有机硅改性聚氨酯的合成与性能

在无溶剂条件下利用二步法合成了一系列氨基硅油改性聚氨酯,采用红外光谱对预聚体进行了表征,同时测试了材料的力学性能、耐热性、表面水接触角及微观形态,结果表明,改性后的聚氨酯具有优良的力学性能、耐热性及表面疏水性,且材料呈微观相分离形态。     

聚氨酯改性环氧树脂的研究进展

环氧树脂具有优异的粘接性能和力学性能因而被广泛应用,但其耐热性差、脆性大等缺陷限制了其在高性能领域中的应用。聚氨酯具有高弹性、耐磨、抗撕裂等特点,且与环氧树脂相容性好。因此,利用聚氨酯改性环氧树脂能显著提高其力学性能,实现环氧树脂在众多领域的应用。本文综述了不同类型的聚氨酯改性环氧树脂的进展,指出了不同类型的聚氨酯改性环氧树脂的机理、改性效果及影响因素,并对其发展前景进行展望。     

氨基硅油改性聚醚型聚氨酯

以甲苯二异氰酸酯、聚氧化丙烯二醇、氨乙基氨丙基聚二甲基硅氧烷为原料在无溶剂条件下合成了有机硅改性聚氨酯预聚体 ,用红外光谱对其进行了表征。以 3,3′ 二氯 4 ,4′ 二氨基 二苯基甲烷复合固化剂固化得氨基硅油改性聚氨酯材料 ,对材料的力学性能、耐热性、表面水接触角测试等表明 ,改性聚氨酯在ω(氨基硅油 ) =3%～ 15 %时 ,有较明显的改性效果 ,且在ω(氨基硅油 ) =10 %时 ,具有最佳综合性能 ,其拉伸强度和伸长率较未改性的分别提高 31%和 5 2 % ,表面水接触角提高了 2 3° ,耐热性也有所提高     

无机纳米填料改性聚氨酯研究及其应用进展

无机纳米填料改性可改善聚氨酯材料的机械力学性能和耐水、耐热、选择透气性等以及引入抗菌、电磁屏蔽、形状记忆等一些功能特性,近年来,纳米无机填料改性聚氨酯成为聚氨酯改性研究的前沿热点之一。本文综述了聚氨酯纳米复合材料的最新研究进展,在扼要介绍无机纳米填料改性聚氨酯的主要制备方法基础上,着重总结了通过无机纳米填料引入功能特性并应用于多功能涂料、合成革、生物医用材料及形状记忆材料等方面的研究进展,并展望了纳米无机填料改性聚氨酯的一些主要研究方向。     

蓖麻油及其衍生物在聚氨酯中的应用研究进展

蓖麻油是一种重要的可再生生物资源,在许多精细化学品以及聚合物方面有广泛的应用,介绍了蓖麻油及其衍生物在聚氨酯,互穿网络聚合物,聚氨酯弹性体,以及功能聚合物等方面的应用研究进展.指出以蓖麻油为原料改性和制备的聚合物材料不仅可以解决日趋紧缺的石油资源,加快聚合物工业的发展,而且改善了传统聚氨酯的耐热性,耐化学品性和力学性能等,拓宽了聚合物的应用领域.     

有机硅/蒙脱土复合改性聚氨酯弹性体的制备和性能

采用先将聚醚三元醇N330与有机蒙脱土(OMMT)研磨,制得N330/OMMT复合物,再将其与有机硅改性聚氨酯的预聚体混合的方法,以二甲硫基甲苯二胺(DMTDA)为固化剂,制备了有机硅/蒙脱土复合改性聚氨酯弹性体,并用FTIR对产物结构进行了表征.XRD和TEM表明,蒙脱土片层被撑开,并分散在基体中;SEM显示,加入蒙脱土后,有机硅与聚氨酯之间的相容性提高;TGA表明,有机硅和OMMT共同改性聚氨酯后,其耐热性比有机硅单一改性聚氨酯有所提高,并在OMMT含量为5 wt％时提高最大;DSC数据表明,在OMMT含量为5 wt％时,有机硅/蒙脱土复合改性聚氨酯弹性体的Tg明显升高.复合改性材料具有良好的表面性能和力学性能,其拉伸强度、断裂伸长率和硬度在OMMT含量为3 wt％时达到最大值.     

改性纳米炭黑/聚氨酯复合物的制备及表征

利用有机硅偶联剂改性的纳米炭黑和聚氨酯制备了纳米炭黑/聚氨酯复合物. 采用红外光谱、透射电镜、流变学及力学性能等测试方法对纳米粒子及其聚氨酯复合物进行了表征. 红外光谱表明, 纳米粒子的存在使聚氨酯的氢键结构发生了改变. 适量改性纳米炭黑粒子明显提高了聚氨酯的拉伸强度和断裂伸长率等力学性能. 流变学测试结果表明, 溶液中改性纳米炭黑粒子与聚氨酯分子间存在明显的相互作用.     

聚碳酸亚丙酯聚氨酯的合成与性能

用ＣＯ２与环氧丙烷共聚产物聚碳酸亚丙酯制备出聚氨酯（ＰＰＣＰＵ）．同时探讨了ＰＰＣＰＵ最佳合成方法,考察了异氰酸酯基与羟基的比值、扩链交联剂用量等因素对其力学性能的影响．研究了ＰＰＣＰＵ的形态结构及其性能对配比的依赖关系．发现聚碳酸亚丙酯的耐热性因聚氨酯的形成而得到较大的改善,并发现该类材料具有优异的耐水性能．     

高醚化三聚氰胺甲醛树脂交联水性聚氨酯的制备与表征

合成了高醚化三聚氰胺甲醛树脂(HMMM)交联改性含聚乙二醇单甲醚(Ymer N120)亲水基团的阴离子型水性聚氨酯。 通过全反射红外(ATR-FTIR)、差示扫描量热仪(DSC)、电子拉力机等技术手段表征了改性后的水性聚氨酯胶膜结构、热性能和力学性能。 结果表明,随着HMMM质量分数的增加,聚氨酯胶膜中氢键相互作用减弱,胶膜耐热性、耐水性、拉伸强度、粘接性均有所提高;当HMMM为8%时,聚氨酯胶膜的拉伸强度增加了125%,T-型剥离强度增加了7.4 N/cm,硬段最大热分解速率对应温度增加了38 ℃。 此外,交联水性聚氨酯胶膜的耐水性也得到了很大程度的提高。     

水性聚氨酯涂料改性研究进展

随着环保理念的日益增长,水性涂料将逐步取代溶剂型涂料.水性聚氨酯涂料由于其综合性能优越,是水性涂料中发展最快的品种之一,得到了广泛研究.为了进一步提高水性聚氨酯涂料的性能,通常要对聚氨酯树脂进行改性.对近些年常用的改性技术,如有机树脂改性、无机纳米材料改性和植物油改性的原理与方法进行了综述.这些改性技术可以提高水性聚氨酯的耐热性、耐水性、光泽度、物理机械性能、固含量等综合性能.     

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%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.     

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.     

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.