New polyurethane cationomers with naphthyl and phenyltriazene pendants: Synthesis and properties

Two new diols bearing triazene moiety, 1‐(α‐naphthyl)‐3,3‐di(2‐hydroxyethyl) triazene‐1 (NT‐D) and 1‐phenyl‐3,3‐di(2‐hydroxyethyl) triazene‐1 (PT‐D), were synthesized from aromatic amines and diethanolamine. These monomers were used as chain coextenders in the two‐step addition reaction between poly(tetramethylene oxide) diol, 2,4‐tolylene diisocyanate, and N‐methyldiethanolamine to obtain photosensitive polyurethanes of elastomer type. Triazene polyurethane cationomers with chlorine counterions were prepared via a quaternization reaction of the above polymers with benzyl chloride. All polyurethanes had a quantity of triazene units between 7.02 and 8.93 wt % polymer, and the content of ammonium quaternary groups in the cationic ones was of 30.56 meq/100 g naphthyl triazene polyurethane cationomer (PUC‐NT) and 30.19 meq/100 g phenyl triazene polyurethane cationomer (PUC‐PT), respectively. Photobehavior of the triazene units in all polymers under continuous Hg‐lamp irradiation was similar to that found for monomers, when both chromophores were transformed during UV irradiation. It is concluded that the PT‐D acts as a more efficient sensitizer in the UV light‐induced reaction but the photolysis in elastomeric films was lower than that observed in solution. The presence of quaternary ammonium structure on the same polymer backbone decreases the constant rates of photolysis. Because the triazene polyurethanes become crosslinked during UV irradiation could be assessed as potential negative‐resist polymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2599–2605, 2004     

Poly(etherurethane) anionomers with azobenzene carboxylate groups: Synthesis and properties

A new diol with a one‐sided azobenzene‐carboxyl group was prepared to be used for photosensible polymers synthesis. Azobenzene carboxyl containing polyurethane based on poly(tetramethylene oxide) diol of 2000 average molecular weight, 2,4‐tolylene diisocyanate, and the mentioned azo diol, was obtained and characterized. Upon neutralization the acid form with metal acetate (Li⁺¹, Ca⁺²) or triethylamine azo carboxylate anionomers with an improved phase separation were obtained. Viscometric measurements of diluted dimethylformamide solutions exhibited evidence of polyelectrolyte behavior. Some aspects of the trans‐cis photoisomerization have been examined to design in future various dyed aqueous dispersions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 577–582, 2005     

Properties of segmented polyurethanes derived from different diisocyanates

Various segmented polyurethane materials with a polyurethane hard segment (HS) content of 40 wt % were prepared by bulk polymerization of a poly(tetramethylene ether) glycol with M_n of 2000, 1,4‐butanediol, and various diisocyanates. The diisocyanates used were pure 4,4′‐diphenylmethane diisocyanate (MDI), 2,4‐toluene diisocyanate (T100), toluene diisocyanate containing 80% 2,4‐isomer and 20% 2,6‐isomer (T80), isophorone diisocyanate (IPDI), hydrogenated 4,4′‐diphenylmethane diisocyanate (HMDI), and 1,6‐hexane diisocyanate (HDI). The segmented polyurethane materials were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile properties, tear strength, and Shore A hardness. The DSC and DMA data show that the thermal transitions are influenced significantly by the diisocyanate structure. In the segmented polyurethane materials with aliphatic HS, the polyether soft segment (SS) is immiscible with the HS. However, in the segmented polyurethane materials with aromatic HS, the SS is partially miscible with the HS. The diisocyanate structure also influences the mechanical properties significantly and is described as the effect of symmetry and chemical structure of the HS. Various solution polymerized polyurethane resins with solid content of 30 wt % were also prepared and their thickness retention, water resistance, and yellowing resistance were determined for the evaluation of their usage as wet process polyurethane leather. The polyurethane resin with aliphatic HS show poorer thickness retention but better yellowing resistance. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 167–174, 2000     

Synthesis and properties of new polyurethane ionomers. I. Photosensitive cationomers with triazene units

New bifunctional triazene compounds 1‐(m‐ hydroxymethyl)phenyl‐3‐(2‐hydroxyethyl)‐3‐methyltriaz(1)ene and l‐p‐nitrophenyl‐3,3‐di(2‐hydroxyethyl)triaz(1)ene as intermediates in polyurethane synthesis were prepared. Photosensitive polyetherurethane cationomers based on poly(tetramethylene oxide) diol of 2,000 average molecular weight, tolylene‐2,4‐diisocyanate, and N‐methyldiethanolamine/triazene diols, as cochain extender, followed by a quaternization with benzyl chloride, were synthesized and characterized. Upon UV irradiation, feniltriazene chromophore in monomer and both polymers (ionomeric or nonionomeric type) is irreversibly cleaved, as evidenced in photolytic and kinetic studies. The rate constant of photolysis in ionomer film was lower than for the corresponding nonionic film. A positive pattern can then be developed by treatment with CHCl₃ that dissolves the exposed zone, while the unexposed area remains resistant and insoluble. By incorporating side nitrofeniltriazene groups, photostable polyurethanes were obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1203–1210, 2003     

N,N‐diethyl dithiocarbamato group induced photografting of methyl methacrylate onto polyurethane

The N,N‐diethyl dithiocarbamato group present in a variety of compounds acts as an initiator in the photopolymerization processes. The photolability of this group is due to the cleavage of the C S bond by UV irradiation. N,N‐Diethyl dithiocarbamato‐(1,2)‐propane diol with a pendent N,N‐diethyl dithiocarbamato group was prepared from 3‐chloro‐(1,2)‐propane diol and sodium diethyl dithiocarbamate. A polyurethane macrophotoinitiator was then synthesized by a two‐step process, where N,N‐diethyl dithiocarbamato‐(1,2)‐propane diol was used as the chain extender. Other components used included 4,4′‐diphenylmethane diisocyanate and poly(propylene glycol) (molecular weight = 1000). The polyurethane thus synthesized had pendent N,N‐diethyl dithiocarbamato groups. This polyurethane macrophotoinitiator was then used to polymerize methyl methacrylate in a photochemical reactor (Compact‐LP‐MP 88) at 254 nm. The resulting graft copolymer, polyurethane‐g‐poly(methyl methacrylate), was freed from the homopolymer by a standard procedure. The graft copolymer was characterized by Fourier transform infrared spectroscopy, ¹H‐NMR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, solution viscometry, and scanning electron microscopy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rheo‐kinetic measurement of thermoplastic polyurethane polymerization in a measurement kneader

The rheo‐kinetics of thermoplastic polyurethane (TPU) formation was investigated in a measurement kneader at high temperatures. The TPU was made of a polyester polyol, methyl‐propane‐diol and a 50/50 mixture of 2,4′‐ and 4,4′‐diphenylmethane diisocyanate (MDI). The reaction proceeded according to a second order reaction for which the kinetic constants were determined by size exclusion chromatography (SEC) analysis. The activation energy was found to be equal to 61.3 kJ/mol, and the pre‐exponential factor was equal to 2.18e6 mol/kg K. For the temperature range under investigation, the flow activation energy was equal to 42.7 kJ/mol, which is comparable to that of a linear polymer. This indicates that the hard segments are completely dissolved at the temperatures investigated. The initial part of the reaction was much faster than anticipated from the kinetic measurements. Diffusion limitations at higher conversions probably cause this decrease in reaction velocity. At longer reaction times, the molecular weight leveled off because of depolymerization. Therefore, additional experiments are necessary to describe the complete polymerization of thermoplastic polyurethane. Polym. Eng. Sci. 44:1648–1655, 2004. © 2004 Society of Plastics Engineers.     

Preparation and characterization of novel polyurethanes containing 4,4′‐{oxy‐1,4‐diphenyl bis(nitromethylidine)}diphenol schiff base diol

Four novel segmented polyurethanes (PUs) based on4,4′‐{oxy‐1,4‐diphenyl bis(nitromethylidine)}diphenol (ODBNMD) diol with different diisocyanates such as 4,4′‐diphenylmethane diisocyanate, toluene 2,4‐diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate have been prepared by solution method. The structures of ODBNMD and PUs have been confirmed by Fourier transform infrared (FTIR), nuclear magnetic resonance (¹H‐NMR and ¹³C‐NMR), UV‐visible, and fluorescence spectroscopies. The segmented PUs were further characterized by thermogravimetry (TGA), differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction. FTIR confirmed hydrogen bonding interactions, whereas TGA and DSC suggested that introduction of aromatic/phenyl ring in the main chain considerably increased the thermal stability. POLYM. ENG. SCI., 54:24–32, 2014. © 2013 Society of Plastics Engineers     

A kinetic investigation of polyurethane polymerization for reactive extrusion purposes

The effects of the reaction conditions on the kinetics of two different polyurethane systems were investigated. To do so, three different kinetic methods were compared: adiabatic temperature rise (ATR), measurement kneader, and high‐temperature measurements. For the first polyurethane system, consisting of 4,4‐diphenylmethane diisocyanate (4,4‐MDI), butane diol, and a polyester polyol, the reaction conditions did not seem to matter; a kinetically controlled reaction was implicated for all reaction conditions. The reaction was second order in isocyanate concentration and 0.5th order in catalyst concentration and had an activation energy of 52 kJ/mol. The second polyurethane system consisted of a mixture of 2,4‐diphenylmethane diisocyanate and 4,4‐MDI, methyl propane diol, and a polyester polyol. For this system, each of the three measurement methods showed different behavior. Only at a low catalyst concentration did the ATR experiments show catalyst dependence; at higher catalyst levels and for the other two measurement methods, no catalyst dependence was present. Furthermore, the ATR experiments proceeded much faster. Presumably, for this system, the rapid diffusion interfacial of the species present was hindered by the presence of bulky oligomer molecules. The result was a diffusion limitation reaction at low conversions and an inhomogeneous distribution of species at higher conversions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 370–382, 2006     

Synthesis,characterization of novel dihydrazide containing polyurethanes based on N1,N2‐bis[(4‐hydroxyphenyl)methylene]ethanedihydrazide and various diisocyanates

Four novel types of polyurethanes (PUs) were prepared from N¹,N²‐bis[(4‐hydroxyphenyl)methylene]ethanedihydrazide with two aromatic diisocyanates (4,4′‐diphenylmethane diisocyanate and tolylene 2,4‐diisocyanate) and two aliphatic diisocyanates (isophorone diisocyanate and hexamethylene diisocyanate). The chemical structure of both diol and PUs was confirmed by UV–vis, fluoroscence, FTIR, ¹H NMR, and ¹³C NMR spectral data. DSC data show that PUs have multiple endotherm peak. X‐ray diffraction revealed that the PUs contained semicrystalline and amorphous regions that varied with the nature of the backbone structures. PUs were soluble in polar aprotic solvents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of diisocyanate structures on the properties of liquid crystalline polyurethanes

Thermotropic liquid crystalline polyurethanes (LCPUs) were synthesized through the polyaddition reaction of 2,4‐toluene diisocyanate (2,4‐TDI), 4,4′‐diphenylmethane diisocyanate (MDI), or o‐toluidine diisocyanate (ODI) with 4,4′‐bis(6‐hydroxyhexoxy)biphenyl, and the effect of the structures of the diisocyanates on the properties of LCPUs were investigated. Intrinsic viscosities of the polymers were in the range of 0.23–0.30 dL/g. Mesomorphic behavior of the polyurethanes were investigated by differential scanning calorimetry, polarized optical microscopy, and wide‐angle X‐ray scattering. Different mesomorphic behaviors were observed according to the different structural characteristics of diisocyanates. Polyurethanes employing 2,4‐TDI and MDI exhibited monotropic behaviors, while that with ODI showed enantiotropic behavior. POLYM. ENG. SCI., 47:439–446, 2007. © 2007 Society of Plastics Engineers.     

A novel polyurethane sealant based on hydroxy‐terminated polybutadiene

A novel two component polyurethane sealant has been prepared. Component A, known as prepolymer, is synthesized by capping hydroxy‐terminated polybutadiene (HTPB) with toluene diisocyanate. Component B, known as hardener, comprises of a polyol (polyoxypropylene triol) as crosslinker and 4,4′‐diamino‐3,3′‐dichlorodiphenylmethane (DADCDPM) and 4,4′‐diamino‐3,3′‐dichlorotriphenylmethane (DADCTPM) as chain extenders and fillers. Evaluation of mechanical properties and aging studies indicate that the sealant has excellent mechanical properties and stability in different environment. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 884–890, 2006     

Influence of interchange reactions on the miscibility of polyesterurethanes/polycarbonate binary blends

A series of thermoplastic polyurethane elastomers (TPUs) with various hard-segment contents was prepared using 4,4′-diphenylmethane diisocyanate and 1,4-butanediol as the hard segment and poly(ethylene adipate)diol or poly(butylene adipate)diol, whose number-average molecular weight is 2000, as the soft segment. The miscibility of TPU/polycarbonate (PC) blends observed by differential scanning calorimetry was enhanced by the interchange reaction at high temperature. Both hard and soft segments were suggested to be involved in the interchange reaction with PC. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2363–2369, 1997     

Polyurethanes and polyesters from lignin

Lignin, obtained through steam explosion from straw, was completely characterized via elemental analysis, gel permeation chromatography, ultraviolet and infrared spectroscopy, and ¹³C and ¹H nuclear magnetic resonance spectrometry. Polyurethanes were obtained by treating steam‐exploded lignin from straw with 4,4′‐methylenebis(phenylisocyanate), 4,4′‐methylenebis(phenylisocyanate) –ethandiol, and poly(1,4‐butandiol)tolylene‐2,4‐diisocyanate terminated. The obtained materials were characterized by using gel permeation chromatography, infrared spectroscopy, and scanning electron microscopy. Differential scanning calorimetry analysis showed a T_g at ?6°C, assigned to the glass transition of the poly(1,4‐butandiol) chains. The presence of ethylene glycol reduced the yields of the polyurethanes. The use of the prepolymer gave the best results in polyurethane formation. Steam‐exploded lignin was used as the starting material in the synthesis of polyesters. Lignin was treated with dodecanoyl dichloride. The products were characterized by using gel permeation chromatography, infrared spectroscopy, ¹³C and ¹H nuclear magnetic resonance spectrometry, and scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1451–1456, 2005     

Low-temperature behavior of polyurethane elastomers

A study of the performance at low temperatures of various polyurethane elastomer systems, prepared from polyether and polyester diols with 2,4-toluene diisocyanate and 4,4′-methylenebis(2-chloroaniline), p,p′-diphenylmethane diisocyanate and 1,4-butanediol, and 4,4′-methylenebis(cyclohexylisocyanate) and methylenedianiline, has shown the polytetramethylene ether diols to impart the best low-temperature behavior to the elastomers. The properties studied were the apparent modulus of rigidity with the Clash and Berg torsional apparatus, the hardness with a Shore D Durometer, and the resiliency with the Bashore Resiliometer.     

Synthesis and characterization of novel Schiff base polyurethanes

Eight different types of novel polyurethanes (PUs) were synthesized through the polyaddition reaction of 4,4′‐(ethane‐1,2‐diylidenedinitrilo)diphenol and 4,4′‐(pentane‐1,5‐diylidenedinitrilo)diphenol with four different diisocyanates: 4,4′‐diphenylmethane diisocyanate, toluene 2,4‐diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. The resulting PUs were soluble in polar, aprotic solvents. Structures of the diols and PUs were established with ultraviolet–visible, fluorescence, Fourier transform infrared (FTIR), ¹H‐NMR, and ¹³C‐NMR spectroscopy data. FTIR and NMR spectral data indicated the disappearance of both hydroxyl and isocyanate groups in the PUs. The thermal properties were investigated with thermogravimetry and differential scanning calorimetry. The weight losses, glass transitions, onset temperatures, and crystalline melting temperatures were measured. All the PUs exhibited semicrystalline and amorphous morphologies, as indicated by X‐ray diffraction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009.     

Chain‐extended polyurethanes—Synthesis and characterization

Chain‐extended polyurethanes (PUs) were prepared using castor oil and different diisocyanates such as toluene‐2,4‐diisocyanate and 4,4′‐methylene bis(phenylisocyanate) as a crosslinker and different aromatic diamines like 4,4′‐diaminodiphenyl methane and 4,4′‐diaminodiphenyl sulphone as chain extenders. The effect of aromatic diamines on the swelling and thermal degradation behavior of PU have been discussed. A thermogravimetric analyzer (TGA) curve shows that all the chain‐extended PUs are stable up to 194°C and that maximum weight loss occurs at 490°C. The TGA thermograms show that the thermal degradation of the PUs was found to proceed in two steps. The average molecular weight between crosslinks (M?_c) was determined by swelling studies. The properties imparted by the aromatic chain extenders are explained on the basis of groups present in the diamines. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 359–369, 2002; DOI 10.1002/app.10347     

Effect of H12MDI isomer composition on mechanical and physico-chemical properties of polyurethanes based on amorphous and semicrystalline soft segments

Two series of segmented thermoplastic polyurethanes were synthesized having 33 wt % hard segment based on 4,4′-dicyclohexyl methane diisocyanate with different trans–trans isomer contents and 1,3-propanediol chain extender. The soft segments were based on poly(hexamethylene–pentamethylene carbonate)diol and poly(butylene sebacate)diol, amorphous and semicrystalline polyol, respectively. 4,4′-Dicyclohexyl methane diisocyanate with different trans–trans isomer contents were obtained by fractional crystallization of commercial diisocyanate and were characterized by differential scanning calorimetry and nuclear magnetic resonance spectroscopy. 4,4′-Dicyclohexyl methane diisocyanate trans–trans isomer lead to some interesting properties in the synthesized polyurethanes, due to the more ordered hard domains formed by packing of trans–trans 4,4′-dicyclohexyl methane diisocyanate. Thereby, as 4,4′-dicyclohexyl methane diisocyanate trans–trans isomer content increased, a better phase separated structure was observed.     

Temperature sensitive water vapour permeability and shape memory effect of polyurethane with crystalline reversible phase and hydrophilic segments

Polyurethanes based on poly(caprolactone) (PCL) diol, hexamethylene diisocyanate, 4,4′‐diphenylmethane diisocyanate and hexamethylene diamine were modified by hydrophilic segments, diol‐terminated poly(ethylene oxide) or dimethylol propionic acid (DMPA). Differential scanning calorimetry, dynamic mechanical tests, tensile tests, and measurement of water vapour permeability were carried out to characterize these polyurethanes. Temperature sensitive water vapour permeability, that is, the abrupt increase of water vapour permeability at the melting temperature of the PCL phase, was enhanced by modification with hydrophilic segments. Fatigue in shape memory effects was minimized by introducing some amount of DMPA units into the polyurethane chain. © 2000 Society of Chemical Industry     

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     

Synthesis and characterization of polyurethane anionomers

Un‐ionized polyurethane was obtained by the reaction of an isocyanate‐terminated urethane prepolymer, which was synthesized from 4,4′‐diphenylmethane diisocyanate and poly(oxytetramethylene)‐α,ω‐glycol, with 2,2‐bis(hydroxymethyl)propionic acid. A carboxylate‐based polyurethane anionomer was then derived from the polyurethane by the use of the sodium, potassium, or magnesium salt of acetic acid as a neutralizer. The ionomerization resulted in the following changes in the characteristics of the polyurethane: (1) an increase in the tensile strength, (2) a decrease in the glass‐transition temperature, (3) an increase in the wettability and hygroscopicity with respect to water, and (4) susceptibility to thermal decomposition. A sulfonate‐based polyurethane was also synthesized for comparison with the carboxylate‐based polyurethane. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2144–2148, 2005