氧化石墨烯/聚偏氟乙烯共混复合膜研究进展

氧化石墨烯(GO)作为一种新兴的碳纳米材料,具有较大的比表面积和表面丰富的官能团,其潜在的应用前景广阔。近年来聚偏氟乙烯(PVDF)超滤膜在去除天然有机物方面表现出色,为弥补PVDF膜亲水性差的缺陷,常引入GO提高PVDF膜的亲水性能,GO作为阳离子吸附剂的优势突显。从GO与有机高分子聚合物共混PVDF、GO与无机纳米材料共混改性PVDF以及GO与碳纳米管共混改性PVDF这3个方面介绍了GO/PVDF共混复合膜的研究进展。     

纳米SiO2-氧化石墨烯/聚偏氟乙烯杂化膜的制备及特性

采用原位水解的方式制备了新型SiO₂-氧化石墨烯（GO）纳米杂化颗粒。选择GO、SiO₂、SiO₂-GO颗粒和聚乙烯吡咯烷酮（PVP）为添加剂,采用浸没沉淀相转化法分别制备了聚偏氟乙烯（PVDF）杂化膜。测定了PVDF杂化膜的纯水通量、膜面接触角、牛血清白蛋白（BSA）截留率和污染恢复率等参数。结果表明,SiO₂-GO/PVDF-PVP膜的接触角从78.4°减小到66.02°,膜的亲水性能有所提升。同时,SiO₂-GO/PVDF-PVP膜的纯水通量最大（1 018 L/（m²·h））,对BSA的截留率达到81.5%,污染恢复率达到了78.65%以上。新型SiO₂-GO纳米杂化颗粒协同PVP添加剂增强了PVDF超滤膜的水通量、污染物截留和抗污染特性等综合性能,为传统PVDF有机膜的改性提供了一种新方法。     

聚偏氟乙烯/聚氯乙烯共混中空纤维膜的研制

实验表明PVDF/PVC共混体系是部分相容体系,且在共混比是7∶3时,相容性最好.还讨论了不同聚合物配比,不同溶剂,不同添加剂对共混膜性能的影响,并进行了分析.     

两亲性嵌段共聚物共混改性聚偏氟乙烯超滤膜的制备及性能研究

通过原子转移自由基聚合技术（Atom Transfer Radical Polymerization，ATRP）合成聚乙二醇单甲醚／聚甲基丙烯酸甲酯（MPEG-b-PMMA）两亲性嵌段共聚物，运用傅立叶变换红外光谱（FT-IR）、核磁共振氢谱（^1H-NMR）及凝胶渗透色谱（GPC）对所合成的两亲性嵌段共聚物进行表征。然后，将所合成的MPEG-b-PMMA两亲性嵌段共聚物与聚偏氟乙烯（PVDF）进行溶液共混，通过浸没沉淀相转化法制备MPEG-b-PMMA／PVDF共混超滤膜。膜性能测试结果表明：与PVDF膜相比，MPEG-b-PMMA／PVDF共混膜的亲水性、抗污染性、纯水通量及BSA截留率等性能均得到明显提高．     

氟树脂对聚偏氟乙烯膜疏水性的影响

采用N,N-二甲基甲酰胺(DMF)为溶剂,以氟树脂为疏水助剂,制备聚偏氟乙烯(PVDF)膜.采用不同偶联剂对疏水助剂氟树脂进行改性,研究了改性氟树脂对PVDF膜疏水性的影响.研究结果表明:添加疏水助剂氟树脂可改善PVDF膜的疏水性.当经偶联刺G502改性的氟树脂添加量为10%时,PVDF膜与水的静态接触角达到120°.通过集灰实验表明添加改性氟树脂的PVDF膜具有较好的疏水性.     

聚偏氟乙烯膜的Fenton氧化改性研究

采用Fenton试剂对聚偏氟乙烯(PVDF)膜进行氧化改性,研究了[H2O2]/[Fe2 ]及温度对超滤膜性能的影响,测定了改性前后超滤膜的纯水渗透通量、截留性能、膜表面亲水性、耐污染性性能及红外光谱.结果表明,随着[H2O2]/[Fe2 ]比值的增大,纯水渗透通量由纯PVDF膜的26.7L/(m2·h)提高到103.2L/(m2·h),膜表面水接触角由75°降为58.5°,黏附功由91.64mN/m提高到110.84mN/m.温度升高利于改性.[H2O2]/[Fe2 ]比值为12时,红外光谱图中出现了C=C双键及O-H键的伸缩振动特征峰,膜阻力增大系数m由纯PVDF膜的1.049减小到0.448,膜的耐污染性能得到明显改善.     

聚两性电解质修饰聚偏氟乙烯膜的制备及抗污染性能

膜污染是膜分离技术广泛应用的瓶颈之一。文中通过自由基接枝聚合法将2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和甲基丙烯酰氧乙基三甲基氯化铵(DMC)接枝到聚偏氟乙烯(PVDF)膜上构建聚两性电解质化膜表面。研究了改性前后膜表面结构和抗污染性能的变化。随着单体投料量增加,聚两性电解质的接枝率逐渐增加;接枝聚两性电解质后,膜亲水性逐渐增强,膜表面孔尺寸减小。与纯PVDF膜相比,改性膜具有较低的蛋白质吸附量;在牛血清蛋白(BSA)溶液渗透过程中,膜的不可逆污染向可逆污染转化。由于可逆污染可通过简单的纯水清洗得到抑制,改性膜具有较高的通量恢复率。这个结果证明了聚两性电解质的引入赋予PVDF膜良好的抗污染性能。     

热致相分离法制备纳米碳酸钙/聚偏氟乙烯共混膜

以邻苯二甲酸二丁酯(DBP)为主要稀释剂,添加无机粒子CaCO3,采用热致相分离法(TIPS法)制备了聚偏氟乙烯/碳酸钙(PVDF/CaCO3)共混膜。考察了不同冷却条件对共混膜的影响以及CaCO3含量对聚偏氟乙烯结晶温度、结晶度的影响;研究了酸处理对共混膜微观结构、力学性能的影响。实验表明,通过改变冷却条件可以控制球晶的大小以及膜表面皮层的厚度;随着CaCO3含量的增加,PVDF共混膜的水通量先增加后减少,拉伸强度不断增加。经酸处理之后,共混膜水通量显著提高,拉伸强度有所下降。     

Ag对TiO2@Ag/聚偏氟乙烯复合薄膜性能的影响

采用光化学沉积法和溶液刮膜法制备不同Ag含量的TiO₂@Ag/聚偏氟乙烯(PVDF)复合薄膜,并采用电子万能材料试验机、紫外可见近红外分光光度计和XRD等对TiO₂@Ag/PVDF复合薄膜的物理性能和光催化性能进行表征和分析。研究发现:与TiO₂/PVDF复合薄膜相比,TiO₂@Ag/PVDF复合薄膜的拉伸强度明显提高,但断裂伸长降低,且复合薄膜的响应光谱范围拓宽至可见光区;TiO₂@Ag/PVDF复合薄膜的光催化降解能力随Ag负载量的增加而呈先升高后降低的趋势;同时TiO₂@Ag/PVDF复合薄膜具有优异的重复利用性和可见光区自清洁作用。综上所述,实验所制备的TiO₂@Ag/PVDF复合薄膜能够满足实际应用需要,因此其在光催化降解领域具有潜在的应用前景。      

Piezoelectric properties of zinc oxide/iron oxide filled polyvinylidene fluoride nanocomposite fibers

Piezoelectric nanogenerators (PENG) with flexible and simple design have pronounced significance in fabricating sustainable devices for self-powering electronics. This study demonstrates the fabrication of electrospun nanocomposite fibers from polyvinylidene fluoride (PVDF) filled zinc oxide (ZnO)/iron oxide (FeO) nanomaterials. The nanocomposite fiber based flexible PENG shows piezoelectric output voltage of 5.9 V when 3 wt% of ZnO/FeO hybrid nanomaterial is introduced, which is 29.5 times higher than the neat PVDF. No apparent decline in output voltage is observed for almost 2000 s attributed to the outstanding durability. This higher piezoelectric output performance is correlated with the β-phase transformation studies from the Fourier transformation infrared spectroscopy and the crystallinity studies from the differential scanning calorimetry. Both these studies show respective enhancement of 3.79 and 2.16% in the β-phase crystallinity values of PVDF-ZnO/FeO 3 wt% composite. Higher dielectric constant value obtained for the same composite (three times higher than the neat PVDF) confirms the increased energy storage efficiency as well. Thus the proposed soft and flexible PENG is a promising mechanical energy harvester, and its good dielectric properties reveals the ability to use this material as good power sources for wearable and flexible electronic devices.

     

One-pot polyelectrolyte assisted hydrothermal synthesis of TiO2-reduced graphene oxide nanocomposite

We demonstrated a facile and efficient strategy for the fabrication of poly(diallyldimethylammonium chloride) (PDDA)-assisted reduced graphene oxide (RGO) sheets–titanium dioxide (TiO₂) in the absence of any seeds and surfactants. PDDA is used as both a reducing agent and a stabilizer to prepare the colloidal suspension of graphene nanosheets. The incorporation of PDDA successfully turns graphene nanosheets into general platforms for in situ growth of TiO₂. The prepared TiO₂–RGO has been thoroughly characterized by spectroscopic (Fourier-transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy) and thermogravimetric analysis. Microscopy techniques (scanning electron microscopy, atomic force microscopy and transmission electron microscopy) have been employed to probe the morphological structures as well as to investigate the exfoliation of RGO sheets. It is interesting to see that the TiO₂–RGO composites exhibited excellent photocatalytic activity to hydrogen evolution.     

纳米Fe3O4-还原氧化石墨烯复合修饰玻碳电极的制备及电化学检测多巴胺

通过电化学还原法制备纳米Fe₃O₄-还原氧化石墨烯复合修饰玻碳（Fe₃O₄-rGO/GCE）电极,用于多巴胺（DA）的检测。采用SEM、TEM和循环伏安对纳米Fe₃O₄-rGO复合材料进行表征。在pH为7.0的磷酸盐缓冲液（PBS）中,采用循环伏安法研究了DA在纳米Fe₃O₄-rGO/GC上的电化学行为。实验结果表明,较裸GC电极和rGO修饰（rGO/GC）电极,由于纳米Fe₃O₄与rGO的协同作用,纳米Fe₃O₄-rGO/GC显著增大了Fe₃O₄-rGO/GC复合材料电极电化学活性面积和氧化峰电流强度i_pa。DA的浓度在6.0×10^-8~2.0×10^-6 mol/L和2.0×10^-6~8.0×10^-5 mol/L范围内,与氧化峰电流强度i_pa呈良好的线性关系,检出限达4.0×10^-9 mol/L（信噪比S/N=3）。抗坏血酸和尿酸共存物几乎不干扰DA的测定,选择性高。Fe₃O₄-rGO/GC修饰电极用于盐酸DA注射液中的DA含量测定,获得结果较好,回收率为97.1%~103.9%。     

Fabrication and photocatalytic activity of YMn2O5 nanoparticles

In this work, a polyacrylamide gel route is introduced to synthesize YMn₂O₅ nanoparticles. It is demonstrated that high-quality YMn₂O₅ nanoparticles with a uniform size and spherical shape can be prepared using different chelating agents. However, the average particle size of the products is found to have a dependence on the choice of the chelating agent. The sample prepared using citric acid as the chelating agent has an average particle size of ~ 45 nm, while the sample prepared by using the chelating agent EDTA has a particle size centered around 70 nm. The optical energy bandgap of the citric acid- and EDTA-resulted samples is obtained, from optical absorption measurements, to be 1.21 and 1.17 eV, respectively. The photocatalytic experiments reveal that the as-prepared YMn₂O₅ nanoparticles exhibit an interesting photocatalytic activity for oxidative decomposition of methyl red under ultraviolet and visible-light irradiation.     

Fabrication and photocatalytic activity of TiO2 nanofiber membrane

Titanium dioxide is one of the best semiconductor photocatalysts available for photocatalysis. In this paper, titanium dioxide nanofiber membranes are prepared by post-anneal-assisted electrospinning process. The obtained membrane is composed of anatase titanium dioxide continuous and porous nanofibers with diameters ranging from 65 to 115 nm. An optimized annealing scheme is determined. Photocatalytic measurements show that the photocatalytic efficiency of the anatase TiO₂ nanofiber membrane is 72%, which is highly superior to that of the anatase TiO₂ thin film (44%). It is believed that the large specific surface area intensively enhances the photocatalytic reactions and the good shape retention might be favorable for recuperability and practicality. The potential applications for environmental purification are discussed.     

全氟磺酸树脂/PVDF共混膜的研究

为了降低质子交换膜的成本,选用聚偏氟乙烯和全氟磺酸树脂为原料,采用溶液-浇铸法制备了全氟磺酸树脂/聚偏氟乙烯的共混膜.通过XPS测试发现共混膜在制备过程中不同接触面元素含量不同;这些不同的元素含量对共混膜的发电性能产生了一定程度的影响.在相同条件下,O2通往空气成膜一方时的发电性能比通往玻璃一方的发电性能要好.     

聚偏氟乙烯（PVDF）／聚苯乙烯磺酸（PSSA）／TiO2复合膜的制备

制备了聚偏氟乙烯（PVDF）／聚苯乙烯磺酸（PSSA）共混膜，并通过溶胶-凝胶法向共混膜中掺杂无机TiO2粒子制得有机-无机复合膜。利用傅立叶变换红外光谱（FT-IR）、扫描电子显微镜（SEM）、差热分析（DTA）、热重分析（TG）对复合膜的结构、表面形貌、热稳定性分别进行了研究。结果表明，PVDF与PSSA通过溶液共混可以得到混合均匀的共混膜；TiO2粒子通过溶胶-凝胶法能够与共混膜结合并均匀地分散到共混膜中；热分析结果表明，TiO2粒子与共混膜之间已形成了氢键。     

石墨烯/纳米TiO2复合材料的制备及其光催化性能

以氧化石墨烯（GO）和钛酸四丁酯（Ti（OBu）₄）作为初始反应物,采用乙醇溶剂热法合成了石墨烯/纳米TiO₂复合材料,并利用XRD、FE-SEM、TEM、RAMAN和XPS等手段对石墨烯/纳米TiO₂复合材料的晶体结构、形貌及元素形态等性质进行了表征,同时将复合材料应用于光催化降解甲基橙溶液,进行光催化性能评价。结果表明：Ti（OBu）₄在乙醇溶剂中通过化学静电引力吸附到GO表面,经过溶剂热反应,GO被还原成石墨烯的同时,石墨烯的表面负载生长锐钛矿TiO₂颗粒。随着溶剂热反应时间的延长,GO表面的活性基团减少,还原更加彻底,同时TiO₂晶粒有一定的增大趋势;与纯TiO₂相比,石墨烯/纳米TiO₂复合材料光催化活性明显提高,石墨烯含量对复合材料的光催化活性有直接的影响。     

疏松多孔CoFe2O4-还原石墨烯电极复合材料的制备与性能

采用原位溶剂热法,以氧化石墨烯（GO）与Co2+、Fe3+为原料制备疏松多孔的纳米CoFe₂O₄-还原氧化石墨烯（CoFe₂O₄-rGO）复合材料。采用XRD、Raman、SEM和HRTEM测试表征了纳米CoFe₂O₄-rGO复合材料的结构与形貌。测试结果表明,纳米CoFe₂O₄-rGO复合材料具有三维结构。自组装的多孔CoFe₂O₄纳米球粒径约为200 nm,在rGO上均匀分散,解决了CoFe₂O₄易团聚的问题。电化学测试结果表明,纳米CoFe₂O₄-rGO复合材料具有较高的比容量及优异的循环和倍率性能,在100 mA·g-1的电流密度下其比容量为1 262 mAh·g-1,50次循环后比容量仍能保持在642 mAh·g-1;并在2 000 mA·g-1的大电流密度下仍具有221 mAh·g-1的比容量。纳米CoFe₂O₄-rGO复合材料拥有更优异的电化学性能的原因在于CoFe₂O₄纳米球在rGO上均匀分布。三维结构增加了Li+储存的活性位点,有效缓解了电极的体积收缩/膨胀效应,提高了纳米CoFe₂O₄-rGO复合材料的导电性。