Polyurethanes containing sulfur. I. New thermoplastic polyurethanes with benzophenone unit in their structure

New thermoplastic nonsegmented thiopolyurethanes were obtained from the low-melting aliphatic–aromatic thiodiols 4,4′-bis(2-hydroxyethylthiomethyl)benzophenone (BHEB), 4,4′-bis(3-hydroxypropylthiomethyl)benzophenone (BHPB), and 4,4′-bis(6-hydroxyhexylthiomethyl)benzenophenone(BHHB) as well as hexamethylene diisocyanate (HDI), both by melt and solution polymerization with dibutyltin dilaurate as the catalyst. The effect of various solvents on molecular-weight values was examined. The polymers with the highest reduced viscosities (0.63–0.88 dL/g) were obtained when the polymerization was carried out in a solution of tetrachloroethane, N,N-dimethylacetamide, and N,N-dimethylacetamide or N,N-dimethylformamide for BHEB-, BHPB-, and BHHB-derived polyurethanes, respectively. These polymers with a partially crystalline structure showed glass-transition temperatures (T_g) in the range of −1 to 39 °C, melting temperatures (T_m) in the range of 107 to 124 °C, and thermal stabilities up to 230 to 240 °C. The BHEB-derived polyurethane is a low-elasticity material with high tensile strength (ca. 50 MPa), whereas the BHPB- and BHHB-derived polyurethanes are more elastic, showing yield stress at approximately 16 MPa. We also obtained segmented polyurethanes by using BHHB, HDI, and 20 to 80 mol % poly(oxytetramethylene) glycol (PTMG) of M̄_n = 1000 as the soft segment. These are high-molecular thermoplastic elastomers that show a partially crystalline structure. Thermal properties were investigated by thermogravimetric analysis and differential scanning calorimetry. The increase in PTMG content decreases the definite T_g and increases the solubility of the polymers. These segmented polyurethanes exhibit the definite T_g (−67 to −62 °C) nearly independent of the hard-segment content up to approximately 50 wt %, indicating the existence of mainly phase-separated soft and hard segments. Shore A/D hardness and tensile properties were also determined. As the PTMG content increases, the hardness, modulus of elasticity, and tensile strength decrease, whereas elongation at break increases. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4140–4150, 1999     

13C-NMR spectroscopy study of polyurethane obtained from azide hydroxyl-terminated polymer cured with isophorone diisocyanate (IPDI)

Chemical structure investigations of polyurethane binders based on difunctional linear glycidyl azide polymer (GAP) cured with isophorone diisocyanate (IPDI) were performed using ¹³C-NMR spectroscopy in solution. Chemical functions such as urethane, urea, allophanate, and biuret were all expected to be detected in these polymeric binders. ¹³C-NMR assignment of the C O urethane and urea functions were found in these polymers as determined by using model compounds of IPDI. The ¹³C-NMR data gathered in this article can be considered as basic parameters for further characterization of polyurethane structure based on IPDI. Also, ¹³C CP MAS NMR spectra of GAP-IPDI-based polymers were carried out to identify the various chemical functions present in solid polyurethane elastomer. In addition, the curing evolution of a GAP-IPDI-based polymer at 50 and 80°C in bulk was monitored, and the reaction path of the binder was readily determined. Some conclusions on the effects of the cure catalyst and the curing temperature were also drawn. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2991–2998, 1997     

Polymer grafting onto polyurethane backbone via Diels–Alder reaction

The aliphatic polyurethane with pendant anthracene moieties (PU‐anthracene) was prepared from polycondensation of anthracen‐9‐yl methyl 3‐hydroxy‐2‐(hydroxymethyl)‐2‐methylpropanoate (anthracene diol), 1 with hexamethylenediisocyanate in the presence of dibutyltindilaurate in CH₂Cl₂ at room temperature for 10 days. Thereafter, the PU‐anthracene (M_n,GPC = 12,900 g/mol, M_w/M_n = 1.87, relative to PS standards) was clicked with a linear α‐furan protected‐maleimide terminated‐poly(methyl methacrylate) (PMMA‐MI) (M_n,GPC = 2500 g/mol, M_w/M_n = 1.33), or ‐poly(ethylene glycol) (PEG‐MI) (M_n,GPC = 550 g/mol, M_w/M_n = 1.09), to result in well‐defined PU‐graft copolymers, PU‐g‐PMMA (M_n,GPC = 23800 g/mol, M_w/M_n = 1.65, relative to PS standards) or PU‐g‐PEG (M_n,GPC = 11,600 g/mol, M_w/M_n = 1.45, relative to PS standards) using Diels–Alder reaction in dioxane/toluene at 105 °C. The Diels–Alder grafting efficiencies were found to be over 93–99% using UV spectroscopy. Moreover, the structural analyses and the thermal transitions of all copolymers were determined via ¹H NMR and DSC, respectively. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 521–527     

Effect of molecular shape of diisocyanate units on the microscopic/macroscopic phase separation structure of polyurethanes

Three diisocyanate units having different linearity and planarity on the basis of the arrangement of constituent aromatic rings are used to synthesize three polyurethanes (PUs) and the effects of the molecular structure of the diisocyanate units on phase separated morphologies of PUs have been studied. The linear and planar diisocyanate unit allows good packing of the hard segments in the hard domain by extensive intersegmental hydrogen bonding, and it forms a well ordered, long hard domain. However, the nonlinear and noncoplanar diisocyanate unit shows a lesser degree of hydrogen bonding in the short hard domain. Strong preferential orientation of the rigid/long hard domains inside a macroscopic grain boundary has been observed with the polarizing optical microscope especially for the PU based on the rigid diisocyanate. It was concluded that the molecular structure of the diisocyanate unit in PU plays an important role in determining the interchain interaction, the detailed phase‐separated domain structure, and local domain orientation in each grain boundary. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

多元醇对对苯二异氰酸酯基聚氨酯微孔弹性体的形态与性能影响

以对苯二异氰酸酯(PPDI)、1,4-丁二醇、水、聚四氢呋喃醚多元醇(PTMEG)和氢化端羟基丁二烯多元醇(HLBH)为原料,采用两步法制备出聚氨酯微孔弹性体样品。通过傅里叶变换衰减全反射红外光谱(FTIR-ATR)、动态机械分析(DMA)、差示扫描量热仪(DSC)、万能材料试验机等技术手段对样品的微相分离、耐低温性能、动态生热进行了系统表征。结果表明,两种多元醇结构对泡孔尺寸影响不大,微孔尺寸在100~300μm之间,其中以150μm尺寸左右的泡孔居多;HLBH制备的聚氨酯微孔弹性体硬段形成的氢键数量多于PTMEG制备的微孔弹性体,具有更好的微相分离;由于较好的微相分离结构,HLBH样品在-30~150℃具有很宽的模量平台区,而PTMEG样品受软段的低温结晶影响,在0℃以下模量急剧上升,HLBH样品低温下的刚度变化优于PTMEG样品;同时HLBH样品的滞后生热亦小于PTMEG样品,具有更好的动态疲劳性能。     

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。     

氢键作用对基于异佛尔酮发光材料的荧光性能的影响

合成了3种基于异佛尔酮的新型单晶荧光材料:3-二丙烯腈基-5,5-二甲基-1-苯乙烯基环己烯(DCDSC)、3-二丙烯腈基-5,5-二甲基-1-(3-羟基苯乙烯基)环己烯(DCDH3C)及3-二丙烯腈基-5,5-二甲基-1-(4-羟基苯乙烯基)环己烯(DCDH4C)。通过氢核磁共振谱和元素分析确定了它们的分子结构。通过单晶X射线衍射获得了3种材料的晶体结构数据。DCDSC、DCDH_3C和DCDH_4C的紫外吸收光谱依序分布在长波区的390,398,424 nm,短波区分布在268,269,283 nm。DCDSC、DCDH3C和DCDH_4C在THF中的最大发射峰分别位于522,549,567 nm。与DCDSC相比,3位羟基取代的DCDH3C的发射波长红移了27 nm,而4位取代羟基的DCDH4C的发射波长红移了45 nm。其主要原因在于DCDSC、DCDH_3C和DCDH_4C存在不同的氢键作用,当然,取代基的类型及位置等也可能对材料的发射波长产生一定作用。     

以镁铝水滑石为前驱体制备复合氧化物催化丙酮气相缩合反应

采用共沉淀-恒温晶化法制备了系列镁铝水滑石(Mg-Al-LDH)样品,对镁铝水滑石在500 ℃焙烧得到镁铝复合氧化物(Mg-Al-LDO),采用IR、XRD、CO₂-TPD、SEM及N₂吸附-脱附等方法对Mg-Al-LDH和Mg-Al-LDO进行了表征。在温度250 ℃、液时空速1 h^-1条件下,采用固定床对镁铝复合氧化物催化剂对丙酮缩合反应的性能进行微反活性评价。研究结果表明,晶化时间与镁铝复合氧化物的弱碱性位和强碱性位的密度相关。丙酮缩聚反应的主要产物为异佛尔酮(IP)和异丙叉丙酮(MO),以及少量的异丙烯基丙酮、双丙酮醇,均三甲苯等。丙酮缩聚制备异佛尔酮的反应需要催化剂表面弱碱性位(S_w)与强碱性位(S_s)的协同作用,S_w与S_s需要匹配。晶化12 h得到的镁铝复合氧化物催化剂(LDO-12)的S_w/S_s=1.3,异佛尔酮(IP)选择性为65.3%,单程有效收率(IP+MO)为14.8%。     

Effect of 1-n-Dodecanethiol on the Molecular Weight Distribution of Poly(methyl Methacrylate) Synthesized by Suspension Polymerization

Fractionation data of two poly(methyl methacrylate) samples prepared by suspension polymerization up to limiting conversion, in the presence of different amounts of 1-n-dodecanethiol, indicate that both samples have similar polydispersity factors, although the molecular weight distribution curve for the sample obtained with the highest chain transfer agent concentration is shifted to lower molecular weight values. The results obtained are qualitatively correlated with the high conversion polymerization theory proposed by Cardenas and O'Driscoll.