硅烷偶联剂在PPy/SiO2纳米导电复合材料制备中的应用

描述了一种合成PPy／SiO2纳米复合材料的新方法。首先用不同百分含量的氨丙基三乙氧基硅烷(APS)处理SiO2,然后通过化学氧化聚合法合成PPy／APS—SiO2纳米复合材料。文中讨论了偶联剂的使用对复合材料的影响及其作用机理。结果表明,用APS处理过的SiO2合成的复合材料其PPy含量、电导率和稳定性都有很大提高,其中用1％APS—SiO2合成的复合材料电导率最高,为38．4S／cm。文中还阐述了偶联剂的预处理对PPy／SiO2纳米复合材料形貌的影响。     

APS对PPy/ SiO2纳米导电复合材料的界面改性研究

首先用不同百分含量的氨丙基三乙氧基硅烷(APS)处理SiO2，然后以水为反应介质．通过化学氧化聚合法合成PPy／APS-SiO2纳米复合材料．并利用热失重和四探针对复合材料进行表征和测试。结果表明用APS处理过的SiO2合成的复合材料的电导率和稳定性都有很大提高．其中用1％APS-SiO2合成的复合材料电导率最高，为38．46S／cm。     

PPy/SiO2纳米复合材料作锂二次电池正极的研究

首先以化学氧化聚合法制备出电导率较高的聚吡咯/二氧化硅(PPy/SiO2)纳米复合材料,将其制成正极片后,以锂片为负极组装成扣式电池,通过充放电测试初步探索其电化学性能。考察了复合正极材料电导率、充放电电流和正极片成型压力对电池性能的影响。结果表明,以导电率较高的PPy/1% APS SiO2 纳米复合材料作正极活性物质,以较小充电电流0.1mA,适当的成型压力20MPa时电池比容量最高,接近40mAh/g。并且用扫描电镜(SEM)分析了充放电对正极材料结构的影响。     

聚吡咯及其复合材料导电稳定性的研究

对聚吡咯/二氧化硅(PPy/SiO2)、聚吡咯/蒙脱土(PPy/MMT)复合材料的电导率及其导电稳定性进行了研究.通过对材料进行定期和不同条件下的测试发现对PPy/SiO2复合材料而言,导电稳定性随时间延长而下降.对PPy与不同百分含量偶联剂处理过的SiO2的复合材料(PPy/APS-SiO2)而言,聚吡咯导电稳定性提高很多.PPy/MMT复合材料在室温具有较好的导电稳定性,而且合成温度越低,所得产物的稳定性越好.在0℃下合成的PPy/MMT复合物在空气中放置50天,电导率仅降低10%.     

纳米粒子表面修饰与改性--SiO2纳米粒子表面接枝聚合

通过硅烷偶联剂处理SiO2纳米粒子并向其表面引入双键使其功能化，采用溶液聚合方法在SiO2纳米粒子表面进行接枝聚合实现高分子对SiO2纳米粒子的表面包覆处理，制得SiO2／PMMA复合纳米粒子，采用IR、XPS对SiO2纳米粒子表面结构进行了表征研究。     

不同表面修饰纳米SiO2／尼龙66复合材料的热性能

通过熔融共混将不同表面修饰的纳米SiO2与尼龙66在双螺杆挤出机上混合,制备出纳米SiO2／尼龙66复合材料。采用FTIR和XPS等测试手段分析了复合材料体系中不同表面修饰纳米SiO2与尼龙66的相互作用,并在此基础上对复合材料的热性能进行了研究。研究结果表明：不同的表面修饰处理得到不同的纳米SiO2／尼龙66界面相互...     

两亲性纳米SiO2复合材料的合成

以3-缩水甘油醚氧丙基三甲氧基硅烷改性过的纳米SiO2作为原料,通过季铵化反应得到两亲性的纳米SiO2复合材料.利用傅里叶红外(FTIR)、热失重分析(TGA)、X射线光电子能谱(XPS)等检测手段研究了合成材料的结构;通过透射电镜(TEM)对合成的尺寸及微观形貌进行了分析;利用其在水/甲苯混合体系中的分散探讨了合成材料的两亲性.结果表明,合成的纳米SiO2复合材料表面接枝的有机成分约为11wt%,该纳米SiO2复合材料具有很好的两亲性.     

聚酰亚胺/二氧化硅纳米复合材料的制备及渗透汽化性能

利用DSDA—DDBT高聚物作前驱体，在N-甲基吡咯烷酮(NMP)中和正硅酸乙酯(TEOS)进行溶胶-凝胶反应制备出新型聚酰亚胺／二氧化硅纳米复合材料膜，用IR、TGA及SEM等手段对材料膜进行研究。与聚酰亚胺相比，聚酰亚胺／二氧化硅纳米复合膜表现出更好的热力学稳定性。渗透汽化实验结果表明，DSDA—DDBT／SiO2纳米复合膜对苯／环己烷体系的通量Q1大于DSDA—DDBT膜。复合材料中二氧化硅表现出强的吸附性能。含5％(质量)SiO2的DSDA—DDBT／SiO2复合材料膜的通量Q1和分离因子口均大于SiO2含量为17％的DSDA—DDBT／SiO2复合材料膜。     

HNO3处理对TiO2纳米薄膜的光催化活性和表面微结构的影响

通过sol-gel工艺分别在钠钙玻璃和预涂SiO2涂层的钠钙玻璃基体上制备了TiO2光催化纳米薄膜．然后用1mol／L HNO3水溶液对煅烧后的薄膜进行酸处理。用X射线光电子能谱(XPS)、扫描电镜(SEM)和紫外可见光谱(UV—VIS)对酸处理前后TiO2纳米薄膜进行了表征。用甲基橙水溶液的光催化脱色来评价TiO2薄膜的光催化活性。结果表明：SiO2涂层能有效阻止钠离子从玻璃基体向TiO2薄膜的扩散，普通玻璃表面的TiO2纳米薄膜经HNO3处理后，薄膜的光催化活性明显增强。这是由于TiO2纳米薄膜中的钠离子浓度降低以及表面羟基含量增加的缘故。     

纳米SiO2/PEA复合粒子的制备和表征

在经预处理的SiO2表面上通过乳液聚合反应接枝丙烯酸乙酯,用FT-IR和XPS对制备的纳米SiO2/PEA复合粒子进行了表征,研究了由复合粒子填充的PP/POE/SiO2复合材料的力学性能、结晶性能和结构形态。结果表明:通过乳液聚合反应成功地将EA接枝到纳米SiO2的表面上;由复合粒子填充的PP/POE/SiO2复合材料,纳米SiO2在基体中的分散尺寸约为100 nm,分布较均匀,复合材料的冲击强度和断裂伸长率均得到提高,在SiO2含量4%(质量分数)时,PPβ晶峰的强度最强。     

Novel silicon carbide/polypyrrole composites; preparation and physicochemical properties

Novel silicon carbide/polypyrrole (SiC/PPy) conducting composites were prepared using silicon carbide as inorganic substrate. The surface modification of SiC was performed in aqueous solution by oxidative polymerization of pyrrole using ferric chloride as oxidant. Elemental analysis was used to determine the mass loading of polypyrrole in the SiC/PPy composites. Scanning electron microscopy showed the surface modification of SiC by PPy. PPy in composites was confirmed by the presence of PPy bands in the infrared spectra of SiC/PPy containing various amounts of conducting polymer. The conductivity of SiC/PPy composites depends on PPy content on the surface. The composite containing 35 wt.% PPy showed conductivity about 2 S cm⁻¹, which is in the same range as the conductivity of pure polypyrrole powder prepared under the same conditions using the same oxidant. PPy in the composites was clearly detected by X-ray photoelectron spectroscopy (XPS) measurements by its N1s and Cl2p peaks. High resolution scans of the C1s regions distinguished between silicon carbide and polypyrrole carbons. The fraction of polypyrrole at the composite surface was estimated from the silicon and nitrogen levels. The combination of XPS and conductivity measurements suggests that the surface of the SiC/PPy composites is polypyrrole-rich for a conducting polymer mass loading of at least 12.6 wt.%.     

五氧化二钒/聚吡咯的制备及其电化学性能

采用化学氧化法, 通过改变氧化剂的加入方式, 制备了不同结构的五氧化二钒/ 聚吡咯(V₂O₅ / PPy) 复合材料。用四探针测试了材料的电导率, 并用比表面积(BET) 、X 射线粉末衍射(XRD) 和扫描电子显微镜(SEM)对复合材料进行了测试和表征。结果表明: 氧化剂的加入方式不同, 所得复合材料的结构和形貌明显不同。在反应器内先加入氧化剂时, 吡咯在V₂O₅ 的层间聚合; 在反应器内先加入吡咯单体时, 吡咯在V₂O₅ 的表面吸附聚合。为研究不同结构复合材料的电化学性能, 将V₂O₅ / PPy 作为锂二次电池正极, 组装成扣式电池, 采用恒电流充放电及交流阻抗法对复合正极材料进行测试。结果表明: 采用先加入氧化剂方式所得材料的电化学综合性能最好, 锂二次电池的最高放电比容量达230 mAh/ g。      

聚吡咯/纳米二氧化钛的制备及电化学性能

采用化学原位聚合的方法制备了聚吡咯/二氧化钛(PPy/TiO_2)复合物,其中聚吡咯和二氧化钛的质量比分别为1∶1、2∶1、3∶1、4∶1,将其作为电化学超级电容器的电极材料,采用扫描电子显微镜和X射线衍射仪研究了PPy/TiO_2的形貌和相组成,通过电化学测试研究了PPy/TiO_2的电化学性能.结果表明:TiO_2均匀地包覆在PPy基体中,PPy/TiO_2的电化学性能明显优于纯PPy;当PPy与TiO_2的质量比为3∶1时复合材料的电化学性能最佳,即在2 A/g充放电电流密度下,其比电容达到了255.68 F/g,比纯PPy提高了2倍左右;在1 A/g充放电电流密度下,循环充放电1 000圈之后PPy/TiO_2的比电容保持率为87.2%,纯PPy的比电容保持率仅为46.9%.     

Polypyrrole colloids—assisted proton transport in hydrated polyacrylic acid matrix

This paper reports an investigation into the rheological behavior of aqueous suspension systems consisting of colloidal polypyrrole (PPy) particles and polyacrylic acid (PAA). We have observed a strong interaction between PPy colloids and PAA chains in an aqueous medium. Based on this observation, a new polymer composite was prepared, in which PPy colloidal particles were uniformly distributed in a semi-interpenetrating network (semi-IPN) consisting of linear PAA (M.W.=2000) in a cross-linked polymer [poly(acrylamide-methylenebisacrylamide) PAAM-MBAM]. The weight ratio of PPy in the composites was varied in the range of 0.2%–2.3%, and as a result of the low PPy content, the composites are electrically non-conductive in the dry state. However, they become electrically conductive when hydrated. There is a percolation threshold of water content with respect to the electrical resistivity. The semi-IPN composites containing PPy appear to have a lower percolation threshold than the blank semi-IPN composite. For example, as the water content increases from 14 to 15 wt% the resistivity of semi-IPN embracing 0.8% PPy reduces 10 times, while that of the blank semi-IPN reduces only 1.3 times. The difference in electrical resistivity may be attributed to the enhancement of proton transport by PPy colloids. This enhancement is probably due to the fact that PPy possesses a weak Brønsted basicity as well as a rigid conjugated structure. In other words, nitrogen atoms of PPy may coordinate with protons not too strongly and allow the protons to transport along the planar conjugated structure of PPy, thus contributing to the proton conductivity.     

Synthesis and characterization of conductive polypyrrole/multi-walled carbon nanotubes composites with improved solubility and conductivity

High conductivity and solubility of polypyrrole (PPy)/multi-walled carbon nanotubes (MWCNT) composites has been successfully synthesized by in situ chemical oxidation polymerization using various concentrations of cationic polyelectrolyte poly(styrenesulfonate) (PSS) and ammonium peroxodisulfate (APS). Raman spectroscopy, FTIR, EPR, FESEM and HRTEM were used to characterize their structure and morphology. These images of FESEM and HRTEM showed that the fabricated PPy/MWCNT composites are one-dimensional core-shell structures with the average thickness of the PPy/MWCNT composites without PSS is about 250 nm and considerably decreases to 100–150 nm by adding the PSS content. The results of Raman spectrum, FTIR and UV–Vis indicate the synthesized PPy/MWCNT composites are in the doped state. The conductivities of PPy/MWCNT composites synthesized with the weight ratio of PSS/pyrrole monomer at 0.5 are about two times of magnitude higher than that of PPy/MWCNT composites without PSS. These results are perhaps due to the part of cationic electrolyte served as a dopant can be incorporated to the PPy structure to improve the conductivity of fabricated PPy/MWCNT composites.     

Enhanced electrical conductivity of polypyrrole/polypyrrole coated short nylon fiber/natural rubber composites prepared by in situ polymerization in latex

In this paper we report the characterization and properties of conductive elastomeric composites of polypyrrole (PPy) and PPy coated short Nylon-6 fiber (F-PPy) based on natural rubber (NR) prepared by in situ polymerization method. PPy/NR blends were prepared by polymerizing pyrrole in NR latex using anhydrous ferric chloride as oxidizing agent, p-toluene sulphonic acid as dopant and vulcastab VL as stabilizer. PPy/F-PPy/NR composites were prepared as above in presence of short nylon fiber. The products were coagulated out, dried, compounded on a two roll mill and moulded. The cure pattern, DC electrical conductivity, morphology, mechanical properties, thermal degradation parameters and microwave characteristics of the resulting composites were studied. Incorporation of PPy to elastomer retards the cure reaction whereas addition of fiber accelerates the cure reaction. DC conductivity up to 6.25 × 10⁻² was attained for NR/PPy/F-PPy system. The composites containing F-PPy exhibited better mechanical properties compared to NR/PPy systems. The absolute value of the dielectric permittivity, AC conductivity and absorption coefficient of the conducting composites prepared were found to be much greater than the gum vulcanizate. PPy and F-PPy were found to decrease the dielectric heating coefficient and skin depth significantly.     

气液相聚合制备蒙脱土/聚吡咯的结构特征及其导电性能

以FeCl₃为氧化剂,与钠基蒙脱土(MMT)以不同比例进行离子交换后所得悬浮液与吡咯(Py)单体进行气液相聚合,制备出蒙脱土/聚吡咯(MMT/PPy)复合材料。XRD、FTIR和SEM分析表明,Py单体在MMT的片层间发生了聚合反应,MMT的层间距随PPy含量增加不断变大。MMT/PPy复合材料呈现出 MMT和PPy的红外特征吸收峰,但某些吸收峰出现蓝移。SEM 观察显示MMT/PPy呈片状形态特征。当其中的MMT去除后,PPy仍为片状结构,与纯 PPy的球粒形貌不同。电导率测试表明,MMT/PPy复合材料的电导率随PPy含量增加而提高,至40.9 wt% PPy含量时,MMT/PPy的电导率已达到PPy 的电导率水平(10-1S/cm),含54.3 wt% PPy的MMT/PPy电导率甚至略高于PPy。     

纳米Fe_3O_4/聚吡咯复合材料的形貌可控制备及电磁特性

为实现纳米Fe3O4/聚吡咯(PPy)复合材料的形貌可控合成,以十二烷基苯磺酸钠(NaDBS)为表面活性剂,运用乳液聚合方法制备了纳米Fe3O4/PPy复合材料。研究了体系中油相吡咯及表面活性剂用量对纳米Fe3O4/PPy复合材料表面形貌的影响规律,分析了纳米Fe3O4/PPy复合材料形貌与其电磁特性之间的关系。结果表明:吡咯用量的增加改变了体系中胶团的存在状态,使得纳米Fe3O4/PPy复合材料的形貌由草莓状向核-壳结构转变;体系中胶团的数量随着表面活性剂用量的改变发生变化,根据此规律调控了核-壳复合粒子内核的数量,从而得到了单核或多核的纳米Fe3O4/PPy复合材料。     

Polypyrrole/poly(vinyl alcohol-co-ethylene) nanofiber composites on polyethylene terephthalate substrate as flexible electric heating elements

Polypyrrole/poly(vinyl alcohol-co-ethylene) (PPy/PVA-co-PE) nanofiber composites on polyethylene terephthalate (PET) substrates were prepared using spray coating technique and in situ polymerization process. The electric heating behaviors of composites were investigated as functions of the amounts of nanofiber and PPy. It was observed that, the electrical resistivity of composites decreased significantly with increasing nanofiber and PPy contents. Scanning electron microscope images and infrared spectrum studies confirmed the formation of well dispersed network-like structure of PPy/PVA-co-PE nanofibers on PET substrate. Furthermore, maximum temperature attained at a given applied voltage for the composites could be well controlled by changing nanofibers and PPy amounts. PPy/PVA-co-PE nanofiber/PET composites exhibited excellent electric heating performance in aspects of rapid temperature response, long retaining behavior, thermal and operational stability. The incorporation of PPy on PVA-co-PE nanofibers/PET nonwoven substrates resulted in high conductivity and enhanced heating behavior, which have potential to be used as efficient electric heating elements.