemical polyols exhibit good mechanical and thermal properties. Their mechanical properties are more dependent on double bonds from unsaturated contribute to curing with extra cross-linking by an oxidative mechanism.

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Sotomayor, Rene E., and Thomas F. X. Collins. "Mutagenicity, Metabolism, and DNA Interactions of Urethane." Toxicology and Industrial Health 6, no. 1 (January 1990): 71–108. http://dx.doi.org/10.1177/074823379000600106.

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Urethane, a known animal carcinogen, has been the subject of intensive research efforts spanning 40 years. Recent concerns have focused on the presence of urethane in a variety of fermented foods and alcoholic beverages, although no epidemiological studies or human case reports have been published. Much information is available about the mutagenesis, metabolism, and DNA interactions of urethane in experimental systems. Urethane is generally not mutagenic in bacteria although in some instances it acts as a weak mutagen. Urethane is not mutagenic in Neurospora but is weakly mutagenic in Saccharomyces. Drosophila appear to be the only organisms that consistently give positive mutagenic results with urethane, but its mutagenicity is weak and in many cases shows no clear dose dependence. Urethane is a good clastogen in mammalian somatic cells in vivo, but it shows variable results with cells in vitro. It efficiently induces sister chromatid exchanges in a variety of cells. Mammalian spermatogenic cells are insensitive to the induction of specific locus and dominant lethal mutations by urethane. Mutational synergism has been reported to occur between ethyl methanesulfonate and urethane when administered two generations apart, and some investigators have suggested possible synergism for cancer-causing mutations in mice exposed to X-rays and urethane one generation apart. These studies are controversial and have not been confirmed. Studies on the induction of cancer-causing dominant mutations by urethane are at variance with results from extensive studies with the specific locus test in mice. Urethane studies with the unscheduled DNA synthesis assay in mouse spermatogenic cells and with the sperm abnormality test have given negative results. Urethane is rapidly and evenly distributed in the body. The rate of elimination of urethane from plasma is a saturable process and varies according to the strain and age of the animal. Recent studies have concentrated on the effect of ethanol on urethane metabolism. At concentrations similar to those in wine, ethanol inhibits the tissue distribution of urethane in mice. These results are important because they suggest a lower carcinogenic/mutagenic risk than expected from exposure to urethane in alcoholic beverages. Although research on the metabolic activation of urethane has been extensive, no conclusive results have been obtained about its active metabolite, at one time thought to be N-hydroxyurethane. More recently, it has been postulated that urethane is actived to vinyl carbamate and that this metabolite is capable of reacting with DNA. Vinyl carbamate is more carcinogenic and more mutagenic than the parental compound, but despite intensive efforts it has not been identified as a metabolite in animals treated with urethane. Urethane binding to DNA appears to correlate well with tissue susceptibility to cancer. Various studies have attempted to elucidate the molecular nature of the bound molecule and the binding site. Some results have indicated the formation of a single DNA adduct, 7-(2-oxoethyl)guanine. This adduct may isomerize to O6,7-(1'-hydroxyethano)guanine, which might be more mutagenic than the 2-oxoethyl adduct; however, this possibility seems unlikely. Despite extensive research, urethane's metabolism and molecular mechanisms of mutation are still not clearly understood.

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More, Ganesh Sunil, and Rajendra Srivastava. "Synthesis of amino alcohols, cyclic urea, urethanes, and cyclic carbonates and tandem one-pot conversion of an epoxide to urethanes using a Zn–Zr bimetallic oxide catalyst." Sustainable Energy & Fuels 5, no. 5 (2021): 1498–510. http://dx.doi.org/10.1039/d0se01912g.

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The one-pot tandem synthesis of urethanes directly from an epoxide, with urea in solvent-free condition using Zn₂ZrOx is demonstrated. The catalyst exhibits excellent activity in cyclic urea, urethane, and cyclic carbonate production in neat conditions.

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&NA;. "Urethane." Reactions Weekly &NA;, no. 465 (August 1993): 12. http://dx.doi.org/10.2165/00128415-199304650-00056.

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Yen, Fu-Sen, Lieh-Li Lin, and Jin-Long Hong. "Hydrogen-Bond Interactions between Urethane−Urethane and Urethane−Ester Linkages in a Liquid Crystalline Poly(ester−urethane)." Macromolecules 32, no. 9 (May 1999): 3068–79. http://dx.doi.org/10.1021/ma9804186.

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Strel’nikov, Vladimir N., Valeriy Yu Senichev, Alexey I. Slobodinyuk, Anna V. Savchuk, and Elena R. Volkova. "Frost-Resistant Epoxy-Urethane Binders Containing Diglycidyl Urethane." International Journal of Polymer Science 2019 (April 21, 2019): 1–7. http://dx.doi.org/10.1155/2019/5670439.

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A novel method for developing frost-resistant epoxy-urethane binders is proposed that is based on mixtures of epoxy-urethane oligomers and diglycidyl urethane formed during synthesis. The microheterogeneous elastic materials obtained by curing these mixtures by the cycloaliphatic amines have a low glass transition temperature and high mechanical properties.

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Stakisaitis, Donatas, Raminta Mozuraite, Nomeda Juodziukyniene, Janina Didziapetriene, Saule Uleckiene, Paulius Matusevicius, and Angelija Valanciute. "Sodium Valproate Enhances the Urethane-Induced Lung Adenomas and Suppresses Malignization of Adenomas in Ovariectomized Female Mice." International Journal of Endocrinology 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/218219.

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In the present study, the possible effect of sodium valproate (NaVP) on urethane-induced lung tumors in female mice has been evaluated. BALB/c mice (n=60; 4–6 weeks old, females) were used in the following groups: (1) urethane-treated; (2) urethane-NaVP-treated; (3) only NaVP-treated; (4) control. In the same groups, ovariectomized female mice (n=60) were investigated. Urethane was given intraperitoneally, with a total dose of 50 mg/mouse. In NaVP-treated mice groups, 0.4% aqueous solution of NaVP was offered to micead libitum. The duration of the experiment was 6 months. The number of tumors per mouse in ovariectomized mice and in those treated with urethane and NaVP was significantly higher than in mice treated with urethane only (8.29±0.58versus6.0±0.63,p<0.02). No significant difference in the number of tumors per mouse was revealed while comparing the nonovariectomized urethane- and urethane-NaVP-treated groups (p=0.13). A significant decrease of adenocarcinoma number in ovariectomized mice treated with a urethane-NaVP as compared with ovariectomized mice treated with urethane only was found (p=0.031). NaVP together with low estrogen may have a protective effect on the malignization of adenomas in ovariectomized mice.

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10

Benson, R. Wayne, and Frederick A. Beland. "Modulation of Urethane (Ethyl Carbamate) Carcinogenicity by Ethyl Alcohol: A Review." International Journal of Toxicology 16, no. 6 (November 1997): 521–44. http://dx.doi.org/10.1080/109158197226865.

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Urethane (ethyl carbamate) is a carcinogen that has been detected as a contaminant in certain foods and alcoholic beverages. The carcinogenicity of urethane appears to be mediated through a metabolic pathway involving sequential cytochrome P-450-catalyzed oxidation to vinyl carbamate and vinyl carbamate epoxide, the latter of which reacts with DNA to yield etheno-type DNA adducts. The interactions of ethanol on urethane metabolism and carcinogenicity are varied and complex. Urethane is oxidized by cytochrome P-450 IIE1, an isoform induced by ethanol, which suggests that chronic ethanol consumption could increase the oxidation of urethane to its epoxide derivative. On the other hand, ethanol coadministration is known to inhibit the elimination and hydrolysis of urethane. Ethanol has decreased the tumorigenicity of urethane in two bioassays, but did not have an effect in a third. While the results to date suggest that ethanol will decrease the metabolic activation of urethane, with a resultant decrease in tumorigenicity, additional studies are clearly necessary to elucidate the mechanisms by which ethanol influences the carcinogenicity of urethane.

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11

Onusa, Saravari, and Praditvatanakit Sun. "Preparation and Properties of Urethane Oil from Jatropha Oil." Advanced Materials Research 488-489 (March 2012): 1511–15. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.1511.

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In this study, jatropha oil was reacted with glycerol and toluene diisocyanate to obtain urethane oil at hydroxyl to isocyanate ratio of 1:0.8 with methanol acting as a blocking agent. The prepared urethane oil was characterized for molecular weight and its properties were determined and compared with those of the linseed oil-modified and commercial urethane oils. It was found that the jatropha-modified urethane oil was a yellowish viscous liquid with a number-average molecular weight of 2,673. The urethane oil prepared from jatropha oil took longer time to dry than the linseed oil-modified and commercial urethane oils. Results showed that the film properties of the jatropha-modified urethane oil were comparable to those of the commercial urethane oil. The film exhibited good hardness, excellent flexibility and adhesion, and high impact strength. Additionally, it also showed excellent water resistance but only fair alkali resistance.

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12

Wu, Gang, Huan Wang, Jiangwei Xiao, Lilu Wang, Yu Ke, Liming Fang, Chunlin Deng, and Hua Liao. "Blocking of matrix metalloproteinases-13 responsive peptide in poly(urethane urea) for potential cartilage tissue engineering applications." Journal of Biomaterials Applications 32, no. 8 (January 23, 2018): 999–1010. http://dx.doi.org/10.1177/0885328217753414.

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The matching of scaffold degradation rate with neotissue growth is required for tissue engineering applications. Timely provision of proper spaces especially for cartilage tissue engineering plays a pivotal role in chondrocyte cluster formation. In this study, poly(urethane urea) was synthesized using conventional two-stage method by extending the isocyanate group terminated prepolymers with different amounts of GPLGLWARK peptide, which responses the degrading induced by matrix metalloproteinase 13, the main proteinase for cartilage matrix degradation. The Fourier transform infrared spectrometer with the attenuated total reflection and 1H nuclear magnetic resonance spectra revealed that the peptides were introduced to poly(urethane urea) according to the characteristic absorption bands of the peptide and the newly formed urea bonds. The ultraviolet–visible spectroscopy spectra showed that the weight percentages of the peptide in the three poly(urethane urea) were 25%, 32%, and 35%. Atomic force microscopy images revealed that phase separation occurred in all poly(urethane urea) samples and became increasingly apparent with increasing amount of peptides introduced. Mechanical tests showed that the poly(urethane urea) strength increased with increasing amount of peptides in poly(urethane urea). Poly(urethane urea) proteolysis in matrix metalloproteinase 13 solution was more rapid than hydrolysis in aqueous buffer, and proteolysis rate was dependent on the amount of peptides in poly(urethane urea). Cell proliferation on the material surface in vitro displayed nontoxicity for all synthesized poly(urethane urea). In vivo subcutaneous implantation evaluation revealed the presence of local foreign body reactions triggered by poly(urethane urea) but was not due to peptide in poly(urethane urea). Moreover, the synthesized poly(urethane urea) with significant phase separation did not degrade under the matrix metalloproteinase 13 free subcutaneous environment, but poly(urethane urea) with minimal phase separation was degraded by attacking of the enzymes adsorbed on the hydrophobic surface through non-specific adsorption.

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13

van Asselt, Els, Mahipal Choudhary, Francesco Clavica, and Ron van Mastrigt. "Urethane anesthesia in acute lower urinary tract studies in the male rat." Laboratory Animals 51, no. 3 (June 30, 2016): 256–63. http://dx.doi.org/10.1177/0023677216657850.

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Urethane is a widely used anesthetic in animal lower urinary tract research. Our objective was to investigate the quality of anesthesia and the correlation between bladder (voiding) contractions, micturition pressure, bladder capacity and urethane dosage and body weight. Urethane was given subcutaneously and/or intraperitoneally (1.0–1.2 g/kg). The bladder was filled with saline and the bladder pressure was recorded continuously. Animals in which the subcutaneous/intraperitoneal ratio was higher needed less urethane. Heavier animals needed less extra urethane. In animals, in which no bladder contractions could be evoked, the total amount of urethane given was similar to that in those that did show contractions. In the animals that did void, the bladder never emptied completely and residual volumes remained. There was no relationship between animal weight or total amount of urethane and mean capacity. Anesthesia lasted up till 14 h, during which bladder (voiding) contractions could be recorded. Considering all results, we conclude that urethane is a well suited anesthetic for acute lower urinary tract physiological research in the intact rat.

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14

Sceniak, Michael P., and M. Bruce MacIver. "Cellular Actions of Urethane on Rat Visual Cortical Neurons In Vitro." Journal of Neurophysiology 95, no. 6 (June 2006): 3865–74. http://dx.doi.org/10.1152/jn.01196.2005.

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Urethane is widely used in neurophysiological experiments to anesthetize animals, yet little is known about its actions at the cellular and synaptic levels. This limits our ability to model systems-level cortical function using results from urethane-anesthetized preparations. The present study found that action potential discharge of cortical neurons in vitro, in response to depolarizing current, was strongly depressed by urethane and this was accompanied by a significant decrease in membrane resistance. Voltage-clamp experiments suggest that the mechanism of this depression involves selective activation of a Ba2+-sensitive K+ leak conductance. Urethane did not alter excitatory glutamate-mediated or inhibitory (GABAA- or GABAB-mediated) synaptic transmission. Neither the amplitude nor decay time constant of GABAA- or GABAB-mediated monosynaptic inhibitory postsynaptic currents (IPSCs) were altered by urethane, nor was the frequency of spontaneous IPSCs. These results are consistent with observations seen in vivo during urethane anesthesia where urethane produced minimal disruption of signal transmission in the neocortex.

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Tasic, Srba, Branislav Bozic, and Branko Dunjic. "Hyperbranched urethane-acrylates." Chemical Industry 58, no. 11 (2004): 505–13. http://dx.doi.org/10.2298/hemind0411505t.

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The synthesis, characterization and UV-curing of hyperbranched urethaneacrylates (HB-UA) were investigated in this study. They were evaluated as oli-gomers in model UV curable coatings. HB-UAs were synthesized by reaction of an aliphatic hyperbranched polyester of the second generation (HBRG2) and an isocyanate adduct, obtained by the reaction of isophoronediisocyana-te and different hydroxy alkyl acrylates. Their thermal properties and viscosities depend on the degree of modification of HBRG2 and the type of hydroxy alkyl acrylate used. The introduction of a flexible alkoxylated spacer between the HBP core and acrylate end groups reduces steric hindrance by moving the cross linkable acrylate groups away from the HBP core and increase its reactivity. Due to the presence of abstractable H-atoms in the ?-position to the ether links, HB-UAs based on poly(ethylene oxide) monoacrylate are very reactive and do not show oxygen inhibition. The obtained coatings combine a high cross linking density with flexible segments between the cross links, which results in a good compromise between hardness and flexibility and have the potential to be used in different UV-curing applications.

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Wicks, Douglas A., and Zeno W. Wicks. "Autoxidizable urethane resins." Progress in Organic Coatings 54, no. 3 (November 2005): 141–49. http://dx.doi.org/10.1016/j.porgcoat.2004.12.006.

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Oprea, Stefan, Stelian Vlad, Aurelian Stanciu, and Matei Macoveanu. "Epoxy urethane acrylate." European Polymer Journal 36, no. 2 (February 2000): 373–78. http://dx.doi.org/10.1016/s0014-3057(99)00077-4.

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Denissen, Wim, Guadalupe Rivero, Renaud Nicolaÿ, Ludwik Leibler, Johan M. Winne, and Filip E. Du Prez. "Vinylogous Urethane Vitrimers." Advanced Functional Materials 25, no. 16 (March 13, 2015): 2451–57. http://dx.doi.org/10.1002/adfm.201404553.

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Fu, Mingyu, Mengzi Chen, Xiao Yan, Xueying Yang, Jinfang Xiao, and Jie Tang. "The Effects of Urethane on Rat Outer Hair Cells." Neural Plasticity 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/3512098.

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The cochlea converts sound vibration into electrical impulses and amplifies the low-level sound signal. Urethane, a widely used anesthetic in animal research, has been shown to reduce the neural responses to auditory stimuli. However, the effects of urethane on cochlea, especially on the function of outer hair cells, remain largely unknown. In the present study, we compared the cochlear microphonic responses between awake and urethane-anesthetized rats. The results revealed that the amplitude of the cochlear microphonic was decreased by urethane, resulting in an increase in the threshold at all of the sound frequencies examined. To deduce the possible mechanism underlying the urethane-induced decrease in cochlear sensitivity, we examined the electrical response properties of isolated outer hair cells using whole-cell patch-clamp recording. We found that urethane hyperpolarizes the outer hair cell membrane potential in a dose-dependent manner and elicits larger outward current. This urethane-induced outward current was blocked by strychnine, an antagonist of theα9 subunit of the nicotinic acetylcholine receptor. Meanwhile, the function of the outer hair cell motor protein, prestin, was not affected. These results suggest that urethane anesthesia is expected to decrease the responses of outer hair cells, whereas the frequency selectivity of cochlea remains unchanged.

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20

Christenson, Elizabeth M., Mahrokh Dadsetan, Michael Wiggins, James M. Anderson, and Anne Hiltner. "Poly(carbonate urethane) and poly(ether urethane) biodegradation:In vivo studies." Journal of Biomedical Materials Research 69A, no. 3 (2004): 407–16. http://dx.doi.org/10.1002/jbm.a.30002.

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21

Didenko, Andrei, Danila Kuznetcov, Gleb Vaganov, Valentina Smirnova, Elena Popova, Alexey Ivanov, Boris Chernitsa, Valentin Svetlichnyi, Vladimir E. Yudin, and Vladislav Kudryavtsev. "The Thermal Stability and Mechanical Properties of Non-Segregating Blends of Polyimides with Copoly(Urethane-Imide)s." Key Engineering Materials 869 (October 2020): 280–95. http://dx.doi.org/10.4028/www.scientific.net/kem.869.280.

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The series of compositions containing thermodynamically incompatible flexible blocks of aliphatic polyesters and rigid blocks of aromatic bis (urethane) imides in the volume of polymers was obtained on the basis of multiblock (segmented) poly (urethane-imides) and related aromatic polyimides. The series includes segmented poly (urethane-imides) with different relative content of flexible and rigid blocks, non-segregating mixtures of poly (urethane-imides) and thermoplastic partially crystalline polyimide, statistical copolymers of poly (urethane-imide) with imide, and non-segregating mixtures of statistical copolymers with thermoplastic polyimide. The derived polymer systems were studied using thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. The deformation and strength properties of film samples are determined. It is shown that the properties of the studied polymers change as their content of imides blocks increases, and the transition from thermoplastic poly (urethane-imide) elastomers to thermoplastic polyimides is observed.

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Wang, Hai Yan, Yu Wen Liu, Ji Feng Tian, Bin Sun, and Shi Jie Huang. "FT-IR Analysis of Molecular Structure Evolvement of Poly(Ether urethanes) in Ozone Atmosphere." Advanced Materials Research 742 (August 2013): 215–19. http://dx.doi.org/10.4028/www.scientific.net/amr.742.215.

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The failure behavior of Poly (ether urethanes) in ozone atmosphere was investigated by FTIR, UV-Vis spectra and SEM analysis. It is found that some oxygen-containing groups such as the hydroxyl group and the carbonyl group increase first and then slightly decrease with the ozone oxidation time and the carbohydryl and ether bonds decrease slowly. After oxidation by ozone, the polyurethane molecule chains break on C-O in ether and urethane groups instead of chain crosslinking. In addition, ozone oxidization increases the color difference and lowers the UV light transparence of polyurethane.

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23

Amarasekara, Ananda S., and Rocio Garcia-Obregon. "Vanillin based polymers: V. Poly(hydrovanilloin–urethane)." Polymers from Renewable Resources 12, no. 1-2 (February 2021): 35–45. http://dx.doi.org/10.1177/2041247921989898.

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Renewable resources based hydrovanilloin [1,2- bis(4-hydroxy-3-methoxyphenyl)-1,2-ethanediol] was synthesized in 86% yield by electrochemical dimerization of vanillin in aqueous NaOH. This symmetrical bis-phenol monomer was then used for the preparation of urethane polymers by two different methods. In the first method a 1:2 mole ratio mixture of hydrovanilloin and diisocyanate was polymerized in DMF using 1,4-diazabicyclo[2,2,2]octane as the catalyst at 60°C, for 1 h to give poly(hydrovanilloin–urethane)s. In the second method diisocyanates were first reacted with polyethylene glycol-400 to give pre-polymers. Then prepolymers were reacted with equivalent amount of hydrovanilloin at 60°C for 4 days to produce poly(hydrovanilloin-ethylene glycol-urethane)s. The first method resulted hard poly(hydrovanilloin–urethane)s showing Tg values in the range of 121–172°C. The second method yielded softer poly(hydrovanilloin-ethylene glycol-urethane)s and these polymers failed to show distinct glass transition temperatures in the DSC analysis. However, poly(hydrovanilloin-ethylene glycol-urethane)s showed better thermal stabilities than polymers without polyethylene glycol units.

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Yoshiyama, Mitsuharu, James R. Roppolo, Masayuki Takeda, and William C. de Groat. "Effects of urethane on reflex activity of lower urinary tract in decerebrate unanesthetized rats." American Journal of Physiology-Renal Physiology 304, no. 4 (February 15, 2013): F390—F396. http://dx.doi.org/10.1152/ajprenal.00574.2012.

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Effects of urethane on lower urinary tract function were examined in decerebrate unanesthetized rats. During single slow infusion (0.04 ml/min) cystometrograms (CMGs), urethane (0.3 g/kg) increased micturition pressure threshold (PT) by 73%, postvoid residual volume (RV) by 425%, and decreased voiding efficiency (VE) by 57%, but did not change maximal voiding pressure (MVP), closing peak pressure (CPP), bladder compliance, bladder contraction duration (BCD), or volume threshold (VT) for inducing micturition. Lower doses (0.01–0.1 g/kg) did not alter any parameter. During continuous fast infusion (0.21 ml/min) CMGs, urethane at doses of 0.6–1.2 g/kg (iv) markedly decreased CPP by 69–85%, whereas only the largest dose (1.2 g/kg iv) decreased MVP and external urethral sphincter electromyogram activity by 42 and by 80%, respectively. Doses of 0.001–0.6 g/kg did not alter the intercontraction interval and BCD. Taken together, these results suggest that urethral activity, which is essential for efficient voiding, is more sensitive to the suppressive effect of urethane than afferent or efferent mechanisms controlling the bladder. The threshold dose of MK-801 (0.3 mg/kg), an NMDA antagonist, required to decrease MVP and increase VT in urethane (1.2 g/kg)-anesthetized rats, only increased VT in rats treated with a subanesthetic dose of urethane (0.3 g/kg), suggesting a higher sensitivity of the afferent vs. efferent limb of the micturition reflex pathway to urethane-MK-801 interactions. Because effects of urethane persisted after removal of the forebrain, they must be mediated by actions on the brain stem, spinal cord, or peripheral nervous system.

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Klohr, E., and P. Zugenmaier. "Polymer-solvent effects in cellulose urethane and methyl cellulose urethane solutions." Cellulose 1, no. 4 (December 1994): 259–80. http://dx.doi.org/10.1007/bf00812509.

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Radusch, H. J. "DMTA study of the urethane network in rubber waste-urethane composites." Journal of Thermal Analysis and Calorimetry 79, no. 3 (February 2005): 623–30. http://dx.doi.org/10.1007/s10973-005-0587-8.

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Endo, Takeshi, and Atsushi Sudo. "Well-Defined Construction of Functional Macromolecular Architectures Based on Polymerization of Amino Acid Urethanes." Biomedicines 8, no. 9 (August 29, 2020): 317. http://dx.doi.org/10.3390/biomedicines8090317.

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Polypeptide synthesis was accomplished using the urethane derivatives of amino acids as monomers, which can be easily prepared, purified, and stored at ambient temperature without the requirement for special precautions. The urethanes of amino acids are readily synthesized by the N-carbamoylation of onium salts of amino acids using diphenyl carbonate (DPC). The prepared urethanes are then efficiently cyclized to produce amino acid N-carboxyanhydrides (NCAs). Thereafter, in the presence of primary amines, the ring-opening polymerization (ROP) of NCAs is initiated using the amines, to yield polypeptides with controlled molecular weights. The polypeptides have propagating chains bearing reactive amino groups and initiating chain ends endowed with functional moieties that originate from the amines. Aiming to benefit from these interesting characteristics of the polypeptide synthesis using the urethanes of amino acids, various macromolecular architectures containing polypeptide components have been constructed and applied as biofunctional materials in highly efficient antifouling coatings against proteins and cells, as biosensors for specific molecules, and in targeted drug delivery.

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Shaneh, Shideh, Fatemeh Shokrolahi, Parvin Shokrollahi, Hamid Yeganeh, and Hossein Omidian. "Structural engineering to control density, conformation, and bioactivity of the poly(ethylene glycol)-grafted poly(urethane urea) scaffolds." Journal of Bioactive and Compatible Polymers 34, no. 2 (December 19, 2018): 209–23. http://dx.doi.org/10.1177/0883911518819224.

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Poly(urethane urea) scaffolds were fabricated through combined salt leaching and solvent casting methods. The scaffolds were then functionalized via aminolysis with poly(ethylene glycol) (PEG- g-PUU). To compare its bioactivity, gelatin was also grafted onto the aminolyzed poly(urethane urea) surface (Gel- g-PUU). Chemical changes at the surface were then monitored using quantitative/qualitative methods. Grafting with both gelatin and poly(ethylene glycol) remarkably enhanced the wettability of poly(urethane urea). Proliferation of human adipose–derived mesenchymal stem cells on poly(urethane urea) and the modified poly(urethane urea)s was evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay. The cell experiment results showed that both the modified poly(urethane urea)s enhanced the attachment and proliferation of human adipose–derived mesenchymal stem cells compared to pure poly(urethane urea). Based on previous reports, while a supportive role is observed at adequate poly(ethylene glycol) graft densities, cell adhesion and proliferation are inhibited at very high grafting densities. To correlate the cell data to poly(ethylene glycol) conformations, the surface tension was measured. Data on human adipose–derived mesenchymal stem cells’ attachment/proliferation and contact angle/surface free energy together showed that the grafting density of poly(ethylene glycol) was regulated by optimizing aminolysis conditions, careful selection of poly(ethylene glycol)’s molecular weight, and bulk properties of the matrix poly(urethane urea). As a result, surface overcrowding and brush conformation of the poly(ethylene glycol) chains were avoided, and human adipose–derived mesenchymal stem cell attachment and proliferation occurred on the PEG- g-PUU scaffold at a comparable level to the Gel- g-PUU.

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Huang, Kuanchen, Zichen Ling, and Qixin Zhou. "Urethane Diols through Non-Isocyanate Approach and Their Application in MF Coating." Journal of Composites Science 5, no. 7 (July 20, 2021): 194. http://dx.doi.org/10.3390/jcs5070194.

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In this work, two urethane diols with different middle chain lengths were prepared by the non-isocyanate approach from 1,4-diaminobutane or 1,6-diaminohexane with ethylene cyclic carbonate at room temperature without the aid of a catalyst. Different weight percentages of hexa(methoxymethyl) melamine (HMMM) crosslinker was mixed with urethane diols then cured under elevated temperature to generate the melamine-formaldehyde (MF) coating films. Two different linear diols without urethane linkage were chosen to crosslink with HMMM as the control group. The mechanical properties of these MF coatings were investigated by tensile test, adhesion test, and conical mandrel bend test. It was found that coatings incorporated with urethane diols exhibited enhanced mechanical properties and flexibility. These properties were also influenced by the weight percentage of HMMM crosslinker. This study provided a facile non-isocyanate way to produce urethane diols and successfully applied them in MF coating.

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30

PARK, MI NA, YOUNG SOO KANG, SUN WHA OH, BYUNG HYUN AHN, and MYUNG JUN MOON. "SYNTHESIS AND CHARACTERIZATION OF POLYURETHANE ACRYLATES FOR UV CURABLE COATING AGENTS." Surface Review and Letters 14, no. 04 (August 2007): 713–17. http://dx.doi.org/10.1142/s0218625x07009980.

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The single hydroxyl-terminated urethane acrylate oligomers were synthesized from 2-mercaptoethanol (2-MEOH), alkyl (methyl, butyl, and 2-ethylhexyl) acrylate, and 2,2-azobisisobutyronitrile (AIBN, initiator), with dibutyltin dilaurate (DBTDL) as a catalyst. 2-MEOH was used as a functional chain transfer agent. Poly(alkyl urethane) acrylate oligomers were obtained by the reaction of single hydroxyl-terminated polyalkyl acrylates and 2-isocyanatoethyl acrylate. They were characterized by NMR, FT-IR spectroscopy, rheometer, and DSC. Because poly(alkyl urethane) acrylate oligomers have lower Tg and viscosity than hydroxyl-terminated polyalkyl acrylate oligomers (HTPAO) non-containing urethane groups, they can be used for ultraviolet (UV) curable coatings, inks, and adhesives.

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31

Webb, D. D. "Urethane Systems Reactivity Measurement." Journal of Cellular Plastics 21, no. 3 (May 1985): 208–12. http://dx.doi.org/10.1177/0021955x8502100308.

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Koblin, Donald D. "Urethane: Help or Hindrance?" Anesthesia & Analgesia 94, no. 2 (February 2002): 241–42. http://dx.doi.org/10.1213/00000539-200202000-00002.

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Jonstam, Rune. "Urethane - Induced Hepatic Failure." Acta Medica Scandinavica 170, no. 6 (April 24, 2009): 701–2. http://dx.doi.org/10.1111/j.0954-6820.1961.tb00288.x.

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34

Gladkikh, S. N., and L. I. Kuznetsova. "Urethane adhesives and sealants." Polymer Science Series C 49, no. 1 (March 2007): 34–36. http://dx.doi.org/10.1134/s1811238207010079.

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Koblin, Donald D. "Urethane: Help or Hindrance?" Anesthesia & Analgesia 94, no. 2 (February 2002): 241–42. http://dx.doi.org/10.1097/00000539-200202000-00002.

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36

HALASA, EUGENIUSZ. "Urethane-modified epoxide resins." Polimery 34, no. 12 (December 1989): 527–31. http://dx.doi.org/10.14314/polimery.1989.527.

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Komerska, James F. "Urethane Films— Transdermal Opportunities." Journal of Plastic Film & Sheeting 3, no. 1 (January 1987): 58–64. http://dx.doi.org/10.1177/875608798700300108.

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38

Diaconu, I., C. Ciobanu, and Cr I. Simionescu. "Properties of urethane elastomers." Polymer Bulletin 24, no. 5 (November 1990): 573–76. http://dx.doi.org/10.1007/bf00395582.

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Jönsson, Kersti, and Per Flodin. "Modelling of urethane formation." British Polymer Journal 23, no. 1-2 (1990): 71–75. http://dx.doi.org/10.1002/pi.4980230113.

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Papastergiou, Maria, Aspasia Kanellou, Despoina Chriti, Grigorios Raptopoulos, and Patrina Paraskevopoulou. "Poly(Urethane-Acrylate) Aerogels via Radical Polymerization of Dendritic Urethane-Acrylate Monomers." Materials 11, no. 11 (November 12, 2018): 2249. http://dx.doi.org/10.3390/ma11112249.

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The purpose of this work was to investigate the effect of multifunctionality on material properties of synthetic polymer aerogels. For this purpose, we present the synthesis and characterization of monolithic dendritic-type urethane-acrylate monomers based on an aliphatic/flexible (Desmodur N3300), or an aromatic/rigid (Desmodur RE) triisocyanate core. The terminal acrylate groups (three at the tip of each of the three branches, nine in total) were polymerized with 2,2′-azobis(isobutyronitrile) (AIBN) via free radical chemistry. The resulting wet-gels were dried with supercritical fluid (SCF) CO2. Aerogels were characterized with ATR-FTIR and solid-state 13C NMR. The porous network was probed with N2-sorption and scanning electron microscopy (SEM). The thermal stability of aerogels was studied with thermogravimetric analysis (TGA). Most aerogels were macroporous materials (porosity > 80%), with high thermal stability (up to 300 °C). Aerogels were softer at low monomer concentrations and more rigid at higher concentrations. The material properties were compared with those of analogous aerogels bearing only one acrylate moiety at the tip of each branch and the same cores, and with those of analogous aerogels bearing norbornene instead of acrylate moieties. The nine-terminal acrylate-based monomers of this study caused rapid decrease of the solubility of the growing polymer and made possible aerogels with much smaller particles and much higher surface areas. For the first time, aliphatic/flexible triisocyanate-based materials could be made with similar properties in terms of particle size and surface areas to their aromatic/rigid analogues. Finally, it was found that with monomers with a high number of crosslinkable groups, material properties are determined by multifunctionality and thus aerogels based on 9-acrylate- and 9-norbornene-terminated monomers were similar. Materials with aromatic cores are carbonizable with satisfactory yields (20–30% w/w) to mostly microporous materials (BET surface areas: 640–740 m2 g−1; micropore surface areas: 360–430 m2 g−1).

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Meng, Lei, Xiaojiang Wang, Martin Ocepek, and Mark D. Soucek. "A new class of non-isocyanate urethane methacrylates for the urethane latexes." Polymer 109 (January 2017): 146–59. http://dx.doi.org/10.1016/j.polymer.2016.12.022.

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Lupu, Mihaela, Doina Macocinschi, Ghiocel Ioanid, Maria Butnaru, and Silvia Ioan. "Surface tension of poly(ester urethane)s and poly(ether urethane)s." Polymer International 56, no. 3 (2007): 389–98. http://dx.doi.org/10.1002/pi.2163.

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Xu, Yuling, and Dong Xie. "A triethylene glycol dimethacrylate- free dental composite for reduced water-sorption and shrinkage." Journal of Composite Materials 52, no. 12 (September 4, 2017): 1579–88. http://dx.doi.org/10.1177/0021998317729004.

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A number of new liquid urethane-based oligomers were synthesized, characterized and used to formulate the dental composites. Compressive strength and viscosity were used as a screen tool to evaluate the formed composites. Commercial available bisphenol A glycidyl methacrylate and urethane dimethacrylate-based systems were used as controls. Degree of conversion, shrinkage, water-sorption, solubility, flexural strength and diametrial tensile strength were evaluated. The results show that using mixed acrylate/methacrylate or methacrylates with different length to derivatize diisocyanates could be a good strategy to synthesize urethane-based oligomers in a liquid state. The developed triethylene glycol dimethacrylate-free urethane-based composites showed significantly reduced water sorption and solubility, decreased shrinkage and enhanced mechanical strength as compared to commercial resin-based ones.

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Oschatz, Stefan, Stefanie Kohse, Volkmar Senz, Thomas Eickner, Klaus-Peter Schmitz, and Niels Grabow. "Accelerated in vitro-calcification of potential urethane based heart valve replacement materials." Current Directions in Biomedical Engineering 4, no. 1 (September 1, 2018): 221–24. http://dx.doi.org/10.1515/cdbme-2018-0054.

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AbstractPolycarbonate urethane and polyether urethane nonwovens as promising representatives of novel polymer heart valve materials were analysed regarding the susceptibility to calcification in comparison to porcine pericardium and polyamide 6. The applied method represents an accelerated calcification out of a metastable solution in short time with significant precipitates on the reference material. As our results show, urethane based nonwoven structures exhibit considerably lower susceptibility to calcification compared to pericardium as widely established material for leaflet design.

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OKAMURA, HIROKAZU, KAORI SUZUKI, TAKESHI MORI, KEIJI MINAGAWA, SEIZO MASUDA, and MASAMI TANAKA. "CHAIN BEHAVIOR IN MODEL HOMOGENEOUS ER FLUIDS DEPENDING ON TEMPERATURE." International Journal of Modern Physics B 16, no. 17n18 (July 20, 2002): 2385–91. http://dx.doi.org/10.1142/s0217979202012402.

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Water-soluble urethane-modified polyethers were prepared by addition of poly(ethylene oxide)-co-poly(propylene oxide) and aromatic isocyanate compounds. These polymers were found to dissolve in water at lower temperature and separate from solution upon heating. The temperature showing this unusual solubility change is called lower critical solution temperature (LCST). These chemical structures of thermo-responsive polymers were similar to those of urethane-modified ER active polymers containing poly(tetramethylene oxide) and aromatic urethane moiety. The thermo-responsive and ER polymers may have various intra- and intermolecular interactions through the urethane moiety. It is considered that both thermo-responsivility and ER effect are dependent on the conformational stability of the polymers under different conditions possibly related to these stimuli-responsivility through the molecular interactions. In order to clarify molecular motion of thermo-responsive polymers near the LCST, 1 H-NMR spin-lattice relaxation time ( T 1) was measured in D 2 O . The result indicated that hydrophobic interaction of terminal urethane moiety would strongly affect the LCST behavior.

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Czachor-Jadacka, Dominika, Barbara Pilch-Pitera, Maciej Kisiel, and Justyna Gumieniak. "Hydrophobic UV-Curable Powder Clear Coatings: Study on the Synthesis of New Crosslinking Agents Based on Raw Materials Derived from Renewable Sources." Materials 14, no. 16 (August 20, 2021): 4710. http://dx.doi.org/10.3390/ma14164710.

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Methods for the synthesis of urethane acrylates used as new crosslinking agents for hydrophobic UV-curable powder clear coatings were developed. In the synthesis of urethane acrylates, isophorone diisocyanate, glycerin, xylitol, polyethylene glycol and polysiloxane KF-6000, as well as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, were used. In order to increase the functionality of urethane acrylates, glycerin and xylitol derived from renewable sources were introduced. The chemical structure of the urethane acrylates was verified by IR spectroscopy. UV-curable powder clear coatings were obtained through a combination of urethane acrylates with unsaturated polyester resins. The thermal behavior and crosslinking density were examined using DMA. The obtained coatings were evaluated by performing the following tests: roughness, gloss, scratch resistance, hardness, adhesion to steel and water contact angle. As part of this research, high hydrophobicity and scratch resistance of UV-curable powder clear coatings were developed, which are a VOC-free and economically attractive alternative method for low thermal resistance surface protection, such as for composites, wood and wood-based materials.

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Lee, Dae-Woo, Han-Na Kim, and Dai-Soo Lee. "Introduction of Reversible Urethane Bonds Based on Vanillyl Alcohol for Efficient Self-Healing of Polyurethane Elastomers." Molecules 24, no. 12 (June 12, 2019): 2201. http://dx.doi.org/10.3390/molecules24122201.

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Urethane groups formed by reacting phenolic hydroxyl groups with isocyanates are known to be reversible at high temperatures. To investigate the intrinsic self-healing of polyurethane via a reversible urethane group, we synthesized vanillyl alcohol (VA)-based polyurethanes. The phenolic hydroxyl group of vanillyl alcohol allows the introduction of a reversible urethane group into the polyurethane backbone. Particularly, we investigated the effects of varying the concentration of reversible urethane groups on the self-healing of the polyurethane, and we proposed a method that improved the mobility of the molecules contributing to the self-healing process. The concentration of reversible urethane groups in the polyurethanes was controlled by varying the vanillyl alcohol content. Increasing the concentration of the reversible urethane group worsened the self-healing property by increasing hydrogen bonding and microphase separation, which consequently decreased the molecular mobility. On the other hand, after formulating a modified chain extender (m-CE), hydrogen bonding and microphase separation decreased, and the mobility (and hence the self-healing efficiency) of the molecules improved. In VA40-10 (40% VA; 10% m-CE) heated to 140 °C, the self-healing efficiency reached 96.5% after 30 min, a 139% improvement over the control polyurethane elastomer (PU). We conclude that the self-healing and mechanical properties of polyurethanes might be tailored for applications by adjusting the vanillyl alcohol content and modifying the chain extender.

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48

Accorsi-Mendonça, Daniela, Ricardo M. Leão, José F. Aguiar, Wamberto A. Varanda, and Benedito H. Machado. "Urethane inhibits the GABAergic neurotransmission in the nucleus of the solitary tract of rat brain stem slices." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 292, no. 1 (January 2007): R396—R402. http://dx.doi.org/10.1152/ajpregu.00776.2005.

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Because urethane is a widely used anesthetic in animal experimentation, in the present study, we evaluated its effects on neurons of the nucleus of the solitary tract (NTS) in brain stem slices from young rats (25–30 days old). Using the whole cell configuration of the patch-clamp technique, spontaneous postsynaptic currents (sPSCs) and evoked excitatory postsynaptic currents (eEPSCs) were recorded. Urethane (20 mM) decreased by ∼60% the frequency of GABAergic sPSCs (1.0 ± 0.2 vs. 0.4 ± 0.1 Hz) but did not change the frequency, amplitude, or half-width of glutamatergic events or TTX-resistant inhibitory sPSCs [miniature inhibitory postsynaptic currents (IPSCs)]. Miniature IPSCs were measured in the presence of urethane plus 1 mM diazepam (1 mM), and no changes were seen in their amplitude. This suggests that the GABA concentration in the NTS synapses is set at saturating level. We also evaluated the effect of urethane on eEPSCs, and no significant change was observed in the amplitude of N-methyl-d-aspartate [NMDA; 44.2 ± 11.5 vs. 37.6 ± 10.6 pA (holding potential = 40 mV)] and non-NMDA currents [204.4 ± 35.5 vs. 196.6 ± 31.2 pA (holding potential = −70 mV)]. Current-clamp experiments showed that urethane did not alter the action potential characteristics and passive membrane properties. These data suggest that urethane has an inhibitory effect on GABAergic neurons in the NTS but does not change the spontaneous or evoked excitatory responses.

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Rimdusit S, Rimdusit S., Kasemsiri P. Kasemsiri P., and Okhawilai M. Okhawilai M. "Thermomechanical Properties of KevlarTM Reinforced Benzoxazine-Urethane Alloys." ASEAN Journal of Chemical Engineering 13, no. 1 (September 25, 2013): 11. http://dx.doi.org/10.22146/ajche.49720.

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Ballistic armor is one of an important application which required high performance of fiber-reinforced polymer due to its outstanding specific mechanical properties. Therefore, KevlarTM reinforced benzoxazine-urethane alloys as ballistic impact resistance composites were developed in this research. The polybenzoxazine alloy composites were fabricated by compression molding at 200ºC and 5 MPa by a compression molder. The amount of urethane fraction in the alloy matrix was ranging from 0-40wt% while the fiber content was kept constant at 80wt%. The mechanical properties of the matrix alloys and their KevlarTM fiber composites were characterized by dynamic mechanical analysis and universal testing machine. The results revealed that storage modulus at room temperature of the composites was reduced from 16.82 GPa when using the neat polybenzoxazine as a matrix to the value of 11.89 GPa at 40wt% of urethane content in the alloy matrix. Moreover, the more urethane in the alloy matrix resulted in lower flexural modulus of the KevlarTM composites i.e. 22 GPa when using the neat polybenzoxazine as a matrix to the value of 12 GPa when using 40wt% of urethane in the alloy matrix. Interestingly, glass transition temperature (Tg) obtained from the maximum peak of the loss modulus was observed to be in the range of 187-247ºC, which was significantly higher than those of the two parent polymers. Furthermore, the activation energy of the alloys was found to increase with increasing urethane content, which corresponded to the observed Tg value enhancement. The observed synergism in Tg of KevlarTM reinforced benzoxazine-urethane was an outstanding characteristic for a wide range of applications, which requires high thermal stability.

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Wibowo, Heri Budi, Widhi Cahyo, and Ratih Sanggra. "Bulk Polymerization Kinetics of Hydroxy Terminated Polybutadiene and Toluene Diisocyanate with Infrared Spectroscopy." Indonesian Journal of Chemistry 18, no. 3 (August 30, 2018): 552. http://dx.doi.org/10.22146/ijc.24807.

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A study on bulk polymerization kinetics of HTPB (Hydroxy Terminated Polybutadiene) and TDI (Toluene Diisocyanate) with infrared (IR) spectroscopy has been conducted. The investigations included the molar ratio of 2,4-TDI to 2,6-TDI isomers, the initial molar ratio of isocyanate group to a hydroxyl group, and the reaction temperature. The polymerization rate constant was calculated based on the decrease rate of TDI. Kinetics model had been evaluated through the following reaction steps: (1) 2,4-urethane production, (2) 2,6-urethane production, (3) the reaction between 2,4-urethane and the isocyanate group of 2,4-TDI, (4) the reaction between 2,4-urethane and the isocyanate group of 2,4-TDI, (5) the reaction between 2,6-urethane and isocyanate group of 2,4-TDI, and (6) the reaction between 2,6-urethane and the isocyanate group of 2,6-TDI. Those reaction steps were assumed to be the first order reaction with the reaction rate constants k1, k2, k3, k4, k5, and k6, respectively. The reaction rate constants obtained at molar ratio of 2,4-TDI to 2,6-TDI of 80:20, isocyanate group to hydroxyl group (RNCO/OH) initial molar ratio of 1:1, and reaction temperature of 40 °C were 6.2 × 10-5, 5.8 × 10-5, 3.1 × 10-5, 2.8 × 10-5, and 2.5 × 10-5 L.mole-1.min-1 for k1, k2, k3, k4, k5, and k6, respectively, with the activation energy of 1152, 952, 1001, 656, and 1001 kJ/mole for reaction (1)–(6), respectively. The results show that the polymerization reaction rate-determining step was the reaction of 2,6-urethane and isocyanate group of 2,6-TDI (reaction (6)).

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Journal articles on the topic 'Urethane A'

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