Dual-interface regulation of two-dimensional ZIF-based composite membranes for efficient and stable pervaporation desalination.

Polymer/Ceramic Composite Membranes and Their Application in Pervaporation Process

A dual regulation strategy for MXene-based composite membrane to achieve photocatalytic self-cleaning properties and multi-functional applications

A new generation of organic solvent nanofiltration (NF) composite membranes was prepared combining a support layer with a selective layer made both from the same polymeric material (P84 copolyimide). These membranes, homogeneous in composition, but composite in structure, were defined as polymeric homogeneous composite (PHC) membranes. The composite membranes have the advantage over the asymmetric ones that each layer can be optimized independently. Moreover, the use of the same material for the preparation of both, the selective and the support layer, ensures a high affinity between the two layers and increases the long‐term stability of the composite membranes, reducing the possibility of delamination phenomena. In the design of the PHC membranes, a great attention was devoted to the support layer development. The effects of the composition of the casting solutions on the structure of porous P84 copolyimide membranes were investigated allowing to identify the conditions for the preparation of highly permeable, chemically, and mechanically stable P84 sponge like porous membranes. PHC membranes were prepared by coating and controlled solvent evaporation of a P84 solution on the optimized support crosslinked by reaction with a diamine (1,5‐diamino‐2‐methylpentane). Pure solvent permeation test and rejection experiments were carried out on the P84 supports and the corresponding PHC membranes in aggressive organic solvents like N‐methyl‐2‐pyrrolidone and N,N‐dimethyformamide, in which the original polymer was soluble. The PHC membrane resulted completely stable over long times (>96 h). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A novel composite polymer electrolyte membrane composed of PVA polymer matrix and nanosized Montmorillonite (MMT) filler (2~20wt.%), was prepared by a solution casting method. The characteristic properties of the PVA/MMT composite polymer membrane were investigated using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), atomic force microscopy (AFM), micro-Raman spectroscopy, and the AC impedance method. The PVA/MMT composite polymer membrane showed good thermal and mechanical properties, ionic conductivity. The PVA/10wt.%MMT composite polymer membrane with the highest ionic conductivity was around 0.0368 S cm-1 at 30oC. The methanol permeability (P) values were 3~4×10-6 cm2 s-1, which are smaller than that of Nafion 117 membrane of 5.8×10-6 cm2 s-1. It was revealed that the addition of nanosized MMT fillers into the PVA matrix could markedly improve the electrochemical properties of the PVA/MMT composite membrane; it can be accomplished by a simple blend method. As a result, the PVA/MMT composite polymer appears to be a potential candidate for the DMFC applications.

Development of novel ionic covalent organic frameworks composite nanofiltration membranes for dye/salt separation

Hydrophilic nanomaterials were always used to improve the pervaporation (PV) performance of polyvinyl alcohol (PVA) membrane in the process of ethanol dehydration. In this work, the PVA/MXene composite membrane with high water flux and separation factor was fabricated with spin coating method. Induced by the hypergravity force, the MXene nanosheets were segregated and stacked layer‐by‐layer between the interface of the PVA/MXene layer and the support. The self‐assembly 2D MXene in the PVA not only improved the binding force between the separation layer and the support but also enhanced the PV performance. The water flux and separation factor of the PVA/SSA/MXene composite membrane reached 1.22 kg·m−2·h−1 and 1577, respectively. Both were higher than those of most reported PVA membranes. Nano indentation and scratch tests also revealed that due to the high modulus and hardness of the PVA/SSA/MXene composite membrane, 0.2822 and 0.019 GPa, strong binding force was existed between the separation layer and the support. Partly based on this reason, the structure of the PVA/SSA/MXene composite membrane remained stable during 300 hours of the PV test. It is believed that the prepared PVA/SSA/MXene composite membrane has a broad application prospect in the PV process for ethanol dehydration.

Ion transport behavior in diffusion layer of new designed ion exchange-mosaic composite polymer membrane

Direct methanol fuel cell (DMFC) based on PVA/MMT composite polymer membranes

Nanostructured Polymer Composite Electrolytes with Self-Assembled Polyoxometalate Networks for Proton Conduction

A composite polymer membrane with reversible overcharge protection mechanism for lithium ion batteries

Multifunctional stable PDA/RGO/MOFs&SiO2-COOH membrane with excellent flux and anti-fouling performance for the separation of organic dye and oil/water

Metal-organic framework (MOF)/polymer composite proton exchange membranes (PEMs) are being intensively investigated due to their potentials for the systematic design of proton-conducting properties. However, the development of MOF/polymer composite PEMs possessing high selectivity remains exceedingly desirable and challenging for practical application. Herein, two-dimensional (2D) zeolitic imidazolate framework (ZIF-8)/carbon nanotube (CNT) hybrid cross-linked networks (ZCN) were synthesized via the rational design of the physical form of ZIF-8, and then a series of composite PEMs were prepared by hybridizing ZCN with sulfonated poly(ether ether ketone) (SPEEK) matrix. The effect of the incorporation of zero-dimensional (0D) raw ZIF-8 nanoparticles and 2D ZCN on the proton conduction and methanol permeability of the composite membranes was systemically studied. Benefiting from the morphological and compositional advantages of ZCN, the SPEEK/ZCN composite membranes displayed a significant enhancement in proton conductivity under various conditions. In particular, the proton conductivity of SPEEK/ZCN-2.5 membrane was up to 50.24 mS cm-1 at 120 °C-30% RH, which was 11.2 times that of the recast SPEEK membrane (4.50 mS cm-1) and 2.1 times that of SPEEK/ZIF membrane (24.1 mS cm-1) under the same condition. Meanwhile, the methanol permeability of the SPEEK/ZCN composite membranes was greatly reduced. Therefore, novel MOF/polymer composite PEMs with high selectivity were obtained. Our investigation results reveal that the proton conductivity and methanol permeability of the MOF/polymer composite membranes can be effectively tailored via creating more elaborate superstructures of MOFs rather than altering the chemical component. This effective strategy may provide a useful guideline to integrate with other interesting MOFs to design MOF/polymer composite membranes.

본 연구에서는 투과증발 공정에서 지지체에 따른 투과특성의 차이를 알아보기 위해 고분자 지지체 복합막과 세라믹 지지체 복합막을 제조하였다. 고분자 지지체로는 polyvinylidene fluoride (PVDF)를 사용하였으며 세라믹 지지체로는 <TEX>$a-Al_2O_3$</TEX> 를 사용하였다. 활성층으로는 각각의 지지체에 고무상 고분자인 polydimethoxysilane (PDMS)를 코팅하였다. 제조한 복합막의 구조와 특성을 살펴보기 위해 SEM, contact angle, XPS로 분석하였으며, 이를 투과증발 공정에 적용하여 다성분계의 혼합용액에서 복합막의 지지체에 따른 투과 특성을 알아보았다. 투과 증발 실험 결과 세라믹 지지체 복합막의 투과 플럭스는 <TEX>$250.87g/m^2h$</TEX>로 고분자 지지체 복합막의 <TEX>$159.64g/m^2h$</TEX> 보다 높은 투과 플럭스를 나타내었다. 그러나 선택도의 경우 고분자 지지체 복합막이 31.98로 20.66인 세라믹 지지체 복합막보다 더 높게 나타나는 것을 확인하였다. In this paper, polymer composite membranes and ceramic composite membranes were prepared in order to compare differences in pervaporation performances relative to the support layers. PVDF was used for the polymer support layers, and <TEX>$a-Al_2O_3$</TEX> was used for the ceramic support layers. For active layer was coated for PDMS, which is a rubbery polymer. The characterization of membranes were analysed by SEM, contact angle, and XPS. We studied performances relative to the composite membrane support layers in the ABE mixture solutions. The results of the pervaporation, the flux of the ceramic composite membrane was shown to be <TEX>$250.87g/m^2h$</TEX>, which was higher than that of polymer composite membranes, at <TEX>$195.64g/m^2h$</TEX>. However, it was determined that the separation factor of the polymer composite membranes was 31.98 which were higher than that of the ceramic composite membranes, at 20.66.

New poly(vinyl alcohol)/silica (designated as PVA/SiO2) alkaline micro-porous polymer electrolytes (AMPEs) were prepared by soaking PVA/SiO2 micro-porous composite membranes, obtained by solution casting of PVA/PEG/SiO2 membrane in acetone solution, into an electrolyte solution of 6 mol/L KOH aqueous solution. The morphology and structure of PVA/SiO2 composite polymer membranes were characterized by scanning electron microscopy (SEM) and X-Ray diffrac- tion (XRD). The SEM photographs showed that the nano-SiO2 filler content was a crucial issue for the well-dispersed and optimal-sized pores which could storage charge carrier durably. Meanwhile, the crystalline of PVA decreased effectively for a large number of crystal defects and free volume appeared in the interface of inorganic particles and polymer for the addition of nano-SiO2 filler. The electrochemical properties of the AMPEs were measured by the alternating current impedance (AC impedance) and the cyclic voltammetry (CV) techniques. The results indicated that the PVA/SiO2 AMPEs containing 5 ω nano-SiO2 filler exhibited good performances at room temperature, such as 1.62×10 -2 Scm -1 for ionic conductivity and 2.20 V for electrochemical stability window. What's more, we used the gravimetric method to obtain the electrolyte uptake of various PVA/SiO2 composite micro-porous polymer membranes. From the data, we learned that the maximum electrolyte uptake could reach to 102.7% and it had very relevance to the size of pores in PVA/SiO2 composite polymer membranes, and then influenced the ionic conductivity. Each polymer Ni-MH battery was assembled by three parts: the new AMPE, Mg-based hydrogen storage alloy and the commercial sintered Ni(OH)2/NiOOH electrode, in which each part did for electro- lyte and diaphragm, negative electrode and positive electrode, respectively. The cycle experiments of the batteries exhibited a high first-cycle discharge capacity of 613 mAhg -1 and stable discharge capacities about 330 mAhg -1 for the following 5 cycles. The results encouraged that the novel AMPEs are prospective for the applications of polymer electrolyte in Ni-MH battery field. Keywords PVA; alkaline micro-porous polymer electrolyte; ionic conductivity; cycling stability; polymer Ni-MH battery

Low-permeation resistance thin-film composite nanofiltration membrane based on high-precision 3D-printed support layer