聚苯胺/凹凸棒纳米纤维的制备及性能研究

使用硅烷偶联剂苯胺甲基三乙氧基硅烷(AMTES)改性凹凸棒粘土(ATP),制备了表面具有自组装单片层的SAM-ATP,并以其为模板,制备了结构较为均一的SAM-ATP/PANI纳米纤维。对制备工艺中SAM-ATP的用量进行了探讨,研究表明,当SAM-ATP含量为15.4%(质量分数)时,SAM-ATP/PANI纳米纤维结构较为均一、分散性良好,且具有最好的室温电导率2.3×10-4S/cm,使用紫外-可见分光光度计(UV-Vis)对电导率的变化原因进行了分析,使用热重分析仪(TGA)对材料的热稳定性进行了探讨,研究显示SAM-ATP的引入可有效提高PANI热稳定性。使用傅立叶变换红外分光光度计(FT-IR)和透射电子显微镜(TEM)对SAM-ATP/PANI纳米复合材料的结构和形貌进行了表征。     

Effects of Microwave on Drug Release Property of Poly(Methyl Vinyl Ether-co-Maleic Acid) Matrix

ABSTRACT

The drug release behavior of beads made of poly(methyl vinyl ether-co-maleic acid) was investigated with respect to the influence of microwave irradiation. The beads were prepared by an extrusion method with sodium diclofenac as a model water-soluble drug. The beads were subjected to microwave irradiation at 80 W for 5 and 20 min, and at 300 W for 1 min 20 s and 5 min 20 s. The profiles of drug dissolution, drug content, drug-polymer interaction, and polymer-polymer interaction were determined by using dissolution testing, drug content assay, differential scanning calorimetry, and Fourier transform infra-red spectroscopy. Keeping the level of supplied irradiation energy identical, treatment of beads by microwave at varying intensities of irradiation did not bring about similar drug release profiles. The extent and rate of drug released from beads were markedly enhanced through treating the samples by microwave at 80 W as a result of loss of polymer-polymer interaction via the (CH₂)_n moiety, but decreased upon treating the beads by microwave at 300 W following polymer-polymer interaction via the O-H, COOH, and COO^? moieties as well as drug-polymer interaction via the N-H, O-H, COO^?, and C-O moieties. The beads treated by microwave at 300 W exhibited a higher level of drug release retardation capacity than those that were treated by microwave at 80 W in spite of polymer-polymer interaction via the (CH₂)_n moiety was similarly reduced in the matrix. The mechanism of drug release of both microwave-treated and untreated beads tended to follow zero order kinetics. The drug release was markedly governed by the state of polymer relaxation of the matrix and was in turn affected by the state of polymer-polymer and/or drug-polymer interaction in beads.     

High-Throughput Analysis of Plasma Fatty Acid Methyl Esters Employing Robotic Transesterification and Fast Gas Chromatography

Fatty acid analysis is an important research tool, and indices derived from essential fatty acid contents serve as useful biomarkers related to cardiovascular and other chronic disease risk. Both clinical and basic studies of essential fatty acid composition are becoming ever larger in magnitude leading to delays while the rather laborious lipid analyses are performed. A robotic transesterification procedure has been developed for high-throughput analysis of plasma fatty acid methyl esters. In this approach, robots perform most steps including plasma and reagent transfer, transesterification reaction via heating at 80 °C in open tubes with multiple reagent additions, followed by two-phase extraction and transfer of lipid extracts to GC vials. The vials are then placed directly onto a GC autosampler carousel for robotic sample injection. An improved fast GC method is presented in which the peaks of interest are eluted within 6 min. This method is readily scalable to prepare and analyze 200 samples per day (1,000 samples per week) so that large clinical trials can be accommodated. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Viscoelastic properties of blends of poly(methyl methacrylate) and poly(styrene‐co‐acrylonitrile) having various acrylonitrile contents

Dynamic viscoelastic properties of blends of poly(methyl methacrylate) (PMMA) and poly(styrene‐co‐acrylonitrile) (SAN) with various AN contents were measured to evaluate the influence of SAN composition, consequently χ parameter, upon the melt rheology. PMMA/SAN blends were miscible and exhibited a terminal flow region characterized by Newtonian flow, when the acrylonitrile (AN) content of SAN ranges from 10 to 27 wt %. Whereas, PMMA/SAN blends were immiscible and exhibited a long time relaxation, when the AN content in SAN is less than several wt % or greater than 30 wt %. Correspondingly, melt rheology of the blends was characterized by the plots of storage modulus G′ against loss modulus G″. Log G′ versus log G″ plots exhibited a straight line of slope 2 for the miscible blends, but did not show a straight line for the immiscible blends because of their long time relaxation mechanism. The plateau modulus, determined as the storage modulus G′ in the plateau zone at the frequency where tan δ is at maximum, varied linearly with the AN content of SAN irrespective of blend miscibility. This result indicates that the additivity rule holds well for the entanglement molecular weights in miscible PMMA/SAN blends. However, the entanglement molecular weights in immiscible blends should have “apparent” values, because the above method to determine the plateau modulus is not applicable for the immiscible blends. Effect of χ parameter on the plateau modulus of the miscible blends could not be found. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

酸性离子液体［HSO3-bpy］CF3SO3催化合成MDC

制备了一系列磺酸吡啶功能化酸性离子液体(ILs),采用Hammett指示剂与紫外联用法测定了其酸强度。考察了各酸性离子液体在苯氨基甲酸甲酯(MPC)与甲醛缩合制备二苯甲烷二氨基甲酸甲酯(MDC)反应中的催化活性。结果表明,离子液体的酸强度与其催化活性关联较好;［HSO₃-bpy］CF₃SO₃酸强度最高,催化活性也最好。以［HSO₃-bpy］CF₃SO₃为催化剂兼溶剂,优化了MDC合成反应条件。在反应温度70℃,反应时间60 min,MPC与甲醛的摩尔比为12,离子液体与MPC的质量比为4的条件下,MDC产率最高可达91.5％。用水处理反应液,通过减压蒸馏后的离子液体可以循环使用5次以上。     

High-performance Cu/MgO–Na catalyst for methanol synthesis via ethyl formate

A novel hybrid catalyst system containing alkali formate and Cu/MgO–Na was developed to synthesize methanol from syngas via ethyl formate in a slurry reactor. The results exhibited that high CO conversion (>80%) and methanol selectivity (90%) with a mass space velocity of 1800 L(STP)/(h kg) were achieved at a low temperature of 433 K and at 5.0 MPa. A synergic function between HCOOM (M = Li, Na, K, Rb and Cs) and Cu/MgO–Na was in existence for promoting the reaction performance, in which sodium formate showed the optimizing synergy with Cu/MgO–Na catalyst. In addition, the nature of the solid copper catalysts also had a remarkable influence on the catalytic activity.     

聚阴离子纤维素与羟丙基甲基纤维素复配水溶液性质的研究

研究了不同配比下,2种型号的聚阴离子纤维素(PAC)与2种型号的羟丙基甲基纤维素(HPMC)复配水溶液的性质。结果表明,复配后溶液粘度表现出了协同增效作用。经过红外与紫外分析,以及PAC、黄原胶复配产生相反现象的比较分析,证明这种协同增效作用是由于在溶液中PAC与HPMC分子间形成氢键缔合的缘故。     

微波辅助十一烯酸制备工艺研究

以10-十一烯酸甲酯为原料,通过正交实验设计,在微波辅助条件下与氢氧化钠发生皂化反应生成十一烯酸钠,用稀硫酸酸化,得到10-十一烯酸。微波辅助的方法大大缩短了反应时间,降低了反应成本。所得产品通过凝固点测定、酸度测定、红外光谱等方法进行了表征。实验结果表明,最优反应条件为:微波功率100 W,反应时间20 min,反应温度100℃,10-十一烯酸甲酯与氢氧化钠的摩尔比为1∶1.2时,10-十一烯酸收率为99.33%。与传统工艺比较,该方法大大缩短了水解时间,节约了成本。     

固相法微晶纤维素接枝甲基丙烯酸甲酯共聚物的制备与表征

以过硫酸铵为引发剂,在少量水存在下,研究了微晶纤维素（MCC）与甲基丙烯酸甲酯（MMA）接枝共聚的反应规律。考察了含水量、反应时间与温度、MMA单体和引发剂用量等因素对接枝共聚反应的影响。实验结果表明,体系含水质量分数为50％左右,MMA用量为MCC质量的20％,过硫酸铵用量为MCC质量的10％,反应温度在80℃,反应时间为40min左右,可得到接枝率和接枝效率均较高的接枝共聚物。通过红外光谱（FTIR）、热重分析法（TGA）以及X射线衍射法（XRD）对合成的接枝共聚物进行了表征。     

甲基丙烯酸甲酯本体聚合动力学研究

对甲基丙烯酸甲酯（MMA）本体聚合动力学进行了研究。发现采用不同活性的偶氮二异丁腈和过氧化新癸酸叔丁酯单独引发MMA本体聚合．在不同含量下均出现明显的自动加速现象;在相同含量下,采用高低活性复合引发剂引发的MMA聚合动力学行为介于分别采用单一引发剂的聚合,但仍难消除聚合自动加速;采用聚合初后期高温、中期降温的聚合工艺对削弱聚合自动加速的效果较好。