The interfacial compatibility of composite membrane is an important factor to its structural stability, andseparation performance. In this study, poly （ether sulfone） （PES） support layer was first hydrophilically ...The interfacial compatibility of composite membrane is an important factor to its structural stability, andseparation performance. In this study, poly （ether sulfone） （PES） support layer was first hydrophilically modified with poly（vinyl alcohol） （PVA） via surface segregation during the phase inversion process. Gelatin （GE） was then cast on the PVA-modified PES support layer as the active layer followed by crosslinking to fabricate composite membranes for ethanol dehydration. The enrichment of PVA on the surface of support layer improved interfacial compatibility of the as-prepared GE/PVA-PES composite membrane. The water contact angle measurement and X-ray photoelectron spectroscopy （XPS） data confirmed the surface segregation of PVA with a surface coverage density of -80%. T-peel test showed that the maxima/force to separate the support layer and the active layer was enhanced by 3 times compared with the GE/PES membrane. The effects of PVA content in the support layer, crosslinking of GE active layer and operating parameters on the pervaporative dehydration performance were investigated. The operational stability of the composite membrane was tested by immersing the membrane in ethanol aqueous solution for a period of time. Stable pervaporation performance for dehydration of 90% ethanol solution was obtained for GE/PVA-PES membrane with a separation factor of -60 and a permeation flux of -1910 g.m^-2.h1 without peeling over 28 days immersion.展开更多
Reduction of graphene oxide （GO） is a promising low-cost synthetic approach to bulk graphene, which offers an accessible route to transparent conducting films and flexible electronics. Unfortunately, the release of ...Reduction of graphene oxide （GO） is a promising low-cost synthetic approach to bulk graphene, which offers an accessible route to transparent conducting films and flexible electronics. Unfortunately, the release of oxygen-containing functional groups inevitably leaves behind vacancies and topological defects on the reduced GO sheet, and its low electrical conductivity hinders the development of practical applications. Here, we present a strategy for real-time repair of the newborn vacancies with carbon radicals produced by thermal decomposition of a suitable precursor. The sheet conductivity of thus-obtained single-layer graphene was raised more than six-fold to 350-410 S/cm （whilst retaining 〉96% transparency）. X-ray photoelectron spectroscopy （XPS） and Raman spectroscopy revealed that the conductivity enhancement can be attributed to the formation of additional sp2-C structures. This method provides a simple and efficient process for obtaining highly conductive transparent graphene films.展开更多
基金Supported by the New Century Excellent Talents in University(NCET-10-0623)National Natural Science Foundation for Distinguished Young Scholars(21125627)+1 种基金National Basic Research Program of China(2009CB623404)State Key Laboratory for Modification of Chemical Fibers and Polymer Materials(Dong Hua University)
文摘The interfacial compatibility of composite membrane is an important factor to its structural stability, andseparation performance. In this study, poly （ether sulfone） （PES） support layer was first hydrophilically modified with poly（vinyl alcohol） （PVA） via surface segregation during the phase inversion process. Gelatin （GE） was then cast on the PVA-modified PES support layer as the active layer followed by crosslinking to fabricate composite membranes for ethanol dehydration. The enrichment of PVA on the surface of support layer improved interfacial compatibility of the as-prepared GE/PVA-PES composite membrane. The water contact angle measurement and X-ray photoelectron spectroscopy （XPS） data confirmed the surface segregation of PVA with a surface coverage density of -80%. T-peel test showed that the maxima/force to separate the support layer and the active layer was enhanced by 3 times compared with the GE/PES membrane. The effects of PVA content in the support layer, crosslinking of GE active layer and operating parameters on the pervaporative dehydration performance were investigated. The operational stability of the composite membrane was tested by immersing the membrane in ethanol aqueous solution for a period of time. Stable pervaporation performance for dehydration of 90% ethanol solution was obtained for GE/PVA-PES membrane with a separation factor of -60 and a permeation flux of -1910 g.m^-2.h1 without peeling over 28 days immersion.
基金This work was supported by the National Natural Science Foundation of China （Grants Nos. 50802003, 20973013, 51072004, 50821061, and 20973006） and Ministry of Science and Technology of the people＇s Republic of China （Grants Nos. 2007CB936203, 2006CBP32602, and 2009CB929403）.
文摘Reduction of graphene oxide （GO） is a promising low-cost synthetic approach to bulk graphene, which offers an accessible route to transparent conducting films and flexible electronics. Unfortunately, the release of oxygen-containing functional groups inevitably leaves behind vacancies and topological defects on the reduced GO sheet, and its low electrical conductivity hinders the development of practical applications. Here, we present a strategy for real-time repair of the newborn vacancies with carbon radicals produced by thermal decomposition of a suitable precursor. The sheet conductivity of thus-obtained single-layer graphene was raised more than six-fold to 350-410 S/cm （whilst retaining 〉96% transparency）. X-ray photoelectron spectroscopy （XPS） and Raman spectroscopy revealed that the conductivity enhancement can be attributed to the formation of additional sp2-C structures. This method provides a simple and efficient process for obtaining highly conductive transparent graphene films.
