Preparation and characterization of soluble polyimides

Two kinds of soluble polyimides from pyromellitic dianhydride with Congo red and 4-sulfanilamide were prepared, respectively. Their structures were characterized by IR and ¹H-NMR, and the thermal properties were investigated by DSC and TG–DTA. © 1995 John Wiley & Sons, Inc.     

DNA生物传感器金薄膜电极的制备及性能

用两种不同溅射工艺制备金薄膜电极。利用扫描电子显微镜、拉曼光谱法和循环伏安法对这两种电极的表面形貌、单链DNA在电极表面的自组装性能和其电化学行为进行了研究。发现不同工艺条件制作的电极性能差异较大;特别是金电极表面有其它金属存在互扩散时,对电极的电化学行为和单链DNA自组装性能具有直接影响。     

采用Raman光谱研究硅烷接枝LLDPE的结晶结构

采用傅里叶变换红外光谱(FTIR)和Raman光谱表征了硅烷接枝线型低密度聚乙烯(LLDPE)的结晶结构。用FTIR和Raman光谱上硅烷特征峰与LLDPE亚甲基峰的强度比,可相对比较硅烷接枝LLDPE的接枝率,随着硅烷用量的增加,由FTIR计算的吸光比从0.96增至2.62,由Raman光谱计算的强度比从11.53增至14．00,两者的变化趋势相同。Raman光谱分析还表明,随着硅烷用量的增加,硅烷接枝聚乙烯的结晶相质量分数由57．58％降至46．99％,非晶相质量分数由11．58％升至16．52％,中间相质量分数从30．84％升至36．48％。     

合成皂石为前驱物制备高稳定性含镍介孔分子筛

以无机盐为原料通过控制pH值,用水热法合成含Ni皂石,并以此皂石为前驱物、十六烷基三甲基溴化铵为模板剂,制备含Ni介孔分子筛.用X射线粉末衍射、Fourier变换红外光谱、程序升温还原、透射电子显微镜、比表面积和孔径测定等仪器和方法表征样品的物化性能.结果表明:制得了有序性好的含Ni介孔分子筛,其比表面积为811.2m2/g,平均孔径为3.64nm.所制备的含Ni介孔分子筛经850℃焙烧3h或100℃水热处理10d后仍然具有介孔结构,说明样品具有高的(水)热稳定性.     

Synthesis of polystyrene end-capped with pyrene via reversible addition-fragmentation chain transfer polymerization

A novel benzodithioate compound with a pyrene structure in the R group, pyrenylmethyl benzodithioate (PMB) was synthesized. Using PMB as the chain transfer agent (CTA), the RAFT polymerizations of styrene with AIBN as an initiator were carried out in different reaction conditions. The results indicated that PMB was an effective CTA for the RAFT polymerizations of styrene with the “living”/controlled characteristics. The structures of the obtained polymers were characterized by ¹H NMR. The results showed that majority of the polymer chains contained the pyrene moiety in the chain end. The enhanced fluorescence property in CHCl₃ solution was observed. The chain-extension experiments of the obtained polystyrene (PS) with the monomers of styrene and methyl acrylate were successfully carried out.     

RuO2含量对Ti／SnO2＋Sb2O3／RuO2＋PbO2阳极性台皂的影响

采用热分解法制备了以钛为基体、SnO2＋Sb2O3为中间层、RuO2＋PbO2为活性层的Ti／SnO2＋Sb2O3／RuO2＋PbO2电极。应用极化曲线法和循环伏安法测定不同RuO2含量下电极在25℃，0．5mol／LH2SO4溶液中的电催化活性。实验结果表明，随着RuO2含量的增加，相同电极电位下的电流密度增大；相同的扫描速率下，RuO2含量增加，电极的伏安电荷值增加，即电极的电催化活性随着RuO2含量的增加而增加。在1．0mol／LH2SO4溶液中，60℃、电流密度为2．0A／cm^2条件下，电极寿命快速检测结果表明，Ti／SnO2＋Sb2O3／RuO2＋PbO2电极的寿命随RuO2含量的增加而下降；但与不加有SnO2＋Sb2O3中间层的Ti／RuO2＋PbO2电极相比，电极寿命则显著增加。RuO2的含量还对电极的表面形貌有明显的影响。     

RuO2含量对Ti/SnO2+Sb2O3/RuO2+PbO2阳极性能的影响

采用热分解法制备了以钛为基体、SnO2+Sb2O3为中间层、RuO2+PbO2为活性层的Ti/SnO2+Sb2O3/RuO2+PbO2电极.应用极化曲线法和循环伏安法测定不同RuO2含量下电极在25℃,0.5 mol/LH2SO4溶液中的电催化活性.实验结果表明,随着RuO2含量的增加,相同电极电位下的电流密度增大;相同的扫描速率下,RuO2含量增加,电极的伏安电荷值增加,即电极的电催化活性随着RuO2含量的增加而增加.在1.0mol/LH2SO4溶液中,60℃、电流密度为2.0A/cm2条件下,电极寿命快速检测结果表明,Ti/SnO2+Sb2O3/RuO2+PbO2电极的寿命随RuO2含量的增加而下降;但与不加有SnO2+Sb2O3中间层的Ti/RuO2+PbO2电极相比,电极寿命则显著增加.RuO2的含量还对电极的表面形貌有明显的影响.     

Synthesis and Property of H2La2Ti3O10/CdS Layered Nanocomposite Photocatalyst

H2La2Ti3O10/CdS nanocomposite with er photoactivity was synthesized by a stepwise exchange process from H2La2Ti3O10, which was obtained by H^＋ -exchanging reaction of H2La2Ti3O10 with HCl other than the normally used HNO3. The pillaring process was investigated by XRD, TEM, FT-IR and BET methods. The photocatalytic decomposition of aniline was used as the model system to evaluate the photochemical properties of H2La2Ti3O10/CdS,H2La2Ti3O10 and K2La2Ti3O10. It is found that the photoactivity of layered H2La2Ti3O10 is greatly improved by the intercalation of CdS in the interlayer. In general, the excellent photoactivity of the H2La2Ti3O10/CdS nanocomposite might be attributing to the extremely small particle size of incorporated CdS and good contact between CdS and La2Ti3O10^2- layers. On the other hand, the coupling of two semiconductor particles with different energy gap is useful to achieve effective charge separation. In H2La2Ti3O10/CdS, a photo-generated electron can transfer from CdS to the La2Ti3O10^2- layer, while the holes remain in the CdS particles. This helps to diffuse the electrons and holes before reaching the interface, and the holes and electrons can be effectively captured by the electrolyte in the solution. Simuhaneously, the optimal operating condition of photodecomposition aniline was investigated.     

Solution-Phase Synthesis and Characterization of Perovskite LaCoO3 Nanocrystals via A Co-Precipitation Route

A facile co-precipitation route for the synthesis of well-dispersed LaCoO3 nanocrystals was developed. The asprepared products were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, energy dispersive X-ray spectrometer （EDX）, and laser Raman spectroscopy （LRS）. The resuks showed that modulating the growth parameters, such as the addition of surfactants as well as the adding manner of the precipitator had a significant effect on the overall shape and size of the obtained nanocrystals. The nanorods with the diameter of 20 nm and spherical LaCoO3 nanocrystals with the size of about 25 nm could be obtained at a relatively low calcining temperature of 600℃. Furthermore, the Raman properties of LaCoO3 products obtained at different calcining temperatures were investigated.