四乙基氢氧化铵改性聚偏氟乙烯接枝聚丙烯酸油水分离膜的制备

使用四乙基氢氧化铵(TEAH)液相本体改性聚偏氟乙烯(PVDF), 以过氧化苯甲酰(BPO)为引发剂, 将丙烯酸(AA)接枝到改性PVDF骨架上, 合成了聚偏氟乙烯接枝聚丙烯酸(PVDF-g-PAA)共聚物, 通过浸没沉淀法制备了PVDF-g-PAA亲水性油水分离膜. 通过傅里叶变换红外光谱(FTIR)、 扫描电子显微镜(SEM)和过滤试验分析了膜的结构和分离性能. 研究了不同接枝条件对PVDF-g-PAA膜接枝率的影响. 同时, 通过膜接枝率与膜表面接触角的关系确定最佳接枝条件. 结果表明, TEAH使PVDF脱去HF产生碳碳双键且PAA接枝到改性的PVDF骨架上, 膜内外孔隙分布均匀; PVDF-g-PAA膜的接触角随着接枝率的提高而降低. 接枝单体AA含量为45%, 接枝温度为85 ℃, 接枝4 h制备的PVDF-g-PAA膜的接枝率为20.1%, 孔隙度为65.3%, 平均孔径为78.0 nm, 接触角为57.5°, 且在60 s内接触角降至14.3°; 纯水通量提高到571.33 L/(m²·h), 截留率和水通量恢复率分别达到94.3%和88.7%, 且通量衰减率仅为9.8%. 与纯PVDF膜相比, PVDF-g-PAA膜的分离性能显著提高.     

聚偏氟乙烯接枝甲基丙烯酸甲酯油水分离膜的研究

使用四乙基氢氧化铵(TEAH)液相本体改性聚偏氟乙烯(PVDF),以过氧化苯甲酰(BPO)为引发剂,将甲基丙烯酸甲酯(MMA)接枝到改性PVDF骨架上,合成聚偏氟乙烯接枝聚甲基丙烯酸甲酯(PVDF-gPMMA)共聚物,通过浸没沉淀法制备PVDF-g-PMMA亲水性油水分离膜.通过傅里叶红外光谱(FTIR)、扫描电镜(SEM)和过滤试验分析了膜的结构和性能.同时研究了TEAH浓度和改性时间对PVDF-g-PMMA膜表面接触角的影响.结果表明,TEAH使PVDF脱去HF产生碳碳双键且MMA成功接枝到改性的PVDF骨架上,膜内外孔隙分布均匀;PVDF-g-PMMA膜的接触角随着TEAH浓度的增加、改性时间的加长而减小.TEAH浓度为2.0 wt%,改性20 min制备的PVDF-g-PMMA膜,接枝率为27.1%,孔隙度为71.6%,平均孔径为78.9 nm,接触角降至55.9°,且在50 s内降为0;纯水通量提高到665.34 L/(m2·h),截留率和水通量恢复率分别达到95.6%和90.1%.与纯PVDF膜相比,PVDF-g-PMMA膜的分离性能显著提高.     

TMAH改性PVDF一步接枝PSBMA质子交换膜的制备与性能

使用四甲基氢氧化铵(TMAH)液相改性聚偏氟乙烯(PVDF),以过氧化苯甲酰(BPO)为引发剂,一步将磺酸基甲基丙烯酸甲酯(SBMA)接枝到改性的PVDF上,制备了聚偏氟乙烯接枝聚磺酸基甲基丙烯酸甲酯(PVDFg-PSBMA)质子交换膜.利用傅里叶变换红外(FTIR)光谱和扫描电镜-X射线能谱(SEM-EDX)分析了膜的结构、形貌及硫元素分布情况.同时研究了不同质量分数的TMAH甲醇溶液对PVDF-g-PSBMA膜电导率和甲醇渗透率的影响.结果表明, TMAH使PVDF脱去HF产生碳碳双键且SBMA成功接枝到改性的PVDF骨架上,硫元素在膜内外分布均匀; PVDF-g-PSBMA膜的电导率和甲醇渗透率随TMAH在甲醇中质量分数的增多而增大, TMAH质量分数为20%的膜的质子电导率在20 ℃下达到0.0892 S·cm^-1,常温下的甲醇渗透率为4.04 × 10^-7cm²·s^-1;热重分析(TGA)表明,膜的热稳定性良好,耐热温度高达270 ℃.该膜作为电解质材料的直接甲醇燃料电池(DMFC)的最大功率密度达到17.06 mW·cm^-2.     

四甲基氢氧化铵改性聚偏氟乙烯接枝苯乙烯磺化膜的制备和性能

使用四甲基氢氧化铵(TMAH)甲醇溶液在液相中改性聚偏氟乙烯(PVDF),挥发溶剂得到改性聚偏氟乙烯膜(g-PVDF-M),再以过氧化苯甲酰(BPO)为引发剂,将苯乙烯接枝到g-PVDF-M膜中,磺化后制得改性聚偏氟乙烯接枝苯乙烯磺化(PVDF-g-PSSA)膜.利用傅里叶变换红外光谱(FTIR)和能谱仪的扫描电子显微镜分析了PVDF-g-PSSA膜(TMAH-25)的结构、形貌及硫元素分布情况.通过电化学工作站和气相色谱仪研究了TMAH在甲醇中的不同含量对PVDF-g-PSSA膜质子电导率和甲醇渗透率的影响.结果表明,TMAH使PVDF脱去HF生成碳碳双键,并且苯乙烯接枝到改性的聚偏氟乙烯膜中,磺化后S元素在PVDF-g-PSSA膜内部均匀分布;PVDF-g-PSSA膜的质子电导率和甲醇渗透率随TMAH在甲醇溶液中质量分数的增加而增大;TMAH的质量分数为25%时,PVDF-g-PSSA膜的电导率达1.28×10~(-2)S/cm,甲醇渗透率为4.58×10~(-7)cm~2/s.热重分析(TGA)表明,PVDF-g-PSSA膜的热稳性良好,耐热温度高达195℃,PVDF-g-PSSA膜作为电解质材料的直接甲醇燃料单电池(DMFC)功率密度达到16.45 mW/cm~2.     

超亲水聚偏氟乙烯中空纤维膜的制备及性能

采用超声辅助接枝聚合技术, 将甲基丙烯酸缩水甘油酯(GMA)接枝到聚偏氟乙烯(PVDF)膜表面, 制备PVDF-g-GMA膜; 再利用氨基诱导环氧基团发生开环反应, 将苏氨酸(Thr)接枝到PVDF-g-GMA膜表面, 制备了具有两性离子结构表面的PVDF-g-GMA-Thr膜. 通过衰减全反射傅里叶变换红外光谱(ATR-FTIR)、 X射线光电子能谱(XPS)、 接触角测试仪、 场发射扫描电子显微镜(FESEM)和牛血清白蛋白(BSA)过滤实验等系统研究了改性前后PVDF膜表面的化学组成、 润湿性能、 表面形貌和抗污染性能. 研究结果表明, 随着PVDF-g-GMA接枝Thr反应时间的增加, PVDF-g-GMA-Thr膜的亲水性能明显提高, 接触角从90°降为0°, 呈现出超亲水性能. 同时PVDF-g-GMA-Thr膜的水通量明显提高, 当Thr诱导开环反应时间为12 h时, PVDF-g-GMA-Thr膜的水通量高达686 L/(m ²·h), 与PVDF原膜相比, 水通量提高了204.5%. 在BSA的过滤测试中, 与PVDF膜相比, PVDF-g-GMA-Thr膜呈现出良好的截留性能和抗污染性能, BSA截留率从42%提高到84%,水通量恢复率从53%提高到87%, 不可逆污染率从47%降到12%, 表明通过接枝Thr构筑两性离子结构表面可以有效减小膜污染.     

聚偏氟乙烯溶液法接枝苯乙烯磺酸膜的结构与形貌研究

以过氧化苯甲酰(BPO)作引发剂，通过溶液接枝聚合法把苯乙烯接枝到碱处理过的聚偏氟乙烯(PVDF)膜上，磺化后得到聚偏氟乙烯接枝苯乙烯磺酸(PVDF-g-PSSA)电解质膜。研究发现碱处理过的PVDF膜更容易与苯乙烯发生接枝聚合反应，且接枝率与碱处理时间呈线性变化关系。用红外光谱、差示扫描量热法检测PVDF膜经过接枝以及随后的磺化所发生的膜结构变化，并用SEM观察PVDF膜接枝前后以及接枝磺化后产物PVDF-g-PSSA膜的形貌及硫分布。研究表明，用KOH碱处理过的PVDF膜与苯乙烯进行接枝共聚反应时，PVDF膜结构在接枝前后和磺化前后发生变化，说明苯乙烯确实接枝到PVDF膜上。     

PVDF膜改性的方法研究

本文介绍了目前国内外聚偏氟乙烯(PVDF)超滤膜改性中常用的膜表面改性方法和膜材料改性方法。PVDF膜表面改性主要通过膜表面的物理改性、磺化改性、表面接枝改性、光化学改性、低温等离子体改性等方法来实现;而PVDF膜材料的改性主要是通过PVDF与亲水性高分子材料或小分子无机粒子的共混以及膜材料本体的化学改性来实现。改性PVDF膜的亲水性增强,使水通量增加,提高了机械性能,改善了抗污染性,增加了膜的使用寿命。     

PVDF膜改性方法研究进展

本文介绍了目前国内外聚偏氟乙烯(PVDF)超滤膜改性中常用的膜表面改性方法和膜材料改性方法。PVDF膜表面改性主要通过膜表面的物理改性、磺化改性、表面接枝改性、光化学改性、低温等离子体改性等方法来实现;而PVDF膜材料的改性主要是通过PVDF与亲水性高分子材料或小分子无机粒子的共混以及膜材料本体的化学改性来实现。改性PVDF膜的亲水性增强,使水通量增加,提高了机械性能,改善了抗污染性,增加了膜的使用寿命。     

碱处理PVDF膜对制备高电导率质子交换膜的作用

燃料电池是一种高能量密度、低污染的新型能源. 质子交换膜是燃料电池的核心组件之一. 在对聚偏氟乙烯(PVDF)膜进行了碱处理改性的基础上制备了高电导率的聚偏氟乙烯接枝聚苯乙烯磺酸(PVDF-g-PSSA)质子交换膜, 对碱处理后的PVDF膜进行了傅立叶变换红外光谱(FTIR)、傅立叶变换拉曼光谱(FT-Raman)及电子自旋共振(ESR)分析. 振动光谱显示在处理后的膜中存在共轭碳碳双键. 首次用ESR检测到碱处理后的PVDF膜中形成了自由基, 其浓度在10¹⁶ spin/g. 研究表明碱处理引起的膜结构变化有利于接枝反应的进行, 对提高所合成的质子交换膜的电导率有重要作用, 电导率提高一个数量级, 至6.40×10^－2 S/cm.     

超亲水-水下超疏油PVDF-g-PAA多孔膜的制备及油水分离性能

采用相反转方法制备了丙烯酸(AA)接枝的超亲水-水下超疏油聚偏氟乙烯膜(PVDF-g-PAA),通过加入一定量的聚乙烯吡咯烷酮获得可用于油水分离的多孔聚偏氟乙烯膜.多孔聚偏氟乙烯膜具有较好的抗油污染性能及较高的力学强度,可以快速高效地分离油水混合体系和乳化油水体系,分离性质稳定,多次使用后对油水混合物的分离效率在98%以上,对油水乳化液的分离效率在91%以上,可广泛应用于油水混合体系和乳化油水体系的油水分离.     

Improving the hydrophilic and antifouling properties of poly(vinyl chloride) membranes by atom transfer radical polymerization grafting of poly(ionic liquid) brushes

In this study, poly(1‐butyl‐3‐vinylimidazolium bromide) (PBVIm‐Br) was grafted onto the poly(vinyl chloride) (PVC) membrane surface via a 2‐step atom transfer radical polymerization (ATRP) reaction. Poly(2‐hydroxyethylmethacrylate) (PHEMA) was grafted onto the membrane surface by aqueous ATRP reaction; then, BVIm‐Br was introduced onto the surface of the PHEMA‐modified PVC membrane through traditional ATRP reaction. The analysis of surface chemistry confirmed the successful grafting of PHEMA and PBVIm‐Br on PVC membrane surface, and the grafting density (GD) of PBVIm‐Br gradually increased as the grafting time was prolonged. The modified membrane exhibited a positive charge and significantly enhanced surface hydrophilicity. The static water contact angle of the membrane surface decreased from 92.3° to 51.6° as the GD of the PBVIm‐Br brushes increased. Filtration experiments indicated that the water flux of the modified membrane increased with increasing GD, and their recovered fluxes were more than twice than the original. In addition, the total fouling ratio of the membranes decreased from 89% in M0 to 67% in M5, and most of the fouling was reversible as the GD of PBVIm‐Br brushes increased. These results indicated that the positive charged poly(ionic liquid) brushes featuring hydrophilic properties would have potential applications in membrane separation.     

PVDF Hollow fiber Membrane with High Flux and High Rejection Ratio Prepared by Irradiation Induced Grafting of PAA

Summary: A modified poly (vinylidene fluoride) (PVDF) hollow fiber membrane with higher flux and flux recovery rate was prepared by γ-radiation induced grafting of acrylic acid (AA). The influence of radiation dose and monomer concentration on the grafting degree was investigated. The results indicated that the grafting degree increased in the lower monomer volume fraction until the monomer volume fraction exceeded 20%. The grafting degree increased with the increase of radiation dose. Structural and morphological of the original and grafted membrane surface were characterized by FT-IR, scanning electron microscopy (SEM). The results indicated that acrylic acid was grafted onto PVDF hollow fiber membrane and the grafted membrane was more hydrophilic than original PVDF. There was a slight increase of breaking strength and yield stress with the increase of the grafting degree of AA. The pure water flux increased initially but decreased subsequently with the raise of grafting degree. When the grafting degree was 4.4%, the maximum pure water flux reached 1496.3 L/m² × h, 1.79 times of original membrane. The pure water flux, flux recovery rate and rejection ratio for bovine serum albumin could improve simultaneously in a low grafting degree (<4.4%).     

Radiation grafted poly(vinylidene fluoride)-graft-polystyrene sulfonic acid membranes for fuel cells: Structure-property relationships

<正>Structure-property relationships for poly(vinylidene fluoride)-graft-polystyrene sulfonic acid(PVDF-g-PSSA) fuel cell membranes prepared by a single step method involving radiation-induced grafting of sodium styrene sulfonate(SSS) onto electron beam(EB) irradiated poly(vinylidene fluoride)(PVDF) films were established.The physico-chemical properties of the membranes such as ion exchange capacity,water swelling and proton conductivity were correlated with the degree of grafting(G,%) and the structural changes taking place in the membrane matrix during the preparation procedure. The variation in the crystallinity and the thermal stability of membranes was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis(TGA),respectively.The membranes were found to undergo substantial structural changes in forms of ionic sites increase,hydrophilicity enhancement,hydrophobicity reduction and crystallinity decrease with the variation in G(%) and the preparation method.The structural and thermal properties of the obtained membranes were also compared with their counterparts prepared by a conventional two-steps method i.e.radiation induced grafting of styrene onto EB irradiated PVDF films followed by sulfonation.The PVDF-g-PSSA membranes obtained by a single-step method were found to have superior properties compared to those obtained by the conventional two-steps method.     

超临界二氧化碳体系中PVDF微孔膜的表面接枝改性

超临界二氧化碳（SCCO2）是一种T〉31．1℃,P〉7．38MPa的二氧化碳流体,不仅具有类似于气体的粘度和类似于液体的密度,而且可以通过改变温度或压力控制SCCO2的密度及溶解性．SCCO2对有机小分子具有优良的溶解、扩散和渗透性能,化学惰性,无污染,易于分离,作为一种聚合反应介质,受到学术界日益增多重视．SCCO2极低的粘度使其具有良好的流动性和扩散渗透性能,零表面张力使其对聚合物具有良好的润湿和增塑性,这将促进引发剂和聚合单体向微孔膜的外表面及内表面扩散．利用温度和压力改变SCCO2的溶解性能调整单体在聚合物相和SCCO2相之间的分布,进而控制微孔膜内外表面的接枝程度．所以SCCO2接枝聚合反应对于聚合物膜的表面改性具有极其重要的意义．     

Improving hydrophilicity and protein resistance of poly(vinylidene fluoride) membranes by blending with amphiphilic hyperbranched-star polymer

To endow hydrophobic poly(vinylidene fluoride) (PVDF) membranes with reliable hydrophilicity and protein resistance, an amphiphilic hyperbranched-star polymer (HPE-g-MPEG) with about 12 hydrophilic arms in each molecule was synthesized by grafting methoxy poly(ethylene glycol) (MPEG) to the hyperbranched polyester (HPE) molecule using terephthaloyl chloride (TPC) as the coupling agent and blended with PVDF to fabricate porous membranes via phase inversion process. The chemical composition changes of the membrane surface were confirmed by X-ray photoelectron spectroscopy (XPS), and the membrane morphologies were measured by scanning electron microscopy (SEM). Water contact angle, static protein adsorption, and filtration experiments were used to evaluate the hydrophilicity and anti-fouling properties of the membranes. It was found that MPEG segments of HPE-g-MPEG enriched at the membrane surface substantially, while the water contact angle decreased as low as 49 degrees for the membrane with a HPE-g-MPEG/PVDF ratio of 3/10. More importantly, the water contact angle of the blend membrane changed little after being leached continuously in water at 60 degrees C for 30 days, indicating a quite stable presence of HPE-g-MPEG in the blend membranes. Furthermore, the blend membranes showed lower static protein adsorption, higher water and protein solution fluxes, and better water flux recovery after cleaning than the pure PVDF membrane.     

Versatility of hydrophilic and antifouling PVDF ultrafiltration membranes tailored with polyhexanide coated copper oxide nanoparticles

Hydrophilic poly(vinylidene fluoride) (PVDF) nanocomposite ultrafiltration (UF) membranes with excellent antifouling and antibiofouling characteristics are fabricated by employing polyhexanide coated copper oxide nanoparticles (P–CuO NPs). The presence of P–CuO NPs is played a significant role in altering the PVDF membrane matrix and probed by XRD, FTIR, FESEM and contact angle analysis. The PVDF/P–CuO nanocomposite membranes exhibited an outstanding antifouling performance indicated by the superior pure water flux, effective foulant separation and maximum flux recovery ratio during UF experiments as a result of the formation of the hydrophilic and more porous membrane due to the uniform distribution of P–CuO NPs. Particularly, the PVDF/P–CuO-3 membrane showed higher PWF of 152.5 ± 2.4 lm⁻²h⁻¹ and porosity of 64.5% whereas the lower contact angle of 52.5°. Further, it showed the higher rejection of 99.5 and 98.4% and the flux recovery ratio of 99.5 and 98.5% respectively for BSA and HA foulants, demonstrated its increased water permeation, foulant separation and antifouling behavior. Further, the decent antibacterial activity is showed by the PVDF/P–CuO nanocomposite membranes with the formation of halo-zone around the membrane when exposed to the bacterial medium demonstrated that, by this process an antibacterial water treatment membrane can be developed by simple phase inversion technique with good membrane stability.     

改性聚偏氟乙烯接枝共混聚苯乙烯磺酸膜的制备与性能

将苯乙烯添加到溶有原硅酸钠改性的聚偏氟乙烯(PVDF)N-甲基吡咯烷酮溶液中, 以过氧化苯甲酰(BPO)作引发剂, 苯乙烯直接接枝到原硅酸钠改性的PVDF链上, 成膜后磺化制备了聚偏氟乙烯接枝苯乙烯(PVDF-g-PSSA)膜. 采用傅立叶变换红外光谱(FT-IR)、扫描电镜(SEM)、能量扩散X射线(EDX)和多功能材料实验机表征了膜的结构、形貌及硫和硅的分布、机械强度、溶胀度, 使用阻抗分析和气相色谱仪研究了苯乙烯含量(w)对PVDF-g-PSSA膜的质子导电性能和阻醇性能的影响. 结果表明, 苯乙烯加入后, 原硅酸钠改性的PVDF与苯乙烯进行接枝共聚反应, 苯乙烯磺化反应不只是在膜表面进行, 同时渗入到膜中进行, 机械性能得到了改善. 质子电导率(σ)随苯乙烯质量分数的提高而升高. Na4SiO4为8%和苯乙烯为20%的PVDF-g-PSSA膜, 在25 ℃时溶胀度仅为20.4%, 甲醇透过系数在10-7 cm2·s-1数量级上, 比Nafion115膜的低一个数量级. 该膜具有较高的选择性, 在直接甲醇燃料电池中具有良好的应用前景.     

一种新型的亲水性聚丙烯酸-陶瓷复合膜

通过化学气相沉积和丙烯酸(AA)在大孔陶瓷膜表面的接枝共聚制备了一种新型的亲水性PAA-陶瓷复合膜. 用FT-IR、SEM、EDS、表面接触角等方法对复合膜接枝层的化学组成、表面形态、元素分布和亲水性进行了表征. 通过系统研究气相沉积和接枝反应的主要条件对膜的渗透汽化性能的影响, 发现当TEOS用量为5 mL, 汽化温度为175 ℃时进行气相沉积, 然后在丙烯酸浓度为7.5%的溶液中进行接枝聚合, 制得的复合膜对醇水混合物显示了优良的分离性能.