苯基聚倍半硅氧烷改性大豆油基聚氨酯的合成及其性能研究

以环氧大豆油为起始原料经开环反应合成出大豆油多元醇,并与聚乙二醇(PEG-600)互混作为多元醇原料制备出植物油基聚氨酯.在预聚体合成过程中,加入不同含量的七苯基三环庚硅氧烷三硅醇,通过醇羟基与异氰酸酯基的反应,将聚倍半硅氧烷(POSS)引入到植物油聚氨酯基体中,制备出聚氨酯(PU/POSS)纳米复合材料,并探讨纳米粒子—聚倍半硅氧烷对聚氨酯材料热稳定性,表面疏水性及力学性能的影响.热重分析(TGA)结果表明,在O2条件下,复合材料的初始降解温度Td5和最终稳定温度Tf都会提高,特别是当POSS含量达到9.27 wt%后,聚氨酯在450~500℃之间较强的失重现象消失;DSC结果表明玻璃化温度Tg随粒子含量的增加呈现先增大后减小的趋势;静态接触角测试结果表明随POSS含量的增加,材料表面的疏水、疏油性随之增大.拉伸测试结果表明POSS的引入能在一定程度上提高材料的拉伸强度.     

木材溶液中羟基与异氰酸酯反应的研究

以涂料工业广泛应用的新型助剂二元酸酯 (DBE)为液化试剂 ,盐酸为催化剂 ,将苯甲基化木材溶液化后 ,与不同结构的异氰酸酯反应 .利用FT IR及1 3C NMR分析液化苯甲基木质纤维素与不同结构异氰酸酯得到了聚氨酯树脂 ,证明了木材中羟基可以用来作为聚醚多元醇与异氰酸酯制备聚氨酯材料 .通过准确测量体系中游离的NCO含量 ,从而得出不同结构异氰酸酯与木材溶液中羟基的反应规律 .实验结果表明 ,异氰酸酯的存在大大促进了木材结构中羟基的释放 ,由于不同异氰酸酯的活性不同 ,使得羟基值变化亦不相同 ,其顺序为IPDI>HDI>TDI .为了保证最终的材料性能 ,选择TDI和IPDI作为木材溶液制备聚氨酯树脂的异氰酸酯组份较好     

生物基弹性体研究进展

出于对节约石油资源、保护环境、发展循环经济等考虑,用可再生的生物资源代替石油化学品生产高分子材料已成为人们研究的热点。弹性体是一类应用领域非常广泛的材料,但是绝大多数的弹性体都是以石油基化学品为原料合成的,因此研究生物基弹性体对节约石油资源及保护环境具有重要意义。本文对目前研究较多的三类生物基弹性体—生物基聚氨酯弹性体、生物基聚酰胺弹性体、生物基聚酯弹性体作了简要的综述。主要介绍了合成生物基弹性体的原料、合成路线以及相关的生物基弹性体的性能比较。     

非异氰酸酯聚氨酯的合成与应用

聚氨酯是一种重要的高分子材料,但其关键原料异氰酸酯有毒和湿敏的缺点限制了其应用前景.环碳酸酯化合物与伯胺反应是制备得到聚氨酯的一条新途径,用这种方法合成的非异氰酸酯聚氨酯(NIPU),其羟基氨基甲酸酯基形成分子内氢键而具有比传统聚氨酯更好的耐水解性和机械性能.本文介绍了NIPU的合成机理,总结了环碳酸酯的合成方法,综述...     

提高聚氨酯生物稳定性和相容性的研究进展

聚氨酯因其具有优异的机械性能、良好的生物稳定性和生物相容性等成为目前研究和应用广泛的一种生物高分子材料.但是作为长期植入材料,其生物稳定性和相容性并不完美,因此对聚氨酯材料进行改性来提高其生物稳定性和相容性已成为目前研究的重要方向.本文首先介绍了聚氨酯生物材料的结构特点,概述了其作为生物材料的合成进展情况,然后总结了提...     

生物医用蓖麻油基聚氨酯及其接枝改性的研究进展

蓖麻油是价格低廉的可再生资源,含有大量的羟基,可代替聚酯(醚),合成出蓖麻油基聚氨酯,在生物医学领域有着广阔的发展空间。本文阐述了聚氨酯合成方法,分析了结构特性,并对其蓖麻油基聚氨酯接枝改性进行了较详细的探讨。报道了蓖麻油基聚氨酯接枝改性后的生物医用发展趋势。随着组织修复材料的发展,以天然生物质为原料而制备的该种复合生物材料是有广阔的发展前景。     

CO2/生物基环氢化合物共聚制备绿色聚碳酸酯材料

以CO_2为原料合成脂肪族聚碳酸酯材料不仅利用了廉价、可再生的CO_2资源,而且可以实现全生物降解高分子材料的制备,是一条绿色可持续的高分子材料合成路线。但长期以来,该领域研究多集中在利用CO_2与一些石油来源的环氧烷烃(如环氧丙烷、环氧环己烷等)共聚方面,未能完全摆脱对石油资源的依赖。因此,发展基于生物基的环氧单体制备全生物基高分子材料逐渐成为CO_2基高分子材料研究的热点。生物基来源化合物的引入有助于丰富CO_2基高分子材料的结构和性能,拓展其应用领域。本文综述了近年来利用生物基环氧化合物与CO_2共聚合成全生物基高分子材料的研究进展,并对未来该领域发展的趋势进行了展望。     

pH响应性聚氨酯薄膜的制备

聚氨酯基水凝胶是一种重要的生物医学材料[1 ] ,文献中已报道了块状聚氨酯水凝胶[2 ,3] 、聚氨酯与聚丙烯酸酯的互穿网络水凝胶[4] 、温度及 pH双敏性聚氨酯基水凝胶[5] 等 ,但有关薄膜状聚氨酯凝胶材料还未见报道。本文合成了 5个端丙烯酸酯基聚氨酯预聚物 ,通过紫外光照射固化 ,得到了具有快速pH响应性的敏感薄膜。端丙烯酸酯基聚氨酯预聚物乳液 (PU)参照 [5 ]方法合成。固定聚乙二醇 (PEG)与 2 ,2 二羟甲基丙酸 (DMPA)摩尔比为 3∶7,先使全部的 1 ,6 六亚甲基二异氰酸酯 (HMDI)与PEG及DMPA反应制得异氰酸酯封端的预聚物 ,将该…     

可用于建材防水涂料的含氟聚氨酯的研制及性能研究

以聚醚二元醇和异氰酸酯合成两端含异氰酸酯基的聚氨酯预聚物,将含氟醇与聚氨酯预聚物进行反应,得到端基含氟的聚氨酯,制备了一系列含氟聚氨酯涂料。对涂料的性能研究显示,聚合物对基材具有良好的附着力,且随着含氟量的增大,制备的含氟聚氨酯涂层对水及乙二醇的接触角数值逐渐增大,表面能和吸水率逐渐降低;聚合物体系均一,未发生相分离。表明通过化学方法将含氟链段引入聚氨酯结构,得到了稳定的含氟聚氨酯聚合物,且涂料的表面性能得到提高。该含氟聚氨酯在建材防水涂料领域有广阔的应用前景。     

浅谈聚氨酯产业现状与发展趋势

聚氨酯材料是一类广泛应用的高分子材料,本文针对目前我国聚氨酯制品的广泛应用及其产业的迅猛发展,预测了国内聚氨酯三大基础原料甲苯异氰酸酯(TDI)、二苯基甲烷二异氰酸酯(MDI)和聚醚多元醇(PPG)的未来产能,同时从我国人口总量的优势、交通运输业的增长、建筑节能的新需求、休闲市场的新发展及医用材料的应用等几个方面分析了未来拉动聚氨酯产业发展的几大因素,指出国内聚氨酯产业的发展趋势。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.