Block microfibrils prepared by quasi-steady state electrospinning and their chromosome-like structures

• Block microfibrils were processed for the first time.
• Block microfibrils showed chromosome-like structures upon dispersion in a medium.
• Preparation of anisometric microfibrils used quasi-steady state electrospinning.

Materials science research has focused primarily on isometric structures rather than anisometric structures. This is typically driven by the associated levels of processing complexity rather than importance. Pulsating instability is not recognized as a useful phenomenon in electrospinning, while it has been systematically examined in electrospraying. We prepared anisometric block microfibrils for the first time by using pulsating instability of electrospinning. A low frequency pulsating mode which represents a quasi-steady state was achieved using systems consisting of multiple inner nozzles in conjunction with an outer nozzle. A fully-electrospinnable viscous sheath solution confines the pulsating inner flows, generating uniform fibers of separate core blocks. The blocks inside a sheath can be extracted by selective dissolution, and the resulting diblock or triblock microfibrils have amphiphilic surface activity and are self-assembled into chromosome-like structures. Flow rate and solution conductivity were able to control block length, which was explained by the low frequency pulsating mechanism and the driving fluid concept of electrohydrodynamic jetting. This pulsating mode processing of block microfibrils has the potential to open up a new area of anisometric fibers for emerging applications.

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