原位聚合法制备聚酰胺/聚苯胺复合导电纤维

研究了原位聚合法制备聚酰胺/聚苯胺导电纤维,并对制备的复合纤维进行红外及光学显微镜测试,结果表明聚苯胺与纤维成功复合。对制备的复合纤维进行电导率测试,采用控制单一变量法探讨了苯胺单体在不同的条件下聚合对纤维电导率的影响,并讨论了反应温度对聚合过程和电导率的影响,得出最佳的工艺条件为:纤维经30%的甲酸溶液预处理20min,苯胺单体浓度为0.8M,氧化剂过硫酸铵浓度为1M,掺杂酸为盐酸,浓度为0.8M,冰水浴条件,反应时间为4h,得到的聚酰胺/聚苯胺导电纤维的电导率为3.7S/m。     

聚苯胺/离子液体/蒙脱土纳米复合材料的制备及其导电性能研究

采用1-羧甲基-3-甲基咪唑氯化盐离子液体对钠化蒙脱土进行插层改性,然后用苯胺的盐酸溶液进行二次插层,以过硫酸铵为氧化剂,盐酸溶液为掺杂剂,使进入离子液体/蒙脱土(CMMIm/MMT)层间的苯胺(An)发生氧化聚合反应,制备了一种具有良好导电性的聚苯胺/离子液体/蒙脱土复合材料(PANI/CMMIm/MMT).用红外光谱、X-射线衍射,热重分析和DSC对样品进行了表征.结果表明当离子液体/蒙脱土用量为7.5%、盐酸浓度为1mol/L、过硫酸铵与苯胺的摩尔比为1∶1、0℃下反应6h时制备的PANI/CMMIm/MMT纳米复合材料电导率最高,达到了0.3S/cm,是相同条件下聚苯胺/钠化蒙脱土纳米复合材料电导率的2.5倍,聚苯胺的7.5倍.     

聚酰亚胺/绢云母复合材料的制备及表征

首先采用加热和酸浸、硝酸锂处理、十六烷基三甲基溴化铵(HDTMAB)阳离子交换等多步反应制备了有机绢云母,随后通过原位聚合插层法合成了不同种类的聚酰亚胺(PI)/绢云母复合材料.研究了反应温度及有机阳离子HDTMAB加入量对绢云母改性效果的影响,采用X-射线衍射(XRD)、傅里叶变换红外光谱(FTIR)和扫描电子显微镜(SEM)对改性前后的绢云母进行了系统的分析.结果表明,改性反应温度为180℃,有机阳离子加入量为15倍的阳离子交换容量(CEC)时插层效果最理想,在此条件下,绢云母d002晶面间距从0.99 nm扩大到2.77 nm.通过XRD和高分辨透射电子显微镜(HRTEM)对复合材料的微观结构进行了研究,采用热重分析(TGA)和力学性能测试研究了复合材料的热性能,拉伸强度、杨氏模量和断裂伸长率.结果表明,用原样绢云母制备的PI/原样绢云母复合材料是一种简单物理混合物,而PI/有机绢云母复合材料是一种剥离型纳米复合材料,同时,有机绢云母含量为1%~7%的纳米复合材料在2θ=0.5°~10°的衍射角范围内,均没有出现明显的衍射峰,表明有机绢云母的d002晶面间距被扩大到4.42 nm以上.绢云母与PI质量比为5∶100时,PI/有机绢云母纳米复合材料的拉伸强度、杨氏模量、断裂伸长率是PI/原样绢云母复合材料相应值的1.79,1.40和1.83倍.纳米复合材料的T5(质量损失5%时的温度)随着有机绢云母含量的增加而显著提高,当有机绢云母含量为7%时,纳米复合材料的T5相比纯PI可提高36℃.     

有机膨润土改性高吸油树脂复合材料的合成及性质

以十六烷基三甲基溴化铵为表面改性剂制备了有机膨润土,并制备了以甲基丙烯酸十六酯为单体的吸油树脂/有机膨润土复合材料.采用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、扫描电子显微镜(SEM)对样品进行分析.结果表明,经十六烷基三甲基溴化铵改性的膨润土层间距由原来的1.12 nm增大到1.87 nm;所得有机膨润土/吸油树脂复合材料对四氯化碳的饱和吸油率为16.3 g/g.     

含水状态对细菌纤维素/聚苯胺复合凝胶膜制备及性能的影响

以不同含水量细菌纤维素为模板,苯胺单体为原料原位聚合生成聚苯胺,制备出不同含水量细菌纤维素/聚苯胺(HBC/PANI、LBC/PANI及DBC/PANI)复合凝胶膜,系统研究了细菌纤维素凝胶膜含水量和反应时间对苯胺原位聚合以及复合凝胶膜微观形貌、电学性能和力学性能的影响.扫描电镜照片表明聚苯胺均匀包覆在BC纤维上形成导电网络结构;四探针测试表明聚合时间90 min时导电率最高;低含水量加快了聚合反应速度,提高了复合凝胶膜的电导率,而完全干燥则使电导率降低;交流阻抗测试也表明低含水量可以明显提高材料的离子导电性;力学性能测试结果表明了BC/PANI复合凝胶膜具有良好的机械性能,抗拉强度可达0.21 MPa,同时低含水量不会降低复合凝胶膜的力学性能.     

聚苯胺/碳化钨导电复合材料的合成

以苯胺和过硫酸胺为原料,采用原位聚合方法合成了聚苯胺/碳化钨(PANI/WC)导电复合材料。研究了反应体系中碳化钨的含量对复合材料电导率的影响,确定了较佳的聚合条件,并且通过FT-IR、XRD、XPS和DSC-TGA等手段对复合材料的结构和性能进行了表征和分析。结果表明:碳化钨(WC)的加入提高了聚苯胺的电子导电性能,复合材料中聚苯胺组分为无定型,WC的晶型在反应前后并未发生变化,复合材料的热稳定性好并且质子化程度更高。     

聚苯胺/纳米二氧化锰复合材料Ⅱ.形貌表征

通过先用过硫酸铵引发苯胺的聚合,然后再将纳米二氧化锰(nm-MnO2)加入过硫酸铵和苯胺的反应体系中。原住制备了导电聚苯胺／纳米二氧化锰复合材料(PANL／nm-MnO2),并有效地避免了nm-MnO2在苯胺氧化聚合中的消耗。扫描电镜和透射电镜显示复合材料中nm-MnO2为聚苯胺所包裹。X射线衍射研究表明,在复合材料制备过程中nm-MnO2的晶型未发生变化,在复合材料中聚苯胺为非晶相结构。     

原位聚合法制备PANI/PET导电织物及其性能分析

在聚酯纤维基材及其织物表面,原位聚合形成厚度约1~2μm聚苯胺包覆层,制得聚苯胺(PANI)/聚酯(PET)导电织物.PANI层优异的导电性能使之成为有广阔发展前景的柔性电磁屏蔽材料.正交试验分析研究了苯胺单体浓度、氧化剂:苯胺摩尔比、掺杂酸浓度、反应时间对PANI包覆层外观形态、与基体结合牢度以及导电性的影响.实验表明:在经适当前处理的PET基材表面,以苯胺单体浓度为0.25mol/L、氧化剂与苯胺摩尔比为1∶1、掺杂酸浓度0.5 mol/L、反应时间60 min、反应温度为0~20℃时制备的PANI/PET导电织物方阻最小,导电性最好;掺杂酸酸性越强,导电性越好.SEM、FTIR及XRD测试表明涤纶织物表面有均匀连续的聚苯胺膜存在.分析表明聚苯胺分子链中氧化结构与还原结构含量基本相等,说明聚苯胺渗入纤维内部,使纤维无定形区面积增加,结晶度减小.     

丙烯酸树脂／蒙脱土纳米复合材料的制备研究

采用离子交换法,用十六烷基三甲基溴化铵对钠基蒙脱土(Na-MMT)进行改性制备了有机蒙脱土(OMMT).用丙烯酸(AA)、硫酸化蓖麻油、乳化剂OP-10、过硫酸钾为原料进行水溶液聚合制得丙烯酸树脂.将丙烯酸树脂与改性蒙脱土通过聚合插层制备了丙烯酸树脂/ 蒙脱土纳米复合材料.通过傅立叶变换红外(FTIR)和X-射线衍射 (XRD)等手段对复合材料的结构进行了表征,结果表明:丙烯酸树脂插层进入有机蒙脱土内可形成插层型或剥离型的纳米复合材料.蒙脱土含量及蒙脱土与丙烯酸树脂的反应温度、反应时间均对复合材料的剥离行为产生影响,在蒙脱土含量为树脂固含量的7%、温度为70℃、反应4h的条件下可得到完全剥离的纳米复合材料.     

苯胺在十二烷基苯磺酸/水体系中的乳液聚合过程研究

利用光学显微镜和扫描电镜,对以水为介质、十二烷基苯磺酸(DBSA)为乳化剂的苯胺乳液聚合过程进行监测,发现苯胺在水体系中与DBSA反应形成DBSA-苯胺盐的棒状聚集结构,讨论了DBSA、苯胺、氧化剂的配比及浓度对聚合过程中棒状聚集结构的长度和数量及生成聚苯胺的电导率的影响,提出苯胺在DBSA/水体系中的乳液聚合反应是在胶束表面进行的,而棒状聚集结构中的DBSA-苯胺盐单体经水相扩散到乳胶粒子中,形成颗粒状的聚苯胺.     

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.     

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.     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

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%).