Urethane Oligomers Research Articles

Study of the structure and properties of adhesives and compounds based on epoxy urethane oligomers synthesized from polyesters

Study of the structure and properties of adhesives and compounds based on epoxy urethane oligomers synthesized from polyesters

X-ray and thermogravimetric studies of montmorillonite modified with cationic urethane oligomers

X-ray and thermogravimetric studies of montmorillonite modified with cationic urethane oligomers

Synthesis and characterization of ureidopyrimidinone-functionalized polyurethane acrylates and their hybrid nanocomposites for UV coating applications

In this study, ureidopyrimidinone moieties (UPy), capable of physical crosslinking via quadruple hydrogen bonding, were successfully incorporated into UV-curable polyurethane acrylate prepolymers. First, a hydroxyl-terminated unsaturated ester monomer was synthesized and reacted with isophorone diisocyanate to create a hydroxyl-terminated UV-curable urethane oligomer (U–OH). Then, isocyanate-terminated building blocks (UPy moieties and an acrylate-based photosensitive monomer) were synthesized and used in various ratios to functionalize U–OH for the preparation of a series of UV-curable UPy-containing polyurethane acrylate (PUA) resins. The resulting products were structurally characterized using 1H NMR and FTIR spectroscopy. Furthermore, organic–inorganic hybrid nanocomposites were obtained by introducing silane coupling agents into PUA resins using the sol–gel process. A series of UV-curable UPy-containing PUA coatings and hybrid nanocomposites were prepared, and their synergistic effect on coating properties was investigated. The dynamic mechanical analysis revealed that the Tg of the samples increased with increasing UPy content, although the mechanical properties remained largely unaltered, as shown by the stress–strain test. The studies also demonstrated that the hybrid nanocomposites exhibited higher decomposition temperatures and better thermal stability compared to pure PUAs. All the coatings exhibited good transparency in the visible region. An optical microscope was used to investigate the self-healing property by scratching the plexiglass panels with a razor blade. Among the other samples, the coating with the highest percentage of UPy content exhibited the best self-healing ability after heat treatment at 90 °C for 10 min.Graphical abstract

Engineering Toughness in a Brittle Vinyl Ester Resin Using Urethane Acrylate for Additive Manufacturing.

Thermosetting polymers tend to have a stiffness-toughness trade-off due to the opposing relationship of stiffness and toughness on crosslink density. We hypothesize that engineering the polymer network, e.g., by incorporating urethane oligomers, we can improve the toughness by introducing variations in crosslink density. In this work, we show that a brittle methacrylated Bis-GMA resin (known as DA2) is toughened by adding a commercial urethane acrylate resin (known as Tenacious) in different proportions. The formulations are 3D printed using a vat photopolymerization technique, and their mechanical, thermal, and fracture properties are investigated. Our results show that a significant amount of Tenacious 60% w/w is required to produce parts with improved toughness. However, mechanical properties drop when the Tenacious amount is higher than 60% w/w. Overall, our results show that optimizing the amount of urethane acrylate can improve toughness without significantly sacrificing mechanical properties. In fact, the results show that synergistic effects in modulus and strength exist at specific blend concentrations.

Urethane oligomers as the models for liquid crystalline polymers

Urethane oligomers as the models for liquid crystalline polymers

Modified oligoether-diamine synthesis for the preparation of crystallizable polymers based on epoxyurethane oligomers

Abstract A modified synthetic method for amino-terminated oligo tetramethylene oxides is presented. Diamines were synthesized via a three-step route from oligo tetramethylene oxide diol with an average molecular weight of 2000. The final step – oligoether-diphthalimide hydrazinolysis – has been improved. The yield of the target product has been shown to be more than 1.5 times higher when the molar ratio of the reacting components was changed. The oligoether-diamine and the reaction intermediates have been identified by 1H and 13C NMR spectroscopy. It has been demonstrated that the synthesized amine can be used as a curing agent for epoxy urethane oligomers. It is shown that the glass transition temperature of the cured elastomers is lower than −70 °C. These elastomers can be recommended for the use in the conditions of the Arctic and the Far North or Far South of the globe.

A method for the preparation and characterization of single molecular weight urethane oligomers: A preliminary ion mobility and mass spectrometry study

Commercial polyurethanes (PURs) are produced on the industrial scale by reacting methylene diphenyl diisocyanate (MDI) with low MW polyols which are distributions of multiple individual diols. Thus, the resulting PUR oligomers consist of a mixture of structural isomers at each discrete mass in the distribution. The contribution of specific isomers can be studied by starting with monodisperse, structurally-pure polyols, however this approach becomes intractable for larger MW polyols, which are challenging to synthesize and purify. Here we demonstrate a straightforward synthesis approach for generating PUR oligomer distributions with unique numbers of polyol attachments. Four readily-available, low MW polyols (PEG, PPG, PTHF, and PBA) were reacted with phenyl isocyanate (PhNCO) to produce distributions of PUR oligomers exhibiting unique numbers of polyol attachments. Structural characterization by ion mobility (IM) and high resolution mass spectrometry (HRMS) confirmed these PUR oligomers are of a single measurable structure and unique mass, and tandem MS/MS results indicated the oligomer products follow known fragmentation mechanisms.

Development of Bisphenol-A-Glycidyl-Methacrylate- and Trimethylolpropane-Triacrylate-Based Stereolithography 3D Printing Materials

The main advantages of the three-dimensional (3D) printing process are flexible design, rapid prototyping, multi-component structures, and minimal waste. For stereolithography (SLA) 3D printing, common photocurable polymers, such as bisphenol-A glycidyl methacrylate (Bis-EMA), trimethylolpropane triacrylate (TMPTMA), as well as urethane oligomers, have been widely used. For a successful 3D printing process, these photocurable polymers must satisfy several requirements, including transparency, a low viscosity, good mechanical strength, and low shrinkage post-ultraviolet curing process. Herein, we investigated SLA-type photocurable resins prepared using Bis-EMA, TMPTMA, and urethane oligomers. The flexural strength, hardness, conversion rate, output resolution, water absorption, and solubility of the printed materials were investigated. The degree of conversion of the printed specimens measured by infrared spectroscopy ranged from 30 to 60%. We also observed that 64-80 MPa of the flexural strength, 40-60 HV of the surface hardness, 15.6-29.1 MPa of the compression strength, and 3.3-14.5 MPa of the tensile strength. The output resolution was tested using three different structures comprising a series of columns (5-50 mm), circles (0.6-6 mm), and lines (0.2-5 mm). In addition, we used five different pigments to create colored resins and successfully printed complex models of the Eiffel Tower. The research on resins, according to the characteristics of these materials, will help in the design of new materials. These results suggests that acrylate-based resins have the potential for 3D printing.

Fully cross-linked UV-induced peelable acrylic PSA prepared from a dual curable castor oil based urethane acrylate oligomer for wafer dicing

For UV-induced peelable pressure sensitive adhesive (PSA) used in the wafer dicing process, improving the peel performance can effectively increase the process reliability and the yield of subsequent packaging process. In this work, a NCO-containing castor oil-based urethane acrylate oligomer called CO-PUB with dual curable functions (UV-induced polymerization and NCO/OH reaction) was obtained by partially sealing a castor oil-based urethane oligomer with hydroxyethyl acrylate. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectrometer (NMR) results indicated that CO-PUB was successfully prepared. CO-PUB, OH-containing acrylic copolymer, multifunctional acrylate monomer and photo-initiator were used to construct a UV-induced peelable adhesive for silicon wafer dicing. The results showed that NCO groups in CO-PUB underwent the NCO/OH reaction with the acrylic copolymer to obtain a vinyl pendant cross-linked acrylic copolymer. The peel strength of this peelable adhesive before UV irradiation could exceed 20 N/25 mm. After UV irradiation, the unsaturated vinyl bonds contained in it were copolymerized with the multifunctional acrylate monomer to form a fully cross-linked adhesive film and the peel strength could be reduced to below 1 N/25 mm. Compared with UV-induced peelable adhesives prepared by other reported curing agents, the adhesive prepared from CO-PUB reduced UV dose required for curing. The cross-linking degree of cured adhesive film was also increased and the gel content was up to 95%. The residual adhesive after peeling off could be reduced to about 0.32%. In addition, CO-PUB used renewable castor oil as polyol and did not need to add any organic solvent during the preparation process, providing a new idea for the green preparation of UV-induced peelable adhesive with excellent performances.

Resin, cure, and polymer properties of photopolymerizable resins containing bio‐derived isosorbide

AbstractWe have developed photocurable bio‐derived isosorbide (meth)acrylates for use in photoinitiated additive manufacturing (AM). We have shown that the viscosity of isosorbide‐based resins obeyed logarithmic rule of mixtures, and the viscosity values were significantly lower than that of commercial stereolithography (SLA) resins as well as various other urethane (meth)acrylates and bisphenol A (meth)acrylates‐containing blends. Using isobornyl acrylate or 4‐acryloylmorpholine as reactive diluents, we were able to reduce the brittleness of the isosorbide‐based polymers and retain high glass transition temperatures (Tg) of up to 231°C. The isosorbide‐based resins were still somewhat brittle but had both greater Tg and strength relative to analogous bisphenol A dimethacrylate resins. Addition of oligomeric urethane (meth)acrylate crosslinkers further improved the mechanical properties of the polymers, whereby the strength approximately doubled to 55 MPa at 25°C, while maintaining high thermal properties, Tg > 190°C, and low viscosities, <140 cP, that are desirable for photoinduced AM applications. Furthermore, we were able to print this resin using SLA which produced specimens with similar moduls, but reduced strength relative to photocured resins and a commercial high temperature SLA resin.

Frost-Resistant Elastomers with Controllable Microphase Segregation, Based on Epoxy–Ether–Urethane Oligomers

The influence exerted by the molecular mass of the oligoether and structure of the diisocyanate (starting compounds in the synthesis of epoxy–urethane oligomers) on the thermal behavior and physicomechanical properties of elastomers synthesized from them was studied. The use of isophorone diisocyanate allowed synthesis of materials with a higher degree of microphase segregation compared to 2,4-toluene diisocyanate, which led to the preparation of materials with a lower glass transition point.

Effect of castor oil based urethane oligomer on properties of UV-curable pressure sensitive adhesive for peelable wafer dicing tape

In this work, the isocyanate terminated castor oil based urethane oligomer (CO-IPDI) was prepared by the reaction of castor oil and isophorone diisocyanate (IPDI) without adding any organic solvent. After the acrylic copolymer pressure sensitive adhesive (PSA) was heated at 80 °C for 20 min, it was mixed with CO-IPDI, trifunctional acrylic monomer and photo-initiator in a certain proportion to give a UV-curable peelable adhesive for silicon wafer cutting process. Before UV irradiation, the acrylate copolymer chains were cross-linked by CO-IPDI to form a network. After UV irradiation, another polymer network formed by photo-polymerization of trifunctional acrylic monomer hold together with it to form an interpenetrating network (IPN) structure. The results showed that this IPN structured UV-curable peelable PSA had a high peeling strength of 13.99 N/25 mm before UV curing to meet the suggested requirements for silicon wafer cutting process. The peeling strength was significantly decreased to 0.49 N/25 mm after UV curing, and the tape was easily peeled off from wafer with about 0.96% residual adhesive estimated by the area ratio of all residual adhesive particles to silicon wafer observed by scanning electron microscopy. This work provides a new candidate idea for green and efficient preparation of UV-curable peelable PSA.

Evolution of Reaction‐Induced Phase Segregations in Bi‐Soft Segment Urethane Oligomers

AbstractOligomeric bi‐soft segment isocyanate‐terminated polyurethanes (ITPUs) are semi‐finished goods crucial for the fabrication of various polyurethane (PU) products such as foams, thermoplastics, adhesives, dispersions, and elastomers. Incompatibilities and thus phase segregation phenomena play an essential role in tailoring the properties of the final products. In this work, the evolution of reaction‐induced phase segregation (RIPS) in ITPUs is explored in terms of composition and morphology of the phase segregated products as well as competing second order kinetics of the reaction. The results suggest that mechanism and extent of the phase segregation are thermodynamically controlled following the ternary phase diagram of the reactants. A comprehensive description of the phase behavior during the reaction is provided demonstrating excellent control over the morphology of ITPUs by means of appropriate adjustment of the initial reactant composition. These results are fundamental for tailored morphology design as it is employed for instance in membrane synthesis.

Rheological Properties of Epoxy Urethane Oligomers and Сuring Kinetics of Polymer Composites on Their Basis

The rheological properties of epoxy urethane oligomers (EUOs) synthesized at different stoichiometric ratios of reaction groups NCO : OH have been examined over a wide range of temperatures and shear rates using rotational viscometry. The effect of the NCO : OH ratio on the kinetic parameters (dynamic viscosity increase constant and gelation time) of epoxy polyurethane compositions curing at a temperature of 25 ± 1°C have been revealed. Evaluation of the adhesion tensile strength of cold-cured adhesive EUOs joints is presented.

Microheterogeneous Polyetherhydroxylurethane Elastomers with Controlled Phase Structure for Structural Adhesives

Polyetherhydroxylurethane elastomers were prepared from mixtures of epoxy urethane oligomers and diglycidyl urethane, synthesized using isophorone diisocyanate, and the properties of the products obtained were studied. Calorimetric and optical microscopic studies proved the heterogeneity of the materials obtained. These materials surpass in the strength and adhesion characteristics the analogs synthesized using toluene-2,4-diisocyanate.

IPN structured UV-induced peelable adhesive tape prepared by isocyanate terminated urethane oligomer crosslinked acrylic copolymer and photo-crosslinkable trifunctional acrylic monomer

In this paper, a linear isocyanate terminated urethane oligomer, polyethylene glycol modified isophorone diisocyanate oligomer (PEG-IPDI), was prepared by the reaction of polyethylene glycol and isophorone diisocyanate. It is mixed as a cross-linking agent with an acrylic copolymer composed of 2-ethylhexyl acrylate, butyl acrylate, methyl methacrylate, hydroxyethyl acrylate and acrylic acid to form a network pressure sensitive adhesive (PSA) through the reaction of isocyanate groups in PEG-IPDI with hydroxyl and carboxyl groups in acrylic copolymer chains. By blending this network PSA with a photo-initiator and a trifunctional acrylic monomer in a certain ratio, the UV-curable PSA was obtained. After uniformly coating it on the treated polyethylene terephthalate film, a UV-induced peelable PSA tape for a silicon wafer dicing process was prepared. The PSA network formed before UV irradiation was held together with another network produced by UV irradiation of the trifunctional acrylate monomer to give an interpenetrating network (IPN) structure. The results showed that this novel UV-curable PSA tape with IPN structure had strong peel strength before UV irradiation, and could meet the fixed requirements of silicon wafer cutting process. After UV curing, the peel strength was remarkably lowered due to the formation of IPN structure. Compared to those semi-IPN structured PSA tapes prepared with traditional multi-functional urethane acrylate oligomers, the adhesion performances of IPN structured UV peelable PSA tape prepared in this work were similar, but the remaining adhesive on the wafer after the release of the UV cured tape was greatly reduced.

Mechanical Properties of Phenolic Foam Modified Insulation Board by Urethane Oligomer

In this paper, the major research contents include improving the properties of phenolic foams through making urethane oligomer modifiers. Various characterization methods were adopted to analyze the properties and microstructure of phenolic foams. Finally, a new type of phenolic foam, which has good insulation effect and excellent mechanical properties, has been made. The results have shown that this new phenolic foam has the following features: good insulation effect (thermal conductivity is 0.030W/m•K), good hardness (apparent density can reach 40-60kg/m3), and high toughness (the flexural strength can reach to 4.0N/cm2, and the compression strength can be improved by 16% and reach to 0.134Mpa). The phenolic foams can be widely used in construction field of external wall insulation, which is significant in energy conservation

Preparation and Properties of Frost-Resistant Materials Based on Compounds of Oligoether Urethane Epoxides and Diglycidyl Urethane

A procedure was suggested for preparing epoxy ether urethane oligomers via intermediate oligodiisocyanates with increased content of the starting 2,4-toluene diisocyanate. The procedure allows preparation of epoxy-containing oligomers with appreciable fraction of low-molecular-mass diglycidyl urethane. The presence of diglycidyl urethane in the binder enhances not only the adhesion but also the strength of the cured material without significantly affecting the glass transition point of the binder. Elastic materials prepared by curing the compounds studied with cylcoaliphatic amines exhibit enhanced levels of strength and low-temperature elasticity.

The effect of epoxyurethane modification on surface and thermal properties of fluorinated epoxyfunctional siloxane high—solid coatings

Abstract In this work series of high-solids crosslinked hybrid networks based on the comb-like structure fluorinated epoxyfunctional siloxane modified with the epoxy-terminated urethane oligomer and cured with diethylenetriamine, were obtained. The structure of the obtained poly(urethane-siloxane) thermosets was confirmed by FTIR spectroscopy. The thermal properties of the samples were investigated by DSC and TG analyses. The coupled TG-FTIR-MS technique for analysis of gases evolved during thermal decomposition of hybrid materials, was employed. The water contact angles, water absorption and some performance properties of the obtained hybrid coatings were also investigated. The synthesized poly(urethane-siloxane) networks are basically hydrophobic materials. An increased amount of epoxyurethane resulted in a decrease of glass transition temperature, Persoz hardness, and thermal stability as well as in increase of water absorption.

Thermal behaviour and flame retardancy of polyurethane high-solid coatings modified with hexakis(2,3-epoxypropyl)cyclotriphosphazene

Abstract Hexakis(2,3-epoxypropyl)cyclotriphosphazene was employed for preparation of high − solid hybrid organic-inorganic poly(urethane-cyclophosphazene) coatings based on epoxy-terminated urethane oligomer which were cured with ethylenediamine. The flame retardancy, thermal degradation behavior and some surface properties of the coatings were investigated. The results of thermogravimetric analysis suggested that thermal degradation of poly(urethane-cyclophosphazene) occurred in two main stages and the introduction of cyclophosphazene resulted in increase of thermal stability. The main gases released during thermal decomposition of the samples were carbon dioxide, ammonia, water and tetrahydrofuran. The microscale combustion calorimetry revealed that the maximum specific heat release rate and the heat release capacity of the hybrid materials decreased significantly with incorporation of cyclotriphosphazene. The water contact angle and gloss decreased while hardness increased with the increase of hexakis(2,3-epoxypropyl)cyclotriphosphazene contribution in the coating.