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Electronic waste (e-waste) is the fastest growing waste stream and its negative impact on the environment and human health is major because of the toxicity and non-biodegradability of its constituents. For their biodegradability and nontoxicity, bio-based materials have been proposed as potential material candidates in the field of electronics. Among these, cellulose nanocrystals (CNCs) have many interesting properties including biodegradability, high mechanical strength, and possibility to functionalize. In terms of electrical properties, CNCs are electrically insulated, limiting their potential in electronics. This work aims to build up a poly(o-toluidine)-like shell around the CNCs to render them conductive. For this goal, the surface of the CNCs was carbamated using 2,4-toluene diisocyanate through the para-isocyanates and the ortho-isocyanates were later hydrolyzed to amine groups using HCl-acidified dimethylsulfoxide. The resultant o-toluidine-like molecules on the CNC surface were then polymerized using ammonium persulfate to form an electrically conductive shell around each CNC. The resultant CNCs were then characterized for their chemical, morphological, and electrical properties. Fourier-transform infrared analysis of the CNCs at each stage confirmed the expected chemical changes upon carbamation, hydrolysis, and polymerization and X-ray diffraction confirmed the permanence of the native crystalline structure of the CNCs. The atomic force microscopy images showed that the obtained CNCs were on average slightly thicker than the original ones, possibly due to the growth of the poly(o-toluidine) shell around them. Finally, using the four-point method, the obtained CNCs were electrically conductive with a conductivity of 0.46 S/cm. Such novel electrically conductive CNCs should have great potential in a wide range of applications including electronics, sensing, and medicine.

Here, a series of half-sandwich arene Ru(II) complexes with difluorinated ligands [Ru(η6-arene)(L)Cl] (L1 = 2-(2,3-difluorophenyl)imidazole[4,5f][1,10]-phenanthroline; L2 = 2-(2,4-difluorophenyl)imidazole[4,5f][1,10]-phenanthroline; arene = benzene, toluene, and p-cymene) were synthesized and characterized. Molecular docking analysis showed that these complexes bind to c-myc G-quadruplex DNA through either groove binding or π–π stacking, and the relative difluorinated site in the main ligand plays a role in regulating the binding mode. The binding behavior of these complexes with c-myc G-quadruplex DNA was evaluated using ultraviolet–visible spectroscopy, fluorescence intercalator displacement assay, fluorescence resonance energy transfer melting assay, and polymerase chain reaction. The comprehensive analysis indicated that complex 1 exhibited a better affinity and stability in relation to c-myc G-quadruplex DNA with a DC50 of 6.6 μM and ΔTm values of 13.09 °C, than other molecules. Further activity evaluation results displayed that this class of complexes can also inhibit the growth of various tumor cells, especially complexes 3 and 6, which exhibited a better inhibitory effect against human U87 glioblastoma cells (51.61 and 23.75 μM) than other complexes, even superior to cisplatin (32.59 μM). Owing to a befitting lipophilicity associated with the high intake of drugs by tumor cells, complexes 3 and 6 had favorable lipid-water partition coefficients of −0.6615 and −0.8077, respectively. Moreover, it was found that complex 6 suppressed the proliferation of U87 cells mainly through an induced obvious S phase arrest and slight apoptosis, which may have resulted from the stabilization of c-myc G-quadruplex DNA to block the transcription and expression of c-myc. In brief, these types of arene Ru(II) complexes with difluorinated ligands can be developed as potential inducers of S-phase arrest and apoptosis through the binding and stabilization of c-myc G-quadruplex DNA, and could be used in clinical applications in the future. [ABSTRACT FROM AUTHOR]

The kinetics of hexogen coating with polyurethane-based hydroxyl-terminated polybutadiene (HTPB) using infrared spectrometry was investigated. The kinetics model was evaluated through reaction steps: (1) hydroxyl and isocyanate to produce urethane, (2) urethane and isocyanate to produce allophanate, and (3) nitro and isocyanate to produce diazene oxide and carbon dioxide. HTPB, ethyl acetate, TDI (toluene diisocyanate), and hexogen were mixed for 60 min at 40 °C. The sample was withdrawn and analyzed with infrared spectroscopy every ten minutes at reference wavelengths of 2270 (the specific absorption for isocyanate groups) and 1768 cm−1 (the specific absorption for N=N groups). The solvent was vaporized; then, the coated hexogen was cured in the oven for 7 days at 60 °C. The effect of temperature on the coating kinetics was studied by adjusting the reaction temperature at 40, 50, and 60 °C. This procedure was repeated with IPDI (isophorone diisocyanate) as a curing agent. The reaction rate constant, k3, was calculated from an independent graphic based on increasing diazene oxide concentration every ten minutes. The reaction rate constants, k1 and k2, were numerically calculated using the Newton–Raphson and Runge–Kutta methods based on decreasing isocyanate concentrations. The activation energy of those steps was 1178, 1021, and 912 kJ mole−1. The reaction rate of hexogen coating with IPDI was slightly faster than with TDI. [ABSTRACT FROM AUTHOR]

The effects of several typical ingredients on the thermal curing reactions of poly (3,3′‐bis‐azidomethyl oxetane)‐tetrahydrofuran (PBT) adhesive with curing agent toluene diisocyanate (TDI) were carried out using density functional theory. The results show that the most energetic favorable curing route is the reaction with the cured product with two urethane segments and its rate‐determining step is the nucleophilic addition reaction of TDI with triethanolamine (TEA). Compared to the reaction of TDI with PBT, the reaction with trimethylolpropane (TMP) shows relatively lower activation free energy mainly due to the weakening of N‐H bond in corresponding TS structures. After the pre‐modification of TDI by diethylene glycol (DEG), the reactivity of the remaining isocyanate group is significantly decreased, which is supported by the smallest absolute value of torsion angle when the electron density in NH and CO bond areas maintains locally concentrated. In contrast, the final curing reactions with PBT are remarkably facilitated as the participation of the intermediate structures formed through TEA. The stronger hindrance to the last step curing reaction of biuret molecule obtained through the continuous reaction stemming from H2O basically attributes to the reduction in the electrophilicity of relevant ‐NCO groups. [ABSTRACT FROM AUTHOR]

A written computer-based MatLab simulation program was employed to determine the reactivities of a polymeric isocyanate. The program redeems experiments needed for isocyanate characterization. Experimental results of reaction temperature profile and polyurethane gel viscosity were required to verify the simulation program's reaction parameters. Isocyanates reactivity characterization and polyol characterization was done earlier, increasing the accuracy of the reaction temperature results, making polyurethane raw materials optimum selection faster. In the current research, a MatLab computer program was developed to characterize the reactivates of different isocyanates moieties based on para versus ortho isocyanate moieties. This approach assists in predicting the fractional content of isocyanate moieties of unknown polymeric isocyanates. Experimental data, including temperature profiles and viscosity profiles of urethane gel reactions, were used to validate the simulation results. Methylene diphenyl diisocyanate, toluene diisocyanate, and Diethylene glycol were utilized for getting the kinetic parameters. The para-isocyanate moieties were found to be more reactive compared to the ortho-isocyanate moieties. [ABSTRACT FROM AUTHOR]

A Novel calix[4]pyrrole system bearing carboxylic acid functionality [ABuCP] has been synthesized and its interaction towards various nitroaromatics compounds [NACs] were investigated. ABuCP showed significant color change with 1,3-dinitro benzene (1,3-DNB) in comparison to the solution of other nitroaromatic compounds such as 2,3-dinitro toluene (2,3-DNT), 2,4-dinitro toluene (2,4-DNT), 2,6-dinitro toluene (2,6-DNT), 4-NBB (4-nitrobenzyl bromide) and 4-nitro toluene (4-NT). The ABuCP-1,3-DNB complex produces a red shift in absorption spectra based on charge transfer mediated recognition. Additionally, the density functional theory calculation confirmed the possible mechanism for the binding of 1,3-DNB as a guest is well supported by the calculation of other parameters such as hardness, stabilization energy, softness, electrophilicity index and chemical potential. The TDDFT calculation facilitates the understanding of the proper binding mechanism in reference to experimental results. Additionally we have also developed its derivative which acts as a new fluorescent sensor which can selectively recognize Sr(II) ions. In this view its aminoanthraquinone derivative of calix[4]pyrrole i.e. ABuCPTAA is synthesized which also results in generation of high fluorescence capability sensor. [ABSTRACT FROM AUTHOR]

Rheometry was the main method to characterize the curing process of binders made of functional polyurethanes (PUs). The macroglycols characterization by means of additional techniques, such as nuclear magnetic resonance, size exclusion chromatography, and differential scanning calorimetry, provided further information for the chemorheological description. Materials were based on Butacene ((ferrocenylbutyl)dimethylsilane grafted to hydroxyl‐terminated polybutadiene (HTPB)), used in the solid propulsion field. First, the flow parameters for the uncured reactive mixtures of Butacene and four different diisocyanates were analyzed via viscometry and these were markedly influenced by the chemical structure of the curing agents. Analyzing the rheokinetic constant values of the pre‐gel stage for Butacene‐ and HTPB‐reactive systems, relevant catalysis caused by the ferrocene moiety was detected when aliphatic reactants were used, such as isophorone diisocyanate or 1,6‐hexamethylene diisocyanate (IPDI and HMDI, respectively). No catalytic effect was found for 2,4‐toluene diisocyanate (2,4‐TDI) or even for 4,4′‐methylenediphenyl diisocyanate (4,4′‐MDI). Finally, the use of dynamic rheology was useful to evaluate the critical points during gelation process, where the reactivity of curing agents was associated with the achievement of elastic properties. Both techniques agreed the reactivity order of curing agents with Butacene, which is 4,4′‐MDI > HMDI > > 2,4‐TDI ≥ IPDI. The knowledge of the structure–reactivity relationship and, moreover, the kinetics of the urethane network formation for these metallo‐PUs is paramount in manufacturing processes for advanced thermoplastic elastomer applications. [ABSTRACT FROM AUTHOR]

Background: Exposure to toluene diisocyanate (TDI) is a significant pathogenic factor for asthma. We previously reported that the receptor for advanced glycation end products (RAGE) plays a key role in TDI-induced asthma. Histone deacetylase (HDAC) has been reported to be important in asthmatic pathogenesis. However, its effect on TDI-induced asthma is not known. The aim of this study was to determine the role of RAGE and HDAC in regulating airway inflammation using a TDI-induced murine asthma model.Methods: BALB/c mice were sensitized and challenged with TDI to establish an asthma model. FPS-ZM1 (RAGE inhibitor), JNJ-26482585 and romidepsin (HDAC inhibitors) were administered intraperitoneally before each challenge. In vitro, the human bronchial epithelial cell line 16HBE was stimulated with TDI-human serum albumin (TDI-HSA). RAGE knockdown cells were constructed and evaluated, and MK2006 (AKT inhibitor) was also used in the experiments.Results: In TDI-induced asthmatic mice, the expression of RAGE, HDAC1, and p-AKT/t-AKT was upregulated, and these expressions were attenuated by FPS-ZM1. Airway reactivity, Th2 cytokine levels in lymph supernatant, IgE, airway inflammation, and goblet cell metaplasia were significantly increased in the TDI-induced asthmatic mice. These increases were suppressed by JNJ-26482585 and romidepsin. In addition, JNJ-26482585 and romidepsin ameliorated the redistribution of E-cadherin and β-catenin in TDI-induced asthma. In TDI-HSA-stimulated 16HBE cells, knockdown of RAGE attenuated the upregulation of HDAC1 and phospho-AKT (p-AKT). Treatment with the AKT inhibitor MK2006 suppressed TDI-induced HDAC1 expression.Conclusions: These findings indicate that RAGE modulates HDAC1 expression via the PI3K/AKT pathway, and that inhibition of HDAC prevents TDI-induced airway inflammation. [ABSTRACT FROM AUTHOR]

Methyl methacrylate (MMA) is classified under GHS as a weak skin sensitiser and a skin and respiratory irritant. It has recently been proposed that MMA be classified as a respiratory sensitiser (a designation that in a regulatory context embraces both true respiratory allergens, as well as chemicals that cause asthma through non-immunological mechanisms). This proposal was based primarily upon the interpretation of human data. This review, and a detailed weight of evidence analysis, has led to another interpretation of these data. The conclusion drawn is that persuasive evidence consistent with the designation of MMA as a respiratory sensitiser is lacking. It is suggested that one reason for different interpretations of these data is that occupational asthma poses several challenges with respect to establishing causation. Among these is that it is difficult to distinguish between allergic asthma, non-allergic asthma, and work-related exacerbation of pre-existing asthma. Moreover, there is a lack of methods for the identification of true chemical respiratory allergens. The characterisation and causation of occupational asthma is consequently largely dependent upon interpretation of human data of various types. Recommendations are made that are designed to improve the utility and interpretation of human data for establishing causation in occupational asthma. [ABSTRACT FROM AUTHOR]

The aim of the present study was to design and synthesis a novel monomer to produce polyurethanes with improved thermal stability as well as good solubility. Herein, N1,N3-bis(5-hydroxynaphthalene-1-yl) isophthalamide was synthesized by the nucleophilic reaction of 5-amino-1-naphthol and isophthaloyl chloride. Afterward, the synthesized diol was reacted with various diisocyanates such as toluene diisocyanate and methylene diphenyl diisocyanate to attain novel poly(urethane-amide)s via condensation reaction. The chemical structure of the monomer and the resulting polymers were thoroughly investigated and approved via spectroscopic techniques and elemental analysis. Also, physical properties of the prepared polymers like thermal characteristics, molecular weight, solubility, and viscosity together with their structure-property relationship were evaluated. The obtained results showed improved thermal stability of the synthesized poly(urethane-amide)s compared to other common polyurethanes. Also, the results indicated that the higher the aromatic groups in the polymer chain, the higher the thermal stability and glass transition temperature. Presence of bulky naphthyl groups from another side, improve their solubility as well. The synthesized poly(urethane-amide)s with remarkable thermal stability and solubility might open up new possibilities for a wide range of applications in various industries such as transportation, aerospace, electronics, appliances, and so on. [ABSTRACT FROM AUTHOR]

Effects of the chemical nature, structure and molecular weight of oligoether and diisocyanate blocks of crosslinked polyurethanes on the spectral-luminescent properties of the xanthene dye Rhodamine 6G in polyurethanes, based on ether and ester oligodiols, aromatic and aliphatic diisocyanates have been studied. A number of polyurethanes were synthesized and investigated: polyurethane, based on oligooxypropylene glycol with a molecular weight of 1000, toluene diisocyanate, trimethylolpropane; polyurethane, based on oligodiethylene glycol adipate with a molecular weight of 1500, toluene diisocyanate, trimethylolpropane; and polyurethane, based on oligodiethylene glycol adipate with a molecular weight 1500, hexamethylene diisocyanate, trimethylolpropane. The analysis of absorption spectra showed that the monomer-dimer ratio of the dye in these polymers (the degree of dye association), as well as, the Stokes shift depended on the value of dielectric permeability - one of the main factors of the polymer polarity. Despite the overall efficient use of polyurethane matrices as active laser media in the development of dye lasers, the value of dielectric constant was found out to be taken into account at the polyurethane choosing. This parameter depends on the number of polar groups in the polymer, and it is determined by the molecular weight, nature and chemical structure of the polymer components. Among a number of selected polyurethanes, the best optical properties of Rhodamine 6G were observed in the polyurethane, based on oligooxypropylene glycol with a molecular weight of 1000, toluene diisocyanate and trimethylolpropane. [ABSTRACT FROM AUTHOR]

Purpose: Poly(ethylene terephthalate) (PET) waste from soft drink bottles was incorporated into palm olein alkyd to produce new polyol for use in polyurethane resins as surface protection on metal surfaces. Design/methodology/approach: Alkyd was prepared from palm olein, glycerol and phthalic anhydride. PET underwent simultaneous glycolysis and transesterification reactions with the alkyd. Varying the amount of PET has led to polyols with different viscosities. Polyurethane resins were produced by reacting the polyols with toluene diisocyanate. The resins were coated on mild steel panels and cured. Performances of the cured films were tested. Findings: The polyurethanes (PU) resin cured to a harder film with better thermal stability. Films showed excellent adhesion properties, while higher content of PET exhibited higher pencil hardness, better water, salt, acid and alkali resistance. Research limitations/implications: Other vegetable oils could also be used. The alkyd structure could be changed by formulation to have different functionality and the ability to incorporate higher amount of PET waste. Rate of glycolysis of PET could be increased by higher amount of ethylene glycol. Practical implications: This method has managed to use waste PET in producing new polyol and PU resins. The cured films exhibit good mechanical and chemical properties, as well as excellent adhesion and thermal stability. Social implications: The non-biodegradable PET has created environmental pollution problems connected to littering and illegal landfilling. It has become necessary to pay greater attention to recycling PET bottles for obtaining valuable products. Originality/value: This approach is different from the earlier reports, where PET was recycled to recover the raw materials. [ABSTRACT FROM AUTHOR]

Accumulating evidence indicated the crucial role for interleukin 6 (IL-6) signaling in the development of allergic asthma. Yet, the role of IL-6 signaling in toluene diisocyanate (TDI)-induced mixed granulocytic airway inflammation still remains unclear. Thus, the aims of this study were to dissect the role of IL-6 signaling and to evaluate the effect of tocilizumab on TDI-induced steroid-resistant asthma. TDI-induced asthma model was prepared and asthmatic mice were respectively given IL-6 monoclonal antibody, IL-6R monoclonal antibody (tocilizumab, 5 mg/kg, i.p. after each challenge) for therapeutic purposes or isotype IgG as control. TDI exposure just elevated IL-6R expression in the infiltrated inflammatory cells around the airway, but increased glycoprotein 130 expression in the whole lung, especially in bronchial epithelium. Moreover, TDI inhalation increased airway hyperresponsiveness (AHR) to methacholine, coupled with mixed granulocytic inflammation, exaggerated epithelial denudation, airway smooth muscle thickening, goblet cell metaplasia, extensive submucosal collagen deposition, dysregulated Th2/Th17 responses, as well as innate immune responses and raised serum IgE. And almost all these responses except for raised serum IgE were markedly ameliorated by the administration of IL-6 neutralizing antibody or tocilizumab, but exhibited poor response to systemic steroid treatment. Also, TDI challenge induced nucleocytoplasm translocation of HMGB1 and promoted its release in the BALF, as well as elevated lung level of STAT3 phosphorylation, which were inhibited by anti-IL-6 and anti-IL-6R treatment. Our data suggested that IL-6 monoclonal antibody and tocilizumab might effectively abrogate TDI-induced airway inflammation and remodeling, which could be used as a clinical potential therapy for patients with severe asthma. [ABSTRACT FROM AUTHOR]

A simple method to prepare an emulsifier was proposed to form a stable nano size emulsion as a sizing agent to enhance the interfacial bonding strength between carbon fiber (CF) and epoxy resin. The toluene diisocyanate (TDI) grafting strategy can effectively introduce hydrophilic polyethylene glycol (PEG) and hydrophobic poly(propylene glycol) (PPG) into the side chain of the epoxy resin without consuming epoxy groups. The PPG chain segment length was controlled to improve the stability of the emulsion. An emulsion prepared with EP–PEG6000–PPG2000 (EE-P20) as the emulsifier had the highest stability, and could be placed for more than 6 months without changes in the droplet size. The wettability of CF modified by this sizing agent was obviously improved, and the interfacial shear strength (IFSS) and interlaminar shear strength (ILSS) of CF(EE-P20) were increased by 42.33% and 17.41%, respectively. It was worth noting that the moisture absorption of CF(EE-P20) was 3.12% at 90% relative humidity. The introduction of the PPG segment not only improved the storage stability of the emulsion, but also improved the moisture resistance of CF after sizing. This simple continuous grafting method provides a new idea for adjusting the structure of the epoxy sizing agent, and the obtained emulsifier has a wide application prospect in the field of the CF sizing agent. [ABSTRACT FROM AUTHOR]

Occupational exposure to 4,4′-methylene diphenyl diisocyanate (MDI), the most widely used monomeric diisocyanate, is one of the leading causes of occupational asthma (OA). Previously, we identified microRNA (miR)-206-3p/miR-381-3p-mediated PPP3CA/calcineurin signalling regulated iNOS transcription in macrophages and bronchoalveolar lavage cells (BALCs) after acute MDI exposure; however, whether PPP3CA/calcineurin signalling participates in regulation of other asthma-associated mediators secreted by macrophages/BALCs after MDI exposure is unknown. Several asthma-associated, macrophage-secreted mediator mRNAs from MDI exposed murine BALCs and MDI-glutathione (GSH) conjugate treated differentiated THP-1 macrophages were analysed using RT-qPCR. Endogenous IL1B, TNF, CCL2, CCL3, CCL5, and TGFB1 were upregulated in MDI or MDI-GSH conjugate exposed BALCs and macrophages, respectively. Calcineurin inhibitor tacrolimus (FK506) attenuated the MDI-GSH conjugate-mediated induction of CCL2, CCL3, CCL5, and CXCL8/IL8 but not others. Transfection of either miR-inhibitor-206-3p or miR-inhibitor-381-3p in macrophages induced chemokine CCL2, CCL3, CCL5, and CXCL8 transcription, whereas FK506 attenuated the miR-inhibitor-206-3p or miR-inhibitor-381-3p-mediated effects. Finally, MDI-GSH conjugate treated macrophages showed increased chemotactic ability to various immune cells, which may be attenuated by FK506. In conclusion, these results indicate that MDI exposure to macrophages/BALCs may recruit immune cells into the airway via induction of chemokines by miR-206-3p and miR-381-3p-mediated calcineurin signalling activation. [ABSTRACT FROM AUTHOR]

The present study aimed to examine the procedure for adhesion of sheets extracted from waste tire rubber by using polyurethane (PU) as an adhesive and by applying an elastomer layer to the surface. Surface treatments were performed with trichloroisocyanuric acid and potassium permanganate. Three adhesion promoters were used: 1) toluene diisocyanate, 2) 3-aminopropyltriethoxysilane, and 3) vinyltrimethoxysilane. Test pieces were adhered and subjected to peel tensile tests to determine the best adhesion procedure. Adhesion tests were analyzed by using Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray dispersive energy. The best result was achieved when surfaces were treated with trichloroisocyanuric acid. In conclusion, this treatment was the most effective in increasing adherence values in between PU sheets and in between sheets and elastomer layers. [ABSTRACT FROM AUTHOR]

An efficient two-component domino reaction strategy has been developed for the synthesis of 2,6-dicyanoaniline and 3-amino-9,10-dihydrophenanthrene-2,4-dicarbonitrile derivatives in moderate to good yield by the reaction between malononitrile and β-chloro-α,β-unsaturated aldehydes catalyzed by potassium hydroxide-18-crown-6 in methanol. In-vitro intercalation studies of 3-amino-9,10-dihydrophenanthrene-2,4-dicarbonitriles with Calf-Thymus DNA have been carried out which reveal that the moiety interacts with an affinity greater than that of ethidium bromide (EtBr). [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous properties of polyurea microspheres (PPM) are regulated by microfluidics. • Size of PPM is tuned by changing the flow channels size of microfluidics device. • Process and operational parameters are optimized to get uniform PPM. • Pd is immobilized on PPM to get hybrid composite, Pd@PPM. • Pd@PPM exhibited good efficiency as catalyst for the reduction of Cr6+ to Cr3+. Developing new strategies for fabrication of porous materials with tunable morphology which have fewer environmental impacts is highly desired. Herein, conventional precipitation polymerization of polyurea (PU) synthesis is converted to interfacial polymerization via simple microfluidics and hierarchically porous and uniform PU microspheres (PPM) are prepared by the reaction of toluene diisocyanate and water, eliminating the use of toxic amines and organic solvents. The morphology and porosity of PPM are probed. The size of PPM is controlled by changing the diameter of flow channels of microfluidic device and their pore size and porosity are tuned by optimizing the polymerization conditions. Moreover, palladium (Pd) is immobilized on PPM by impregnation and subsequent reduction approach to get Pd@PPM. The hybrid composite, Pd@PPM, is used for catalytic reduction of toxic Cr6+ to benign Cr3+ by formic acid as a reductant along with sodium format as a promoter in aqueous system. Pd@PPM exhibited high catalytic activity and good stability for Cr6+ reduction and their large size with high uniformity eased their recovery to reuse them in subsequent Cr6+ reduction. Porous PU with controllable shape and morphology are rarely available. This work therefore provides new strategy to synthesis PPM with controllable porous morphology and their use as an effective support for catalysis. [ABSTRACT FROM AUTHOR]

Polyurethanes (PUs) are highly resistant materials used for building insulation or automotive seats. The polyurethane end‐of‐life issue must be addressed by the development of efficient recycling techniques. Since conventional recycling processes are not suitable for thermosets, waste management of PU foam is particularly questioning. By coupling biological and chemical processes, this study aimed at developing a green recycling pathway for PU foam using enzymes for depolymerization. For instance, enzymatic degradation of a PU foam synthesized with polycaprolactone and toluene diisocyanate led to a weight loss of 25 % after 24 h of incubation. The corresponding degradation products were recovered and identified as 6‐hydroxycaproic acid and a short acid‐terminated diurethane. An organometallic‐catalyzed synthesis of second‐generation polymers from these building blocks was carried out. A polymer with a high average molar mass of 74000 (Mw) was obtained by mixing 50 % of recycled building blocks and 50 % of neat 6‐hydroxycaproic acid. A poly(ester urethane) was synthesized without the use of toxic and decried polyisocyanates. It is the first time that a study offers the vision of a recycling loop starting from PU wastes and finishing with a second‐generation polymer in a full circular approach. [ABSTRACT FROM AUTHOR]

2,4- and 2,6-isomers of toluene diisocyanates (2,4-TDI and 2,6-TDI) are important raw materials in the polyurethane industry. These reactive compounds associate even under ambient conditions to form oligomers, changing the physicochemical properties of the raw material. Kinetically and thermodynamically relevant dimerization reactions were selected based on G3MP2B3 calculations from all possible dimers of phenyl isocyanate using these isocyanates as proxies. As it turned out, only the formation of the diazetidine-2,4-dione ring (11-dimer, uretdione) resulted in a species having an exothermic enthalpy of formation (−30.4 kJ/mol at 298.15 K). The oxazetidin-2-one ring product (1-2-dimer) had a slightly endothermic standard enthalpy of formation (37.2 kJ/mol at 298.15 K). The mechanism of the relevant cyclodimerization reactions was investigated further for 2,4-TDI and 2,6-TDI species using G3MP2B3 and SMD solvent model for diazetidine as well as oxazetidin-2-one ring formation. The formation of the uretdione ring structures, from the 2,4-TDI dimer with both NCO groups in the meta position for each phenyl ring and one methyl group in the para and one in the meta position, had the lowest-lying transition state (Δ#E0 = 94.4 kJ/mol) in the gas phase. The one- and two-step mechanisms of the TDI cyclotrimerization were also studied based on the quasi-G3MP2B3 (qG3MP2B3) computational protocol. The one-step mechanism had an activation barrier as high as 149.0 kJ/mol, while the relative energies in the two-step mechanism were significantly lower for both transition states in the gas phase (94.7 and 60.5 kJ/mol) and in ODCB (87.0 and 54.0 kJ/mol).

3-Dimensional (3D) printing and bioprinting are the new technologies. In 3D printing, synthetic polymers such as acrylonitrile, butadiene, and styrene, polylactic acid, nylon, and some metals are used as feedstocks. During 3D printing, volatile organic compounds (VOCs) and nanoparticles can be released. In the bioprinting process, natural polymers are most commonly used. All of these materials have direct and indirect toxic effects in exposed people. Therefore, the aim of this study was to provide a comprehensive review of toxicity risks due to occupational exposure to pollutants in the 3D printing and bioprinting industries. The Cochrane review method was used as a guideline for systematic review. Articles were searched in the databases including PubMed, Scopus, Web of Science, and Google Scholar. This systematic review showed that VOCs and ultra-fine particles are often released in fused deposition modeling and selective laser sintering, respectively. Asthma, chronic obstructive pulmonary disease, allergic rhinitis, and DNA damage were observed in occupational exposure to synthetic polymers. Metal nanoparticles can induce adverse health effects on the respiratory and nervous systems. This study emphasized the need to further study the toxicity of 3D printing and bioprinting-induced air pollutants. Also, consideration of safety and health principles is necessary in 3D printing and bioprinting workplaces. [ABSTRACT FROM AUTHOR]

Oxidative stress is involved in the pathophysiology of inflammatory airway diseases, including asthma. In this study, we elucidated the possible protective effects of the antioxidant N-acetylcysteine (NAC) on a toluene diisocyanate (TDI)-induced murine asthma model. Male BALB/c mice were sensitized and challenged with TDI to generate a chemical-induced asthma model. NAC was given intraperitoneally to mice immediately after each TDI challenge. Airway reactivity to methacholine and bronchoalveolar lavage fluid was analyzed. Lungs were examined by histology. NAC treatment dramatically reduced the increased airway hyperresponsiveness, inflammatory infiltration, and goblet cell metaplasia in TDI-exposed mice. Numbers of total cells, neutrophils, and eosinophils in the bronchoalveolar lavage fluid of TDI-challenged mice were significantly higher than vehicle control, but the administration of NAC decreased these inflammatory cell counts. TDI exposure led to significantly increased levels of interleukin 4 (IL-4) and IL-5, which were also suppressed by NAC. In addition, diminished lung reduced oxidized glutathione ratio and superoxide dismutase activity were observed after TDI challenge, and these changes were attenuated by NAC. NAC treatment has beneficial effects in TDI-induced asthma. [ABSTRACT FROM AUTHOR]

An energetic composite of an octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine with a polymer matrix is generally developed to reduce sensitivity, improve mechanical strength and furnish engineering shape. A hydroxyl-terminated polybutadiene (HTPB) and various curatives, namely methylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI) and trimethyl-hexamethylene diisocyanate (TMDI), were mixed in 1:1 [NCO]/[OH] equivalent ratio to form polyurethane, and these samples were designated by HTPB/MDI, HTPB/IPDI, HTPB/TDI and HTPB/TMDI, respectively. The four kinds of energetic composites were prepared by mixing of an energetic HMX with various HTPB/MDI, HTPB/IPDI, HTPB/TDI and HTPB/TMDI matrices. These composites were studied for the thermal stability by employing thermogravitry analysis (TGA) and found to be almost similar. The kinetic parameters of all kinds of composites were investigated through the isoconversional Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods for the first and second stages of the thermal decomposition using TGA data. The results of the activation energy obtained from the FWO method were analogous to those values obtained from the isoconversional KAS method. In addition, the kinetic parameters were also investigated through isoconversional KAS method using DSC data. The overall values of the activation energy of the HMX/HTPB/MDI, HMX/HTPB/IPDI, HMX/HTPB/TDI and HMX/HTPB/TMDI samples were varied in a range of 168–263, 277–409, 210–421 and 206–324 kJ mol−1 at a constant value of conversion (α = 0.1–0.9), respectively. The results indicated that there was significant variation in the activation energy with varying curative groups in the HTPB-based PU matrices. The compensation effect method was used to calculate the pre-exponential factor. The energetic composites were also investigated for the thermodynamic parameters for formation of the activated complexes and are discussed. [ABSTRACT FROM AUTHOR]

Hydroxyl-terminated natural rubber can be used as an eco-friendly and renewable bio-based polyol for the production of sustainable polyurethanes. It can also have other advantages such as high elasticity and thermal stability over many other conventional polyols. Liquid natural rubber (LNR) with primary and secondary hydroxyl end-groups was prepared via ozonolysis of natural rubber (NR) in chloroform at 60 °C followed by the subsequent reduction with sodium borohydride. Mn and Mw of the prepared hydroxyl-telechelic liquid natural rubber were 2368 g/mol and 3949 g/mol, respectively. The prepared liquid natural rubber has a narrow unimodal molecular weight distribution and a relatively low polydispersity index of 1.9. The presence of terminal hydroxyl groups and cis-1,4-isoprenic microstructures of hydroxyl-telechelic liquid natural rubber were determined by FT-IR, 1H and 13C NMR spectroscopy. The prepared hydroxyl-telechelic liquid natural rubber was successfully cured with toluene diisocyanate (TDI) and a polyurethane elastomer was obtained. [ABSTRACT FROM AUTHOR]

Magnetite nanoparticles are widely used in current medicine because their magnetite properties allow several uses as drug delivery systems, contrasts in imaging tests, and even for magnetohyperthermia. However, magnetic nanoparticles possess meager Zeta potential, presenting a strong tendency to agglomerate. For clinical use, they must be covered with a biocompatible material to maintain colloidal stability, without, however, altering its magnetic properties. Thus, for biomedical applications in general, magnetic nanocomposites are more interesting than pure magnetite. The present work applies poly(butylene succinate) (PBS), as a coating on magnetite nanoparticles, aiming to increase their biocompatibility. PBS is a polymer obtained from renewable sources, being entirely suitable for pharmacological uses. In this work, the synthesis of ricinoleic acid from natural castor oil is carried out through the saponification method and subsequent acid hydrolysis. In turn, the synthesis of magnetite nanoparticles is performed by coprecipitation. Then, by an acid‐base reaction, the nanoparticles are treated with ricinoleic acid. Soon afterward, toluene diisocyanate is used to produce bonding between the modified particles and PBS. Fourier‐transform infrared spectroscopy confirms the synthesis of the material. Also, scanning electron microscopy and dynamic light scattering experiments are performed. The obtained results allow inferring the success in the preparation of the pursued hybrid material. [ABSTRACT FROM AUTHOR]

An efficient and facile synthesis of 2,4‐ and 2,6‐diarylpyridines has been developed. It involves one‐pot [2+2+1+1] pseudo four‐component annulation of aromatic ketones, a nitrogen source and a carbon donor. N,N‐Dimethylaminoethanol is oxidized in the presence of Co(II) to provide a carbon synthon. Two C−C and two C−N bonds are formed during the oxidative annulation process. The products are strictly controlled due to the steric hindrance: 2,4‐diarylpyridines are afforded effectively with small ketones while 2,6‐diaryl analogues predominate when bulky ketones are employed. [ABSTRACT FROM AUTHOR]

Bio-based polylactide (PLA) derived from fermented co rn starch was blended with poly(butylene adipate- co -terephthalate) (PBAT) and triethyl citrate (TEC) plasticizer using a twin screw extruder. PLA- grafted -maleic anhydride (PLA- g -MA) synthesized via reactive maleation and toluene diisocyanate (TDI) were used as compatibilizers for these blends. Improvements in the toughness, phase morphology and thermal behavior of the PLA/PBAT/TEC (PBT) blend films were evaluated in terms of compatibilization effect. The compatibilized PBT blends showed noticeably superior tensile strength, elongation, and tensile-impact toughness compared with uncompatibilized ones due to the greater compatibility of PLA and PBAT phases. Well dispersed PBAT particles and many elongated fibrils were observed on the fracture surface of the film after compatibilization. Both TDI and PLA- g -MA were effective compatibilizers for the blend at an appropriate level. The addition of PLA- g -MA to the plasticized blends not only significantly enhanced mechanical properties and phase adhesion, but also accelerated cold crystallization and formed crystal perfection, a result of improvements in chain mobility and packing efficiency. Differential scanning calorimetry (DSC) results revealed changes in T g and melting behavior of the blends from influences of compatibilization. The different types and levels of compatibilizer affected the thermal stability of the PLA phase but did not affect char remaining. [Display omitted] • PLA- g -MA was successfully synthesized via reactive maleation. • The compatibilized PLA/PBAT/TEC blend films showed noticeably superior toughness. • TDI and PLA- g -MA acted as an effective compatibilizer for these blends. • Crystal behavior was key factor affecting the toughness of blend films. • Influences of compatibilizer produced a variety of changes in properties of blends. [ABSTRACT FROM AUTHOR]

The polyester‐based transition layers were first synthesized with poly (diethylene glycol adipate), glycerin, and toluene diisocyanate. Then they were coated between the propellant and the liner to improve the bonding performance of the charge and inhibit the migration of the energetic plasticizer in the propellant. The effects of R value (the ratio of the quantity of isocyanate functions NCO with respect to the quantity of hydroxyl functions OH) on migration resistance and bonding performance were also studied. The overall performance was optimized at R = 1.5: after the transition layer was applied, the binding strength was greatly increased from 0.14 to 0.64 MPa, which had good application prospects. Meanwhile, due to the strong interactions between the polar ester groups and N‐butyl‐N‐nitratoethyl nitramine (NENA) in the transition layers, the portion of NENA migrating into liners were reduced from 7.6% to 6.0% (reduced by 21%), indicating that the introduction of polyester transition layers could significantly improve the anti‐migration effect. The activation energies of migration for NENA in the transition layers were about 66.3 ~ 94.3 kJ/mol, which were equivalent to the value of strong hydrogen bonding. [ABSTRACT FROM AUTHOR]

Silicone can be used to improve the antifouling properties of polyurethane (PU) coatings. A series of uniform and stable nano-scale waterborne PU were prepared by using toluene diisocyanate (TDI), polycaprolactone diol (PCL2000) and hydroxy-terminated polydimethylsiloxane (PDMS) as the main raw materials. Fourier transform infrared spectrometer (FT-IR), dynamic light scattering (DLS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarizing microscope (PM) were used to test the structures and properties of the material.Subsequently, the coatings with different PDMS mass fractions (w(PDMS) were painted on the panels and immersed in the river. The practical antifouling levels of the materials were tested. Results showed that the thermal stability of the film increased with the increase of w(PDMS). While the surface free energy (γ), gradually decreased to 13.87 mJ/m2. PDMS reduced the glass transition temperature (Tg) of the material, and enhanced the water resistance of the coatings. Besides, the addition of silicon oil effectively reduced the elastic modulus (E) of the coatings. Correlation (between the theory that the adhesion of pollutants on antifouling coating is positively relevant to the square root of the product of the elastic modulus of the coating and the surface energy and the actual antifouling level (coatings actually immersed in water) was explored. Results showed that the PDMS-modified PU had excellent antifouling performance, and the actual antifouling effect of the coating was consistent with the calculation results of the theoretical reference value √ γ,E. [ABSTRACT FROM AUTHOR]

Institute of Chemistry of Macromolecular Chemistry NAS of Ukraine, 48, Kharkivske shose, Kyiv, 02160, Ukraine Developed polymer composite material with Cefazolin based on polyurethane with isocyanurate fragments (PU), synthesized on the basis of polyoxypropylene glycol (POPG 1000), TDI (2,4;2,6-toluene diisocyanate) and 2,4,6-triisocy anate(trishexamethylene) isocyanate (ICC, Tolonate ™ HDT-LV, MM 1200) at a ratio of NCO: OH = 1: 1 in the medium N,N’-dimethylacetamide (DMAA) and Cefazolin (CFZ). CFZ is immobilized on isocyanurate-containing polyurethane by introducing a solution of CFZ with DMA into the reaction the amount of 5 wt. %. Th e synthesized polymeric material (PU-CFZ) represents a transparent film of yellow color with physical and mechanical characteristics: σ = 0,15 MPa; ε = 63.40%. According to IR spectroscopy, Cefazolin is immobilized on the polymer matrix by physically due to hydrogen interactions. Th e influence of biological medium 199 (BM 199) on the structure and properties of PU-CFZ during incubation for 1, 3 and 6 months was studied. It was found that after incubation in BM 199, the structure of PU-CFZ changes as a result of the interaction of enzyme molecules that are part of BM 199 with urethane and amide groups of PU. According to the results of physical and mechanical studies, after incubation in BM 199 for 6 months, PU-CFZ samples are characterized by tensile strength of 0.36 MPa and elongation at break of 98%, ie retain sufficient performance for use in biological objects for up to 6 months. Composite materials with Cefazolin are able to prolong the release of the drug for 28 days in an amount of about 30%, which is sufficient to provide a local therapeutic effect. According to the results of the cytotoxicity study of the developed material by in vitro tissue culture, it was found that the composite material based on isocyanurate-containing polyurethane with Cefazolin is biocompatible. [ABSTRACT FROM AUTHOR]

Synthesis and characterization of a new class of polybutadiene polyol polyurethanes were investigated with three consecutive reactions, namely polybutadiene (PB) chain cleavage by a two-step oxidation reaction using meta-chloroperbenzoic acid (m-CPBA) and periodic acid (H5IO6) in order to prepare polybutadiene polyol precursor, continued by telechelic amine polyol synthesis by an amination reaction using diethanolamine (DEA) in the presence of sodium borohydride (NaBH4) and finally telechelic polyurethane preparation by the reaction of synthesized polyol and toluene diisocyanate (TDI). Nanocomposites were prepared through an in situ polymerization reaction by incorporation of 1–3 wt% of graphene conductive nanosheets. Successful structural elucidation of the synthesized polymeric binder and nanocomposites was investigated by using well-known methods. TGA analysis revealed slower degradation and moderate thermal stability in higher weight percent nanocomposite. SEM images and XRD patterns resulted in fine nanoparticle distribution, lack of agglomeration and approximately constant nanoparticle size. Conductometry confirmed higher electrical conductivity data for nanocomposites by increasing graphene nanosheet contents. [ABSTRACT FROM AUTHOR]

In this article, we are studied an effect of molecular weight of amineterminated oligo(urethane-urea)s (OUU) on the morphology and mechanical properties of the oligomer–polymer blends with poly(vinyl chloride) (PVC) stabilized by hydrogen bonding. OUU are fabricated from poly(tetramethylene glycol) (PTMG) with a molecular weight of 1000, 2,4- tolylene diisocyanate (TDI) and excess of 4,4-methylenedianiline (MDA) as a chain extender via conventional two-step ‘prepolymer’ approach in N,Ndimethylformamide (DMF) solution. For comparative purpose, the linear poly(urethane-urea) (PUU) is synthesized from PTMG, TDI and MDA using the same synthesize pathway at a molar ratio of isocyanate-terminated prepolymer to diamine of 1:1. The polymer-composite films with 3% (by weight) LiCl or 10–90% (by weight) PVC are prepared using solution casting technique from DMF. A presence of intra- and intermolecular hydrogen bonding (HB) in neat OUU and the composites is studied by FTIR. It is find out a formation of stronger H-bonding network in OUU/LiCl and oligomer–polymer blends in comparison with PUU/LiCl and polymer– polymer blends due to participation of the NH2 and NH groups of OUU rigid segments in interfacial interactions with polar groups of PVC. Studying the morphology by SEM demonstrates that a maximum size of the particles of dispersed PVC phase in polymer–polymer blends with 30% of PVC is as high as 150 μm, whereas the strong interfacial interactions in oligomer–polymer blends provide an efficient dispersing of the components and reducing their particle size to nanoscale level. Compatibility of the components reduces at increasing molecular weight of OUU and decreasing NH2 -groups’ content, and PVC content increases above 50%. Experimental tensile strength of oligomer–polymer nanocomposites obtained overcomes a theoretical one by 50–60%. [ABSTRACT FROM AUTHOR]

In this report, smart polyurethane‐polystyrene interpenetrating polymer network (IPN)‐based nanocomposites were fabricated using simultaneous polymerization technique with different doses of functionalized reduced graphene oxide (f‐RGO). RGO was functionalized with monoglyceride of sunflower oil in the presence of toluene diisocyanate. Successful functionalization of RGO was supported by Fourier‐transform infrared spectroscopy, X‐Ray diffraction, and transmission electron microscopy analyses. Most interestingly, the fabricated IPN‐based nanocomposites showed significant enhancements in mechanical (tensile strength: 165%; elongation at break: 198%; toughness: 340%) and thermal (thermally stable up to 262°C) properties upon incorporation of 1 weight% of f‐RGO. Moreover, the fabricated nanocomposites exhibited outstanding chemical resistance, self‐cleaning behavior through surface hydrophobicity (static contact angle: 125.6–136.5°), multi‐stimuli responsive shape memory effect (100% recovery within 33–44 s by microwave and 265–308 s by sunlight) and thermally actuated artificial muscle‐like behavior. Therefore, the studied smart nanocomposites with the aforementioned properties hold significant potential for possible advanced applications. [ABSTRACT FROM AUTHOR]

In this work, preparation and characterization of new classes of polybutadiene-based polyols and polyurethanes investigated with consecutive reactions namely, polybutadiene chain scission by a two- step oxidation procedure using meta-chloroperbenzoic acid and periodic acid to prepare terminal aldehyde functionalized polybutadiene, followed by telechelic amine polyol preparation by an amination reaction using diethanolamine finally telechelic polyurethane synthesis by the reaction of synthesized polyol and toluene diisocyanate. Magnetic nanocomposites were synthesized during an in-situ polymerization reaction by incorporation of 1 to 3 wt % of Fe3O4 surface modified nanoparticles by aminopropyltriethoxysilane. 1H NMR and FT-IR spectroscopy techniques proved successful synthesis of polymer binder, polyurethane and nanocomposites. TEM micrographs and XRD patterns indicated homogeneous nanoparticle distribution, almost constant nanoparticle size and lack of agglomeration. TGA/DTG analysis proved significant thermal stabilities with slower degradation rates especially in 3 wt % nanocomposite. VSM hysteresis confirmed superparamagnetic behavior of the magnetic nanocomposites that increased with higher nano Fe3O4@APTS content. [ABSTRACT FROM AUTHOR]

Polyurea microcapsules containing oxyfluorfen herbicide were synthesized by interfacial polymerization reaction between toluene diisocyanate and ethylene diamine at various core to shell ratios using green solvent N-N-dimethyldecanamide as carrier medium and using biodegradable PVA203S and Kraft lignin grade (varying molecular weight) as the emulsifying agent. The study was done to understand the effect of stirring rate on preparing microcapsules and find out how the process conditions changed the attributes of microcapsules such as particle size distribution, encapsulation efficiency and release kinetics. The formation of capsules was confirmed by FT-IR, SEM and TGA. The study indicated that the encapsulation efficiency decreased with increasing core to shell ratio. The change in release kinetics was based on the stirring rate and was dependent on the pH of release medium. Particle size distribution was influenced by the agitation speed during formation of emulsion. Kraft lignins of varying molecular weight were used to synthesize the polyurea capsules. It was found that capsules with high molecular weight lignin showed slow and sustained release. Synthesized polyurea capsules was subjected to safety study on paddy crop and compared with commercially available oxyfluorfen and was found to be safe for use on paddy crop. [ABSTRACT FROM AUTHOR]

Solution speciation of Rh(η5-C5Me5), Ru(η6-p-cymene) and Ru(η6- toluene) complexes of 2,4-pyridinedicarboxylic acid (2,4-dipicH2) was studied and compared to that of 2-picolinic acid (picH) in addition to their reactivity towards chloride and bromide ions, 1-methylimidazole and guanosine. Structures of [Rh(η5- C5Me5)(2,4-dipicH)Cl] ·3H2O (1), 2[Ru(η6-toluene)(2,4-dipicH) Cl] ·3H2O (2) and [Ru(η6-toluene)(2,4-dipic)]3 ·7H2O (3) were analyzed by X-ray diffraction. 1 and 2 show typical piano stool geometry, while 3 is a triangular complex stabilized via the monodentate coordination of the second carboxylate group to the neighboring Ru(II) center. High stability [M(arene)L(H2O/Cl)] species predominate at pH 7.4. 2,4-Dipic forms more stable complexes with Ru(η6-arene) than pic, with this difference being minor in the case of the Rh(η5-C5Me5) complexes. A lower affinity of 2,4-dipic complexes to halide ions was found compared to the corresponding pic complexes due to the additional COO- moiety. [ABSTRACT FROM AUTHOR]

The purpose is to enhance the working properties of waterborne epoxy resin and improve the quality of cold pavement binder usage. In this study, a modified waterborne polyurethane/epoxy composite was prepared. The influence of the type and content of the polyurethane on the working properties of a composite was studied. The optimum composition and ratio of the composite were determined. The properties of the waterborne epoxy at different working conditions and treatment times were analyzed. The long-term evolution law of property of waterborne epoxy was clarified. The correlation between different working properties of waterborne epoxy was studied. The results show polyurethane can improve the working properties of waterborne epoxy resin. Considering the tensile, bending, and bonding properties, the suitable type of polyurethane is toluene diisocyanate-polybutylene adipate (TDI-PBA), and the suitable content is 15%–20%. With the increase of hydrothermal aging time, the strength of waterborne epoxy resin increases 5%–10%, the flexibility reduces 6%–12%, and the bonding property decreases 70%–75%. After polyurethane modification, the property stability of waterborne epoxy resin is enhanced. The retention rate of the bonding property increases significantly, at approximately 120%–150%. [ABSTRACT FROM AUTHOR]

Two chain extenders having different molecular structures; an alternating copolymer of ethylene and maleic anhydride (EMA) and a novel chain extender, dimeric 2,4-toluene diisocyanate (DTDI), both at two different concentrations (0.5 and 1 wt%), were melt compounded with recycled polyamide 6 (rPA6) using a twin-screw extruder. In order to investigate the effect of temperature profile and residence time on the chain extension behaviors of these chain extenders three different temperature profiles and four different throughput rates were selected for the melt compounding. Effects of the parameters were observed through differential scanning calorimetry (DSC) measurements, relative viscosity measurements, and tensile and impact tests. Temperature and time dependent improvements of the chain extended products with EMA and DTDI showed different tendencies. While chain extension of rPA6 with EMA became more effective with the optimization of the barrel temperature profile, chain extension with DTDI was not affected by temperature changes. By adjusting the temperature profile 9.1% higher viscosity, 1.3 times higher elongation at break and 10.6% higher impact strength were obtained for the chain extension reaction of rPA6 with EMA. Longer residence time promoted the chain extension reaction of rPA6 with EMA. On the other hand, chain extension of rPA6 with DTDI was not significantly affected by residence time. [ABSTRACT FROM AUTHOR]

The expansion of various industries, such as the textile industry in the world, has led to the production of dye wastewater, which has caused a lot of pollution and damage to the environment. Therefore, the use of efficient methods such as nanofiltration to treat these wastewaters is one of the most important issues related to the environment. In the present study, in order to prepare the nanofiltration membrane by interfacial polymerization method, piperazine, and toluene diisocyanate monomers in the aqueous and organic phases were used. κ-Carrageenan biopolymer was used in the process of membrane modification to increase the hydrophilicity of the membrane surface and enhance a negative surface charge on it and thus improve the performance of the final membrane in removing anionic pollutes. After preparing nanofiltration membranes, they were tested to remove the anionic dyes. The results showed that the presence of κ-Carrageenan increased the hydrophilicity of the membrane surface and ultimately increased the flux of the membrane, and at the same time not only did not reduce the rejection of the anionic dyes, but increased somewhat. Finally, scanning electron microscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, contact angle, and zeta potential analyzes were used. The results obtained by measuring contact angle confirmed hydrophilicity increase of the membrane surface in the presence of κ-Carrageenan and approved negative surface charge by measuring zeta potential. [ABSTRACT FROM AUTHOR]

This work uses the change of elongation with temperature in a composite solid propellant to assess its shelf life for the air and nitrogen atmospheres applying two methods for the temperature parameterization of the measured quantity, the Arrhenius and Berthelot equation. The samples of the composite propellant contain aluminum (Al), ammonium perchlorate (AP), and hydroxyl-terminated polybutadiene (HTPB) as well as curing agent toluene diisocyanate (TDI), which were aged at three temperatures 323.15, 333.15, and 343.15 K during 15, 30, 60, 90, and 120 days. Stress-strain curves for the samples are investigated to study the effects of the atmospheres of air and nitrogen on the samples. The ratio of the changes in percentage elongation (ɛ) to the initial value of percentage elongation (ɛr) is the degradation criterion, which is defined as a reduction of the elongation to less than 50%. The calculated activation energy by the Arrhenius method is 80.48 kJmol-1 for the air atmosphere. The shelf life of the samples were found to be 7.912 and 7.906 years (air atmosphere) to 23.38 and 23.36 years (nitrogen atmosphere) as well as Arrhenius and Berthelot methods, respectively. [ABSTRACT FROM AUTHOR]

The aim of the work was to develop methods for the synthesis and study of the properties of silicon-containing oligomeric azo- and polyazoinitiators based on bis-γ-hydroxypropylpolysiloxane (HPS) and bis-γ-aminopropylpolysiloxane (APS). Silicon-containing oligomeric azoinitiators using HPS were synthesized on the basis of cyclohexanone azo-bisisobutyrohydrazone (AGN-CH) and bis-γ-hydroxypropylpolysiloxane bifunctional macrodiisocyanate (MDIHPS). MDIHPS was obtained by the interaction of GPS with 2,4 toluene diisocyanate (2,4-TDI). Oligomeric azoinitiators have been obtained, which have the structure RXR and (RX)nR, where R is a propylpolysiloxane block, X is a azo initiator block. For the synthesis of an oligomeric azo initiator based on bis-γ-aminopropyl polysiloxane (APS), a method was first developed for the synthesis of a monomeric azo initiator with terminal oxadiazolinylcarbamanate isocyanate groups (AGN-NCO) by the interaction of AGN-CH and 2,4-TDI at a molar ratio of 1: 2. On the basis of the obtained AGN-NCO and APS at a molar ratio of AGN-NCO: APS = 1: 1, an oligomeric azo initiator (OAI APS-P) was synthesized, which has the structure (RX)nR, where R is a propylpolysiloxane block, X is an azo initiator block. The structures of monomeric and oligomeric azo initiators have been studied by UV and IR spectroscopy, and the kinetic regularities of their synthesis have been calculated. On the basis of oligomeric azo initiators and styrene, block copolymers of the (AB)nA type were obtained by the method of thermal and photoinitiated radical polymerization, where A is a propylpolysiloxane block, B is an oligosyrene block with a constant value of the organosilicon block and a different size of the oligostyrene block. The structure of block copolymers was investigated by IR spectroscopy. It was shown that during photopolymerization, oligostyrene blocks of shorter length are formed than during thermopolymerization, and possible oxidation processes. The study of relaxation transitions by DSC in oligostyrene and propylpolysiloxane blocks of the BCP showed that the common heat capacity curves are the presence of two jumps in the heat capacity at the glass transition temperatures of the polysiloxane and oligostyrene microphase. A slight shift in the glass transition temperature of polysiloxane microphases in BCP towards higher temperatures compared to the homopolymer may be associated with the effect of oligostyrene microphase. With a decrease in the length of the oligosyrene block, a low-temperature shift in the glass transition temperature of oligostyrene blocks relative to the homopolymer and a depression of ΔCp, 2 are observed, which is associated with the suppression of mobility in oligodienic microphases by less mobile propylpolysiloxane blocks. [ABSTRACT FROM AUTHOR]

A novel class of phosphorous‐containing polyurethane triazoles (PUTs) with self‐extinguishing property is reported. Initially, a set of new urethane diazide monomers were synthesized by reacting diisocyanates (DI) (isophorone (IPDI), hexamethylene (HDI), and toluene (TDI)) with 2‐azidoethanol and characterized by FTIR, 1H NMR, 13C NMR, and ESI‐MS analysis. Later, the corresponding PUTs were synthesized via azide–alkyne cycloaddition of urethane diazides with triprop‐2‐ynyl phosphate under solvent‐free and catalyst‐free conditions at 80°C via thermal polymerization. Cure kinetic study of the thermally induced polymerization of PUTs was performed to correlate with isocyanate functionality. The activation energies (Ea) of the PUTs derived from nonisothermal multiheating rate DSC tests were fitted to Borchardt–Daniels model. The Ea's were found to be proportional to heating rates for all PUTs and confirmed optimum percentage conversion at lower heating rates. The experimental findings were found to corroborate well with Borchardt–Daniels model. The PUTs were characterized by FTIR, TGA, DSC, MCC, LOI, lab‐scale flame tests, and EDX analysis. All PUTs were self‐extinguishable, but TD‐PUT with aromatic functionality (TDI‐based) demonstrated superior extinguishing performance with lowest total heat release (6.11 kJ/g), peak heat release rate (42.04 W/g), heat release capacity (85.59 J/g K), and 31% LOI comparatively. Lab‐scale flame tests on PUTs confirmed their self‐extinguishing property with little or no smoke evolution. Such PUT resins can be blended with conventional polyurethane coatings for fire‐retardant applications. [ABSTRACT FROM AUTHOR]

Development of high-performance nanofiltration membranes with extreme-pH stability is an urgent need for treatment of wastewater from metallurgical and paper industries. In this study, we design a kind of oil phase monomer toluene diisocyanate (TDI) and the aqueous phase monomer polyethyleneimine (PEI) to prepare polyurea nanofiltration membranes. The special bonding type and dense crosslinking structure of polyurea were used to resist the attack of extreme pH conditions. The support-free interface polymerization was employed to minimize the membrane thickness. The TDI-PEI 10000 composite membranes achieved rejection of 97.5% for MgCl 2 , with a corresponding pure water permeance of 20.0 L m-2 h-1 bar-1. After exposure to H 2 SO 4 solution with pH=1 for 440 h or NaOH solution with pH=13 for 200 h, the MgCl 2 rejection remained above 90%. Our study provides a facile approach to constructing extreme pH-stable separation membranes. [Display omitted] • Polyurea membranes were fabricated by support-free interfacial polymerization. • The membrane exhibits superior tolerance to extreme pH conditions. • The membrane exhibits 22.0 (L m-2 h-1 bar -1) water permeance and 97.8% MgCl 2 rejection. [ABSTRACT FROM AUTHOR]

The slow crystallization and weak mechanical features of poly (butylene adipate- co -terephthalate) (PBAT) have become a severe industrial problem in food packaging. Inspired by principle of bionic structure, functional cellulose nanocrystals (CNC) modified with hexamethylene diisocyanate (HMDI) and toluene diisocyanate (TDI) can enhance the crystallization ability and mechanical properties of PBAT nanocomposites. Significantly, CNC-T (CNC modified by TDI) showed a stronger reinforced effect on PBAT properties than unmodified CNCs and CNC-H (CNC modified by HMDI) nanofillers due to hydrogen bonds, π-π interaction between PBAT matrix and CNC-T nanofillers with benzene ring structure. Thus, compared with pure PBAT, PBAT/5CNC-T composites displayed an enhancement of 34.5 % on the tensile strength and exhibited the most robust nucleation ability on PBAT crystallization than CNC and CNC-H. Meanwhile, the possible nucleation, crystallization, and performance reinforcement mechanisms of PBAT nanocomposites have been presented, which is very beneficial for designing robust PBAT nanocomposites with functional cellulose nanocrystals for potential green packaging. • Hydrophobic CNC-T showed excellent compatibility with industrial PBAT matrix. • CNC- T induced π-π interactions and hydrogen bonds within PBAT via its benzene ring structure and hydroxyl group. • CNC-T nanofillers gave better enhancing effect and crystallization ability on PBAT. • Crystallization kinetics show excellent nucleation and crystallization ability of PBAT/CNC-T. • PBAT composites with outstanding performance were suitable for green packagings. [ABSTRACT FROM AUTHOR]

• We further studied the novel phosgenation reaction based on flash atomization. • An atomization reaction model was established for high temperature environments. • The toluene diisocyanate yield can reach 97.41%. • The superiority of this method was validated by comparing with gas phase method. Toluene diisocyanate stands as a pivotal chemical, predominantly synthesized through the phosgenation reaction between toluene diamine and phosgene. To address the inherent limitations of existing phosgenation methods, we pioneered a novel phosgenation reaction based on flash atomization and confirmed its feasibility with preliminary theoretical calculations. This manuscript delves deeper into the superiority of this method and refines its reaction parameters. By integrating the discrete phase model with the Eulerian model, we studied the reaction dynamics of droplet sprays, exploring the effects of spray velocity, droplet size, phosgene temperature, and particle size distribution on the reaction. Our results highlight that, with a mean droplet diameter of 70 μm and a spray velocity of 40 m/s, an impressive reaction yield of 97.4 % can be achieved. This research enriches our understanding of the gas–liquid two-phase phosgenation method, setting the stage for its future exploration and potential applications in Toluene diisocyanate and other isocyanate industry. [ABSTRACT FROM AUTHOR]

The high cost and high dosage of polyurethane (PU) used in asphalt modification limit its application in asphalt pavement construction. To address these problems, two novel PUs were synthesized by the reaction of low-cost polypropylene glycol (PPG-2000) separately with 4,4 - diphenylmethane diisocyanate (MDI) and with toluene diisocyanate (TDI). This study has further optimized the preparation process and analyzed the influence of the PU synthesis materials on the modified asphalt. Dynamic shear rheology, multiple-stress creep recovery, Fourier-transform infrared spectroscopy, and fluorescence microscopy were used to evaluate the rheological properties and aging resistance of modified asphalt. Results show that the PUs synthesized by MDI and TDI significantly improved the high-temperature performance, low-temperature performance, and aging resistance of modified asphalt compared to unmodified asphalt. Asphalt modified with the PU synthesized by MDI had better high-temperature performance, but the low-temperature performance and aging resistance were worse than those for asphalt modified with the PU synthesized by TDI. The results of rheological aging and chemical aging evaluation showed that the PU synthesized by TDI provided better anti-aging performance. The optimum dosages of both PUs were not more than 6%. These PUs reduce the cost of construction engineering and show excellent application prospects in pavement construction. These two PU-modified asphalts can be applied to pavement construction in different regions based on the properties required. • Low-cost and environmental TPU and MPU modified asphalt are prepared. • Optimal dosages of MPU and TPU for asphalt modification are lower than 6%. • The types of polyurethane have a significant impact on the performance of PUMA. • MPUMA and TPUMA are suitable for road in hot and cold region, respectively. [ABSTRACT FROM AUTHOR]