Porous microfibers by the electrospinning of amphiphilic graft copolymer solutions with multi-walled carbon nanotubes

Graft copolymers of polyacrylonitrile-graft-poly(dimethyl siloxane) (PAN-g-PDMS) were synthesized and the solution electrospinning of these materials from dimethylformamide (DMF) was investigated. The amphiphilic nature of the graft copolymers induced phase segregation and self-assembly of the molecules in the electrospinning solution to form a network-like structure. The self-assembly was shown to have a direct effect on the electrospinning parameters affecting the final fiber morphology. The amphiphilic nature of the molecules led to the formation of porous microfibers. Porous fibers are usually obtained via the selective removal of a polymer component in a co-electrospun solution of polymer blends, however, this works presents a novel and direct route for obtaining highly porous electrospun fibers. Multi-walled carbon nanotubes (MWCNT) were also successfully electrospun in the amphiphilic graft copolymer solutions. The inclusion of MWCNT's produces fibers with much smaller diameters, but the porous structure of the fibers is maintained. Excellent dispersion and alignment of the nanotubes along the electrospun fiber axis were obtained. It is shown how the porous electrospun fibers can be used as precursor materials for the production of porous carbon fibers. (C) 2012 Elsevier Ltd. All rights reserved.