Synthesis Of Polyurethanes Research Articles

Stoichiometric reaction and catalytic effect of 2-dimethylaminoethanol in urethane formation.

A computational study of the stoichiometric reaction and catalytic effect of 2-dimethylaminoethanol (DMEA) in urethane formation was performed. DMEA, besides its catalytic tertiary amine site, contains a hydroxyl group that can react with isocyanates and thus, it can affect the synthesis of polyurethane. In the catalytic system, the reaction between phenyl isocyanate and butan-1-ol, involving DMEA as a catalyst, was investigated. Meanwhile, for the competitive stoichiometric process, the reaction between phenyl isocyanate and DMEA was also considered. Both reactions were investigated by using the G3MP2BHandHLYP composite method and acetonitrile was chosen as the solvent. It was revealed that both pathways (catalytic and stoichiometric processes) are similar thermodynamically, but the catalytic reaction is preferred kinetically, which indicates the applicability of DMEA in urethane synthesis.

Preparation and characterization of potato crust-based polyurethane foam-I

Polyurethanes (PUs) are polymers obtained by reacting diisocyanates with a group of polyols. The first synthesized PU compounds were prepared using petroleum subproduct compounds. In this research study, biomass-containing polyols, which have been studied by other scientists, were prepared using potato crust and polymerized with diisocyanates to produce PU foam. Polyol reactions were carried out using the microwave heating method. Synthesis reactions and structural properties of polyols have been studied in many aspects. The most available polyol was used for PU synthesis. Different formulations were tried for PU synthesis and as a result, PU foam containing nearly 25% starch-polyol was synthesized. The chemical structure of PU polymer was identified by ATR-FTIR spectroscopy and crystallographic properties by WA-XRD analysis. The physical and mechanical properties of PU foam, which is used as a large number of building and construction materials, including thermal insulation materials, were evaluated by comparing them with a commercial PU foam. According to the results of our research, it was detected that the incorporation of biomass into the structure of PU polymer improved its density, heat conduction coefficient, pressure based mechanical properties. PU foam derived from potato waste has a WA XRD-ray diffraction peak between 13.1-28.5o. This data is between 12.5-23o in synthetic commercial foam and has been positively improved in the product we synthesized as a result of combining biomass into the structure. The synthesized biomass-based PU foam can be used as thermal insulation material. Biomass-based PU foam has been synthesized with features that can be used as a thermal insulation material.

Preparation and properties of block copolymerization thermoset polyurethane elastomers prepared in situ

Polyurethane elastomers are commonly employed as binder in propellant propellants and explosives due to their excellent mechanical properties. In-situ block copolymer synthesis of polyurethane for several advantages, including the elimination of the need for solvents in the reaction process, avoidance of excessive reaction steps, and minimizing the generation of byproducts. On the other hand, the in-situ method utilizes a low-cost prepolymer, making it highly suitable for large-scale production. Polyethylene glycol is currently one of the most widely used prepolymer in polymerization. PCL possesses favorable solubility and exhibits hydrophobicity with a low melting point, remarkably noteworthy are its thermoplastic properties, including a high decomposition temperature and a low glass transition temperature. This work employed an in-situ block copolymerization method to synthesize polyurethane elastomers and subsequently investigated their mechanical properties, surface structure, evolution over time, and thermal decomposition process. Polyurethane elastomers exhibited favorable mechanical properties, the elongation properties of these polyurethane systems herein are influenced by the proportion of hydrogen-bonded carbonyl groups within the urethane. The thermal decomposition of polyurethane elastomers can be divided into two distinct processes. Random scission of the polyurethane yielding PCL occurs under low-temperature conditions, while specific cleavage events take place at higher temperatures.

Introducing the Reversible Reaction of CO2 with Diamines into Nonisocyanate Polyurethane Synthesis.

Nonisocyanate polyurethanes (NIPUs) are considered greener alternatives to traditional polyurethanes, and the preparation of NIPUs considerably depends on the design and synthesis of suitable monomers. Herein, we propose a toolbox for in situ capturing and conversion of CO2 into α,ω-diene-functionalized carbamate monomers by taking advantage of the facile reversible reaction of CO2 with diamines in the presence of organic superbases. The activation of CO2 into carbamate intermedia was demonstrated by NMR and in situ FTIR, and the optimal conditions to prepare α,ω-diene-functionalized carbamate monomers were established. Thiol-ene and acyclic diene metathesis (ADMET) polymerization of these monomers under mild conditions yielded a series of poly(thioether urethane)s and unsaturated aromatic-aliphatic polyurethanes with high yield and glass transition temperatures ranging from -26.8 to -1.1 °C. These obtained NIPUs could be further modified via postpolymerization oxidation or hydrogenation to yield poly(sulfone urethane) and saturated polyurethane with tunable properties.

Synthesis and Characterization of Cardanol-Based Non-Isocyanate Polyurethane.

This paper describes the synthesis of NIPU by using cardanol as starting material. A cardanol formaldehyde oligomer was first prepared through the reaction of cardanol and formaldehyde, catalyzed by citric acid. The resulting oligomer was then subjected to epoxidation with m-chloroperbenzoic acid to obtain an epoxide compound, which was subsequently used to fix carbon dioxide (CO2) and form a cyclic carbonate. Using this cyclic carbonate, along with an amine, cardanol-based isocyanate polyurethane (NIPU) was prepared. Different characterization methods, such as Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), and thermogravimetric analysis (TGA), were used to confirm the synthesis of the four intermediate products and NIPU in the reaction process. This study highlights the promise of bio-based NIPU as a sustainable alternative in a number of applications while offering insightful information on the synthesis and characterization of the material.

Synthesis of waterborne polyurethane–humic acid cross-linked biomass porous materials for the adsorption of methylene blue

A series of adsorbent materials (WPU-HAx-y) with a three-dimensional porous structure, green sustainability, and excellent performance were prepared and evaluated for the removal of methylene blue using nontoxic and environmentally friendly waterborne polyurethane as the matrix material and humic acid, a biomass material, as the functional material. The newly synthesized adsorbents were characterized by infrared spectroscopy, scanning electron microscopy, specific surface area, and thermogravimetric. The effects of contact time (0–8 h), starting concentration (10–100 mg·L−1), pH (3–11), solution temperature (30–60 °C), and coexisting ions (Ca2+, Na+, K+, Mg2+) on the performance were investigated. Pseudo-first-order, pseudo-second-order, elovich, and intra-particle diffusion models were used to analyze the adsorption kinetics; the Langmuir, Freundlich, Temkin, and Dubin–Radushkovich adsorption isotherms were evaluated; and the adsorption behavior of the adsorbent materials was found to be more appropriate for the pseudo-second-order model for chemical pollutant removal than the Langmuir model, which depends on monolayer adsorption. WPU-HA2-3 stood out with a maximum adsorption capacity of 813.0081 mg·g−1 fitted to the pseudo-second-order and 309.2832 mg·g−1 fitted to the Langmuir model, showing superior adsorption performance and regenerability.

Tuning physical properties of polyurethane hard segments through extender chain length variation and doping of pentaerythritol and their effect on in vitro protein adsorption

AbstractThis study explores the synthesis and characterization of polyurethanes (PUs) derived from hexamethylene diisocyanate (HDI) and 1,n‐alkane diols with varying chain lengths (n = 4, 6, and 10). Additionally, pentaerythritol (PE) is introduced as a dopant in PU6 at different weight percentages (25%, 50%, 75%, and 1:1%w/w). The research encompasses a comprehensive analysis of PU properties, including morphology, crystallinity, surface area, porosity, thermal behavior, rheological properties, and electrical conductivity. Of particular interest is the evaluation of protein adsorption capabilities employing bovine serum albumin (BSA) and fibrinogen proteins in in vitro tests. The study emphasizes the crucial role played by the chain length between isocyanate and diol groups and the nature and strength of hydrogen bonds among chains in shaping the polymer's properties, especially crystallinity and biocompatibility. Among the synthesized PUs, PU6 emerges as the top performer in terms of crystallinity and biocompatibility. Furthermore, the addition of PE is found to act as a plasticizer, reducing the glass transition temperature (Tg) from 75°C to 31°C. Electrochemical Impedance Spectroscopy shows that doping influences charge transfer processes, rendering the material semi‐conducting, as evidenced by decreased conductance when adding silver nanoparticles to PU6. Notably, protein adsorption studies reveal that undoped PU6 displays superior protein resistance compared to its doped counterpart, with fibrinogen exhibiting a higher adsorption affinity than BSA. The study discusses a plausible mechanism underlying protein adsorption.

Preparation and properties of high molecular weight high temperature resistant carborane polyurethane adhesive

The long-term use temperature of the traditional high-temperature adhesive can only reach about 280 °C, and it cannot be used in extreme environments such as acid and alkali for a long time, which greatly limits its application in aerospace and other fields. Because of its unique three-dimensional structure, carborane has excellent thermal stability and chemical stability. Based on this, first, this article introduced carborane monomer into polyurethane structure, using indirect copolymerization method, Hydroxyl carborane derivative (m8) and conventional polyether diols were used as soft segments. By adjusting the introduction ratio of m8, a series of copolymerized carborane polyurethane (Co-CBR-PU) with controllable thermal and mechanical properties were successfully prepared. Its structure and molecular weight were characterized by FTIR and gel permeation chromatography (GPC), its surface morphology were observed by SEM. The thermal stability and mechanical properties were studied by thermogravimetric test, tensile test and rheological dynamic mechanical analysis test., and its activity, solvent resistance and hydrophobic properties were studied by finger contact method, solvent resistance test and contact Angle test. Second, the high temperature resistant carborane polyurethane adhesive (PUAS) was prepared using Co-CBR-PU as matrix and its adhesion was studied. The results show that a series of Co-CBR-PU has good high temperature resistance, mechanical properties and solvent resistance after adding carborane monomer, and its various properties were optimal when the addition amount of m8 was 15 wt%. The carborane PUAS prepared by using it as the substrate has excellent high temperature adhesion to different adhesive parts. The aim of this study is to reduce the cost of synthesis of carborane polyurethane by regulating the proportion of carborane, and then realize the industrial trial production of high temperature resistant carborane adhesive.

Evaluation of the rheological properties and aging resistance of asphalt modified by MDI/TDI polyurethane

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.

Synthesis and characterization of polyurethane flexible foams provided from PET derivatives, fly ash, and glass wastes

The aim of this study involved the synthesis and characterization of polyurethane (PUR) foams obtained from poly(ethylene terephthalate) (PET) depolymerization products and two types of filling agents, namely fly ash and glass waste. The depolymerized PET-based products were obtained by zinc acetate-catalyzed glycolysis process in diethylene glycol (DEG) as a co-reactant. The resulting glycolysis products were contacted with methylene diphenyl diisocyanate, castor oil, and reinforcing agents. The resulting PUR specimens were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), EDX mapping, mechanical tests, and thermal analysis. The analysis confirmed that the best mechanical performances were registered by the specimens with the lowest concentration of filling agent, while the highest thermal resistance was achieved by the PUR foams with the highest concentration of reinforcing agent.

Kinetic Analysis of the Reaction between Tannic Acid (TA) and L-Lysine Diisocyanate (LDI) Systems

The kinetics of the synthesis of green polyurethane from the reaction between tannic acid (TA) and L-lysine diisocyanate (LDI) were investigated using the differential scanning calorimeter (DSC) technique and dynamic rheological tests. The evaluation of the reaction behavior of the prepared samples was carried out using nonisothermal conditions at dynamic heating rates of 5, 10, 15, and 20°C/min. The evolution of the activation energy with conversion was computed through the five isoconversional methods of Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose (KAS), the Ozawa-Flynn-Wall method (OFW), Friedman (FR), Starink, and Vyazovkin. The average activation energy calculated from these methods was estimated at 46.5, 46.8, 47.2, 47.3, and 51.4 KJ/mol, respectively. The preexponential factor was evaluated at 5.04 × 10 5 1/s. The overall reaction order ( n + m ) was also found to be around 1.8912. The results of the combination of the model-free method and model-fitting approach exhibited that the reaction mechanism was an autocatalytic type, implying the autocatalytic effect of the urethane groups formed during the reaction. The obtained kinetic for TA/LDI was verified through its good agreement with the experimental data. Moreover, the results found from the isothermal rheological test show that with increasing temperature, the gelation time decreases.

Correction: Green Synthesis of Polyurethanes Using Soybean Oil-Based Polyols for Bioactive Functional Fabrics

Correction: Green Synthesis of Polyurethanes Using Soybean Oil-Based Polyols for Bioactive Functional Fabrics

Synthesis and characterization of novel polyurethanes, polypyridazine, and polyamide based on s‐1,2,4,5‐tetrazine

AbstractThe synthesis and analysis of new polymeric materials based on 1,2,4,5‐tetrazine are discussed in this study. Tetrazine was mixed with thermoplastic polyurethane in dimethylformamide (DMF) as solvent and dibutyl tin dilaurate as catalyst at 50°C for 24 h to create brush polyurethane‐urea, which was then reacted with an unsaturated center in dimethyl sulfoxide as solvent at 60°C for 48 h made of either polyenol or thermoplastic polyurethane through π–π interaction. Because 1,2,4,5‐tetrazine (red color) is known to act as an electron‐deficient dine in inverse electron demand Diels–Alder reactions and can be easily converted to pyridazine (peach color) via [4 + 2] cycloaddition with suitable followed by expulsion of molecular nitrogen (cycloreversion), we observed a highly colored red shift to peach and this monitor for this reaction. Additionally, polyamide was prepared via reaction of 3,6‐diamino‐1,2,4,5‐tetrazine with terephthaloyl chloride in DMF as a suitable solvent and triethylamine as basic catalyst at 0°C for 3 h and then 36 h at room temperature. The new polymers that were produced were elucidated by spectral data.

Use of Polyols of Petroleum Chemical Processing as Raw Materials for the Synthesis of Polyurethanes

Use of Polyols of Petroleum Chemical Processing as Raw Materials for the Synthesis of Polyurethanes

Paving the Way towards Sustainability of Polyurethanes: Synthesis and Properties of Terpene-Based Diisocyanate.

Due to growing concerns about environmental issues and the decline of petroleum-based resources, the synthesis of new biobased compounds for the polymer industry has become a prominent and timely topic. P-menthane-1,8-diamine (PMDA) is a readily available compound synthesized from turpentine, a cheap mixture of natural compounds isolated from pine trees. PMDA has been extensively used for its biological activities, but it can also serve as a source of valuable monomers for the polymer industry. In this work, commercial PMDA (ca. 85% pure) was purified by salinization, crystallization, and alkali treatment and then converted into p-menthane-1,8-diisocyanate (PMDI) through a phosgene-free synthesis at room temperature. A thorough analytical study using NMR techniques (1H, 13C, 13C-1H HSQC, 13C-1H HMBC, and 1H-1H NOESY) enables the characterization of the cis-trans isomeric mixtures of both PMDA and PMDI. These structural studies allowed for a better understanding of the spatial configuration of both isomers. Then, the reactivity of PMDI with a primary alcohol (benzyl alcohol) was studied in the presence of nine different catalysts exhibiting different activation modes. Finally, the use of PMDI in the synthesis of polyurethanes was explored to demonstrate that PMDI can be employed as a new biobased alternative to petrochemical-based isocyanates such as isophorone diisocyanate (IPDI).

The Effect of Concentration of Titanium Dioxide Nanoparticles on Their Antibacterial Activity in the Synthesis of Polyurethane Biopolymers

In the health sector, the use of polyurethane (PU) as a basic material for medical devices still causes problems related to local and systemic infections. One of the most appropriate ways to overcome this problem is to synthesize PU biopolymer with titanium dioxide (TiO2) nanoparticles. The use of nano-shaped materials in this synthesis has many advantages, including being easier to synthesize and being antibacterial. Meanwhile, starch is the result of isolation from banana weevils, where banana weevils are agricultural waste that has not been utilized properly. Particle size and the use of agricultural waste are a form of modification and innovation in PU synthesis, as well as a novelty in the development of this research. In PU synthesis, several characterization techniques are carried out, including polymer tests, namely strain and stress, functional group analysis using (Fourier Transform Infra-Red), and antibacterial tests. Based on the results of the FTIR test analysis, it show that at a wave number of 1724.36 cm-1, the N-H functional group is visible, and the absorption of urethane and TiO2 groups is in the range of 513.07 cm-1. The mechanical properties test shows the strain (28.92 - 21.88% GL) and young's modulus in the interval (5.484-3.268 MPa). The antibacterial test showed that the inhibitory power of test samples A1 and A4 with diameters of 8 mm and 8 mm proved to be very effective in killing E. Coli bacteria, while test samples A1¹, A2¹, A3¹, and A4 were not able to kill E. Coli bacteria. S. Aureus. bacteria. The characterization results show that PU biopolymer can be used as a basic material for making bacterial decontaminant medical devices.

Soybean-Based Polyol as a Substitute of Fossil-Based Polyol on the Synthesis of Thermoplastic Polyurethanes: The Effect of Its Content on Morphological and Physicochemical Properties.

Thermoplastic polyurethanes (TPUs) are remarkably versatile polymers due to the wide range of raw materials available for their synthesis, resulting in physicochemical characteristics that can be tailored according to the specific requirements of their final applications. In this study, a renewable bio-based polyol obtained from soybean oil is used for the synthesis of TPU via reactive extrusion, and the influence of the bio-based polyol on the multi-phase structure and properties of the TPU is studied. As raw materials, 4,4'-diphenylmethane (MDI), 1,4-butanediol, a fossil-based polyester polyol, and a bio-based polyol are used. The fossil-based to soybean-based polyol ratios studied are 100/0, 99/1, 95/5, 90/10, 80/20, and 50/50% by weight, respectively. The TPUs were characterized by size exclusion chromatography (SEC), gel content analysis, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), dynamic mechanical analysis (DMA), and contact angle measurements. The results reveal that incorporating the renewable polyol enhances the compatibility between the rigid and flexible segments of the TPU. However, due to its high functionality, the addition of soybean-based polyol can promote cross-linking. This phenomenon reduces the density of hydrogen bonds within the material, also reducing polarity and restricting macromolecular mobility, as corroborated by higher glass transition temperature (Tg) values. Remarkably, the addition of small amounts of the bio-based polyol (up to 5 wt.% of the total polyol content) results in high-molecular-weight TPUs with lower polarity, combined with suitable processability and mechanical properties, thus broadening the range of applications and improving their sustainability.

Development of vanillin-based crosslinking agent with phase-locked dynamic imine bonds for shape-memory polyurethanes

Scientists have gained so much attention due to one of polyurethane's tuneable and unique characteristics, i.e., the shape-memory effect. But, the simplistic fabrication of such materials persists a challenging work. In the current work, we report the synthesis and detailed characterization of shape-memory polyurethane obtained by incorporating lower concentrations of imine bonds, which readily undergo phase-locking systems beneficial for microphase separation. A symmetric imine moiety (DIM) was designed through the simple Schiff-base reaction of naphthalene diamine and vanillin. The tensile strength of the films reached up to 30 MPa with an %elongation of 87% by tuning the hard segment content and the concentration of imine bonds. Also, in the meantime, the films showed excellent shape memory effect, where the shape could recover its original form within 2 s at the highest loading of DIM. The remarkable balance between the mechanical properties and the shape memory effect could be associated with the two main factors. Firstly, incorporating symmetrical and rigid CN along with the naphthalene promoted the microphase separation and smoothened the orientation of the chain segments at the strain-induced crystallization at lower temperatures. Secondly, the phase locking occurred at lowered temperatures due to dynamic imine exchange reaction and H-bonding. The phase recovery started, and chains settled at their original positions once the temperature was elevated.

Synthesis and application of comb-like waterborne polyurethane as a dispersant for disperse dyes

Disperse dyes are hardly soluble in water and are usually milled with large numbers of dispersants in the dye industry. A branched waterborne polyurethane (WPU) as a dispersant with different side chain lengths (WPU350, WPU550 and WPU750) was synthesized through an acetone process. The effects of the side chain length on the stability and dispersibility of disperse dyes were particularly discussed and analyzed. The results showed that due to their special comb-like structures, these WPUs were able to achieve good dispersive ability for disperse dyes and WPU550 had the best dispersibility through steric hindrance and electrostatic repulsion on the surface of dyes. In addition, WPU was further employed to prepare the dispersion to dye the polyester fabric. These dispersions with WPU not only demonstrated an improved K/S value, wet and dry rubbing fastness and soaping fastness but also had better dispersing and dyeing performance than commercial dispersants.

Sunflower oil-based polyurethane/graphene composite: Synthesis and properties

Polyurethane/graphene composites have attracted significant attention featuring their wide applications in automotive interiors, coatings, and leather parts to bioengineering. This research focuses on the facile synthesis of biobased polyurethane (PU) by employing sunflower oil as a renewable resource. The synthesized biobased PU was reinforced with graphene nanoplatelets (GNP) and graphene nanoribbons (GNR) to fabricate composite films by solution-casting technique. By changing the filler content (0.01-0.05 wt%), a series of composite films were prepared. The addition of graphene derivatives to the PU matrix improved the mechanical, thermal, and surface properties of the composites compared to the pristine PU film. The incorporation of GNR and GNP fillers enhanced the storage modulus of polymeric film, as for neat PU, was noted maximum at 892 MPa which increased and noticed a maximum of 1121 MPa and 1487 MPa for 0.02 wt % GNP/PU and GNR/PU composite films, respectively. The tensile strength was obtained at 35 MPa and 14 MPa for 0.02 wt % GNP/PU and 0.01 wt % GNR/PU, as compared to 9.45 MPa for the pure PU film. The morphological studies by atomic force microscopy showed a good distribution of GNR and GNP fillers within the polyurethane matrix. The GNP/PU and GNR/PU composite films displayed excellent chemical resistance to different solvents. This work put forward a great utilization of renewable sunflower oil and graphene derivatives to fabricate PU composites with improved properties for potential applications.