Synthesis and evaluation of the thermal properties of biosourced poly(ether)ureas and copoly(ether)ureas from 1,4:3,6‐dianhydrohexitols

A new series of poly(ether)ureas were prepared by solution polyaddition of three diamines based on 1,4:3,6‐dianhydrohexitols with three types of diisocyanate. The corresponding poly(ether)ureas were obtained with high yields. They were characterized by various analytical techniques (NMR, TGA and differential thermal analysis, DSC). NMR spectroscopy allowed us to confirm structure type and to optimize reaction conditions and DSC proved the high thermal properties of the products obtained (T_g and T_m in the range 126 ? 158 °C and 235 ? 330 °C respectively). Then, copoly(ether)ureas partially based on commercial diamines were synthesized in order to reduce polymer cost and tune their thermal behaviour. The reactivity of both diamines was evaluated by their incorporation in the polymer by means of NMR spectra. Then their thermal properties were compared with fully commercial diamine based polyureas by DSC studies. © 2014 Society of Chemical Industry     

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     

Effects of low molecular weight aliphatic diols on the polyurethane elastomers prepared from hydroxyl-terminated polybutadienes

Hydroxyl-terminated polybutadienes were prepared by using azo initiators such as di(4-hydroxybutyl)-2,2′-azobisisobutyrate and di(3-hydroxybutyl)-2,2′-azobisisobutyrate, one of which contains primary and the other secondary hydroxyl groups. The effects of aliphatic diols and 2,4-toluene diisocyanate (TDI) in the presence of dibutyltindilaurate (DBTDL) as catalyst, on crosslinking of primary and secondary hydroxyl groups, were studied. Polyurethane elastomers from these polymers are prepared by using different ratios of diols, 2,4-toluene diisocyanate and catalyst. Physical properties such as hardness, tensile strength, 100% modulus, and elongation at break of these polymers were studied with a view to compare them with the physical properties of elastomers prepared from ARCO R-45M.     

Studies on thermotropic liquid crystalline polymers part XIII. Synthesis and properties of fully aromatic liquid crystalline poly(amide-ester)s

Four series of novel fully aromatic thermotropic liquid crystalline high molecular weight poly(amide-esters were prepared by direct polycondensation from terephthalic acid (TPA) and 2,6-naphthalene dicarboxlic acid with various aromatic diols and diamines in the presence of diphenyl chlorophosphate (DPCP), LiCl, and pyridine. The structures and thermal properties of the synthesized poly(amide-ester) s were examined by FTIR spectrum, wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermal optical polarized microscope and thermogravimetric analysis (TGA). The effects of the amounts and kinds of the aromatic diols and diamines (bisphenyl units, naphthalene and (un)substituted phenylene structures) on the molecular weight and thermal properties of the synthesized poly (amide-ester) s were investigated in this study. When a portion of the amide groups were replaced with the ester groups, most of the synthesized poly(amide-ester)s containing naphthalene or substituted hydroquinone units showed excellent mesophase and thermal stability, but the poly(amide-ester)s containing bisphenyl structures lost the mesophase behaviors. The P3 series of poly(amide-ester)s derived from TPA and 2,6-naphthalene dicarboxlic acid with phenylhydroquinone and various diamines possess liquid crystalline properties, even some of the diamines containing kink structures.     

Optical and thermal properties of diethyl‐(2R, 3R) (+)‐tartrate based chiral polyurethanes with main chain amido chromophores

The toluene diisocyanate based optically active chiral polyurethanes were synthesized according to the symmetry conditions. The noncentrosymmetric (both charge asymmetry and spatial asymmetry) environment were attained by the incorporation of the chiral units (diethyl‐(2R,3R)(+)‐tartrate) and donor‐acceptor building blocks in the main chain which induce a helical conformation in the macromolecular chain. A series of optically active polyurethanes containing chiral linkages in the polymer back bone have been synthesized by using DBTDL catalyst by incorporating the amido diols which were obtained by the aminolysis of ε‐caprolactone by using the diamines, diaminoethane, diaminobutane, and diaminohexane respectively. The effect of incorporation of the chiral molecule diethyl‐(2R,3R)(+)‐tartrate on the properties of polyurethanes was studied by changing the chromophores and also by varying the chiral‐chromophore composition. Various properties of polyurethanes were investigated by UV, Fluorescence, TG/DTA, XRD, polarimetric techniques, Kurtz‐Perry powder techniques, etc. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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,Characterization and in Vitro Evaluation of New Composite Bisphosphonate Delivery Systems

In this study, new composite bisphosphonate delivery systems were obtained from polyurethanes (PUs) and nanocrystalline hydroxyapatite (HA). The biodegradable PUs were first synthesized from poly(ε-caprolactone) diols (PCL diols), poly(ethylene adipate) diol, 1,6-hexamethylene diisocyanate, 1,4-butanediol and HA. Moreover, the PCL diols were synthesized by the ring-opening polymerization catalysed by the lipase from Candida antarctica. Next, composite drug delivery systems for clodronate were prepared. The mechanical properties of the obtained biomaterials were determined. The cytotoxicity of the synthesized polymers was tested. The preliminary results show that the obtained composites are perspective biomaterials and they can be potentially applied in the technology of implantation drug delivery systems.     

Structure–property study of polyurethane anionomers based on various polyols and diisocyanates

Polyurethane (PU) anionomers were prepared as aqueous dispersions using dimethylol propionic acid (DMPA) as the stabilizing moiety. The principal diols used were polytetrahydrofuran of molecular weight 1000 (PTHF1000) and cyclohexane dimethanol (CHDM). The diisocyanates used in this study were isophorone diisocyanate (IPDI), hydrogenated methylene bisphenylene diisocyanate (H₁₂MDI), tetramethylene xylene diisocyanate (TMXDI), hexamethylene diisocyanate (HDI), and a 50 : 50 blend of IPDI and HDI. All these samples were neutralized using triethylamine (TEA) and chain-extended using hydrazine monohydrate. The dispersions were prepared at a NCO/OH ratio of 2 so that a comparison of their structure–property relationships could be made with respect to their mechanical and viscoelastic properties and solvent resistance. Also, two further samples were prepared of similar composition to the IPDI-based sample, but using poly (propylene glycol), PPG1000, and PTHF2000 polyols. The effects on the structure and properties of the PPG1000 and the higher molecular weight PTHF sample were compared with the PTHF1000 sample. Dynamic mechanical thermal analysis, tensile testing, solvent spot, and swelling studies were employed for the characterization of these materials. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2035–2044, 1997     

A novel solid polymer electrolyte: Synthesis and characterization

Summary A new polyether network was prepared using a polyethylene oxide (PEO) triol and a PEO diisocyanate, the latter component arising from the chemical modification of commercial PEO diamines. The physico-chemical properties of the network alone and with LiClO₄ were assessed in comparison with those of previously obtained structures. Ionic conductivities were found to be higher with this new system. Replacement of LiClO₄ by LiN(CF₃SO₂)₂ improved the conductivity further because of the plasticizing role of the imidic anion.     

Effect of the diisocyanate structure and the molecular weight of diols on bio‐based polyurethanes

Bio‐based polyurethanes (PU) containing poly(ε‐caprolactone) diol (PCL) and hydroxyl telechelic natural rubber (HTNR) were synthesized. The effect of the diisocyanate structure and the molecular weights of diols on the mechanical properties of PU were investigated. Three different molecular structures of diisocyanate were employed: an aliphatic diisocyanate (hexamethylene diisocyanate, HDI), an aromatic diisocyanate (toluene‐2,4‐diisocyanate, TDI) and a cycloalkane diisocyanate (isophorone diisocyanate, IPDI). Two molecular weights of each diol were selected. When HDI was employed, a crystalline PU was generated while asymmetrical structures of TDI and IPDI provided an amorphous PU. The presence of crystalline domains was responsible of a change in tensile behavior and physical properties. PU containing TDI and IPDI showed a rubber‐like behavior: low Young's modulus and high elongation at break. The crystalline domains in PU containing HDI acted as physical crosslinks, enhancing the Young's modulus and reducing the elongation at break, and they are responsible of the plastic yielding. The crystallinity increased the tear strength, the hardness and the thermal stability of PU. There was no significant difference between the TDI and IPDI on the mechanical properties and the physical characteristics. Higher molecular weight of PCL diol changed tensile behavior from the rubber‐like materials to the plastic yielding. Thermal and dynamic mechanical properties were determined by using DSC, TGA and DMTA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and properties of nanosilica‐reinforced polyurethane for grouting

A polyurethane/nanosilica (PU/SiO₂) hybrid for grouting was prepared in a two‐step polymerization using poly(propylene glycol) diols as the soft segment, toluene 2,4‐diisocyanate (TDI) as the diisocyanate, 3,3′‐dichloro‐4,4′‐diaminodiphenylmethane (MOCA) as the chain extender, and acetone as the solvent. The size and dispersion of nanosilica, the molecular structure, mechanical properties, rheological behavior, thermal performance, and the UV absorbance characteristic of the PU/SiO₂ hybrid were investigated by transmission electron microscopy (TEM), FTIR, mechanical tests, viscometry, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and UV spectroscopy. Nanosilica dispersed homogeneously in the PU matrix. The maximum values of mechanical properties such as tensile strength, elongation break, and adhesive strength showed an addition of nanosilica of about 2 wt %. Resistance to both high and low temperatures was better than with PU. And the UV absorbance of the PU/SiO₂ hybrid increased in the range of 290–330 nm with increasing nanosilica content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4333–4337, 2006     

聚酯型水性聚氨酯油墨连接料的研究

以聚酯二元醇、二异氰酸酯和二羟甲基丙酸(DMPA)为主要原料,合成了聚酯型水性聚氨酯(WPU)乳液。研究了聚酯二元醇的种类、R值[R=n(-NCO)/n(-OH)]和DMPA用量等对WPU乳液的附着力、稳定性和T型剥离强度等影响。结果表明:以Pol-356(由己二酸、乙二醇和1,4-丁二醇聚合而成)为聚酯二元醇、端羟基聚酯多元醇(Pol-350)为小分子扩链剂,当w(DMPA)=9%、R值为1.200～1.225时,制成的WPU乳液固含量高、储存稳定性好,其对非极性BOPP(双向拉伸聚丙烯)薄膜等具有相对较高的附着力和T型剥离强度。     

聚醚-聚酯型水性聚氨酯胶粘剂的合成

文章以聚醚二元醇、聚酯二元醇为软段,以甲苯二异氰酸酯、1,4-丁二醇等为硬段,采用两步法合成水性聚氨酯胶粘剂。研究了亲水基团的含量、异氰酸酯基(-NCO)与羟基(-OH)的摩尔比、聚醚/聚酯二元醇复配比例等对水性聚氨酯胶粘剂性能的影响。结果表明:亲水性基团含量1.5%～1.7%,异氰酸酯基与羟基的摩尔比为1.13～1.27,聚醚/聚酯复配比例为25/75～35/65时所合成的胶粘剂对BOPP/PET软包装复合材料有较佳的粘结性能。     

聚氨酯型不饱和聚酯树脂的合成及其性能的研究

采用两步法由二元醇、二元酸酐和甲苯二异氰酸酯(TDI)合成了一种聚氨酯型不饱和聚酯树脂(UPPU)。第一步由二元醇和二元酸酐合成出以—OH封端的不饱和聚酯(UP);第二步利用UP的—OH与TDI的—NCO的高反应活性由UP与TDI合成UPPU。同时研究了反应温度、反应时间、原料配比等对UPPU树脂涂膜性能的影响。结果表明,当乙二醇:邻苯二甲酸酐:顺丁烯二酸酐物质的量比为1.2:0.7:0.3,反应温度为205℃,反应时间8 h,酸值在40mgKOH/g以下时,得到UPPU树脂涂膜性能较好。     

Preparation,Mechanical and Thermal Properties of Polyurethane/Nanosilica Composites via High Pressure Shearing Methods

Nanosilica particles were dispersed into polymer diols by high pressure shearing homogenizer (HPSH), then polyurethane nanocomposites were prepared via in-situ polymerization of diphenylmethane diisocyanate (MDI) and polymer diols. FTIR analysis indicated that the -NCO groups of MDI had reacted with the hydroxy on the surface of nanosilica during in-situ polymerization. TGA suggested that polyurethane/nanosilica composites obtained by in-situ polymerization had better thermal stability than pure polyurethane. Meanwhile, the tensile and dynamic mechanical properties of the samples prepared by HPSH were superior to those by directly ultrasonic dispersing nanosilica, accompanied by more homogeneous dispersion of nanosilica particles in the polymer matrix.     

Polymers containing sulfur in the side chain

We synthesized new thiodicarboxylic acids, p-tolylmethylthiomethylsuccinic acid and 1-naphthylmethylthiomethylsuccinic acid, and thiodiols, 2-(p-tolylmethylthiomethyl)-1,4-butanediol and 2-(1-naphthylmethylthiomethyl)-1,4-butanediol, by the addition of dimethyl itaconate with p-tolylmethanethiol or 1-naphthylmethanethiol, followed by hydrolysis or reduction, respectively, of the resultant dimethyl esters. These difunctional monomers were used for the synthesis of new linear polyesters and polyurethanes containing sulfur in the side chain. The polyesters were synthesized by melt polycondensation of the obtained acids with 2,2′-oxydiethanol. We found reduced viscosity, molecular weight (by GPC), and softening temperature for the reaction products. Low molecular weights, low softening temperature, and very good solubility in organic solvents are their characteristics. The polyurethanes were prepared by polyaddition diols with hexamethylene diisocyanate and tolylene diisocyanate in benzene. They were characterized by reduced viscosity and some tensile properties. The polyurethane derived from 2-(p-tolylmethylthiomethyl)-1,4-butanediol and hexamethylene diisocyanate (η_red. 1.17 dL/g) behaves like a high elasticity thermoplastic elastomer. Thermal stability of all polymers was determined by thermogravimetric analysis. The structure of the monomers and polymers were confirmed by elemental analysis and FTIR and ¹H-NMR spectroscopy. © 1996 John Wiley & Sons, Inc.     

Synthesis,characterization, and pervaporation properties of segmented poly(urethane‐urea)s

Poly(urethane‐urea)s (PUUs) from 2,4‐tolylene diisocyanate (2,4‐TDI), poly(oxytetramethylene)diols (PTMO) or poly(butylene adipate)diol (PBA), and various diamines were synthesized and characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry, and density measurements. Transport properties of the dense PUU‐based membranes were investigated in the pervaporation of benzene–cyclohexane mixtures. It was shown that the pervaporation characteristics of the prepared membranes depend on the structure and length of the PUU segments. The PBA‐based PUUs exhibit good pervaporation performance along with a very good durability in separation of the azeotropic benzene–cyclohexane mixture. They are characterized by the flux value of 25.5 (kg μm m⁻² h⁻¹) and the separation factor of 5.8 at 25°C, which is a reasonable compromise between the both transport parameters. The PTMO‐based PUUs display high permeation flux and low selectivity in separation of the benzene‐rich mixtures. At the feed composition of 5% benzene in cyclohexane, their selectivity and flux are in the range of 3.2 to 11.7 and 0.4 to 40.3, respectively, depending on the length of the hard and soft segments. The chemical constitution of the hard segments resulting from the chain extender used does not affect the selectivity of the PUU membranes. It enables, however, the permeability of the membranes to be tailored. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1615–1625, 1999     

Plastic zone radius of crosslinked bismaleimide resins

Polytetrahydrofuran diols are polyurethane precursors obtainable from carbohydrate feedstocks. A range of commercial diols of different molecular weights were selected and supplemented by synthesised diols of lower molecular weights. To increase the carbohydrate content of derived polymers each diol was reacted with 1 or 2 moles of glucose and converted to a glucoside in high yield using a solution reaction. Complex products resulted, which approximately may be represented by mono- or bisglucoside structures. The parent diols and the glucosides were characterised using a wide range of techniques including acetylation equivalent weight, functionality towards diisocyanate, GPC, DSC, GLC, IR, HPLC, viscosity determinations and various wet chemical analyses. Relative to the parent diols, the properties of the glucosides (such as high viscosity, wider range of functionality towards MDI, and the relationships between transition temperatures and (diol) molecular weight) are explained as due to the rigidity and large free volume of the terminal glucose unit, its potential for increasing hydrogen bonding, and its ability to cause disruption of polytetramethylene oxide chain ordering.     

Thermal stability of chemically crosslinked moisture‐cured polyurethane coatings

Polyurethane prepolymers are widely used in reactive hot melt adhesives and moisture‐cured coatings. The segmented moisture‐cured formulations, based on polytetramethylene glycol (PTMG‐1000)/trimethylol propane (TMP)/isophorone diisocyanate (IPDI) and PTMG/TMP/toluene diisocyanate (TDI), were prepared with NCO/OH ratio of 1.6 : 1.0. The excess isocyanate groups of the prepolymers were chain extended in the ratio of 2 : 1 (NCO/OH) with different aliphatic diols and 4 : 1 with different aromatic diamines. The surplus isocyanate groups of the formulations were completely reacted with atmospheric moisture, and the thermal stability of the postcured materials obtained as cast films were evaluated by thermogravimetric (TG) analysis. It was observed that initial degradation temperatures were above 270°C, with two‐ or three‐step degradation profiles. The degradation parameters were evaluated using the Broido and Coats–Redfern methods. The thermal resistance of moisture‐cured formulations using diisocyanates with the cycloaliphatic structures (IPDI) and the aromatic TDI, at the same NCO/OH ratio (1.6), and TMP content were compared from the isothermal TG experiments at different temperatures and dynamic TG experiments at different heating rates in nitrogen and oxygen environments. The observation suggests that polyurethane‐containing sulfone groups and straight‐chain diol chain extenders were more stable. It was also observed that at lower temperature polyurethane, prepared from aliphatic diisocyanates (IPDI), was more stable than the aromatic diisocyanate (TDI) containing polyurethanes. At high temperature, the stability order follows the reverse trend. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1509–1518, 2005     

Polyurethane elastomers made from linear polybutadiene diols

Segmented polyurethane elastomers made from linear polybutadiene diols terminated with primary (Krasol LBH‐P) or secondary (Krasol LBH) hydroxy groups, alicyclic diisocyanate, and aliphatic chain extender were prepared and tested. The system was chemically crosslinked either through isocyanurate, that is, hexahydro‐1,3,5‐triazine‐2,4,6‐trione groups (formed by catalyzed cyclotrimerization of isocyanate groups), or by low molecular weight triols. The best balance of stress‐strain properties and reasonable thermal stability was obtained for systems in which only a small amount of chemical crosslinks was present in predominantly physically crosslinked networks. The influence of the type of polymer diol, chemical crosslinking, diisocyanate, and technique of preparation on mechanical, thermal, and swelling properties is discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 84–91, 2002