연구에서는 고분자전해질 연료전지(PEMFC)의 전해질막의 성능향상을 위하여 sulfonated graphene oxide (sGO)와 Nafion을 이용하여 복합막을 개발하였다. sGO/Nafion 복합막 안의 sGO의 균일한 분산을 위해 각기 다른 용매를 사 용한 sGO 분산액과 Nafion 현탁액을 혼합하여 복합막들을 제조하였다. 제조된 복합막들의 물성 및 전기화학적 특성을 평가 하기 위해 SEM, FT-IR, 이온 전도도, 이온 교환 용량, 함수율, 열안정성 등을 수행하였다. 연구 결과 ODB와 DMAc 혼합 용 매로 sGO를 분산하여 고분자 용액 내에서의 분산도를 향상시켰으며, 이 결과 11 wt%의 낮은 함수율에도 불구하고, 0.06 S cm-1의 기존 연구와 유사한 이온 전도도를 나타내었다.

Graphene oxide (GO) has received a lot of attention in membrane science for its CO2-philic nature, which can facilitate CO2 separation performance. In addition, GO has attractive properties for gas separation membrane material due to thin-film membrane formation and tunable transport channel. GO membrane can be generally prepared by coating GO nanosheets on microporous polymer supports for mechanical stability. However, the substrates for in thin GO layer should be carefully chosen for good adhesion between GO layer and support surface with maintaining good separation performance. In this study, we tried to modify the surface properties of high permeable support membranes by using gutter layer as an intermediate layer, and measured the gas transport properties of these GO thin-film composite membranes.

Recently, graphene oxide (GO) has been extensively investigated for gas and liquid separation because thin-film GO membranes show quite interesting separation performance. However, even GO membranes exhibit relatively low gas permeability due to high tortuosity caused by high aspect ratio of GO. Normally, the size of GO is in the range from a few hundred nanometers to a few micrometers, so inherent gas permeability would be very varied. For practical applications of GO membranes, the gas permeability should be improved. As such, in this study, we have modified the pristine GO sheets to reduce the gas permeation pathway, with maintaining GO’s excellent gas separation properties. This study will provide a further insight on how such two-dimensional nanosheets can be used for membrane applications, competing with existing membrane materials.

Graphene oxide (GO) is an intriguing two-dimensional nanosheet, a highly oxidized graphene sheet. Due to its various oxygen-containing polar functional groups, graphene oxide shows high CO2 sorption properties, and also thin-film GO membranes exhibit good CO2 separation properties, particularly in the presence of water molecules. Recently, GO nanosheets have been incorporated into polymer membranes, in the form of mixed-matrix membranes, to expect the synergistic effect of GO and polymer matrix. Here, we prepared novel GO/polymer membranes via crosslinking reactions between polar groups on basal plane of GO and bi-functional crosslinking agents, and then conducted the gas permeation measurements to see the possible enhancement for permeability/selectivity performance.

Graphene oxide (GO) can be used as a membrane material itself or a nanofiller to enhance gas separation performance of polymer membranes. Since GO has high CO2 affinity due to some polar groups, particularly GO membranes or GO/polymer membranes have been extensively studied for CO2 separation. Although ultrathin GO membranes show outstanding CO2 separation properties, the gas permeance through GO membranes is still low owing to high tortuosity caused by high aspect ratio of GO sheets. In this study, mixed-matrix membranes consisting of modified GO (as a dispersed phase) and high permeable polymer were prepared by combining each advantage of GO and high permeable polymer for improving gas separation performance. Both single-gas and mixed-gas permeation experiments were conducted with or without humidified feeds for post-combustion CO2 capture.

Usually olefin/paraffin separations (e.g., ethane/ethylene and propane/ propylene) by distillation process are energy-intensive because such molecules have very similar molecular size and boiling point. Membrane process has been considered as an alternative method to achieve energy- efficient olefin/paraffin separation. However, based on solution-diffusion mechanism, it is hard to design good membrane materials to separate them efficiently. Here we report fundamental separation properties of olefin/paraffin through graphene oxide (GO) membranes having slit-like channels. Analogue to carbon molecular sieve membranes, GO membranes showed ability to separate these molecules. To improve the separation properties, GO membranes have been modified by various methods.

Graphene oxide (GO), a highly oxidized graphene sheet, is a distinguished 2-D nanosheet. GO membranes exhibit good CO2 separation properties due to its various polar functional groups with oxygen resulting in high CO2 sorption properties. Recently, GO nanosheets have been incorporated into polymer membranes expecting the synergistic effect. There is, however, little research on GO as a crosslinker even though it has high potential due to available functional groups for further reaction. Here, we prepared GO/polymer membranes by crosslinking reactions between polar groups of GO and bi-functional polymer matrix at different temperatures. Optimum crosslinking condition was found by analyzing gas transport, chemical properties of samples. Degree of crosslinking in GO/polymer nanocomposites affected gas transport behavior.

Graphene oxide (GO) has been extensively studied for membrane material for gas and liquid separation due to its outstanding features such as selective CO2 or water vapor transport properties. Although GO membranes can be easily fabricated in the form of thin-film composite membranes by using high-flux polymeric support membranes, it shows relatively low gas permeability due to high tortuosity. Here we report the way to improve gas permeation rate through porous graphene oxide by reducing the gas permeation pathway, with maintaining GO’s two-dimensional structure. We also used polymer, which has high CO2/N2 selectivity, and prepared GO/polymer composite membranes as a function of GO concentration. This study will provide a further insight on how such two-dimensional nanosheets can be harmonized with polymer and improved membrane properties.

Membrane bioreactor (MBR) and reverse osmosis (RO) process have attracted much attention in the field of wastewater treatment and desalination, respectively. However, MBR has membrane fouling which is the major obstacle in maximizing their efficiency. Also, for the RO process, low energy efficiency still remains unanswered in RO process. In this study, it is demonstrated that the application of graphene oxide (GO) to membrane fabrication can be a novel strategy to overcome the residual problems. In detail, GO was applied to fabrication of polysulfone ultrafiltration membrane for improving anti-biofouling capability of membrane. Furthermore, addition of GO enhanced mechanical strength of highly porous support layer, which enabled the thin-film composite RO membrane to have 1.6 to 4 times higher water flux compared to other RO membranes.

We prepared ethylene vinyl alcohol (EVOH)/graphene oxide (GO) membranes by solution casting method. X-ray diffraction analysis showed that GOs were fully exfoliated in the EVOH/GO membrane. The glass transition temperatures of EVOH were increased by adding GOs into EVOH. The melting temperatures of EVOH/GO composites were decreased by adding GOs into EVOH, indicating that GOs may inhibit the crystallization of EVOH during non-isothermal crystallization. However, the equilibrium melting temperatures of EVOH were not changed by adding GOs into EVOH. The oxygen permeability of the EVOH/GO (0.3 wt%) film was reduced to 63% of that of pure EVOH film, with 84% light transmittance at 550 nm. The EVOH/GO membranes exhibited 100 times better (water vapor)/(oxygen) selectivity performance than pure EVOH membrane.

In this study, we present a facile method of fabricating graphene oxide (GO) filmson the surface of polyimide (PI) via layer-by-layer (LBL) assembly of charged GO. The positively charged amino-phenyl functionalized GO (APGO) is alternatively complexed with the nega-tively charged GO through an electrostatic LBL assembly process. Furthermore, we investi-gated the water vapor transmission rate and oxygen transmission rate of the prepared (reduced GO [rGO]/rAPGO)10 deposited PI film(rGO/rAPGO/PI) and pure PI film.The water vapor transmission rate of the GO and APGO-coated PI composite filmwas increased due to the intrinsically hydrophilic property of the charged composite films.However, the oxygen trans-mission rate was decreased from 220 to 78 cm3/m2·day·atm, due to the barrier effect of the graphene filmson the PI surface. Since the proposed method allows for large-scale production of graphene films, it is considered to have potential for utiliation in various applications.