Separators electrospinning process

Filato V, Y., A. Budyka, V. Kirichenko, Electrospinning of micro-and nanofibers fundamentals in separation andfiltration processes. 2007, Begell House Inc., Redding, CT. 

DuPont has announced that they will produce hthium-ion battery separators using their Hybrid Membrane Technology (HMT), which is based on a nontraditional electrospinning process. Currently a nano-fiber mat is available based on nylon. Products for lithium-ion batteries are yet to be aimounced. 

There are a number of processing techniques to fabricate nanofibers, which include electrospinning, drawing, template synthesis, phase separation, interfacial polymerization, self-assembly, and so on [39,40]. Among these, electrospinning process is a very effective method to make porous hydrophobic membranes. 

There are several techniques that allow to produce polymeric nanofibers, such as drawing, template synthesis, phase separation, self-assembly, solution blow spinning, and electrospinning. The drawing process requires a polymer with appropriate viscoelastic properties that is able to be deformed and kept connected by cohesive forces. Besides being simple and inexpensive, this technique is very limited for conjugate polymers, since most of them have lower solubility and form solutions with a small viscous modulus. 

Electrospinning [29] is a facUe method to make almost any polymer into nano- and micro-fibers if the polymer can be solution-processed or melt-processed (Figure 7.4). However, due to the low solubility of polyaniline, it is very difficult to make polyaniline fibers thinner than 100 nm. To solve this problem, polyaniline is usually blended with a more soluble polymer to increase the weight percentage of polymer in solution. As a result, the obtained nanofibers are a polymer blend [29—33] this significantly reduces the conductivity of the polymer. Additionally, when the size of the fiber decreases, phase separation may occur, yielding a mixture of nanofibers of polyaniline and other polymers [33]. 

Chromatography on polymer-based layers and their hyphenation to elution-based MS is only possible with nonsolvents of the polymer. Further ultrathin layer processing yielded calcined nanofibers produced by electrospinning of a solution of silica nanoparticles dispersed in polyvinylpyrrolidone followed by heating for calcination and selective removal of the polymer [21]. The application range was further expanded by producing PAN layers equipped with an incorporated photoluminescence indicator and used for the separation of preservatives. This was also the first application of this kind of UTLC layer hyphenated with ESI-MS [1]. 

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