Properties and functions of materials assembled from nanofibrils critically depend on alignment. A material with aligned nanofibrils is typically stiffer compared with a material with a less anisotropic orientation distribution. In this work, we investigate nanofibril alignment during flow focusing, a flow case used for spinning of filaments from nanofibril dispersions. In particular, we combine experimental measurements and simulations of the flow and fibril alignment to demonstrate how a numerical model can be used to investigate how the flow geometry affects and can be used to tailor the nanofibril alignment and filament shape. The confluence angle between sheath flow and core flow, the aspect ratio of the channel and the contractions in the sheath and/or core flow channels are varied. Successful spinning of stiff filaments requires: (i) detachment of the core flow from the top and bottom channel walls and (ii) a high and homogeneous fibril alignment. Somewhat expected, the results show that the confluence angle has a relatively small effect on alignment compared with contractions. Contractions in the sheath flow channels are seen to be beneficial for detachment, and contractions in the core flow channel are found to be an efficient way to increase and homogenise the degree of alignment.

Graphene-based flexible and wearable supercapacitors have been produced by wetspinning, in which organic solvent coagulating bath was prerequisite and spacerswere usually incorporated to improve the electrochemical property butsacrificing the mechanical property. In this work, a nonorganic solvent spinningtechnology named as interfacial polyelectrolyte complexation (IPC), which wasbased on the spontaneous self-assembly of two oppositely charged polyelectrolytesolutions/suspensions to form continuous fibers on drawing in their interfaces,was proposed to fabricate graphene fiber–shaped electrodes forsupercapacitors. Due to the excellent mechanical performance and hydrophilicity,cellulose nanofibrils (CNFs) were added to serve as an efficient reinforcingagent and spacer of graphene fiber electrodes. Consequently, the mechanicalperformance and specific capacitance of the fibers were improved but electricalconductivity was declined. Taking overall consideration, CNF/rGO60 fiberelectrode possessed a superior integrated performance with a capacitance of182.6 F/g, tensile strength of 480 MPa, and electrical conductivity of 5538.7S/m. The IPC spinning provided an environmentally friendly strategy for thefabrication of fiber-shaped functional devices.