The rheological, mechanical and templating effects of graphene oxide nanosheets in filled gel spun polyacrylonitrile

Rapid In Situ Polymerization of Polyacrylonitrile/Graphene Oxide Nanocomposites as Precursors for High-Strength Carbon Nanofibers

“…As the amount of GO increases, the color of polymer products changes from white to gray, directly indicating that GO has been successfully introduced into polymers and dispersed evenly. At present, most researchers use mechanical mixing to introduce GO into PAN polymers. ,,, However, the entanglement of molecular chains makes it difficult for GO nanosheets to disperse uniformly. Meanwhile, high concentration of GO will cause agglomeration. ,, The in situ polymerization of AN between GO nanosheets can greatly improve the mixing efficiency.…”

“…A slightly higher amount of graphene nanosheets will lead to agglomeration, which finally evolves into defects and weakens the performance of nanofibers. , Subsequently, some researchers take graphene oxide (GO) as the alternative of graphene to reinforce PAN-based nanofibers. − In these cases, GO can promote the formation and orientation of turbostratic domains in CNFs such as graphene, and the chemical structure of GO which consists of hydrophobic and hydrophilic components is beneficial for the dissolution of graphitic materials . Besides, the functional groups of GO can initiate the cyclization reaction in the stabilization process via ionic mechanisms and improve the thermal stability by releasing oxygen groups, greatly contributing to the production of high-performance CNFs. , …”

“…Hence, many kinds of polymers have been mixed with additives via solvent mixing, such as nylon 6, polyvinyl alcohol, , poly­(ε-caprolactone), and polymethyl methacrylate . Similarly, in the existing research, the addition of GO in PAN-based CNFs is mainly carried out by mechanically mixing GO with the precursor PAN in solvents. − However, it cannot be ignored that the entanglement of molecular chains causes large molecules to move so slowly that it takes a long time for GO nanosheets to spread evenly among the PAN molecules, which restricts the improvement of production efficiency. ,, Moreover, many studies have prepared the spinning solution with the required concentration by evaporating the solvent after mixing PAN and GO . Despite the existence of some chemical structure that facilitates dispersion, GO can still attract each other via π–π interaction in the interminable solvent mixing and concentration progress .…”

“…18 Besides, the functional groups of GO can initiate the cyclization reaction in the stabilization process via ionic mechanisms and improve the thermal stability by releasing oxygen groups, greatly contributing to the production of high-performance CNFs. 19,20 The uniform dispersion of GO in the polymer matrix is the central part to prepare GO-doped polymer fibers. The commonly used mixing methods at present mainly include melt processing, solvent mixing, and in situ polymerization.…”

“…10,17,29 Moreover, many studies have prepared the spinning solution with the required concentration by evaporating the solvent after mixing PAN and GO. 20 Despite the existence of some chemical structure that facilitates dispersion, GO can still attract each other via π−π interaction in the interminable solvent mixing and concentration progress. 9 High concentration (>0.7 wt %) of GO tends to cause agglomeration, which extremely limits the roles of GO.…”