Preparation and properties of novel polyurethane insulating coatings based on glycerin‐terminated urethane prepolymers and blocked isocyanate

Novel polyurethane insulating coatings were prepared from the reaction of glycerin‐terminated polyurethane prepolymers (GPUPs) and a blocked isocyanate curing agent (BIC). The GPUPs were prepared from the reaction of one equivalent of polycaprolactone polyol (CAPA 210) with an excess amount of 4,4′‐methylene bis(phenyl isocyanate) (MDI) and subsequent reaction of the NCO‐terminated polyurethane with glycerin. The BIC was prepared from the reaction of trimethylol propane (TMP), toluene diisocyanate (TDI) and N‐methylaniline (NMA). The polyols and curing agent were characterized by conventional methods while the curing condition was optimized via gel content measurements. The curing kinetics of the polyurethane coating were investigated and the kinetic parameters derived. The crosslink densities of the samples were determined via the equilibrium swelling method, using the Flory–Rehner equation. The relationships between the crosslink density and the electrical, physical, mechanical and dynamic mechanical properties of the coatings were also studied. Copyright © 2005 Society of Chemical Industry     

Novel polyurethane insulating coatings based on polyhydroxyl compounds,derived from glycolysed PET and castor oil

To prepare versatile polyurethane material suitable as insulating coatings, novel kinds of polyhydroxy compounds (PHCs) were prepared via transesterification reaction of poly(ethylene terphthalate), different molecular weight of poly(ethylene glycol)s (PEGs), and castor oil. The final networks were prepared via crosslinking of PHCs with a novel blocked isocyanate curing agent (BPI) made from trimethylol propane (TMP), toluene diisocyanate (TDI), and N‐methyl aniline (NMA). Polyols and curing agent were characterized by conventional methods and the curing condition was optimized via gel content measurements. Curing kinetic of the polyurethane network formation was investigated by differential scanning calorimetric method and the kinetic parameters were derived. Crosslink density of the samples was determined via equilibrium swelling method and by using Flory‐Rehner equations. Effects of crosslink density on electrical, physical, mechanical, and dynamic mechanical (DMTA) properties of the polyurethane coatings were investigated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1222–1233, 2006     

Synthesis,Characterization and Properties of Novel Poly(urethane‐imide) Networks as Electrical Insulators with Improved Thermal Stability

Summary: A new series of thermoplastic poly(urethane‐imide)s (TPUI1‐4) containing hydroxyl groups in the backbone was synthesized from the reaction of epoxy‐terminated polyurethane prepolymers (EPU1‐4) and an imide containing diacid (DIDA) chain extender under optimized reaction conditions. EPU1‐4 was prepared through end‐functionalization of NCO‐terminated polyurethanes based on polyester polyol (CAPA) and hexamethylene diisocyanate with glycidol. A blocked isocyanate (BIC) was made from the reaction of trimethylol propane (TMP), toluene diisocyanate (TDI) and N‐methylaniline (NMA). Polymer networks were prepared from the reaction of librated isocyanate groups of BIC with hydroxyl groups of TPUIs. The starting materials and polymers were characterized by conventional spectroscopic methods and the physical, thermal and electrical properties of crosslinked networks were studied. Investigation of the recorded properties for these samples showed considerable improvement in thermal and electrical properties in comparison to common polyurethanes.

Synthetic route for preparation of TPUIs.     

Effects of TDI and FA‐703 on physico‐mechanical properties of polyurethane dispersion

A series of water dispersion polyurethanes dispersions (PUDs) were prepared by polyaddition reaction using isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG), dimethylol propionic acid (DMPA), and triol (trade name FA‐703). Various formulations were designed to investigate the effects of process variables such as TDI and FA‐703 on the physico‐mechanical properties of PUD. IR spectroscopy was used to check the end of polymerization reaction and characterization of polymer. Evolution of the particle size distribution, contact angle, T_g, molecular weight, viscosity, and mechanical properties of the emulsion‐cast films were significantly affected by variable content of TDI and FA‐703. Average particle size of the prepared polyurethane emulsions and contact angle decrease with increase of content of FA‐703 and TDI. Molecular weight, T_g, tensile strength, tear strength, hardness, viscosity and elongation at break increase with increase of content of FA‐703 and TDI. The increase of molecular weight, tensile strength, tear strength and elongation at break properties are interpreted in terms of increasing hard segments, chain flexibility, and phase separation in high content of FA‐703 and TDI‐based polyurethane. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of triazole ring‐containing pentol chain extender and its effect on the properties of hyperbranched polyurethane‐urea coatings

This article describes the synthesis and property evaluation of different hyperbranched polyurethane‐urea (HBPUU) coatings based on a newly synthesized triazole ring‐based pentol chain extender. For this initially, the chain extender was synthesized using acetylene azide click reaction and the structure of the intermediate compounds were confirmed by ¹H‐, ¹³C‐NMR, FTIR, and ESI‐mass spectrometry. In the further steps, the required HBPUU coatings were prepared by a systematic three‐step reaction process. In the first step, a isocyanate terminated prepolymer resin was synthesized at NCO/OH ratio of 1.2 : 1, while the second and third step involves the partially chain extension followed by moisture curing. The excess NCO content in the prepolymer was calculated by standard dibutylamine titration method and partially (10, 20, 30, 50, and 70% of the excess NCO content) chain extended with the pentol chain extender and remaining was moisture cured. The structure property relation of different HBPUU coating films were analyzed by FTIR peak deconvulation technique using Gaussian curve fitting procedure while, their viscoelastic and thermo‐mechanical properties were measured by dynamic mechanical thermal analysis, thermo gravimetric analysis, differential scanning calorimetric, and universal testing machine instruments. These results showed that thermal stability, glass transition temperature (T_g), elongation at break increases but the storage and tensile modulus decreases with increasing the percent loading of the triazole chain extender. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Evaluation of disulfide chain extender effect on the mechanical properties of unsaturated polyurethane‐urea networks

4‐Aminophenyl disulfide and bis(4‐aminophenyl)methane chain extenders containing hydroxyl‐terminated polybutadiene‐based polyurethane‐ureas are prepared one‐shot to explore the effect of the chain extender structure on the elastomers mechanical properties. However, the results revealed that the participation of the disulfide chain extender in side reactions like thiol‐ene and proton abstraction prevented disulfide metathesis reaction due to decomposing chain extender in the polyurethane‐urea matrix. Also, these side reactions improved the phase mixing via chemical crosslinking between polyurethane‐ureas soft and hard segments, too. Tensile test results showed higher stress strength of the elastomers in the presence of the disulfide chain extender in comparison with the nondisulfide bond containing elastomers. This result was in agreement with the observed result in dynamical mechanical analysis. Dynamic mechanical analysis results established that the absence of the disulfide bond in the polyurethane‐urea matrix led to the higher viscous modulus. The swelling test revealed chemical crosslinking increased in the presence of the disulfide bond. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46309.     

Preparation and characterization of crosslinked polyurethane‐block‐poly(trifluoropropylmethyl)siloxane elastomers with potential biomedical applications

A series of crosslinked polyurethane‐block‐poly(trifluoropropylmethyl)siloxane elastomers were prepared via two steps. First, poly(trifluoropropylmethyl)siloxane polyurethane (FSPU) prepolymers were synthesized with α,ω‐bis(3‐aminopropyldiethoxylsilane) poly(trifluoropropylmethyl)siloxane (APFS) and toluenediisocyanate (TDI) and then capped with butanediol to generate the macromolecular FSPU diol extender. Second, polyurethane prepolymers synthesized from poly(tetramethylene oxide) and TDI were reacted with FSPU diol extenders with different ratios. The copolymers formed films through moisture curing and were characterized by Fourier transform infrared spectroscopy, DSC, dynamic mechanical analysis, TGA, mechanical testing etc. It is found that the equivalent ratio of reactants gives rise to a high molecular weight of copolymers and that low molecular weight APFS in the copolymers can form a certain number of silicon–oxygen crosslinks resulting from silicon alkoxy to produce higher tensile strength elastomers. The material thus has higher thermal stability and a more stable surface performance. The copolymers are then good candidates for biomedical applications.© 2013 Society of Chemical Industry     

Curing reaction of amino‐terminated aqueous‐based polyurethane dispersions with triglycidyl‐containing compound

Amino‐terminated anionic aqueous‐based polyurethane (PU) dispersion was obtained from NCO‐terminated PU prepolymer, which was neutralized with an excess triethylamine (TEA) and chain extended by ethylenediamine (EDA) during water dispersion process. That PU prepolymer was obtained from a polyaddition reaction of isophorone diisocyanate (IPDI), polypropylene glycol‐2000 (PPG‐2000), and 2,2′‐dimethylol propanoic acid (DMPA). This aqueous‐based PU dispersion was treated with trimethylolpropane triglycidyl ether (TMPTGE) as a latent curing agent and resulted in a self‐cured PU resin on drying. A model ring‐opening curing reaction between oxirane group of TMPTGE with terminal amino group of PU was demonstrated by glycidol with n‐butyl amine. The physical and mechanical properties as well as thermogravimetric analyses of these self‐cured PU resins were evaluated in this article. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of multifunctional thiol‐ and acrylate‐terminated polyurethane: A comparative study on their properties in UV curable coatings

The multifunctional thiol‐ and acrylate‐terminated polyurethane (PU) has been successfully prepared for using as the main resin in the UV curable coatings. The structure and molecule weight of prepared PUs were analyzed by fourier transformed infrared spectroscopy (FTIR) and gel permeation chromatography, respectively. The results showed that the different terminal multifunctional groups have been grafted onto the PU and their difference in molecule weight was significant. Used as the main resin in coatings, the curing kinetic and percentage conversion of the different UV curing coatings system were investigated by real‐time FTIR method, and the effects of terminal functional groups and photoinitiator on the final conversion percentage and conversion rate were also compared. It is observed that the thiol‐terminated PU had higher conversion speed and final conversion percentage due to the remarkable effect of mercapto groups on reducing oxygen inhibition during UV curing process. The shrinkage, viscosity, and adhesion of UV curable coatings with thiol‐ and acrylate‐terminated PUs were also investigated and compared, and the results indicated that the former exhibited lower shrinkage and higher adhesion performances than the latter, along with the lower viscosity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40740.     

Synthesis of hydrolytically stable low elastic modulus polyurethane‐urea for biomedical applications

Polyurethane‐urea without ether linkages was synthesised using dicyclohexyl‐methane diisocyanate (SMDI), hydroxy‐terminated polybutadiene (HTPBD) and m‐phenylenediamine (PDA). The hydrolytic stability of this polymer was investigated under in vitro conditions using Ringer's solution and phosphate‐buffered saline, and the stability of candidate polyurethane‐urea polymers was compared with that of polyurethane prepared with SMDI, HTPBD and 1,4‐butanediol [BD]. The change of tensile properties, hardness and surface properties in the aged polymer is significant for polyurethane when compared with those of polyurethane‐urea polymer. The in vitro study revealed possible applications of polyurethane‐urea for long‐term biomedical applications. © 2000 Society of Chemical Industry     

聚丁二烯聚氨酯-脲密封材料的性能研究

以端羟基聚丁二烯 (HTPB)、二异氰酸酯 (TDI或IPDI)为原料制备预聚体 ,利用多元胺或多元醇作固化剂 ,制成聚氨酯及聚氨酯 脲弹性体。测试了这些材料的力学性能、动态力学性能、粘接性能、耐介质、耐水解及透气性能。结果表明 :HTPB型聚氨酯 脲具有优良的力学性能 ,其耐介质及耐水解性明显优于聚醚型或聚酯型聚氨酯 ,具有很好的密封性能 ,可用作水下密封材料。     

Development of Functional Polyurethane–ZnO Hybrid Nanocomposite Coatings from Thevetia peruviana Seed Oil

The present article reports eco‐friendly multi‐functional polyurethane–ZnO hybrid nanocomposite coatings obtained from Thevetia peruviana seed oil (TPSO). Initially, the polyols were prepared by treating TPSO with glycerol and the formation was supported by Fourier transform infrared (FT‐IR) and ¹H‐NMR studies. In the next stage, siloxane functionalized ZnO nanoparticles were added to the polyol mixture in different weight percentages (0, 1 and 2 %) and then treated with excess 4,4′‐diisocyanatodicyclohexylmethane (H₁₂MDI) in order to synthesize isocyanate terminated polyurethane nanocomposites. The polyurethane hybrids were then casted as thin films and cured under atmospheric moisture. After complete curing they were characterized by using FT‐IR, ¹H‐NMR, ¹³C‐NMR, X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and dynamic mechanical thermal analysis techniques. The hybrid nanocomposites showed superior thermo‐mechanical and anti‐corrosive properties compared to pristine polyurethane. Also, due to the presence of nano ZnO in the polyurethane matrix, the composite coatings are showing excellent resistance towards various bacterial and fungal stains.     

Novel method for preparation of polyurethane elastomers with improved thermal stability and electrical insulating properties

A novel method was developed for the preparation of polyurethane with enhanced thermal stability and electrical insulation properties via the reaction of epoxy‐terminated polyurethane prepolymer (EPU) and poly(amic acid) (PAA). EPUs were synthesized from the reaction of glycidol with NCO‐terminated polyurethane prepolymers, which were prepared from the reaction of polycaprolactone‐based polyol (CAPA) of different molecular weights and some commercially available diisocyanates including hexamethylene diisocyante, toluene diisocyanate, and 4,4′‐methylene bis(phenyl isocyanate). PAA was prepared from the reaction of equimolar amounts of pyromellitic dianhydride and oxydianiline. The effects of PAA content, the nature of diisocyanate, and the molecular weight of CAPA on the mechanical, thermal, thermomechanical, and electrical properties of the final networks were investigated. The crosslink density of the samples was determined according to an equilibrium swelling method using the Flory–Rehner equation and was correlated to the structure of the final polymers. Gel content and activation energy of network formation in the absence and the presence of a tertiary amine catalyst were also studied. The results showed considerable improvement in the thermal, electrical, and mechanical properties compared to those of other common polyurethanes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1776–1785, 2007     

Hybridization of aqueous PU/epoxy resin via a dual self‐curing process

Amino‐terminated and carboxyl‐containing polyurethane (PU) is prepared by an isocyanate‐terminated PU prepolymer process. Carboxyl‐containing epoxy resin is obtained from a half‐esterification of epoxy resin with maleic anhydride. These two aqueous resins are obtained after neutralization with triethylamine and dispersion into water phase, respectively. A latent curing agent (TMPTA‐AZ) is prepared by a Michael addition of aziridine with trimethylolpropane triacrylate (TMPTA). A self‐curing system of PU/epoxy hybrid is obtained from a blending of these two aqueous resins with latent curing agent. PU/epoxy hybrid is derived from two self‐curing reactions on drying. The first curing for hybridization between PU amino groups with oxirane groups of epoxy resin is via a ring‐opening reaction and the secondary curing takes place on carboxyl groups of PU/epoxy hybrid with aziridine of TMPTA‐AZ. The final properties of these dual self‐cured PU/epoxy hybrids are reported. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of novel thermoplastic poly(oligophosphazene‐urethane)s

BACKGROUND: Polyurethanes are some of the most popular polymers used in a variety of products, such as coatings, adhesives, flexible and rigid foams, elastomers, etc. Despite the possibility of tailoring their properties, polyurethanes suffer a serious disadvantage of poor thermal stability. Many attempts have been made in order to improve the thermal stability of polyurethanes. RESULTS: A new hydroxyl‐terminated oligomer containing sulfone groups, 2,2‐bis(4‐hydroxy‐4,4‐sulfonyldiphoneloxy)tetraphenoxyoligocyclotriphosphazene (HSPPZ), was synthesized. HSPPZ was characterized using Fourier transform infrared (FTIR), NMR and gel permeation chromatography analyses. A series of novel thermoplastic poly(oligophosphazene‐urethane)s were then synthesized via the reaction of NCO‐terminated polyurethane prepolymer with HSPPZ containing chain‐extender diols. Their structure and properties were investigated using FTIR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, X‐ray diffraction, water contact angle measurement and tensile measurements. CONCLUSION: Compared to conventional thermoplastic polyurethanes, poly(oligophosphazene‐urethane)s exhibit better thermal stability, low‐temperature resistance and hydrophobicity, but their mechanical properties are slightly poorer. Copyright © 2009 Society of Chemical Industry     

Rapid synthesis of new block copolyurethanes derived from L‐leucine‐PEG in ionic liquids under microwave irradiation

This study concerns the synthesis of novel multi block polyurethane (PU) copolymers containing eco‐friendly segments, taking the advantage of ionic liquids (IL)s under microwave irradiation. For this, L ‐leucine anhydride cyclodipeptide (LAC) was prepared and then a new class of poly(ether‐urethane‐urea)s (PEUUs) was synthesized with two types of ILs, including room temperature imidazolium (RTIL)s and molten ammonium type ILs. ILs were used as reaction media and PUs were prepared via two‐step polymerization method. Polymerization reaction was also conducted under conventional heating method in N‐methyl pyrrolidone (NMP) as reaction solvent. In the first step, 4,4′‐methylene‐bis(4‐phenylisocyanate) (MDI) was reacted with LAC to produce isocyanate‐terminated poly(imide‐urea) oligomers as hard segment. Chain extension of the resulting prepolymer with polyethyleneglycol (PEG) of molecular weights of 400 (PEG‐400) was the second step to furnish a series of new PEUUs. These multiblock copolymers are optically active, thermally stable and soluble in amide‐type solvents. PEUUs prepared in ILs under microwave irradiation showed more phase separation and crystallinity than PEUU prepared under conventional method. Some structural characterization and physical properties of these PEUUs, prepared under different methods, are reported and compared. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Biodegradable polyurethane elastomers prepared from isocyanate‐terminated poly(ethylene adipate), castor oil,and glycerol

The curing reaction of tolylene‐2,4‐diisocyanate‐terminated poly(ethylene adipate) (PEA‐TDI) with a mixture of castor oil (CO) and glycerol (GO) with a NCO/OH ratio of 1.0 at 150°C gave crosslinked polyurethane (CO/GO‐PU). All the polyurethanes were elastomeric materials at room temperature. The glass‐transition temperature of the CO/GO‐PU increased with decreasing CO/GO ratio. All the cured polyurethanes had a higher 5% weight loss temperature than PEA‐TDI. The tensile strength and modulus of the polyurethanes increased with decreasing CO/GO ratio, and tensile residual strain after 300% elongation for all the CO/GO‐PUs was almost 0. All the polyurethanes had biodegradability, when measured by a biochemical oxygen demand method in an aqueous medium using activated sludge. The rate of the biodegradation of the polyurethanes increased with an increase of CO/GO ratio. The crosslinked CO‐PU showed much higher biodegradability than the linear PEA‐TDI. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Self‐curable system of an aqueous‐based polyurethane dispersion via a ring‐opening reaction of azetidine end groups

An azetidine (AZT) containing compound, 3‐azetidinyl propanol was synthesized from methyl acrylate with 3‐amino‐1‐propanol in a four‐step reaction. It was introduced into an isocyanate‐terminated carboxylic acid containing polyurethane (PU) prepolymer as the end group. A single‐component, AZT‐terminated self‐curable aqueous‐based PU dispersion was obtained from the water dispersion process after it was neutralized with triethylamine. Its carboxylic groups served not only as the internal emulsifier stabilizing the aqueous PU dispersion but also as PU self‐curing sites toward its AZT end groups via a ring‐opening reaction. The curing reaction took place on drying and resulted in polymeric network structure formation among the polymers. The performance properties of this self‐cured PU were evaluated in this study. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4383–4393, 2006     

Synthesis and properties of polybenzoxazine modified polyurethanes as a new type of electrical insulators with improved thermal stability

A new class of electrical insulating materials with improved thermal stability was prepared from combination of polybenzoxazine with epoxy terminated polyurethane prepolymer (EPU). EPU was prepared by the reaction of glycidol with NCO‐terminated urethane prepolymer. The prepolymer was prepared from polycaprolactone polyol (molecular weight 1000), and hexamethylene diisocyanate. Bisphenol‐A and aniline were used for preparation of benzoxazine monomer. Mode of reactions and optimum curing condition were determined by DSC and FTIR analysis. Upon these analysis as well as DMTA findings, formation of interpenetrating polymer networks was suggested for blends consisted different weight ratios of two components. Viscoelastic behavior, mechanical, thermal, and electrical properties of the prepared samples was studied and their relation to the chemical structure and composition of blends were elucidated. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Synthesis and properties of novel biodegradable poly(ε‐caprolactone)/ poly(ethylene glycol)‐based polyurethane elastomers

Elastomeric polyurethanes with tunable biodegradation properties and suitable for numerous biomedical applications were synthesized via reaction of epoxy‐terminated polyurethanes (EUPs) with 1,6‐hexamethylenediamine as curing agent. The EUPs themselves were prepared from glycidol and isocyanate‐terminated polyurethanes made from poly(ε‐caprolactone) (PCL) or poly(ethylene glycol) (PEG) and 1,6‐hexamethylene diisocyanate. All the polymers were characterized by conventional methods, and their physical, mechanical, thermal, and degradation properties were studied. The results showed that the degradation rate and mechanical properties of the final products can be controlled by the amount of PEG or PCL present in the EUP. Increasing the PEG content causes an increase of hydrolytic degradation rate, and increasing the PCL content improves the mechanical properties of the final products. Evaluation of cytotoxcicity showed nontoxic behavior of the prepared samples, but the cytocompatibility of these polymers needs to be improved. Copyright © 2006 Society of Chemical Industry