Abstract
The electrospinning of high-performance polyimides (PI) has recently sparked great interest. In this study, we explore the effect of the electrospinning parameters — namely polymer concentration, voltage, tip-to-collector distance and flow rate — and salt addition on the diameter, morphology, and spinnability of electrospun PI nanofibers. Three different polyimides of intrinsic microporosity (PIM-PIs) with high Brunauer–Emmett–Teller (BET) ranging from 270 to 506 m2 g−1, and two microporous polyimides, were synthesized through the polycondensation of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and aromatic diamines. The addition of tetraethylammonium bromide (TEAB) salt considerably increased the conductivity of all the PI solutions, significantly improved spinability, and resulted in thinner fibers. We also used molecular dynamic simulations to investigate the macromolecular mechanism of improved spinnability and fiber morphology in the presence of an ammonium salt. The small droplets detached from the parent droplet, followed by the rapid evaporation of the ions through the hydration effect, which facilitated the electrospinning. The resulting uniform nanofibers have great potential in environmental applications due to the presence of microporosity and hydrophobic pendant trifluoromethyl groups, which enhance the sorption performance of the fibers for hydrophobic species.
Highlights
Electrospinning is a method for generating fibers through the formation of a jet from a charged polymer or non-polymeric system under an electrical field [1]
The chemical structures of the polyimides were confirmed by 1H nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR)
SEM images of the respective fibers are shown in Fig. 13 We found that the effect of tetraethylammonium bromide (TEAB) on the morphology of the structures obtained by electrospinning/electrospraying was negligible compared to other polymers
Summary
Electrospinning is a method for generating fibers through the formation of a jet from a charged polymer or non-polymeric system under an electrical field [1]. Polyimides of intrinsic microporosity (PIM-PIs) are porous polyimides with Brunauer–Emmett–Teller (BET) surface area exceeds 200 m2 g−1 and contain pores with pore size below 2 nm [5, 6] are highperformance polymers that are synthesized by a conventional cycloimidization reaction between dianhydrides and diamines (Fig. 1) [7]. In this regard, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) has been widely used as a building block for the synthesis of PIM-PIs since it allows producing solution-processable polymers [8]. Molecular dynamics (MD) simulations were performed to elucidate the impact of salt addition on the spinnability of the polymer solutions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
