多羧基酞菁铜、乙酰基二茂铁改性CMC/CS双极膜的制备及表征

柔性链高分子聚乙二醇(PEG)分别与阳离子交换膜层羧甲基纤维素钠(CMC)、阴离子交换膜层壳聚糖(CS)共混以增强界面的相容性和膜的机械性能.以金属有机高分子多羧基酞菁铜(CuPc)改性CMC、乙酰基二茂铁改性CS,采用流延法制备了CuPc-mCMC/mCS双极膜.双极膜溶胀性和热重分析结果表明膜改性后稳定性能得到提高.膜交流阻抗、I-V工作曲线的测定结果表明该双极膜阻抗及工作电压均较小.双极膜经改性具有较高的离子渗透性能。     

mCMC-PEG-CS双极膜在电还原制备巯基乙酸中的应用

以Fe3+改性羧甲基纤维素(CMC)和聚乙二醇(PEG)共混物为阳膜, 以戊二醛改性壳聚糖(CS)和聚乙二醇共混物为阴膜, 制备了mCMC-PEG-CS双极膜, 并将其用作电解还原制备巯基乙酸(TGA)电解槽中阴阳两室间的隔膜. 以硫代硫酸钠法合成的巯基乙酸(TGA)和二硫代二乙酸(DTDGA)混合物为原料, 研究了酸浓度、温度及电解电流密度对电还原DTDGA制备TGA的生成量和电流效率的影响. 实验结果表明, 在TGA初始合成质量分数为2.79%, 电流密度为10 mA/cm2, 35 ℃电解时, 阴极室电还原产物巯基乙酸的电流效率为74.69%, 电解过程中的平均电流效率为54.02%. 与传统的金属还原法还原DTDGA制备的TGA相比, 不仅避免了昂贵的金属还原剂锌的消耗, 而且消除了反应副产物锌泥对环境的污染.     

CoPc(COOH)8-SA/mCS双极膜的制备及表征

分别用Fe3+离子和戊二醛作为交联剂对海藻酸钠(SA)阳膜层和壳聚糖(CS)阴膜层进行改性, 制备了八羧基钴酞菁-海藻酸钠/改性壳聚糖(CoPc(COOH)8-SA/mCS)双极膜(BPM). 在海藻酸钠阳膜层中添加八羧基钴酞菁以提高阳膜的离子交换容量, 促进中间层水的解离. 用傅立叶红外(FT-IR)光谱、扫描电镜(SEM)等方法对制备的双极膜进行了表征. 实验结果表明, 经八羧基钴酞菁改性后, 阳离子交换膜层的离子交换容量、H+离子透过率均获得提高. 与Fe3+离子改性或二茂铁离子改性的mSA/mCS双极膜相比, CoPc(COOH)8-SA/mCS双极膜的交流阻抗、电阻压降(IR降)和溶胀度降低. 当电流密度高达105 mA·cm-2时, CoPc(COOH)8-SA/mCS双极膜的IR降仅为0.7 V.     

mSA-CS双极膜在电还原制备巯基乙酸中的应用

用Ca^2＋改性海藻酸钠(SA), 用戊二醛(GA)改性壳聚糖(CS), 制备mSA-CS聚合物双极膜. 测定膜的红外光谱及机械性能, 并作膜的热重分析. 以扫描电镜观察膜表面和界面层形态. 测定了mCS膜制备溶液的粘度以及mSA, mCS膜的含水率、离子交换容量及酸碱浓度对膜溶胀度的影响. 将mSA-CS双极膜应用于电解还原制备巯基乙酸(TGA). 实验结果表明, 以硫代硫酸钠法合成的TGA和二硫代二乙酸(DTDGA)的混合液作阴极液, TGA初始合成质量分数为4.61%, 电流密度为10 mA•cm^－2下常温电解, 产物巯基乙酸的电流效率达66.7%. 与传统的金属还原法还原DTDGA成TGA相比, 不仅省去了昂贵的金属还原剂的消耗, 而且消除了对环境的污染.     

四磺酸基铜酞菁-海藻酸钠/壳聚糖双极膜的制备与表征

分别用Fe3+和戊二醛作为交联剂对海藻酸钠(SA)阳离子交换膜和壳聚糖(CS)阴离子交换膜进行改性,制备了四磺酸基铜酞菁(CuTsPc)-海藻酸钠/改性壳聚糖双极膜(CuTsPc-SA/mCSBPM).在海藻酸钠阳膜层中添加四磺酸基铜酞菁,以提高阳膜层的离子交换容量,促进双极膜中间层中水的解离.采用X射线光电子能谱(XPS)对CuTsPc-SA阳离子交换膜进行了表征.实验结果表明,改性后SA阳膜层的离子交换容量、H+透过率均获得提高.与Fe3+改性或二茂铁离子改性的mSA/mCS双极膜相比,CuTsPc-SA/mCS双极膜的阻抗及电阻压降(即膜IR降)均下降.当电流密度为120mA/cm2时槽电压仅为5.6V.当CuTsPc含量为2.5%(质量分数)时CuTsPc-SA/mCS双极膜在H+离子浓度小于8mol/L的酸溶液中具有稳定的工作性能.     

CuPc(COOH)8-SA/CuTAPc-CS双极膜的制备及表征

分别用八羧基铜酞菁[CuPc(COOH)₈]和四氨基铜酞菁(CuTAPc)改性海藻酸钠(SA)阳膜层和壳聚糖(CS)阴膜层, 制备了CuPc(COOH)₈-SA/CuTAPc-CS双极膜. 实验结果表明, 经八羧基铜酞菁和四氨基铜酞菁改性后, 促进了双极膜中间层水的解离, 增大了阳离子交换膜层和阴离子交换膜层的离子交换容量及H⁺和OH^-的透过率. 与Fe³⁺改性的Fe-SA/mCS双极膜相比, CuPc(COOH)₈-SA/CuTAPc-CS双极膜的阻抗、电阻压降(即IR降)和溶胀度降低. 当电流密度高达120 mA/cm²时, CuPc(COOH)₈-SA/CuTAPc-CS双极膜的IR降仅为0.9 V.     

双极膜技术在电氧化制备3-甲基-2-吡啶甲酰胺中的应用

分别以戊二醛和Fe3+改性壳聚糖和海藻酸钠并分别与柔性链聚乙烯醇(PVA)共混, 制备了Fe-SA-CS-GA/PVA聚合物双极膜. 测定膜的红外光谱, I-V工作曲线, Na+与Cl-透过双极膜的迁移数, 离子交换容量及阴阳两极室中OH-及H+的变化, 并以扫描电镜观察膜表面和界面层形态. IR与接触角分析结果表明, CS经GA/PVA改性后其亲水性能得到显著提高. 将SA-CS/PVA双极膜及Nafion膜应用于电氧化制备3-甲基-2-吡啶甲酰胺. 实验结果表明, 以SA-CS/PVA双极膜为隔膜合成3-甲基-2-吡啶甲酰胺的产率达到49.8%, 高于以Nafion膜为隔膜的产率.与传统的的方法相比, 该方法的反应条件温和且能有效利用能源.     

聚乙二醇对PAMPS/PAM双网络水凝胶性能的影响

采用紫外光引发聚合制备了聚乙二醇(PEG)改性的聚(2-丙烯酰胺-2-甲基丙磺酸)/聚丙烯酰胺(PAMPS/PAM)双网络水凝胶.测定并比较了PEG改性前后双网络水凝胶的溶胀动力学以及单网络水凝胶中丙烯酰胺(AM)的吸收量;用扫描电子显微镜(SEM)观察了单网络水凝胶的结构;测定PEG改性前后双网络水凝胶的压缩及拉伸性能.结果表明,经PEG改性后的双网络水凝胶有较高的溶胀比;改性后单网络水凝胶更易吸收AM;改性后双网络水凝胶压缩形变率达到90%以上、拉伸形变率是未改性双网络水凝胶的2倍.     

磷酸化P-mCMC/mCS双极膜的制备及其性能的研究

以五氧化二磷,磷酸三乙酯和磷酸为反应剂,制备了磷酸化羧甲基纤维素(CMC),经Fe³⁺改性后用作为阳膜;以壳聚糖(CS)和聚乙烯醇共混物用戊二醛改性后用作为阴膜溶胶,将阴膜溶胶流延于阳膜上,制备了P-mCMC/mCS双极膜。测定了CS、CMC胶体的电荷密度,离子透过率,P-mCMC/mCS双极膜的红外光谱与离子交换能力。IR与接触角测定的结果表明,CMC经改性后其亲水性能得到了显著提高。膜交流阻抗、I-V工作曲线的测定结果表明该双极膜阻抗及工作电压均较小。     

PEU/PES共混膜的制备工艺条件研究

利用L-S相转化法将聚醚型聚氨酯（PEU）和聚醚砜（PES）共混,以聚乙二醇（PEG）为添加剂,制备PEU/PES共混膜,并通过测定比较共混膜的结构与性能.结果表明：聚合物浓度、共混组成比、添加剂种类与浓度是影响PEU/PES共混膜性能的主要因素.     

Poly (caprolactone)/poly (ethylene glycol) pervaporation blend membranes: Synthesis,characterization, and performance

Poly (caprolactone) membranes with addition of different poly (ethylene glycol) concentrations were prepared for separation of water/isopropanol azeotropic mixture by pervaporation process. Different characterization tests including Fourier transform infrared, scanning electron microscopy, water contact angle, and thermogravimetric analysis were carried out on the prepared membranes. In addition, the effect of poly (ethylene glycol) PEG content on the swelling degree and the performance of the prepared membranes in pervaporation process were investigated. According to the obtained results, all the membranes were water selective and the blend membrane containing 3 wt% PEG exhibited the best pervaporation performance with a water flux of 0.517 kg/m² hour and separation factor of 1642 at the ambient temperature. Hydrophilicity improvement of the blend membranes was confirmed by constant decrease in water contact angle of the membranes as PEG content increased in the casting solution. Scanning electron microscopy cross‐sectional images indicated that the blend membranes containing PEG had a closed cellular structure. Furthermore, mechanical and thermal properties of the membranes decreased by adding PEG.     

Preparation of PVA-GA-CS/PVA-Fe-SA bipolar membrane and its application in electro-generation of 2,2-dimethyl-3-hydroxypropionic acid

PVA-GA-CS/PVA-Fe-SA bipolar membrane was prepared by a paste method. PVA-sodium alginate (SA) and PVA-chitosan (CS) were cross-linked by FeCl₃ and glutaraldehyde (GA), respectively. The charge densities of PVA-CS and PVA-SA solutions were determined by the colloid titration. The swelling level of bipolar membrane was in the range of 25–85%, meanwhile the permeability and the ion-exchange capacity as well as co-ion transport properties was investigated. FTIR was applied to analyze the functional groups of the bipolar membrane. Furthermore, SEM photographs of the BPM cross-section illustrated a structure that consists of an anion layer (PVA-GA-CS) and a cation layer (PVA-Fe-SA). TG analysis of PVA-GA-CS/PVA-Fe-SA bipolar membranes exhibited a good thermal stability. PVA-GA-CS/PVA-Fe-SA bipolar membranes were used as the separator in the electrolysis cell for electro-generation of 2,2-dimethyl-3-hydroxypropionic acid. The average current efficiency was 52.2%, and the highest current efficiency reached 68.9%.     

PEG-catalytic water splitting in the interface of a bipolar membrane

This paper investigates the effect of polyethylene glycol (PEG) on the water dissociation of bipolar membranes. To do this, bipolar membranes were prepared by immersing anion exchange membranes in different-concentration solutions of different-molecular-weight PEGs and then casting the solutions of sulfonated polyphenylene oxide (SPPO) on the anion exchange membranes. All the bipolar membranes with PEG in the interface are evaluated by current-voltage curves. The experimental results prove that PEG has excellent catalytic function for water dissociation. Furthermore, this function is enhanced by both PEG amount (PEG concentration) and PEG molecular weight in the interface of a bipolar membrane.     

Electrospun Aligned Poly(L-lactide)/Poly(ϵ-caprolactone) /Poly(ethylene glycol) Blend Fibrous Membranes

Aligned poly(L-lactide) (PLLA)/poly(?-caprolactone) (PCL)/poly(ethylene glycol)(PEG) fibrous membranes were fabricated by electrospinning. Their morphology, thermal stability, mechanical properties, hydrophilic properties and in vitro degradation behaviors were investigated. With increasing the content of PEG, the PLLA/PCL/PEG blend fibers become thinner due to the increment in solution conductivity and decrease in solution viscosity. The thermal stability, hydrophilic properties, the tensile strength and elongation-at-break of PLLA/PCL/PEG blend fibrous membranes were improved, but porosity were decreased with the content of PEG changing from 10 wt% to 30 wt%. Furthermore, the incorporation of PEG enhanced the degradation of the PLLA/PCL/PEG fibrous membranes due to the better hydrophilic properties. In addition, the PLLA/PCL/PEG fibrous membranes have no toxic effect on proliferation of adipose-derived stem cells.     

Radiation deterioration of ion-exchange Nafion N117CS membranes

The cation-exchange Nafion N117 membranes swelling in electrolyte solution were irradiated with γ-rays or electron beams at various doses up to 1500 kGy in the temperature range from room temperature to 343 K to obtain detailed information on the effect of ion-exchange on the radiation deterioration in mechanical properties and ion-exchange capacity. Considerable deterioration in mechanical properties was observed when the Nafion membranes swelling in electrolyte solution were irradiated. A reason is the promotion of degradation with oxygen molecules produced by the irradiation of electrolyte solution. The concentration of electrolyte solution influenced strongly the radiation deterioration in mechanical properties. Keeping the concentration of metal ions to be negligible is important when electrolyzed highly radioactive solution in the light of the durability of polyperfluorosulfonic acid (PFSA) membrane. A sort of cation in electrolyte solution negligibly influenced radiation deterioration in mechanical properties. A sort of anion in electrolyte solution had negligible effect on radiation deterioration in mechanical properties and ion-exchange capacity. The discrepancy in the radiation deterioration in mechanical properties of Nafion membranes swelling in NaCl solution was observed between the specimens irradiated with γ-rays and electron beams. This discrepancy can be explained from the low diffusivity of oxygen from bulk into the membrane.     

Effect of polyethylene glycol on sulfonated polyether imide (SPEI) for fuel cell applications

The sulfonated polyetherimide (sPEI) was synthesized by direct sulfonation method using chlorosulfonic acid as a sulfonating agent. Different sulfonation degrees of sPEI was obtained by varying the ratio of PEI to chlorosulfonic acid and reaction time. Then, sulfonated polyetherimide was blended with polyethylene glycol (PEG) and thermally cross-linked in order to achieve high performance proton exchange membrane. It was found that the addition of PEG resulted in a significant increase in porosity and water uptake of the membranes, which favored proton transport at low temperature. The maximum proton conductivity was 11 mS/cm at 75°C for the blend membrane containing 20% PEG. The sulfonation and blend modification of PEI were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy.     

Preparation and Characterization of Chitosan Composite Membranes Crosslinked by Carboxyl-capped Poly（ethylene glycol）

In this study a series of chemically crosslinked chitosan/poly（ethylene glycol） （CS/PEG） composite membranes were prepared with PEG as a crosslinking reagent other than an additional blend. First, carboxyl-eapped poly（ethylene glycol） （HOOC-PEG-COOH） was synthesized. Dense CS/PEG composite membranes were then prepared by casting/evaporation of CS and HOOC-PEG-COOH mixture in acetic acid solution. Chitosan was chemically crosslinked due to the amidation between the carboxyl in HOOC-PEG-COOH and the amino in chitosan under heating, as confirmed by FTIR analysis. The hydrophilicity, water-resistance and mechanical properties of pure and crosslinked chitosan membranes were characterized, respectively. The results of water contact angle and water absorption showed that the hydrophilicity of chitosan membranes could be significantly improved, while no significant difference of weight loss between pure chitosan membranes and crosslinked ones was detected, indicating that composite membranes with amidation crosslinking possess excellent water resistanance ability. Moreover, the tensile strength of chitosan membranes could be significantly enhanced with the addition of certain amount of HOOC-PEG-COOH crosslinker, while the elongation at break didn＇t degrade at the same time. Additionally, the results of swelling behaviors in water at different pH suggested that the composite membranes were pH sensitive.     

Preparation and basic characterization of heterogeneous weak acid cation exchange membrane

The goal of this article is focused on the preparation and the basic characterization of heterogeneous weak acid cation exchange membranes. The six weak cation exchange resins were chosen for the preparation of the membranes. The strong acid cation exchange membrane was prepared for the comparison of properties and preparation parameters. Heterogeneous membranes were prepared in the several steps. The last operations were the extrusion and hydraulic hot-pressing. The torque and pressure in the extrusion head were observed while the extrusion of heterogeneous membranes. According to the type of the ion exchange resin, parameters varied greatly. The strong acid cation exchange membrane and weak acid cation exchange membranes with carboxylic groups had the lowest values of the torque and pressure while the homogenization and extrusion. All membranes were characterized. Electrochemical (permselectivity, ion exchange capacity, resistance), physical (relative water content, swelling in the different solutions), and mechanical properties were measured. Properties varied distinctly according to the type of the ion exchange resins. Swelling dimensional changes of ion exchange membranes in sodium hydroxide and water were bigger than changes in hydrochloric acid. Ion exchange capacity of membranes related with ion exchange capacity of used ion exchange resins. Weak acid cation exchange membranes with carboxylic functional groups compared to the strong membrane had the best specific and areal resistance.