Journal articles: 'Diisocyanate'

1

Hegedus, Ondrej, Zuzana Smotlakova, Alzbeta Hegedusova, et al. "Determination of Isocyanates in Workplace Atmosphere by HPLC." Revista de Chimie 69, no. 2 (2018): 533–38. http://dx.doi.org/10.37358/rc.18.2.6142.

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Determination of diisocyanates in the laboratories of the Authorities of Public Health was described and verified. Air samples collected in the breathing zone of workers exposed to diisocyanates were analyzed in an automotive industry. Diisocyanates (2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4�-methylenediphenyl isocyanate, and 1,6-hexamethylene diisocyanate) were measured by HPLC and the validation characteristics were determined. Diisocyanate exposure was monitored in the workplace atmosphere of 25 workers. Air samples from the breathing zone were collected and analyzed by HPLC after extraction. The results were compared to the occupational exposure limit. Reliability of the method was confirmed by validation characteristics for the diisocyanates. The repeatability of the method ranged from 2.98 to 4.51%, the calculated relative standard uncertainty was 11 � 12% for the parameters, and the recovery was between 99 and 103%. The low LOD and LOQ ensured the determination of the diisocyanates in the harmful concentration. Monitoring of diisocyanate exposure was performed on four different workplaces. The results showed that 2,4-toluene diisocyanate and 2,6-toluene diisocyanate were present in the concentration range from 6.3 to 13.2 �g m-3. The 1,6-hexamethylene diisocyanate was found in all cases below the limit of detection and the 4,4�-methylenediphenyl isocyanate was found only at two workplaces (between 8.3 and 44.8 �g m-3). The HPLC method was found to be appropriate for the determination of diisocyanates. Applying the method for the determination of diisocyanate exposure in four different workplaces, which produce car accessories, showed that the diisocyanate level did not exceed the occupational exposure limit set for average exposure.

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2

Chen, Xiao Dong, and Yu Hua Yi. "Influence of Diisocyanates on Dynamic Mechanical Properties of Castable Polyurethane Elastomers." Applied Mechanics and Materials 217-219 (November 2012): 563–66. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.563.

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A series of castable polyurethane elastomers, based on polytetramethylene glycol as soft segments and toluene diisocyanate, 4, 4’-diphenylmethane diisocyanate, P-phenylene diisocyanate as diisocyanates respectively, were synthesized. The dynamic mechanical analysis method was utilized to determine tan delta property (tanδ). Also the influence of diisocyanates on the dynamic mechanical properties of castable polyurethane elastomers was analyzed. It can be concluded that the P-phenylene diisocyanate system elastomers have the most excellent dynamic mechanical properties.

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Lee, Jong Baek, Kwang Hyun Lee, Byung Chul Kang, Byung Won Kang, Sang Ll Lee, and Jin Kyung Lee. "Thermal Properties of a Liquid-Crystalline Polyurethanes Containing Biphenyl Mesogen." Key Engineering Materials 321-323 (October 2006): 1385–88. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.1385.

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A new type of thermotropic main-chain liquid crystalline polyurethanes containing biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 1,4-phenylene diisocyanate, with 4,4′-Bis(11-hydroxyundeyloxy)biphenyl (BP11). The structure of the monomer and the corresponding polymers were confirmed FT-IR and 1H NMR spectroscopic methods. BP11 exhibited a smectic type mesophase, however, nematic phase was found for all synthesized liquid crystalline polyurethanes except for 1,4-phenylene diisocyanate/BP11 based polyurethane. For example, polyurethane 2,5-TDI/BP11 exhibited monotropic liquid crystallinity in the temperature ranges from 173 to 156 °C on the cooling stage.

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Gebauer, Tim, Axel T. Neffe, and Andreas Lendlein. "Influence of diisocyanate reactivity and water solubility on the formation and the mechanical properties of gelatin-based networks in water." MRS Proceedings 1569 (2013): 15–20. http://dx.doi.org/10.1557/opl.2013.839.

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ABSTRACTGelatin can be covalently crosslinked in aqueous solution by application of diisocyanates like L-lysine diisocyanate ethyl ester in order to form hydrogels. Reaction of isocyanate groups with water is however a limiting factor in hydrogel network formation and can strongly influence the outcome of the crosslinking process. Here, diisocyanates with different water solubility and reactivity were applied for the formation of gelatin-based hydrogel networks and the mechanical properties of the hydrogels were investigated to gain a better understanding of starting material/ hydrogel property relations. L-Lysin diisocyanate ethyl ester (LDI), 2,4-toluene diisocyanate (TDI), 1,4-butane diisocyanate (BDI), and isophorone diisocyanate (IPDI) were selected, having different solubility in water ranging from 10-4 to 10-2 mol·L-1. BDI and LDI were estimated to have average reactive isocyanates groups, whereas TDI is highly reactive and IPDI has low reactivity. Formed hydrogels showed different morphologies and were partially very inhomogeneous. Gelation time (1 to 50 minutes), water uptake (300 to 900 wt.-%), and mechanical properties determined by tensile tests (E-moduli 35 to 370 kPa) and rheology (Shear moduli 4.5 to 19.5 kPa) showed that high water solubility as well as high reactivity leads to the formation of poorly crosslinked or inhomogeneous materials. Nevertheless, diisocyanates with lower solubility in water and low reactivity are able to form stable, homogeneous hydrogel networks with gelatin in water.

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Jiang, Lei, Zhiyong Ren, Wei Zhao, Wentao Liu, Hao Liu, and Chengshen Zhu. "Synthesis and structure/properties characterizations of four polyurethane model hard segments." Royal Society Open Science 5, no. 7 (2018): 180536. http://dx.doi.org/10.1098/rsos.180536.

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Four model polyurethane (PU) hard segments were synthesized by reaction of butanol with four typical diisocyanates. The four diisocyanates were aromatic 4,4′-diphenylmethane diisocyanate (4,4′-MDI) and MDI-50 (50% mixture of 2,4′-MDI and 4,4′-MDI), cycloaliphatic 4,4′-dicyclohexylmethane diisocyanate (HMDI) and linear aliphatic 1,6-hexamethylene diisocyanate (HDI). FTIR, 1 H NMR, 13 C NMR, MS, X-ray and DSC methods were employed to determine their structures and to analyse their crystallization behaviours and hydrogen bonding interactions. Each of the four PU compounds prepared in the present work displays unique spectral characteristics. The FTIR bands and NMR resonance peaks assigned in the four samples thus provide a reliable database and starting point for investigating the relationship between hard segment structure and the crystallization and hydrogen bonding behaviour in more complex-segmented PU compositions.

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Neffe, Axel T., Tim Gebauer, and Andreas Lendlein. "Tailoring of Mechanical Properties of Diisocyanate Crosslinked Gelatin-Based Hydrogels." MRS Proceedings 1569 (2013): 3–8. http://dx.doi.org/10.1557/opl.2013.837.

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ABSTRACTPolymer network formation is an important tool for tailoring mechanical properties of polymeric materials. One option to synthesize a network is the addition of bivalent crosslinkers reacting with functional groups present in a polymer. In case of polymer network syntheses based on biopolymers, performing such a crosslinking reaction in water is sometimes necessary in view of the solubility of the biopolymer, such as gelatin, and can be beneficial to avoid potential contamination of the formed material with organic solvents in view of applications in biomedicine. In the case of applying diisocyanates for the crosslinking in water, it is necessary to show that the low molecular weight bifunctional crosslinker has fully reacted, while tailoring of the mechanical properties of the resulting hydrogels is possible despite the complex reaction mechanism. Here, the formation of gelatin-based hydrogel networks with the diisocyanates 2,4-toluene diisocyanate, 1,4-butane diisocyanate, and isophorone diisocyanate is presented. It is shown that extensive washing of materials is required to ensure full conversion of the diisocyanates. The use of different diisocyanates gives hydrogels covering a large range of Young’s moduli (12-450 kPa). The elongations at break (up to 83%) as well as the maximum tensile strengths (up to 410 kPa) of the hydrogels described here are much higher than for lysine diisocyanate ethyl ester crosslinked gelatin reported before. Rheological investigations suggest that the network formation in some cases is due to physical interactions and entanglements rather than covalent crosslink formation.

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7

Byrne, Catherine A., Daniel P. Mack, and James M. Sloan. "A Study of Aliphatic Polyurethane Elastomers Prepared from Diisocyanate Isomer Mixtures." Rubber Chemistry and Technology 58, no. 5 (1985): 985–96. http://dx.doi.org/10.5254/1.3536109.

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Abstract Linear polyurethane elastomers are block copolymers which are elastomeric because they are phase separated. The soft block is derived from a hydroxy terminated telechelic polymer, frequently a polyether or polyester of a molecular weight less than 3000 and a glass transition temperature well below room temperature. The hard block, having a Tg above room temperature, consists of a diisocyanate and a diol. Most frequently the diisocyanate is aromatic and the diol is 1,4-butanediol. The elastomers produced are frequently opaque and then yellow in storage due to the presence of the aromatic rings. For applications where transparency and nonyellowing are important, aliphatic diisocyanates are the compounds of choice. One such diisocyanate is methylene bis(4-cyclohexyl-isocyanate), which is conveniently called H12MDI. It is prepared from the same diamine as methylene dianiline diisocyanate (MDI), but the aromatic rings are hydrogenated before phosgenation. The hydrogenation leads to a mixture of three aliphatic diamine isomers. Phosgenation leads to a diisocyanate which is a mixture of the three isomers shown in Figure 1. The isomer content is adjusted by the manufacturer, and the product received is a liquid. Another example of a diisocyanate which is marketed as a mixture is toluene diisocyanate, an 80:20 mixture of the 2,4:2,6 isomers being the most common. The aromatic diisocyanates are planar molecules or bent planar molecules like MDI. The H12MDI is also bent, but does not contain planar rings. Even if polymers from one pure diisocyanate isomer are examined, the cycloaliphatic compounds are much less likely to form highly ordered or crystalline regions in the hard-segment phase due to the greater difficulty in packing correctly. A desire to know the isomer composition of the diisocyanate and what effect the isomer composition has on the properties of the elastomers led to this study. Mixtures of the isomers varying from approximately 10% of the trans-trans isomer up to 95% (t-t) have been prepared and the properties of polyurethanes prepared from them have been studied.

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Lee, Jong Baek, and Byung Won Kang. "Synthesis and Properties of Thermotropic Main-Chain Type Liquid Crystalline Polyurethanes Containing Biphenyl Mesogen." Key Engineering Materials 342-343 (July 2007): 729–32. http://dx.doi.org/10.4028/www.scientific.net/kem.342-343.729.

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A new type of thermotropic main-chain liquid crystalline polyurethanes containing biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 1,4-phenylene diisocyanate, with 4,4′-Bis(8-hydroxyoctoxy)biphenyl (BP8). The structure of the monomer and the corresponding polymers were confirmed using FT-IR and 1H-NMR spectroscopic methods. BP8 exhibited a smectic type mesophase, however, nematic phases were found for all synthesized liquid crystalline polyurethanes except for 1,4-phenylene diisocyanate/BP8 based polyurethane. For example, polyurethane 2,5-TDI/BP8 exhibited monotropic liquid crystallinity in the temperature ranging from 172 to 160 °C on the cooling stage. Properties of these polyurethanes were studied by differential scanning calorimetry (DSC), and optical polarizing microscopy. The FT-IR study indicated that the hydrogen bonding among urethane linkages attributed to the mesomorphism.

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LEE, JONG BACK, SANG PILL LEE, and JIN KYUNG LEE. "SYNTHESIS AND CHARACTERIZATION OF NEW THERMOTROPIC LIQUID CRYSTALLINE POLYURETHANES WITH BIPHENYL MOIETY." International Journal of Modern Physics B 20, no. 25n27 (2006): 4487–92. http://dx.doi.org/10.1142/s0217979206041562.

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A new series of thermotropic polyurethanes containing biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 1,4-phenylene diisocyanate, with 4,4□-bis(9-hydroxynonoxy)biphenyl (BP9). Structures of the monomer and the corresponding polymers were identified using FT-IR and 1 H NMR spectroscopic methods. BP9 exhibited a smectic type mesophase, however, nematic phase was found for all synthesized liquid crystalline polyurethanes except for 1,4-phenylene diisocyanate/BP9 based polyurethane. Their phase transition temperatures and thermal stability were investigated by differential scanning calorimetry (DSC), optical polarizing microscopy, and X-ray scattering. The infrared study indicated that the hydrogen bonding among urethane linkages attributed to the mesomorphism. Thermal gravimetric analysis (TGA) of synthesized polyurethanes showed that no weight loss of the polymers observed up to 280°C.

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Li, Ting, Tianze Zheng, Jiarui Han, et al. "Effects of Diisocyanate Structure and Disulfide Chain Extender on Hard Segmental Packing and Self-Healing Property of Polyurea Elastomers." Polymers 11, no. 5 (2019): 838. http://dx.doi.org/10.3390/polym11050838.

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Four linear polyurea elastomers synthesized from two different diisocyanates, two different chain extenders and a common aliphatic amine-terminated polyether were used as models to investigate the effects of both diisocyanate structure and aromatic disulfide chain extender on hard segmental packing and self-healing ability. Both direct investigation on hard segments and indirect investigation on chain mobility and soft segmental dynamics were carried out to compare the levels of hard segmental packing, leading to agreed conclusions that correlated well with the self-healing abilities of the polyureas. Both diisocyanate structure and disulfide bonds had significant effects on hard segmental packing and self-healing property. Diisocyanate structure had more pronounced effect than disulfide bonds. Bulky alicyclic isophorone diisocyanate (IPDI) resulted in looser hard segmental packing than linear aliphatic hexamethylene diisocyanate (HDI), whereas a disulfide chain extender also promoted self-healing ability through loosening of hard segmental packing compared to its C-C counterpart. The polyurea synthesized from IPDI and the disulfide chain extender exhibited the best self-healing ability among the four polyureas because it had the highest chain mobility ascribed to the loosest hard segmental packing. Therefore, a combination of bulky alicyclic diisocyanate and disulfide chain extender is recommended for the design of self-healing polyurea elastomers.

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Okieimen, F. E., I. O. Bakare, and C. Pavithran. "Network Structures, Flexibility and Stability in Thermal and Chemical Environments of Polyurethane Prepared from Rubber Seed Oil." Advanced Materials Research 62-64 (February 2009): 324–34. http://dx.doi.org/10.4028/www.scientific.net/amr.62-64.324.

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Rubber seed oil monoglyceride was prepared by glycerolysis and characterized by chemical and spectroscopic methods. The monoglyceride was reacted with excess diisocyanates (hexamethylene -diisocyanate and toluene diisocyanate), and the network structures and molecular mass of the polyurethane were determined from swelling experiments in toluene and size exclusion chromatography respectively. The polyurethane films obtained were characterized in terms of their resistance to chemicals (water, brine, dilute acid and alkali) thermal stability and tensile and flexural strength and modulus. It was found that under the experimental conditions, conversion of the triglyceride content of the rubber seed oil to monoglyceride not quantitative less than 70%. The measured properties of the RSO-based polyurethanes were attributed to the degree of crosslinking and the observed superior properties of the polyurethane obtained with hexamethylene diisocyanate in comparison with polyurethane obtained with toluene diisocyanate were explained in terms of structure-property relationship. The measured properties of RSO-based polyurethanes compare favourably with the properties reported for polyurethanes derived from other vegetable oils.

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Jones, Kate, Karen S. Galea, Bernice Scholten, et al. "HBM4EU Diisocyanates Study—Research Protocol for a Collaborative European Human Biological Monitoring Study on Occupational Exposure." International Journal of Environmental Research and Public Health 19, no. 14 (2022): 8811. http://dx.doi.org/10.3390/ijerph19148811.

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Diisocyanates have long been a leading cause of occupational asthma in Europe, and recently, they have been subjected to a restriction under the REACH regulations. As part of the European Human Biomonitoring project (HBM4EU), we present a study protocol designed to assess occupational exposure to diisocyanates in five European countries. The objectives of the study are to assess exposure in a number of sectors that have not been widely reported on in the past (for example, the manufacturing of large vehicles, such as in aerospace; the construction sector, where there are potentially several sources of exposure (e.g., sprayed insulation, floor screeds); the use of MDI-based glues, and the manufacture of spray adhesives or coatings) to test the usability of different biomarkers in the assessment of exposure to diisocyanates and to provide background data for regulatory purposes. The study will collect urine samples (analysed for diisocyanate-derived diamines and acetyl–MDI–lysine), blood samples (analysed for diisocyanate-specific IgE and IgG antibodies, inflammatory markers, and diisocyanate-specific Hb adducts for MDI), and buccal cells (micronucleus analysis) and measure fractional exhaled nitric oxide. In addition, occupational hygiene measurements (air monitoring and skin wipe samples) and questionnaire data will be collected. The protocol is harmonised across the participating countries to enable pooling of data, leading to better and more robust insights and recommendations.

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Huuskonen, Pasi, Simo P. Porras, Bernice Scholten, et al. "Occupational Exposure and Health Impact Assessment of Diisocyanates in Finland." Toxics 11, no. 3 (2023): 229. http://dx.doi.org/10.3390/toxics11030229.

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Diisocyanates are a group of chemicals widely used in different industrial applications. The critical health effects related to diisocyanate exposure are isocyanate sensitisation, occupational asthma and bronchial hyperresponsiveness (BHR). Industrial air measurements and human biomonitoring (HBM) samples were gathered in specific occupational sectors to examine MDI, TDI, HDI and IPDI and the respective metabolites from Finnish screening studies. HBM data can give a more accurate picture of diisocyanate exposure, especially if workers have been exposed dermally or used respiratory protection. The HBM data were used for conducting a health impact assessment (HIA) in specific Finnish occupational sectors. For this purpose, exposure reconstruction was performed on the basis of HBM measurements of TDI and MDI exposures using a PBPK model, and a correlation equation was made for HDI exposure. Subsequently, the exposure estimates were compared to a previously published dose–response curve for excess BHR risk. The results showed that the mean and median diisocyanate exposure levels and HBM concentrations were low for all diisocyanates. In HIA, the excess risk of BHR from MDI exposure over a working life period was highest in the construction and motor and vehicle industries and repair sectors, resulting in estimated excess risks of BHR of 2.0% and 2.6%, and 113 and 244 extra BHR cases in Finland, respectively. Occupational exposure to diisocyanates must be monitored because a clear threshold for DI sensitisation cannot be established.

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Rasli @ Rosli, Nur Athirah, and Syazana Ahmad Zubir. "Synthesis and Characterization of Palm Kernel Oil Polyol Based Shape Memory Polyurethane: Effect of Different Diisocyanates." Key Engineering Materials 908 (January 28, 2022): 14–19. http://dx.doi.org/10.4028/p-l49hs4.

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Shape memory polyurethane (SMPU) is a very versatile material that has a broad array of applications. The selection of soft segments and hard segments play critical roles in determining the structure-property behaviors of SMPU. This research was conducted to evaluate the role of distinct types of diisocyanate on the final properties of polyurethane (PU). Palm kernel oil polyol (PKO) based PU were produced by using two-step bulk polymerization method with variations of diisocyanates. Isophorone diisocyanate (IPDI), 4,4-methylenebis (cyclohexyl isocyanate) (HMDI) and hexamethylene diisocyanate (HDI) were used in the preparation of PU and the soft segment crystallinity, thermal and shape memory properties of the PU were evaluated. Based on the analyses, it was found that different types of diisocyanate and combination of diisocyanates had huge impact on the properties of the synthesized PU. The Fourier transformation infrared (FTIR) analysis revealed that IPDI based PU achieved the highest hydrogen bonding index value which promoted the phase separation. This is in accordance with differential scanning calorimetric (DSC) and x-ray diffraction (XRD) analysis which showed that IPDI based PU exhibited crystalline soft phase, hence resulted in an excellent shape fixity behavior. On the other hand, HDI and HMDI based polyurethane prepared showed absence of crystalline soft phase based on the DSC thermogram and XRD diffractogram. These results suggest the phase mixing phenomenon between soft and hard segments which contributed to low shape memory behavior of the resulting polyurethane.

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Ivanova, K. Yu, M. V. Kuzmin, L. G. Rogozhina, A. O. Patianova, V. L. Semenov, and R. I. Alexandrov. "Synthesis and research of polyfunctional silylureas used in electric deposition of tin-indium alloy." Chimica Techno Acta 8, no. 3 (2021): 20210305. http://dx.doi.org/10.15826/chimtech.2021.8.3.05.

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Polyfunctional silylureas were synthesized by the interaction of 3-aminopropyltriethoxysilane with isocyanates of various structures in an inert aromatic solvent. Commercially available diisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, 2,4-toluene diisocyanate were used as isocyanates. In this case, freshly distilled toluene was used as a solvent. The structures of the obtained compounds were confirmed by the data of IR and NMR1H spectroscopy. Using the synthesized compounds, formulations of compositions for electrodeposition of a tin-indium alloy on a copper wire were developed. The possibility of using silylureas of various structures as effective surfactants used in the electrodeposition of the tin-indium alloy is shown. The operational characteristics of the obtained wire were investigated, including the wire diameter, coating thickness, tensile strength, electrical resistance, and direct current electrical resistivity.

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Jana, Sourita, Debasis Samanta, Mir Muhammad Fahad, Sellamuthu N. Jaisankar, and Hongdoo Kim. "Blocking and Deblocking of Diisocyanate to Synthesize Polyurethanes." Polymers 13, no. 17 (2021): 2875. http://dx.doi.org/10.3390/polym13172875.

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Diisocyanates, particularly toluene diisocyanate (TDI), are useful for the preparation of various polyurethanes with specific applications as leather-like materials, adhesives and insoles, etc. Blocking agents can be used for the operational simplicity and to reduce the hazards of TDI. In this paper, we reported the use of 3-(4-bromo-phenyl)-1H-pyrazole to block toluene diisocyanate (TDI). FTIR, NMR, thermogravimetric analysis, contact angle analysis and differential scanning calorimetry (DSC) were used for the characterization. The effectiveness of the blocking was confirmed by spectroscopic techniques. The DSC thermogram showed that blocked adducts deblock at 240 °C, causing the regeneration of TDI, and causing the diisocyanates to react with polyols of different molecular weights, forming polyurethanes. The characterization of the polyurethanes was performed by infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and a contact angle study.

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Mohammed, Issam A., and Govindarajan Sankar. "Synthesis, deblocking and cure reaction studies of secondary alcohol-blocked isocyanates." High Performance Polymers 23, no. 7 (2011): 535–41. http://dx.doi.org/10.1177/0954008311421833.

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A series of 1,3-dichloro-2-propanol-blocked diisocyanates, based on diisocyanates including 4,4′-methylene di(phenyl isocyanate), toluene-2,4-diisocyanate, isophorone diisocyanate and 1,6-diisocyanatohexane, were prepared and characterized thoroughly by Fourier transform infrared, 1 H-NMR, 13 C-NMR spectroscopic methods and elemental analysis (CHN). The blocking reaction of 1,3-dichloro 2-propanol with aromatic diisocyanates occurs faster than with the aliphatic isocyanates. The deblocking temperature of blocked isocyanates was determined by thermogravimetric analysis, differential scanning calorimetry and the CO2 evaluation method. Cure reactions of blocked isocyanates with hydroxyl-terminated polybutadiene were also followed to establish the structure–property relationship of the 1,3-dichloro-2-propanol-blocked isocyanates. The deblocking studies reveal that the aromatic isocyanates undergo deblocking more easily than aliphatic isocyanates. The dissolution behavior of 1,3-dichloro-2-propanol-blocked isocyanates in Terathane-2000, polypropylene glycol-2000, polycaprolactone diol-2000 and hydroxyl-terminated polybutadiene-2500 was also studied, and it was found that all adducts are soluble in these polyols.

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Ioan, Silvia, Mihaela Lupu, and Doina Macocinschi. "Viscometric Study of Poly(ester Urethane) Solutions: 2. Influence of Hard-Segment Composition on the Unperturbed Dimensions." High Performance Polymers 15, no. 3 (2003): 319–28. http://dx.doi.org/10.1177/0954008303015003008.

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Using viscometry, we have studied the dilute solution property of segmented poly(ester urethane)s obtained by the reaction of aromatic diisocyanates with poly(ethylene glycol)adipate and 4,4′-dihidroxydiethoxydiphenyl sulphone as chain extender, using a multistep polyaddition process. A new method proposed by Qian et al. was utilized for the determination of unperturbed dimensions of poly(ester urethane)s having different hard segments by the measurement of the intrinsic viscosity at non-theta conditions only. The influence of the hard segments on the unperturbed dimensions of these polymers was observed. The diisocyanates with methyl substituents in the hard segments, such as 2,4-tolylene diisocyanate, have smaller unperturbed dimensions compared with the samples containing 4,4′-methylene diphenylene diisocyanate, which are believed to possess significant chain rigidity because of the high cohesive energy and bulkiness of the benzene ring.

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Sastre, Joaquin, Anna Poltronieri, Ignacio Mahillo-Fernandez, Erika Aguado, Manuela Garcia del Potro, and Mar Fernandez-Nieto. "Nasal response in patients with diisocyanate asthma." Rhinology journal 52, no. 4 (2014): 431–36. http://dx.doi.org/10.4193/rhino14.005.

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Background: To date, no studies have assessed nasal and bronchial response to diisocyanates during specific inhalation challenges (SIC). Objectives: This study was performed to assess nasal response during SIC with diisocyanates (nasal and oral breathing) in patients with suspected occupational asthma due to these agents. Methods: Fourteen patients with suspected clinical history of diisocyanate-induced asthma were challenged with diisocynates in a 7m3 chamber. Nasal response testing during challenges was assessed by acoustic rhinometry, peak nasal inspiratory flow (PNIF), and visual analog scale (VAS), alongside bronchial responses. Results: Eleven patients had a significant asthmatic response to diisocyanates. None reported clear work-related nasal symptoms. In patients with positive bronchial response to diisocyanates, nasal mean minimal cross-sectional area (MCA) decreased by 26.9%, nasal volume at 5 cm decreased by 33.5%, and PNIF decreased by 28.3%, all from baseline. A positive nasal response was elicited in 45%, 54%, and 45% of patients, respectively. A significant increase in VAS was observed in 4 patients. Three patients with negative bronchial response had a negative nasal response. Conclusion: SIC revealed an objective nasal response in around 50% of patients with occupational asthma due to diisocyanates, in spite of the fact that none of them reported work-related nasal symptoms. The clinical significance of this finding is a poor association between nasal symptoms at work and an objective nasal response during positive SIC with diisocyanates.

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Vella-Zarb, Liana, and Robert E. Dinnebier. "Form, function and functionality of two dimeric toluene-2,4-diisocyanate polymorphs." Acta Crystallographica Section B Structural Science 68, no. 2 (2012): 204–8. http://dx.doi.org/10.1107/s0108768112008592.

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2,4-Dioxo-1,3-diazetidine-1,3-bis(methyl-m-phenylene) diisocyanate (dimerized toluene-2,4-diisocyanate, TDI) is one of the most widely used aromatic diisocyanates in the polymer industry, and it crystallizes in at least two polymorphic forms (form A and form B) depending on reaction conditions. The crystal structures of the two forms were determined from high-resolution laboratory X-ray powder diffraction data using simulated annealing and Rietveld refinement. In spite of a marked structural similarity between them, significant discrepancies in the physical properties of the two forms prompted analysis of their partitioned energy terms in an effort to better our understanding of the driving force behind such differences in behaviour.

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Maier, Günther, Matthias Naumann, Hans Peter Reisenauer, and Jürgen Eckwert. "Diisocyanate." Angewandte Chemie International Edition in English 35, no. 15 (1996): 1696–97. http://dx.doi.org/10.1002/anie.199616961.

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Rubio Hernández-Sampelayo, Alejandra, Rodrigo Navarro, and Ángel Marcos-Fernández. "Preparation of High Molecular Weight Poly(urethane-urea)s Bearing Deactivated Diamines." Polymers 13, no. 12 (2021): 1914. http://dx.doi.org/10.3390/polym13121914.

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The synthesis of poly(urethane-urea) (PUUs) bearing deactivated diamines within the backbone polymer chain is presented. Several deactivated diamines present interesting properties for several applications in the biomaterial field due to their attractive biocompatibility. Through an activation with Chloro-(trimethyl)silane (Cl-TMS) during the polymerization reaction, the reactivity of these diamines against diisocyanates was triggered, leading to PUUs with high performance. Indeed, through this activation protocol, the obtained molecular weights and mechanical features increased considerably respect to PUUs prepared following the standard conditions. In addition, to demonstrate the feasibility and versatility of this synthetic approach, diisocyanate with different reactivity were also addressed. The experimental work is supported by calculations of the electronic parameters of diisocyanate and diamines, using quantum mechanical methods.

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Rapone, Irene, Vincenzo Taresco, Valerio Di Lisio, Antonella Piozzi, and Iolanda Francolini. "Silver- and Zinc-Decorated Polyurethane Ionomers with Tunable Hard/Soft Phase Segregation." International Journal of Molecular Sciences 22, no. 11 (2021): 6134. http://dx.doi.org/10.3390/ijms22116134.

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Segmented polyurethane ionomers find prominent applications in the biomedical field since they can combine the good mechanical and biostability properties of polyurethanes (PUs) with the strong hydrophilicity features of ionomers. In this work, PU ionomers were prepared from a carboxylated diol, poly(tetrahydrofuran) (soft phase) and a small library of diisocyanates (hard phase), either aliphatic or aromatic. The synthesized PUs were characterized to investigate the effect of ionic groups and the nature of diisocyanate upon the structure–property relationship. Results showed how the polymer hard/soft phase segregation was affected by both the concentration of ionic groups and the type of diisocyanate. Specifically, PUs obtained with aliphatic diisocyanates possessed a hard/soft phase segregation stronger than PUs with aromatic diisocyanates, as well as greater bulk and surface hydrophilicity. In contrast, a higher content of ionic groups per polymer repeat unit promoted phase mixing. The neutralization of polymer ionic groups with silver or zinc further increased the hard/soft phase segregation and provided polymers with antimicrobial properties. In particular, the Zinc/PU hybrid systems possessed activity only against the Gram-positive Staphylococcus epidermidis while Silver/PU systems were active also against the Gram-negative Pseudomonas aeruginosa. The herein-obtained polyurethanes could find promising applications as antimicrobial coatings for different kinds of surfaces including medical devices, fabric for wound dressings and other textiles.

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Gamardella, Francesco, Angels Serra, Xavier Ramis, and Silvia De la Flor. "Actuator Behaviour of Tailored Poly(thiourethane) Shape Memory Thermosets." Polymers 13, no. 10 (2021): 1571. http://dx.doi.org/10.3390/polym13101571.

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In this work, a new family of poly(thiourethane) shape memory thermosetting actuators was developed and characterized. These materials can be easily prepared from mixtures of two different aliphatic diisocyanates and a trithiol in the presence of a latent catalyst, allowing an easy manipulation of the formulation. Rheological studies of the curing process confirm the latent character of the formulations. The glass transition temperatures and the mechanical properties can be modified by varying the proportion of diisocyanates (hexamethylene diisocyanate, HDI, and isophorone diisocyanate, IPDI) with stoichiometric amounts of trimethylolpropane tris(3-mercaptopropionate). The shape-memory behavior was deeply investigated under three different conditions: unconstrained, partially constrained, and fully constrained. Tests were performed in single cantilever bending mode to simulate conditions closer to real complex mechanics of thermomechanical actuators under flexural performances. The complex recovery process in single cantilever bending mode was compared with that obtained using tensile mode. The results evidenced that the amount of recovery force in fully constrained conditions, or energy released during the recovery process in partially constrained, can be modulated by simply changing the proportion of both diisocyanates. A simple model based on Timoshenko beam theory was used for the prediction of the amount of work performed. The reported results are an important guideline to design shape-memory materials based on poly(thiourethane) networks, establishing criteria for the choice of the material depending on the expected application.

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FURUSAWA, Teruo. "Toluene Diisocyanate." Journal of Synthetic Organic Chemistry, Japan 45, no. 10 (1987): 1008–10. http://dx.doi.org/10.5059/yukigoseikyokaishi.45.1008.

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26

von Burg, R. "Hexamethylene diisocyanate." Journal of Applied Toxicology 13, no. 6 (1993): 435–39. http://dx.doi.org/10.1002/jat.2550130611.

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PIIRILÄ, PÄIVI L, HENRIK NORDMAN, HELENA M KESKINEN, et al. "Long-term Follow-up of Hexamethylene Diisocyanate-, Diphenylmethane Diisocyanate-, and Toluene Diisocyanate-induced Asthma." American Journal of Respiratory and Critical Care Medicine 162, no. 2 (2000): 516–22. http://dx.doi.org/10.1164/ajrccm.162.2.9909026.

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28

Schulz, M., and T. Salthammer. "Sensitive determination of airborne diisocyanates by HPLC: 4,4′-Diphenylmethane-diisocyanate (MDI)." Fresenius' Journal of Analytical Chemistry 362, no. 3 (1998): 289–93. http://dx.doi.org/10.1007/s002160051076.

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29

Hejna, Aleksander, Mariusz Marć, and Jerzy Korol. "Modification of cellulosic filler with diisocyanates – volatile organic compounds emission assessment and stability of chemical structure over time." Nordic Pulp & Paper Research Journal 36, no. 2 (2021): 353–72. http://dx.doi.org/10.1515/npprj-2020-0104.

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Abstract This paper investigated the impact of type and content of diisocyanate on the structure of modified cellulose fillers. Four the most popular isocyanates were applied – isophorone, hexamethylene, toluene and methylene diphenyl diisocyanate – at loadings of 1–15 wt%. Chemical structure, and its short-term storage stability, were investigated for eight weeks. Moreover, the main volatile organic compounds detected during modification, as well as emitted from fillers before and after storage, were identified. The main compounds detected in the air during modifications were terpenes and terpenoids. No diisocyanates were detected, which is very beneficial considering their toxicity. They were emitted from modified fillers at 40 °C, but only from fresh samples. After storage no emissions were noted, which indicated successful modification of fillers, also confirmed by FTIR spectroscopy and changes in polarity of fillers’ surface. Observed changes should be considered beneficial for the potential applications of modified fillers in manufacturing of polymer composites.

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Scholten, Bernice, Laura Kenny, Radu-Corneliu Duca, et al. "Biomonitoring for Occupational Exposure to Diisocyanates: A Systematic Review." Annals of Work Exposures and Health 64, no. 6 (2020): 569–85. http://dx.doi.org/10.1093/annweh/wxaa038.

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Abstract Diisocyanates are a group of chemicals that are widely used in occupational settings. They are known to induce various health effects, including skin- and respiratory tract sensitization resulting in allergic dermatitis and asthma. Exposure to diisocyanates has been studied in the past decades by using different types of biomonitoring markers and matrices. The aim of this review as part of the HBM4EU project was to assess: (i) which biomarkers and matrices have been used for biomonitoring diisocyanates and what are their strengths and limitations; (ii) what are (current) biomonitoring levels of the major diisocyanates (and metabolites) in workers; and (iii) to characterize potential research gaps. For this purpose we conducted a systematic literature search for the time period 2000–end 2018, thereby focussing on three types of diisocyanates which account for the vast majority of the total isocyanate market volume: hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), and 4,4′-methylenediphenyl diisocyanate (MDI). A total of 28 publications were identified which fulfilled the review inclusion criteria. The majority of these studies (93%) investigated the corresponding diamines in either urine or plasma, but adducts have also been investigated by several research groups. Studies on HDI were mostly in the motor vehicle repair industry [with urinary hexamethylene diamine result ranging from 0.03 to 146.5 µmol mol−1 creatinine]. For TDI, there is mostly data on foam production [results for urinary toluene diamine ranging from ~0.01 to 97 µmol mol−1 creatinine] whereas the available MDI data are mainly from the polyurethane industry (results for methylenediphenyl diamine range from 0.01 to 32.7 µmol mol−1 creatinine). About half of the studies published were prior to 2010 hence might not reflect current workplace exposure. There is large variability within and between studies and across sectors which could be potentially explained by several factors including worker or workplace variability, short half-lives of biomarkers, and differences in sampling strategies and analytical techniques. We identified several research gaps which could further be taken into account when studying diisocyanates biomonitoring levels: (i) the development of specific biomarkers is promising (e.g. to study oligomers of HDI which have been largely neglected to date) but needs more research before they can be widely applied, (ii) since analytical methods differ between studies a more uniform approach would make comparisons between studies easier, and (iii) dermal absorption seems a possible exposure route and needs to be further investigated. The use of MDI, TDI, and HDI has been recently proposed to be restricted in the European Union unless specific conditions for workers’ training and risk management measures apply. This review has highlighted the need for a harmonized approach to establishing a baseline against which the success of the restriction can be evaluated.

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Davis, Matthew C., and Lawrence C. Baldwin. "Alternative Route to the Diisocyanate Building Block 1,4-Diisocyanato-4-methylpentane (DIMP)." Synthetic Communications 40, no. 10 (2010): 1437–44. http://dx.doi.org/10.1080/00397910903097278.

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Moore, R., W. C. Whelchel, and D. D. Russell. "P-Phenylene Diisocyanate." Journal of Cellular Plastics 27, no. 1 (1991): 107. http://dx.doi.org/10.1177/0021955x91027001142.

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Middendorf, Paul J., William Miller, Tim Feeley, and Brent Doney. "Toluene Diisocyanate Exposure." Journal of Occupational and Environmental Medicine 59 (December 2017): S1—S12. http://dx.doi.org/10.1097/jom.0000000000001117.

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Gloe, Karsten, Gudrun Keßler, and Hermann Scheler. "Thiophosphorsäure-dialkylanud-diisocyanate." Zeitschrift für Chemie 12, no. 9 (2010): 337. http://dx.doi.org/10.1002/zfch.19720120911.

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MAIER, G., M. NAUMANN, H. P. REISENAUER, and J. ECKWERT. "ChemInform Abstract: Diisocyanate." ChemInform 27, no. 46 (2010): no. http://dx.doi.org/10.1002/chin.199646077.

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36

Frick-Engfeldt, Malin, Erik Zimerson, Daniel Karlsson, et al. "Chemical Analysis of 2,4-Toluene Diisocyanate, 1,6-Hexamethylene Diisocyanate and Isophorone Diisocyanate in Petrolatum Patch-Test Preparations." Dermatitis (formerly American Journal of Contact Dermatitis) 16, no. 03 (2005): 130. http://dx.doi.org/10.2310/6620.2005.05029.

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37

Frick-Engfeldt, Malin, Erik Zimerson, Daniel Karlsson, et al. "Chemical Analysis of 2,4-Toluene Diisocyanate, 1,6-Hexamethylene Diisocyanate, and Isophorone Diisocyanate in Petrolatum Patch-Test Preparations." Dermatitis 16, no. 3 (2005): 130–35. http://dx.doi.org/10.1097/01206501-200509000-00008.

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38

Riehle, Natascha, Kiriaki Athanasopulu, Larysa Kutuzova, et al. "Influence of Hard Segment Content and Diisocyanate Structure on the Transparency and Mechanical Properties of Poly(dimethylsiloxane)-Based Urea Elastomers for Biomedical Applications." Polymers 13, no. 2 (2021): 212. http://dx.doi.org/10.3390/polym13020212.

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The effect of hard segment content and diisocyanate structure on the transparency and mechanical properties of soft poly(dimethylsiloxane) (PDMS)-based urea elastomers (PSUs) was investigated. A series of PSU elastomers were synthesized from an aminopropyl-terminated PDMS (M¯n: 16,300 g·mol−1), which was prepared by ring chain equilibration of the monomers octamethylcyclotetrasiloxane (D4) and 1,3-bis(3-aminopropyl)-tetramethyldisiloxane (APTMDS). The hard segments (HSs) comprised diisocyanates of different symmetry, i.e., 4,4′-methylenebis(cyclohexyl isocyanate) (H12MDI), 4,4′-methylenebis(phenyl isocyanate) (MDI), isophorone diisocyanate (IPDI), and trans-1,4-cyclohexane diisocyanate (CHDI). The HS contents of the PSU elastomers based on H12MDI and IPDI were systematically varied between 5% and 20% by increasing the ratio of the diisocyanate and the chain extender APTMDS. PSU copolymers of very low urea HS contents (1.0–1.6%) were prepared without the chain extender. All PSU elastomers and copolymers exhibited good elastomeric properties and displayed elongation at break values between 600% and 1100%. The PSUs with HS contents below 10% were transparent and became increasingly translucent at HS contents of 15% and higher. The Young’s modulus (YM) and ultimate tensile strength values of the elastomers increased linearly with increasing HS content. The YM values differed significantly among the PSU copolymers depending on the symmetry of the diisocyanate. The softest elastomer was that based on the asymmetric IPDI. The elastomers synthesized from H12MDI and MDI both exhibited an intermediate YM, while the stiffest elastomer, i.e., that comprising the symmetric CHDI, had a YM three-times higher than that prepared with IPDI. The PSUs were subjected to load–unload cycles at 100% and 300% strain to study the influence of HS morphology on 10-cycle hysteresis behavior. At 100% strain, the first-cycle hysteresis values of the IPDI- and H12MDI-based elastomers first decreased to a minimum of approximately 9–10% at an HS content of 10% and increased again to 22–28% at an HS content of 20%. A similar, though less pronounced, trend was observed at 300% strain. First-cycle hysteresis among the PSU copolymers at 100% strain was lowest in the case of CHDI and highest in the IPDI-based elastomer. However, this effect was reversed at 300% strain, with CHDI displaying the highest hysteresis in the first cycle. In vitro cytotoxicity tests performed using HaCaT cells did not show any adverse effects, revealing their potential suitability for biomedical applications.

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Riehle, Natascha, Kiriaki Athanasopulu, Larysa Kutuzova, et al. "Influence of Hard Segment Content and Diisocyanate Structure on the Transparency and Mechanical Properties of Poly(dimethylsiloxane)-Based Urea Elastomers for Biomedical Applications." Polymers 13, no. 2 (2021): 212. http://dx.doi.org/10.3390/polym13020212.

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The effect of hard segment content and diisocyanate structure on the transparency and mechanical properties of soft poly(dimethylsiloxane) (PDMS)-based urea elastomers (PSUs) was investigated. A series of PSU elastomers were synthesized from an aminopropyl-terminated PDMS (M¯n: 16,300 g·mol−1), which was prepared by ring chain equilibration of the monomers octamethylcyclotetrasiloxane (D4) and 1,3-bis(3-aminopropyl)-tetramethyldisiloxane (APTMDS). The hard segments (HSs) comprised diisocyanates of different symmetry, i.e., 4,4′-methylenebis(cyclohexyl isocyanate) (H12MDI), 4,4′-methylenebis(phenyl isocyanate) (MDI), isophorone diisocyanate (IPDI), and trans-1,4-cyclohexane diisocyanate (CHDI). The HS contents of the PSU elastomers based on H12MDI and IPDI were systematically varied between 5% and 20% by increasing the ratio of the diisocyanate and the chain extender APTMDS. PSU copolymers of very low urea HS contents (1.0–1.6%) were prepared without the chain extender. All PSU elastomers and copolymers exhibited good elastomeric properties and displayed elongation at break values between 600% and 1100%. The PSUs with HS contents below 10% were transparent and became increasingly translucent at HS contents of 15% and higher. The Young’s modulus (YM) and ultimate tensile strength values of the elastomers increased linearly with increasing HS content. The YM values differed significantly among the PSU copolymers depending on the symmetry of the diisocyanate. The softest elastomer was that based on the asymmetric IPDI. The elastomers synthesized from H12MDI and MDI both exhibited an intermediate YM, while the stiffest elastomer, i.e., that comprising the symmetric CHDI, had a YM three-times higher than that prepared with IPDI. The PSUs were subjected to load–unload cycles at 100% and 300% strain to study the influence of HS morphology on 10-cycle hysteresis behavior. At 100% strain, the first-cycle hysteresis values of the IPDI- and H12MDI-based elastomers first decreased to a minimum of approximately 9–10% at an HS content of 10% and increased again to 22–28% at an HS content of 20%. A similar, though less pronounced, trend was observed at 300% strain. First-cycle hysteresis among the PSU copolymers at 100% strain was lowest in the case of CHDI and highest in the IPDI-based elastomer. However, this effect was reversed at 300% strain, with CHDI displaying the highest hysteresis in the first cycle. In vitro cytotoxicity tests performed using HaCaT cells did not show any adverse effects, revealing their potential suitability for biomedical applications.

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40

Asensio, Manuel, Juan-Francisco Ferrer, Andrés Nohales, Mario Culebras, and Clara M. Gómez. "The Role of Diisocyanate Structure to Modify Properties of Segmented Polyurethanes." Materials 16, no. 4 (2023): 1633. http://dx.doi.org/10.3390/ma16041633.

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Segmented thermoplastic polyurethanes (PU) were synthetized using a polycarbonatediol macrodiol as a flexible or soft segment with a molar mass of 2000 g/mol, and different diisocyanate molecules and 1,4-butanediol as a rigid or hard segment. The diisocyanate molecules employed are 3,3′-Dimethyl-4,4′-biphenyl diisocyanate (TODI), 4,4′-diphenylmethane diisocyanate (MDI), 4,4’-Methylenebis(phenyl isocyanate) 1-isocyanato-4- [(4-phenylisocyanate)methyl]benzene and 1-isocyanate-4-[(2-phenylisocyanate) methyl]benzene (ratio 1:1) (MDIi), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI). The polyurethanes obtained reveal a wide variation of microphase separation degree that is correlated with mechanical properties. Different techniques, such as DSC, DMA, and FTIR, have been used to determine flexible–rigid segment phase behavior. Mechanical properties, such as tensile properties, Shore D hardness, and “compression set”, have been determined. This work reveals that the structure of the hard segment is crucial to determine the degree of phase miscibility which affects the resulting mechanical properties, such as tensile properties, hardness, and “compression set”.

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Głowińska, Ewa, Paulina Kasprzyk, and Janusz Datta. "The Green Approach to the Synthesis of Bio-Based Thermoplastic Polyurethane Elastomers with Partially Bio-Based Hard Blocks." Materials 14, no. 9 (2021): 2334. http://dx.doi.org/10.3390/ma14092334.

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Bio-based polymeric materials and green routes for their preparation are current issues of many research works. In this work, we used the diisocyanate mixture based on partially bio-based diisocyanate origin and typical petrochemical diisocyanate for the preparation of novel bio-based thermoplastic polyurethane elastomers (bio-TPUs). We studied the influence of the diisocyanate mixture composition on the chemical structure, thermal, thermomechanical, and mechanical properties of obtained bio-TPUs. Diisocyanate mixture and bio-based 1,4-butanediol (as a low molecular chain extender) created bio-based hard blocks (HS). The diisocyanate mixture contained up to 75 wt % of partially bio-based diisocyanate. It is worth mentioning that the structure and amount of HS impact the phase separation, processing, thermal or mechanical properties of polyurethanes. The soft blocks (SS) in the bio-TPU’s materials were built from α,ω-oligo(ethylene-butylene adipate) diol. Hereby, bio-TPUs differed in hard segments content (c.a. 30; 34; 40, and 53%). We found that already increase of bio-based diisocyanate content of the bio-TPU impact the changes in their thermal stability which was measured by TGA. Based on DMTA results we observed changes in the viscoelastic behavior of bio-TPUs. The DSC analysis revealed decreasing in glass transition temperature and melting temperature of hard segments. In general, obtained materials were characterized by good mechanical properties. The results confirmed the validity of undertaken research problem related to obtaining bio-TPUs consist of bio-based hard building blocks. The application of partially bio-based diisocyanate mixtures and bio-based chain extender for bio-TPU synthesis leads to sustainable chemistry. Therefore the total level of “green carbons” increases with the increase of bio-based diisocyanate content in the bio-TPU structure. Obtained results constitute promising data for further works related to the preparation of fully bio-based thermoplastic polyurethane elastomers and development in the field of bio-based polymeric materials.

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42

Morozova, Sofia M., Elena I. Lozinskaya, Haritz Sardon, et al. "Ionic Polyureas—A Novel Subclass of Poly(Ionic Liquid)s for CO2 Capture." Membranes 10, no. 9 (2020): 240. http://dx.doi.org/10.3390/membranes10090240.

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The growing concern for climate change and global warming has given rise to investigations in various research fields, including one particular area dedicated to the creation of solid sorbents for efficient CO2 capture. In this work, a new family of poly(ionic liquid)s (PILs) comprising cationic polyureas (PURs) with tetrafluoroborate (BF4) anions has been synthesized. Condensation of various diisocyanates with novel ionic diamines and subsequent ion metathesis reaction resulted in high molar mass ionic PURs (Mw = 12 ÷ 173 × 103 g/mol) with high thermal stability (up to 260 °C), glass transition temperatures in the range of 153–286 °C and remarkable CO2 capture (10.5–24.8 mg/g at 0 °C and 1 bar). The CO2 sorption was found to be dependent on the nature of the cation and structure of the diisocyanate. The highest sorption was demonstrated by tetrafluoroborate PUR based on 4,4′-methylene-bis(cyclohexyl isocyanate) diisocyanate and aromatic diamine bearing quinuclidinium cation (24.8 mg/g at 0 °C and 1 bar). It is hoped that the present study will inspire novel design strategies for improving the sorption properties of PILs and the creation of novel effective CO2 sorbents.

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Akram, Nadia, Muhammad Usman, Sajjad Haider, Muhammad Saeed Akhtar, and Kashmala Gul. "Impact of Diisocyanates on Morphological and In Vitro Biological Efficacy of Eco-Friendly Castor-Oil-Based Water-Borne Polyurethane Dispersions." Polymers 14, no. 17 (2022): 3701. http://dx.doi.org/10.3390/polym14173701.

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The search for renewable resources that can replace petroleum products is not only nerve-wracking, but also perplexing, as there is an abundance of plants that have yet to be explored. In this project, virgin castor oil was converted to polyol in two steps: epoxidation and hydroxylation. The resulting polyol was used to synthesize two series of water-borne polyurethane dispersions (WPUDs). The effects of the diisocyanates on the final product were evaluated. Isophorone diisocyanate (IPDI) and dicyclohexylmethane-4,4′-diisocyanate (H12MDI) were used as the hard segment (HS) up to 72 wt%, along with 1–4 butanediol (BD) as the chain extender, for the dispersions. Fourier transform infrared spectroscopy (FTIR) confirmed the bonds required for the synthesis of the dispersions. Thermogravimetric analysis (TGA) showed the multistep degradation for both series: maximum degradation took place at 500 °C for IPDI and 600 °C for H12MDI-based series. Scanning electron microscopy (SEM) showed phase-segmented morphology. Hemolytic activity was observed at biologically safe levels of up to 7.5% for H12MDI-based series. Inhibition of biofilm formation showed comparable results against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus): up to 46%. The results were also confirmed by phase contrast microscopy.

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44

Yakabe, Yoshikuni, Karen M. Henderson, William C. Thompson, Denis Pemberton, Bernard Tury, and Robert E. Bailey. "Fate of Methylenediphenyl Diisocyanate and Toluene Diisocyanate in the Aquatic Environment." Environmental Science & Technology 33, no. 15 (1999): 2579–83. http://dx.doi.org/10.1021/es981350c.

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Komez, Aylin, Senem Buyuksungur, Vasif Hasirci, and Nesrin Hasirci. "Effect of chemical structure on properties of polyurethanes: Temperature responsiveness and biocompatibility." Journal of Bioactive and Compatible Polymers 33, no. 5 (2018): 479–97. http://dx.doi.org/10.1177/0883911518783233.

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Polyurethanes are known as one of the most biocompatible and inherently blood-compatible materials and have a wide range of applications in the medical field due to their controllable structure and properties. Durability, elasticity, elastomeric structure, fatigue resistance, versatility, and easy acceptance by the biological media after the application makes these polymers preferable in medical area. In this study, polyurethane films were prepared using poly(propylene-ethylene glycol) and either toluene-2,4-diisocyanate or 4,4′-methylenediphenyl diisocyanate without adding any other ingredients such as solvent, catalyst, or chain extender to prevent negative effects of leachable molecules. Mechanical tests were performed at room temperature while swelling tests were conducted in water and phosphate-buffered saline at 4°C, 25°C, and 37°C. Temperature responsiveness was observed for the samples synthesized using toluene-2,4-diisocyanate and poly(propylene-ethylene glycol). These samples had more than 100% swelling at 4°C and about 4% swelling at 25°C and 37°C. Cytocompatibility tests were performed by culturing the samples and their extracts with mouse fibroblast cells (L929). Viability of human umbilical vein endothelial cells was studied to examine the compatibility of the films for blood contacting devices. Both toluene-2,4-diisocyanate and 4,4-methylenediphenyl diisocyanate–based polyurethane films showed no cytotoxic effect and good biocompatibility. Oxygen plasma treatment enhanced hydrophilicity of the films. After plasma treatment, human umbilical vein endothelial cell attachment on toluene-2,4-diisocyanate–based polyurethane films improved and 4,4-methylenediphenyl diisocyanate–based polyurethane films maintained their high cell affinity. Polyurethanes presenting temperature responsiveness, high biocompatibility, and high affinity for human umbilical vein endothelial cells were synthesized in medical purity and in a reaction media involving only diisocyanate and diol components without addition of any solvent, chain extender, or catalyst. Polyurethanes with these properties and as produced in this study are reported for the first time in the literature.

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KASE, Mitsuo, Kenji KURIHARA, and Yutaka TACHIKAWA. "Cyclotrimerization of Aliphatic Diisocyanate." KOBUNSHI RONBUNSHU 56, no. 1 (1999): 8–17. http://dx.doi.org/10.1295/koron.56.8.

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47

Collins, Michael A. "Toxicology of Toluene Diisocyanate." Applied Occupational and Environmental Hygiene 17, no. 12 (2002): 846–55. http://dx.doi.org/10.1080/10473220290107048.

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Patterson, Roy, Frederick E. Hargreave, Leslie C. Grammer, Kathleen E. Harris, and Jerry Dolovich. "Toluene Diisocyanate Respiratory Reactions." International Archives of Allergy and Immunology 84, no. 1 (1987): 93–100. http://dx.doi.org/10.1159/000234404.

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49

Akteries, Bernhard, and Johannes C. Jochims. "Cycloadditions of carbonyl diisocyanate." Chemische Berichte 119, no. 4 (1986): 1133–43. http://dx.doi.org/10.1002/cber.19861190405.

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50

Taymaz, Kevser. "The Analysis of Toluene Diisocyanate and Diphenylmethane Diisocyanate by Gel Permeation Chromatography." Journal of Liquid Chromatography 9, no. 15 (1986): 3347–56. http://dx.doi.org/10.1080/01483918608074185.

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Journal articles on the topic 'Diisocyanate'

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