交联对聚己二酸乙二醇酯聚氨酯/甲基丙烯酸甲酯交联聚合物的力学阻尼、相容性及形态的影响

 用紫外光聚合方法制备出一系列端乙烯基聚己二酸乙二醇酯聚氨酯(PEAPU)和甲基丙烯酸甲酯(MMA)AB交联聚合物(ABCP)。用粘弹谱仪、透射电子显微镜(TEM)和平衡溶胀法研究了AB交联聚合物的动态力学性能、玻璃化转变温度、形态和交联密度、观察到相应于聚氨酯和PMMA相两个玻璃化转变温度,TEM照片中的微相分离是更明显的,ABCP中的两个T_g内移表明,两种成分的化学交联增加了相互的可混性、与ABCP具有相同组成的IPN有比ABCP大得多的相区。氢键能够影响ABCP的相容性、形态和动态力学性能。     

交联对聚己二酸乙二醇酯聚氨酯/甲基丙烯酸甲酯交联聚合物的力学阻尼、相容性及形态的影响

用紫外光聚合方法制备出一系列端乙烯基聚己二酸乙二醇酯聚氨酯(PEAPU)和甲基丙烯酸甲酯(MMA)AB交联聚合物(ABCP)。用粘弹谱仪、透射电子显微镜(TEM)和平衡溶胀法研究了AB交联聚合物的动态力学性能、玻璃化转变温度、形态和交联密度、观察到相应于聚氨酯和PMMA相两个玻璃化转变温度,TEM照片中的微相分离是更明显的,ABCP中的两个T_g内移表明,两种成分的化学交联增加了相互的可混性、与ABCP具有相同组成的IPN有比ABCP大得多的相区。氢键能够影响ABCP的相容性、形态和动态力学性能。     

COPU／PMMA AB交联聚合物的性能

AB交联聚合物(ABCP)是由聚合物A链与化学组成不同的聚合物B链交联构成。它的网络结构不同于IPN。IPN是由两个独立的网络构成,而在ABCP中仅存在一个聚合物网络。目前人们对它远不及对IPN了解得多。 本文选用蓖麻油为原料,与甲基丙烯酸甲酯共聚,合成了一种ABCP。研究了它的力学性能,转变与松弛,相容性及形态结构与组成及交联密度的关系。     

蓖麻油聚氨酯/甲基丙烯酸甲酯交联共聚物的合成与表征

<正> AB交联共聚物(ABCP)和互穿网络聚合物(IPN)都属交联网状聚合物,只是前者形成一个网络,后者构成两个独立网络(图1),因此两者的性能有明显差别,特别是相容性。目前对ABCP的研究主要是聚酯,聚醚体系,本工作选用便宜的蓖麻油聚氨酯(COPU)和MMA为原料,合成ABCP,得到具有阻尼性能的材料。     

STUDY ON CASTOR OIL POLYURETHANE/POLY (METHYL METHACRYLATE) AB CROSSLINKED POLYMERS

Castor oil polyurethane/poly(methyl methacrylate) AB crosslinked polymers (ABCP) were synthesized by free radical copolymerization of MMA and vinyl-terminated castor oil polyurethane which was obtained from isocyanate-terminated castor oil polyurethane and hydroxyethyl methacrylate The mechanical properties, transition and relaxation, as well as compatibility and morphology of the ABCP were investigated by changing the component. The results show that the ABCP is a semicompatible system and the compatibility of the two components decreases with increasing content of the hard segment. The mechanical and damping properties of the ABCP are obviously superior to that of their homopolymers. The damping value is mainly controlled by cross[ink density of the ABCP but the T-g value by component.     

蓖麻油聚氨酯／聚甲基丙烯酸甲酯交联聚合物的研究

被称之为AB交联聚合物(ABCP)的多相聚合物是由聚合物A链与化学组成不同的聚合物B链交联构成。它是继互穿网络IPN之     

取代基对系列有机锡单体与MMA共聚活性的影响

本文采用红外光谱技术测定了共聚物的组成,用最小二乘曲线拟合法计算了甲基丙烯酸三甲基锡酯(TMTM),三乙基锡酯(TETM),三丁基锡酯(TBTM),和三苯基锡酯(TPTM)与甲基丙烯酸甲酯(MMA)的共聚合竞聚率,其数值分别为:r_1=1.07,r_2=0.63(TMTM/MMA);0.87,0.62(TETM/MMA);0.62,0.58(TBTM/MMA);0.68,0.60(TPTM/MMA),并计算了各单体的δ和e值,讨论了不同取代基结构对其共聚合相对活性的影响。     

蓖麻油聚氨酯／乙烯类聚合物交联共聚物的动态力学性能

本文研究了蓖麻油聚氨酯(COPU)/聚甲基丙烯酸丁酯(PBMA)交联共聚物(简称ABCP)的动态力学性能,并将其与COPU/PBMA,IPN的动态力学性能作了比较。发现在ABCP中两组份的阻尼峰互相叠加,形成半相容体系,而在IPN中阻尼峰有个宽的平台。透射电镜照片表明,IPN具有更大的相区结构。这些结果证明,化学交联比物理缠结具有更大的强迫互容性。通过对COPU/乙烯类聚合物(VP)交联共聚物相容性的研究,可知COPU/PBMA,COPU/PST和COPU/PMMA交联共聚物,在动态力学性能上是半相容体系,而COPU/PMA和COPU/PBA交联共聚物是互容体系。     

AB交联聚合物的形态

以低分子量的端乙烯基聚氨酯预聚物同乙烯类单体共聚制得的AB交联聚合物(ABCP)呈现出两相形态结构,聚氨酯相形成分散相,塑料组份形成连续相。形态结构最显著特点是分散相区呈现出多分散性;其次,分散相区的形状不规则。这些特征不同于线型AB、ABA嵌段共聚物及A_2B接枝共聚物,这是由于ABCP中,A和B两组份间存在着化学交联。交联密度,预聚物的分子量对两组份的相容性,形态结构有显著影响。     

两亲性含糖三嵌段共聚物的合成与自组装研究

以二(2-溴异丁酸)4,4′-联苯酯(BiBBP)为引发剂,采用顺序加料的方法,用原子转移自由基聚合法(ATRP)合成了一系列窄分子量分布的甲基丙烯酸甲酯(MMA)和6-O-甲基丙烯酰基-1,2;3,4-双-O-亚异丙基-α-D-吡喃半乳糖苷(MAIPGal)的三嵌段共聚物.用GPC和1H-NMR表征了聚合物的相对分子量和链段组成.结果表明,通过改变投料顺序可以合成ABA和BAB型2种三嵌段共聚物,改变投料比和控制单体的转化率可以调控聚合物的链段组成.聚合物脱保护后得到两亲性含糖共聚物.用TEM考察了聚合物在水溶液中的自组装行为,表明具有不同链段组成的共聚物可以形成不同形态的聚集体,含糖段组成高的聚合物易于形成大尺寸的胶团,含糖段组成低的聚合物易于形成结构清晰的囊泡、胶束,其中,含糖段在两边的BAB型共聚物易于形成囊泡,含糖段在中央的ABA型共聚物易于形成胶束.     

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%.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.