Electrospun membranes transport

Schreuder-Gibson et al used nylon-6,6 (N6,6), polybenzimidazole (FBI) and poly(tetrafluoroethylene) membranes produced from electrospun fibers as protective layers. They measured properties of these electrospun membranes, including structural effects upon moisture transport, air convection, aerosol filtration, porosity and tensile strength. 

PW. Gibson, HE. Schreuder-Gibson, D. Rivin. 2001. Transport properties of porous membranes based on electrospun nanofibers. Colloids and Surfaces A Physicochemical and Engineering Aspects, 187.pp.469 81. 

Gibson, R, Gibson, H. S., and Rivin, D. Transport Properties of Porous Membranes Based on Electrospun Nanofiber, Colloids andSutfaces A, 187-188,469-481 (2001). 

The transport properties of electrospun nylon 6 mats have also been investigated by scientists. It has been found that the concentration of the polymer solution affected the fibre diameter, pore size, Brunauer-Emmett-Teller surface area and gas transport properties of the mats. It was shown that the filtration efficiency of nylon 6 nanofilters is superior to that of a commericial high efficiency particulate air filter for 0.3 micrometre test particles. Researchers found that the pore size and pore size distribution of electrospun polylacticacid (PLA) membranes are strongly associated with fibre mass, fibre diameter and fibre length. 

As two important copolymers of PVDF, the P(VDF-HFP) [4] and P(VDF-CTFE) [23] had been developed for gel polymer electrolyte in LIBs. The introduction of copolymer components was to reduce the crystallinity of the PVDF chain. The reduction of crystallinity could increase the ionic conductivity. Electrospun P(VDF-HFP) and P(VDF-CTFE) fibrous membranes had been proved to show high ionic conductivities in the range of several mS cm which was attributed to the easy transportation of the liquid electrolyte through the fully interconnected pore structure of the membrane. For example, the electrospun P(VDF-HFP) fibrous membrane had high ionic conductivities in the range of 4.59 mS cm", high electrolyte uptake of 425 % at room temperature, and good electrochemical stability with a potential of over 4.5 V versus Li/Li+ [29]. 

To date, many kinds of CO2 separation membranes have been reported, including polymeric membranes, composite membranes, and facilitated transport membranes. Further improvements in membrane performance depend on effective CO2 separation materials, and one candidate is ILs. It has been reported that ILs have good CO2 selectivity, suggesting that they may be a possibility for the development of new CO2 separation materials. Since ILs are liquid at room temperature, it is necessary to affix ILs to appropriate support materials. Supported IL membranes have been prepared by impregnation of commercial porous polymer films with 1-n-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([hmim][Tf2N]) and have obtained good C02/He separation properties [40]. Recently, electrospun Nafion/polyethylene oxide (PEO)-supported IL membranes were fabricated for CO2 separation [41]. In this composite membrane, the electrospun Nafion/PEO material acted as a gutter layer for ILs and PEO was added to form clean nanofibrous... 

The porous structures in electrospun nanofibrous membranes could result in much less resistance to mass transport than structures developed by other membranes. This advantage has been transferred to other materials applications. 

Fig. 14.2 Comparison of SEM micrographs (a) mioroporous membrane, (b) layered fabric system with electrospun PU nanofiber web, and (c) spunbond nonwoven fabric, (d) SEM micrographs of electrospun PU nanofiber web. (e) Effects of area density of electrospun polyurethane web on air/moisture vapor transport properties of layered fabric systems, (f) Cross section of laminated nanofiber nonwoven web and (g) vapor permeability before/after wash (a-c Reprinted with permission from Lee and Obendorf [23]. Copyright 2007, The Korean Fiber Society, d, e Reprinted with permission from Lee and Obendorf [24]. Copyright 2007, SAGE Publications, f, g Reprinted with permission from Kimura et al. [25]. Copyright 2010, SAGE Publications)...

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