基于灰色理论的掺杂态导电聚苯胺的制备及导电性能研究

以苯胺(An)为单体,氨基磺酸(SA)为掺杂剂,过硫酸铵(APS)为氧化剂,采用化学氧化聚合法合成了掺杂态导电聚苯胺。考察了n(苯胺)/n(掺杂剂)、n(苯胺)/n(氧化剂)和反应时间对聚苯胺电导率的影响。结果表明,当n(An)∶n(SA)∶n(APS)=1∶6∶0.4、反应时间为6h时,聚苯胺的电导率最高达到0.87S/cm。进一步利用灰色关联分析,定量地分析了各因素对掺杂态导电聚苯胺电导率的影响程度,得出了各因素影响电导率的大小顺序为掺杂剂、氧化剂、反应时间。并以氨基磺酸的添加量为基本建立了掺杂态导电聚苯胺电导率的灰色预测模型(灰色离散Verhulst模型),预测了氨基磺酸不同添加量下的电导率,平均预测精度为97.25%。结果证明,灰色系统理论在掺杂态导电聚苯胺的电导率的预测中是可行的。     

聚乙烯醇-聚吡咯复合纳米纤维的制备及其导电性能

利用化学氧化法制备出导电聚吡咯（PPy）,与聚乙烯醇（PVA）共混后,采用静电纺丝技术制备PVA-PPy纳米共混纤维,随后加入对甲苯磺酸钠（TSNa）、十二烷基磺酸钠（DSNa）、十二烷基苯磺酸钠（DBSNa）和磺基琥珀酸二乙基己酯钠（DEHS）等不同掺杂剂改变纤维的结构和性能,采用SEM、TGA和四探针测试仪检测了纳米纤维的形貌、热稳定性和导电性能。结果表明,掺杂剂、PPy制备技术及聚合物添加剂对PPy的形貌、热稳定性和导电性能有很大影响。纳米纤维的电导率远远高于用同样掺杂剂所制备的PVA-PPy薄膜和PPy粉末,四种纳米纤维中DEHS掺杂PVA-PPy纳米纤维的电导率最高,可达26.64 S/cm。     

酒石酸掺杂微/纳米结构聚苯胺的制备及表征

以酒石酸为掺杂剂,过硫酸铵为氧化剂,采用"无模板"自组装法合成了掺杂态聚苯胺微/纳米纤维。分析了酒石酸与苯胺的不同摩尔比对产物形貌、分子结构及电性能的影响。结果表明,酒石酸与苯胺摩尔比为1时,生成了长径比较大、有序性较好的聚苯胺微/纳米纤维,该比例下电导率达到9.355×10-2 S/cm。改变反应温度和反应时间,酒石酸在常温下自组装掺杂即可得到较高电导率的聚苯胺产物。傅里叶变换红外光谱、紫外可见光分光光度计、X射线衍射仪的表征结果证明,不同酒石酸与苯胺摩尔比下合成的聚苯胺微/纳米纤维均为掺杂态,且具有一定的导电性。     

凝固浴条件对聚酰亚胺纤维形貌和性能的影响

采用湿法纺丝获得聚酰胺酸(PAA)初生纤维,以水和N,N-二甲基乙酰胺(DMAc)的混合溶液作为凝固浴,通过热酰亚胺化制备了均苯四甲酸二酐/4,4’-二氨基二苯醚(PMDA/4,4’-ODA)-聚酰亚胺(PI)纤维。系统研究了阱深长度、凝固浴温度及浓度对PI纤维形貌和性能的影响。结果表明:PAA纤维截面在阱深长度较小、凝固浴温度较低、DMAc浓度较低时呈不规则的腰形,随着阱深长度不断增加,凝固浴温度和浓度的增加,纤维截面都会逐渐趋于圆形。在阱深长度为50cm,凝固浴温度40℃,以3%(体积分数)DMAc作为凝固浴时,所得PAA纤维截面形貌较圆整,且PI纤维性能较好。     

凝固浴条件对湿纺PAN初生纤维截面形状和皮芯结构的影响

借助光学显微镜及图像处理软件研究了凝固浴质量分数、温度、喷丝头牵伸倍率对湿纺PAN初生纤维截面形状和皮芯结构的影响.实验结果表明,较高的凝固浴质量分数(70%)、较高的凝固浴温度能使双扩散比较充分,所得初生纤维截面形状规整趋于圆形,并且芯部致密无孔洞.此外,随着牵伸倍率的升高,皮层厚度降低,皮芯差异增加,牵伸倍率为负牵伸是制备皮芯差异较小初生纤维的手段之一.     

导电聚苯胺二次掺杂制备方法及性能研究

利用化学氧化合成原理,以氨基磺酸(SA)为一次掺杂剂,盐酸为二次掺杂剂,制备了二次掺杂的导电聚苯胺,分别考察了不同掺杂剂量、氧化剂量及掺杂反应时间等因素对聚苯胺电导率的影响。实验结果表明,当n(An)∶n(SA)∶n(APS)=1∶5∶0.4,盐酸为1mol/L,一次掺杂反应时间为3.5h时,所得产物电导率较高且可达3.18S/cm。结果表明,二次掺杂工艺得到的产物具有较好的导电性能,并节约SA用量约40%,是一种绿色、新颖的制备方法。     

凝固浴拉伸对碳纤维前驱体PAN初生纤维结构及性能的影响

采用高锰酸钾反滴定法、X射线衍射法、电子探针、纤维纤度仪及强力仪等考察了聚丙烯腈纤维在湿法成形过程中,凝固浴拉伸对溶剂二甲基亚砜的扩散系数、残留溶剂含量、S元素含量、初生纤维结晶性能、截面形貌及初生纤维应力-应变曲线的影响。结果表明,在凝固浴温度、浓度、凝固时间一定的情况下,表观负牵伸为-10%时,溶剂二甲基亚砜的扩散速率较快,残留溶剂量较小;同时,出浴初生纤维表现出了较均匀、规则的横截面形貌,较好的结晶度以及韧性良好的应力-应变曲线。     

聚苯胺网状纳米结构的合成与表征

以樟脑磺酸为掺杂剂、三氯化铁和过硫酸铵为二元混合氧化剂,在水溶液体系中通过苯胺原位聚合制备得到直径为80～100nm的聚苯胺网状纳米结构,其导电率为10-2～10-1S/cm.进一步研究结果表明,三氯化铁可抑制聚苯胺纤维的形成,并同时起到掺杂剂和氧化剂的双重作用;通过控制FeCl3用量和n(APS):n(FeCl3)的比值,可调节产物的形貌结构和导电率.     

界面聚合法合成有机酸掺杂聚苯胺结构与性能研究

以苯胺为单体,过硫酸铵为氧化剂,分别以乙酸、月桂酸、硬脂酸、十二烷基苯磺酸为掺杂酸,通过界面聚合法成功制备了有机酸掺杂聚苯胺,对其导电性能、溶解性能进行评价,对其化学结构、晶型结构和微观结构进行分析。结果表明:当苯胺与掺杂酸摩尔比为1∶2时电导率普遍较好,约为(1.73～2.43)×10-4S/cm;有机酸掺杂聚苯胺在极性溶剂中溶解性较好;FT-IR分析结果证明有机酸对聚苯胺进行了成功掺杂;XRD结果说明聚苯胺在2θ=6°的衍射峰受掺杂酸尺寸影响较大,且对聚苯胺的微观形貌具有显著影响。     

聚苯胺复合电极的制备及电化学性能研究

以化学法合成导电聚苯胺，研究了氧化剂和掺杂剂以及反应温度和时间对聚苯胺的产率和电导率的影响。在确定的配方和工艺条件下，聚苯胺的合成产率为94％，电导率在5.6S/cm，将合成得到的聚苯胺掺杂导电粉体制备成高分子是合电极材料，在恒电流上进行充放电性能测试。结果表明，开路电位和放电电位较高，在以4mA/cm^2恒电流放电，终止电位为1．2V时，放电时间可持续16.5h，放电容量大。     

Structure and properties of melt-processed PVDF/PMMA/polyaniline blends

Ternary blends composed of the matrix polymer poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) with different proportions of thermally doped polyaniline (PAni) using an alkylated dopant (dodecylbenzenesulfonic acid) (DBSA) were prepared by melt mixing. The effectiveness of these blends was compared with the corresponding binary blends of PVDF or PMMA with PAni–DBSA complex. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) measurements, thermal analysis by differential scanning calorimetry (DSC) and morphological studies by optical microscopy and scanning electron microscopy (SEM) were carried out to characterize the blends in light of the interactions between their components and on the resulting electrical conductivity. Though a notable dispersion of PAni–DBSA in the PMMA matrix was incurred along with better conductivity with respect to PVDF/PAni–DBSA and PVDF/PMMA/PAni–DBSA blends, the thin films based on PMMA/PAni–DBSA were found to be fragile in nature. However, the presence of PMMA in the ternary blends of PVDF/PMMA/PAni–DBSA provided improved dispersion of PAni–DBSA in the PVDF/PMMA host matrix as compared to PVDF/PAni–DBSA binary blends. An enhancement in the conductivity by about two orders of magnitude at >5 wt% PAni–DBSA was witnessed in the ternary blends than that of PVDF/PAni–DBSA binary blends. Thin films made of ternary blends of PVDF/PMMA/PAni–DBSA also offered superior mechanical properties and flexibility than that of PMMA/PAni–DBSA binary blends due to the contribution of PVDF in the blend.     

Multi-walled carbon nanotubes and poly(lactic acid) nanocomposite fibrous membranes prepared by solution blow spinning

Nanocomposite fibers based on multi-walled carbon nanotubes (MWCNT) and poly(lactic acid) (PLA) were prepared by solution blow spinning (SBS). Fiber morphology was characterized by scanning electron microscopy (SEM) and optical microscopy (OM). Electrical, thermal, surface and crystalline properties of the spun fibers were evaluated, respectively, by conductivity measurements (4-point probe), thermogravimetric analyses (TGA), differential scanning calorimetry (DSC), contact angle and X-ray diffraction (XRD). OM analysis of the spun mats showed a poor dispersion of MWCNT in the matrix, however dispersion in solution was increased during spinning where droplets of PLA in solution loaded with MWCNT were pulled by the pressure drop at the nozzle, producing PLA fibers filled with MWCNT. Good electrical conductivity and hydrophobicity can be achieved at low carbon nanotube contents. When only 1 wt% MWCNT was added to low-crystalline PLA, surface conductivity of the composites increased from 5 x 10(-8) to 0.46 S/cm. Addition of MWCNT can slightly influence the degree of crystallinity of PLA fibers as studied by XRD and DSC. Thermogravimetric analyses showed that MWCNT loading can decrease the onset degradation temperature of the composites which was attributed to the catalytic effect of metallic residues in MWCNT. Moreover, it was demonstrated that hydrophilicity slightly increased with an increase in MWCNT content. These results show that solution blow spinning can also be used to produce nanocomposite fibers with many potential applications such as in sensors and biosensors.     

Morphology and conductivity of polyaniline sub-micron fibers prepared by electrospinning

Sub-micron fibers of pure polyaniline (PANI) doped with sulfuric acid or hydrochloric acid were prepared by electrospinning PANI with suitable molecular weight dissolved in hot sulfuric acid. A modified electrospinning setup was employed with a coagulation bath as a collector, where dilute sulfuric acid was used as coagulation bath. The factors influencing the morphology and conductivity of the synthesized PANI fibers were investigated, including the concentration of dilute H₂SO₄ solution in the coagulation bath, the doped PANI concentration in H₂SO₄ solution, the type of doping acid and the voltage applied to the solution. The morphologies of doped PANI fibers were characterized by scanning electron microscope (SEM). The structure of the resulting fibers was analyzed by Fourier transform infrared spectroscopy and UV–vis spectrometer. The conductivity of PANI fibers were characterized by I–V characteristics. Homogeneous PANI fibers with a diameter of 370 nm and a high conductivity of 52.9 S/cm were prepared. The possible mechanisms of different morphology formation and conductivity of PANI fibers were also discussed.     

超声场下导电聚苯胺/纳米铁氧体吸波涂层的制备及其吸波性能

导电聚苯胺/纳米铁氧体复合吸波材料具有吸波能力强,质量轻等特点.采用乳液聚合法以苯胺为单体、十二烷基苯磺酸为掺杂剂、过硫酸铵为氧化剂,在超声场下制备导电聚苯胺粉体;将其与纳米Ni0.5Zn0.5Fe2O45及纳米Co0.5Zn0.5Fe2O4一起用原位合成法制备了复合吸波涂层.结果表明:制备的吸波涂层在17.9,15.9,22.3 GHz时分别具有最大反射损耗-10.0,-15.9,-39.9 dB,2种复合涂层拓展了波段,提高了对电磁渡的吸收效果.     

磺基水杨酸掺杂导电聚苯胺纳米材料的制备与性能研究

采用化学氧化法以苯胺为单体,过硫酸铵为氧化剂,磺基水杨酸为掺杂酸合成聚苯胺纳米棒导电材料。考察了单体/掺杂酸摩尔比对聚苯胺形貌与电性能的影响,采用傅里叶红外光谱,XRD粉末衍射表征聚苯胺结构;电化学工作站、四探针研究表明聚苯胺的导电性随掺杂酸/单体摩尔比的增大而增大,单体/掺杂酸摩尔比为2时电导率为1.43S/cm;SEM、TEM表明聚苯胺纳米棒表面粗糙,直径约为100～200nm,长度约为400～700nm,表面附着了1层10～30nm厚的颗粒;并提出了纳米棒可能的形成机理。     

Low Electrolytic Conductivity Standards

Standards of low electrolytic conductivity were developed to satisfy the demands of the U.S. Navy and American industry for the measurement of high quality water. The criteria for the selection of appropriate solvent and solutes, based on the principles of equivalent conductivity and Onsager’s limiting law, are described. Dilute solutions of potassium chloride and benzoic acid in 30 % n-propanol–water have been chosen as standards. The electrolytic conductivity of both sets of these solutions as a function of molality was determined. Solutions of potassium chloride and of benzoic acid are recommended for use as 5 μS/cm, 10 μS/cm, 15 μS/cm, 20 μS/cm, and 25 μS/cm conductivity standards. Solutions prepared from potassium chloride in 30 % n-propanol–water have been certified as Standard Reference Materials (SRMs). SRM 3198 and SRM 3199 are certified nominally at 5 μS/cm and 15 μS/cm, respectively, at 25.000 °C.     

Electrospinning of polystyrene/dicyanopyrazine-linked porphyrin nanofibers

We have fabricated fluorescing polystyrene/dicyanopyrazine-linked porphyrin (PS/4-TDCPP) nanofibers using the electrospinning technique. UV-vis spectroscopy shows a strong Soret band and two relatively weak Q bands from the PS/4-TDCPP films and fibers, and reveals that the 4-TDCPP molecules are homogeneously dispersed in the films and fibers. Scanning electron microscopy (SEM) reveals the effect of solvent and collecting distance on the morphology of the electro-spun PS/4-TDCPP fibers. Fibers spun from a 50% dimethlyformamide (DMF), 50% methylethylketone (MEK) solution have ultra-fine structures with an average diameter of 300 nm. In the case of fibers from pure DMF and DMF:MEK (1:3) solutions, beads are formed along the length of the fibers. Variation of the collecting distance from 20 to 30 cm does not induce significant differences in the morphology of the electro-spun PS/4-TDCPP fibers. However, at a collecting distance of 15 cm, many beads are formed along the fibers. Acid-sensing capability of the PS/4-TDCPP fibers is demonstrated by fluorescence microscopy.     

硅溶胶电纺性能及其形态研究

以正硅酸乙酯(TEOS)为原料, 采用溶胶-凝胶法制备了硅溶胶, 研究了溶 胶体系中H₂O、盐酸的含量和不同溶剂对其电纺性能及分散形态的影响. FESEM 观察结果表明, 当H₂O/TEOS的摩尔比为1～2时, 电纺纤维表面光滑且连续, 当H₂O/TEOS的摩尔比为4时, 形成堆积在一起的圆形颗粒; 当HCl/TEOS的摩尔比 为0.01～0.10时, 随着HCl的增加, 电纺纤维相互粘结, 形成交叉的网状结 构; 用四氢呋喃和丙酮作溶剂电纺, 形成了珠节较多的纤维, 用乙醇电纺形 成了完全没有珠节的长纤维.