Synthesis and Properties of Imidazole-Blocked Toluene Diisocyanates

Abstract

Imidazole-, 2-methyl imidazole-, and benzimidazole-blocked toluene diisocyanates (TDI) were prepared and characterized by elemental analysis, IR, and NMR spectroscopy. Simultaneous TGA/DTA results showed that the thermal stability of the adduct decreases in the following order: imidazole-TDI > 2-methylimidazole-TDI > benzimidazole-TDI. Gelation test involving imidazole-blocked adducts and hydroxyl-terminated polybutadiene were also carried out. The cure rate of the adduct increases from the imidazole- to the 2-methylimidazole- and to the benzimidazole-blocked adduct. It is also found that the benzimidazole-blocked adduct shows better solubility in the polyols.     

NMR Analysis of Hydroxyl-Terminated Polybutadiene End Groups and Reactivity Differences with Monoisocyanates

Nuclear magnetic resonance (NMR) spectroscopy was employed to investigate both the end group microstructure of R-45HTLO hydroxyl-terminated polybutadiene (HTPB) and reactivity rate differences among the different types of end groups. There is some conflict in the literature about the exact nature of the end groups and which resonance frequencies represent the three main types of methylene-hydroxyl end groups (cis, trans, or vinyl) and other possible branch point end groups (geraniol). NMR spectral analysis of small molecule model compounds supports the cis, trans, and vinyl end groups model. A model reaction scheme is proposed that produces branch points without the requirement of any “geraniol” structures. The reaction, with and without catalyst, of the various HTPB end groups with three different monoisocyanates (2-fluorophenyl isocyanate, phenyl isocyanate, and tert-butyl isocyanate) monitored by NMR spectroscopy, revealed different reactivity rates that are correlated with the assigned structures. In both the catalyzed and uncatalyzed reactions, the vinyl end groups reacted slower than the cis or trans end groups. As expected, the bulky isocyanates were the slowest to react, while the isocyanate group with electron withdrawing groups reacted the fastest. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2665–2671     

端羟基聚丁二烯液体橡胶的合成、化学改性及应用

端羟基聚丁二烯(HTPB)是一种低分子量的遥爪液体橡胶,因具有玻璃化温度低、透明度好、黏度低、不易挥发、耐油耐老化、低温和加工性能好等优点,在军事和民用领域均具有广泛的应用。HTPB的性能主要受其主链微观结构的影响,不同的制备方法得到不同链结构的HTPB,其性能也有较大的差别。另外,通过对HTPB主链中的双键或末端羟基进行化学修饰可将其转变为不同分子结构或不同官能团的遥爪聚合物,赋予改性后的HTPB不同性能,并拓宽其应用领域。本文主要概述端羟基聚丁二烯的合成方法、化学改性和应用。     

Study on synthesis,characterizations, and properties of pyridinol-blocked isocyanates and waterborne polyurethane

A series of pyridinol-blocked isophorone isocyanates were synthesized through esterification reaction, Fries rearrangement, and blocking reaction and characterized by ¹H-NMR, ¹³C-NMR, and Fourier transform infrared spectra. Based on the synthesized blocked isocyanates, the blocked waterborne polyurethane (BWPU) was prepared by the self-emulsification method. The deblocking studies revealed that the deblocking temperature reduces with electron-withdrawing and steric hindrance substituents on the ortho position of pyridinol. The stability, molecular weight (M_w), particle size, viscosity, and hydrophilicity of BWPU were studied and compared. The results showed that with an increased amount of blocking agents, molecular weight, particle size, and viscosity decrease and the hydrophilicity increases.     

Synthesis of poly(urethane‐imide) using aromatic secondary amine‐blocked polyurethane prepolymer

A set of poly(urethane‐imide)s were prepared using blocked Polyurethane (PU) prepolymer and pyromellitic dianhydride (PMDA). The PU prepolymer was prepared by the reaction of polyether glycol and 2,4‐tolylene diisocyanate, and end capped with N‐methyl aniline. The PU prepolymer was reacted with PMDA until the evolution of carbon dioxide ceased. The effect of tertiary amine catalysts, organo tin catalysts, solvents, and reaction temperature were studied and compared with the poly(urethane‐imide) prepared using phenol‐blocked PU prepolymer. N‐methyl aniline blocked PU prepolymer gave a higher molecular weight poly(urethane‐imide) at a lower reaction temperature in a shorter time. Amine catalysts were found to be more efficient than organo tin catalysts. The reaction was favorable in particular with N‐ethylmorpholine and diazabicyclo(2.2.2)octane (DABCO) as catalysts, and dimethylpropylene urea as a reaction medium. The poly(urethane‐imide)s were characterized by FTIR, GPC, TGA, and DSC analyses. The molecular weight decreased with an increase in reaction temperature. The thermal stability of the PU was found to increase by the introduction of imide component. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4032–4037, 2000     

Synthesis and deblocking of cardanol‐ and anacardate‐blocked toluene diisocyanates

Methyl anacardate and secondary butyl anacardate were prepared from anacardic acid and corresponding alcohols and were used, in addition to cardanol, as blocking agents for 2,4‐toluene diisocyanate (TDI). Blocked diisocyanate adducts were characterized via nitrogen estimation, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance spectroscopy. The deblocking temperatures of the adducts were determined using an FTIR spectrophotometer in conjunction with the carbon dioxide evolution method. The gel times of hydroxyl‐terminated polybutadiene–TDI adducts also were determined. Deblocking temperature and gel time analyses revealed that cardanol‐blocked 2,4‐TDI deblocks at a lower temperature and at a higher rate compared with anacardate‐blocked adducts. In addition, it was found that the electron‐withdrawing ester group reduces the deblocking temperature of the adduct only when it is in solvated form. All adducts were waxy solids that were found to be soluble in polyether polyol, polyester polyol, and polyhydrocarbon polyols. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4047–4055, 2004     

端羟基聚丁二烯/增塑剂共混物相容性的分子动力学模拟和介观模拟

应用分子动力学(MD)和介观动力学(MesoDyn)模拟方法对固体推进剂中端羟基聚丁二烯(HTPB)与增塑剂癸二酸二辛酯(DOS)、硝化甘油(NG)的相容性进行了研究. 采用MD模拟方法在COMPASS力场下, 对纯物质、HTPB/增塑剂共混物的密度、内聚能密度、溶度参数和共混物分子间的Flory-Huggins作用参数及结合能等进行了模拟计算, 通过比较溶度参数差值(Δδ)的大小、模拟前后体系密度变化情况均可以预测HTPB与增塑剂的相容性, 结合能的分析揭示了HTPB/增塑剂共混物组分间的相互作用及本质. 将Flory-Huggins作用参数转化为MesoDyn模拟的输入参数, 采用MesoDyn模拟方法对HTPB/增塑剂共混体系的介观形貌与动力学演变过程进行了研究, 通过模拟得到的等密度图、自由能密度和有序度参数等可以判断共混体系的相容性. MD和MesoDyn模拟结果均表明: HTPB/DOS属于相容体系, 而HTPB/NG属于不相容体系, 其结论与实验结果一致.     

气相色谱测定海绵文胸中甲苯二异氰酸酯残留

建立了气相色谱-内标法测定海绵文胸中的甲苯二异氰酸酯(TDI)残留量。样品经均质处理后,用经脱水处理的乙酸乙酯超声萃取25 min,过滤净化后,采用Agilent DB-624色谱柱(30 m×0.32 mm×1.8μm)分析,柱温采用程序升温,检测器为氢火焰离子化检测器,检测器温度为250℃,进样口温度为180℃,载气为氮气。结果表明:甲苯二异氰酸酯在10~200 mg/L范围内峰面积与质量浓度线性关系良好,线性相关系数(R~2)为0.998 9,平均回收率为80.5%~91.6%,RSD不大于7.9%(n=6),方法的检出限和定量限分别为10 mg/kg和100 mg/kg。在优化条件下,对生产企业、实体店和电商平台采购的100批次样品进行了检测。该方法操作简单、耗时短、灵敏度高、稳定性好,应用于日常检测可大大降低检测成本,缩短检测周期,具有实际应用价值。     

Synthesis and characterization of poly(urethane-sulfone)s

Eight poly(urethane-sulfone)s were synthesized from two sulfone-containing diols, 1,3-bis(3-hydroxypropylsulfonyl)propane (Diol-333) and 1,4-bis(3-hydroxypropylsulfonyl)butane (Diol-343), and three diisocyanates, 1,6-hexamethylene diisocyanate (HMDI), 4,4′-diphenylmethane diisocyanate (MDI), and tolylene diisocyanate (TDI, 2,4- 80%; 2,6-20%). As a comparison, eight polyurethanes were also synthesized from two alkanediols, 1,9-nonanediol and 1,10-decanediol, and three diisocyanates. Diol-333 and Diol-343 were prepared by the addition of 1,3-propanedithiol or 1,4-butanedithiol to allyl alcohol and subsequent oxidation of the resulting sulfide-containing diols. The homopoly(urethanesulfone)s from HMDI and MDI are semicrystalline, and are soluble in m-cresol and hot DMF, DMAC, and DMSO. The copoly(urethane-sulfone)s from a 1/1 molar ratio mixture of Diol-333 and Diol-343 with HMDI or MDI have lower crystallinity and better solubility than the corresponding homopoly(urethane-sulfone)s. The poly(urethane-sulfone)s from TDI are amorphous, and are readily soluble in m-cresol, DMF, DMAC, and DMSO at room temperature. Differential scanning calorimetry data showed that poly(urethane-sulfone)s have higher glass transition temperatures and melting points than the corresponding polyurethanes without sulfone groups. The rise in glass transition temperature is 20–25°C while the rise in melting temperature is 46–71°C. © 1994 John Wiley & Sons, Inc.     

季戊四醇型HTPB-PU弹性体的研究

以端羟基聚丁二烯、液化改性MDI为原料,季戊四醇为扩链剂与交联剂制备季戊四醇型聚氨酯,并用IR、TG、DSC和SEM对其进行表征;研究了影响季戊四醇型聚氨酯的力学性能和热性能的因素。结果表明：随扩链剂用量的增大,季戊四醇型聚氨酯的拉伸强度和硬度增大,而断裂伸长率减小,同时热稳定性得到提高。SEM显示此弹性体中存在明显的相分离。     

Chain‐extended,hydroxyterminated‐polybutadiene‐based polyurethaneureas: Synthesis,reaction kinetics,and properties

Hydroxyterminated‐polybutadiene‐based prepolyurethanes were prepared with two different catalysts, dibutyltindilaurate (DBTDL) and triethylamine (TEA); chain extension of the prepolyurethanes followed with two different aromatic diamines, oxydianiline and 4,4′‐diaminodiphenylsulfone, in various concentrations. The prepolyurethane synthesis followed second‐order kinetics, with the DBTDL catalyst showing better efficiency for urethane formation than TEA. TEA‐catalyzed synthesis suffered from the self‐association of isocyanates as a major side reaction, following second‐order kinetics with respect to isocyanate concentration. Although there was a gradual increase in the intrinsic viscosity during prepolyurethane synthesis in the presence of DBTDL, the intrinsic viscosity remained almost constant with the progress of the reaction in the presence of TEA. The tensile properties of prepolyurethane and polyurethaneureas synthesized in DBTDL‐catalyzed reactions were higher than the properties of those synthesized in TEA‐catalyzed reactions. The variation of the tensile strength with the diamine concentration was correlated with the crosslink density and sol fraction. The solubility of the hard segment of polyurethaneurea in the reaction medium appeared to be important in influencing the tensile properties. The effects of the diamine concentration (chain extender) on the diffusion coefficient and activation energy of diffusion of toluene in polyurethaneureas were studied. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2978–2992, 2001     

Synthesis and properties of novel aromatic poly(ester amide)s derived from 1,5-bis(4-aminobenzoyloxy)naphthalene and aromatic dicarboxylic acids

A new naphthalene ring-containing bis(ester amine), 1,5-bis(4-aminobenzoyloxy)naphthalene (2), was synthesized from the condensation of 1,5-dihydroxynaphthalene with 4-nitrobenzoyl chloride followed by catalytic hydrogenation. A series of naphthalene-containing poly(ester amide)s having inherent viscosities of 0.34-0.82 dl/g were prepared by the direct phosphorylation polyamidation from bis(ester amine) 2 with various aromatic dicarboxylic acids. The poly(ester amide)s derived from terephthalic acid, 4,4′-biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-oxydibenzoic acid were semicrystalline and showed less solubility. The other polymers were amorphous and readily soluble in polar organic solvents and gave flexible and tough films via solution casting. Except for four examples, the poly(ester amide)s displayed discernible glass transitions between 190 and 227 °C by differential scanning calorimetry. These poly(ester amide)s did not show significant decomposition below 400 °C in nitrogen or air.     

Pyrazoles—A novel class of blocking agents for isocyanates

Pyrazoles were found as a novel class of blocking groups for isocyanates. Adhesive mixtures of pyrazole blocked isocyanates and amine terminated prepolymers like Jeffamines® (Texaco Chem. Co.) combine excellent reactivities (gelation times within minutes at 100–120°C), good latencies (more than 170 days at 40°C), and good adhesion properties on many substrates. The reactivity of pyrazole blocked isocyanates toward nucleophiles increases with the number of electron donor substituents on the pyrazole nucleus and, thus, can be fine tuned by the appropriate substitution pattern. This behavior contrasts sharply with that of phenolic blocked isocyanates, where reactivities with the same nucleophiles decrease with more and stronger electron donor substituents on the phenol nucleus. Therefore, different deblocking reaction mechanisms were proposed for pyrazole vs. phenol blocked isocyanates. The excellent latency of pyrazole blocked isocyanate/Jeffamine® mixtures is due to the insolubility of the two components at ambient temperature and the slow endothermic dissolution process at higher temperature. The good adhesion of formulations with pyrazole blocked isocyanates as reactive components on most plastic and metal substrates is ascribed to the primer action of the released blocking group. © 1994 John Wiley & Sons, Inc.     

Synthesis and characterization of aromatic amine functional semicrystalline aryl ether ketone macromers

From earlier experiments it was observed that the reactions of aryl fluoride functional aryl ether ketone oligomers (PEK) with m-aminophenol lead to poor levels of amine incorporation because of side-reactions. In this article, a method is presented to protect the m-aminophenol by converting it into a triarylimine group. This protected m-aminophenol was used together with 4-fluoro,4′-hydroxybenzophenone in a typical poly(aryl ether) synthesis. PEKs of different molecular weights were synthesized with number average molecular weights $\overline {M}_n$) of 2600, 4500, and 5400 g/mol. The deprotection of the triarylimine chain end was carried out by an acid treatment to afford a monofunctional aromatic amine end group, amenable towards copolymerization. © 1995 John Wiley & Sons, Inc.     

树枝状尼龙6的合成与研究

用单羧基封端的尼龙6分别与树枝状聚酰胺-胺(PAMAM)的G1代和G2代外围活泼氨基进行缩聚反应,合成出具有规整结构的由核心向外发散增长的树枝状尼龙6,采用红外光谱、扫描电镜、DSC和TGA对缩聚物进行了分析。     

Liquid crystalline epoxies bearing biphenyl ether and aromatic ester mesogenic units: Synthesis and thermal properties

Two liquid crystalline epoxies containing biphenyl ether and aromatic ester mesogenic units, oxybis(4,1-phenylene)bis(4-(oxiran-2-ylmethoxy)benzoate)(LCE1) and oxybis(4,1-phenylene) bis(4-(4-(oxiran-2-yl)butoxy)benzoate)(LCE2), were synthesized and characterized. Subsequently, the epoxy monomers were cured with diaminodiphenylsulfone (DDS). From DSC, XRD and POM results, monomers did not show liquid crystalline phase while the cured samples exhibited nematic phase. The cured samples showed good mechanical properties with strength of 99.1MPa and excellent thermal stabilities with high glass transition temperature up to 168.0?°C, 5% weight loss temperature at 343?°C and high char yield of 24.5% at 800?°C. The relationship between thermal conductivity and network structure was discussed in this work. Due to the introduction of mesogenic units into epoxy networks, the cured resins showed high thermal conductivity as high as 0.292?W/(m*K), more than 1.5times higher than conventional epoxy resins. By introducing alumina (Al₂O₃) into LCE1/DDS cured system, composites of LCE1/DDS/Al₂O₃ with the highest thermal conductivity of 1.61?W/(m*K) was obtained with the content of 80?wt% while that of diglycidyl ether of bisphenol A (DGEBA, E51) epoxy resin/DDS/Al₂O₃ was 1.10?W/(m*K). The as-prepared epoxy resins showed high glass transition temperature and excellent thermal stabilities, indicating the potential of application in microelectronics.     

The effect of organic modifiers with different chain lengths on the dispersion of clay layers in HTPB (hydroxyl terminated polybutadiene)

The series of HTPB (hydroxyl terminated polybutadiene)/organoclay nanocomposite was formed by melt blending with rotationary and revolutionary mixer which generated high shear stress. Organoclays were formed by modifying the pristine clays with organic modifiers which had different hydrophobic chain lengths. As the length of organic modifier increased, the gap size between layers of organoclay became broader. The clays modified with octadecylamine (C18) and dodecyl amine (C12) showed wider gap sizes than that modified with octyl amine (C8). This gap size affected the dispersion state of clays, exfoliation/intercalation in HTPB polymer medium. The mixtures of HTPB with C18 and C12 were transparent without sedimentation and showed almost exfoliated structure. HTPB/C18 mixture showed the higher viscosity and yield strength than HTPB/C12 due to exfoliation. HTPB/C12 showed more elastic behavior than HTPB/C18 mixture because the organoclay C12 had less content of organic modifier.     

Synthesis,electrolyte properties and solar cell performance of hyperbranched poly(aryl-ether-urea)s

Hyperbranched poly(aryl-ether-urea)s with phenyl, N,N-dimethylamino ethyl and polyethylene oxide end-groups linked through urethane group – HBPEU-1, HBPEU-2 and HBPEU-3 respectively – were synthesized from an AB₂-type blocked isocyanate monomer and characterized by FT-IR, ¹H-NMR, SEC-MALLS, TGA and DSC techniques. The molecular weight of the polymers were found to be ranged from 4.9 × 10³ ? 1.96 × 10⁴ g/mol. The TGA results showed that the polymers decompose between 175°C – 220°C. In the DSC curves, HBPEU-1 and HBPEU-3 showed T_g at 160°C and 53°C respectively, whereas HBPEU-2 did not showed clear T_g. All the three polymers were converted into polymer electrolytes by doping with LiI/I₂. The doped polymers showed remarkably high ionic conductivity, up to 222 – 277 times compared to the un-doped polymers and the highest conductivity was observed with doped HBPEU-2. The TiO₂ based dye-sensitized solar cells (DSSCs) were fabricated using the doped polymer electrolytes and their performance was tested; HBPEU-2 showed good performance by yielding energy conversion efficiency (η) of 4.5%.     

Synthesis and properties of novel optically active polyimides

A facile synthesis of an optically active di‐isocyanate containing alkylene groups and a preformed imide structure is described. Polycondensation reactions of the prepared di‐isocyanate with pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and hexafluoroisopropylidene diphthalic anhydride resulted in the preparation of optically active, thermally stable polyimides. The prepared monomer and polymers were characterized by conventional methods. Optical and physical properties of the polymers including thermal stability, thermal behavior, solution viscosity, and solubility behavior were studied. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 514–518, 2001     

Synthesis and properties of novel cardo aromatic poly(ether‐benzoxazole)s

Three new bis(ether‐acyl chloride) monomers, 1,1‐bis[4‐(4‐chloroformylphenoxy)phenyl]cyclohexane ( 1a ), 5,5‐bis[4‐(4‐chloroformylphenoxy)phenyl]‐4,7‐methanohexahydroindan ( 1b ), and 9,9‐bis[4‐(4‐chloroformylphenoxy)phenyl]fluorene ( 1c ), were synthesized from readily available compounds. Aromatic polybenzoxazoles bearing ether and cardo groups were obtained by the low‐temperature solution polycondensation of the bis(ether‐acyl chloride)s with three bis(aminophenol)s and the subsequent thermal cyclodehydration of the resultant poly(o‐hydroxy amide)s. The intermediate poly(o‐hydroxy amide)s exhibited inherent viscosities in the range of 0.35–0.71 dL/g. All of the poly(o‐hydroxy amide)s were amorphous and soluble in many organic polar solvents, and most of them could afford flexible and tough films by solvent casting. The poly(o‐hydroxy amide)s exhibited glass‐transition temperatures (T_g's) in the range of 141–169 °C and could be thermally converted into the corresponding polybenzoxazoles approximately in the region of 240–350 °C, as indicated by the DSC thermograms. Flexible and tough films of polybenzoxazoles could be obtained by thermal cyclodehydration of the poly(o‐hydroxy amide) films. All the polybenzoxazoles were amorphous and showed an enhanced T_g but a dramatically decreased solubility as compared with their poly(o‐hydroxy amide) precursors. They exhibited T_g's of 215–272 °C by DSC and showed insignificant weight loss before 500 °C in nitrogen or air. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4014–4021, 2001