Structure-tunable Janus fibers fabricated using spinnerets with varying port angles

Abstract

aThe preparation of Janus fibers using a new side-by-side electrospinning process is reported. By manipulating the angle between the two ports of the spinneret emitting the working fluids, Janus nanofibers with tunable structures in terms of width, interfacial area and also volume of each side can be easily fabricated.Among the different ''top-down'' processes for nanofabrication, electrohydrodynamic atomization processes (EHDA, including electrospinning, electrospraying and e-jetting printing) have the unique capability of simultaneous modulation of sizes, shapes and compartmentalization of their nanoproducts.1,2 This ability has been broadly exploited for the generation of core-shell nanostructures, both in the form of electrospun fibers, nanotubes 3-5 and electrosprayed particles or bubbles. [6][7][8] Most recently, even complex structures such as tri-axial nanofibers have also been investigated using multi-fluid electrospinning processes. [9][10][11][12] In sharp contrast, there are still very limited studies about the generation of sideby-side structures using these EHDA processes. [13][14][15][16][17][18][19][20][21] To create structures with double compartments, two types of relationships between components are feasible, one is the exterior and interior (i.e. a core-shell structure), and the other is side-by-side. The latter, being a heterojunction structure, can have an advantage for designing novel functional nanomaterials over the core-shell structures because it provides an opportunity for both components to interact with their surroundings. 22,23Side-by-side electrospinning involves a complex interplay between fluid dynamics, electrodynamics and rheology, and presents a challenge in controlling the movement in unison of two fluids in a side-by-side manner under an electrical field from spinneret to collector. To our knowledge, Gupta and Wilkes were the first to report the preparation of side-by-side polymer nanofibers, made of poly(vinyl chloride)/segmented polyurethane and poly(vinyl chloride)-poly(vinylidiene fluoride) using a spinneret consisting of two parallel Teflon capillaries.13 Lin et al. reported the preparation of self-crimping side-by-side nanofibers that spontaneously formed curled helical fibers, composed of polyacrylonitrile and polyurethane, using a homemade silicone microfluidic spinneret, which consisted of three capillary channels with two of them combined in another channel in parallel to form the side-by-side outlet. 14 Later, several publications describe the preparation of side-by-side nanofibers using spinnerets made from two syringes whose needle tips were confined in a side-byside geometry. [15][16][17][18] In all these studies it was possible to control the outlet of the double fluids in a parallel manner for successful preparation of Janus nanofibers. Using a different approach, we report here side-by-side electrospinning in which a series of spinnerets with varying port angles were exploited to create structure-tunable Janus fibers. Our initial purpose was to prepare high...

Electrospun pH-sensitive core–shell polymer nanocomposites fabricated using a tri-axial process

“…To this end, core-shell 74 nanostructures have been very widely studied in the production of functional 75 nanomaterials, including those for biomedical applications [4][5][6]. [19][20][21][22].…”

From Traditional Spinning to Advanced Electrospinning—Material Engineering Teaching in High School

“…5, where the above layer is electrospun polyacrylonitrile (PAN) nanofibers, having a diameter of 0.64 µm by estimation, and the bottom layer is wet spun PAN fibers, having a diameter of 67 µm. [5,[17][18][19][20].…”

Nanosized sustained-release drug depots fabricated using modified tri-axial electrospinning

“…This has mainly been investigated in the context of monolithic fibers with one or two functional ingredients/nanoparticles distributed homogeneously in the filament-forming polymer matrix [19][20][21][22]. The second is the creation of more complex nanostructures (such as core-shell and Janus systems, and combinations thereof) in order to yield materials with improved functional performance [23][24][25][26]. In the biomedical field, if a drug reservoir could be formed as the core of electrospun core-shell fibers, then new fiber-based nanoscale drug depots could be created, such as an electrospun suture [27].…”