Self‐Crimping Bicomponent Nanofibers Electrospun from Polyacrylonitrile and Elastomeric Polyurethane

Abstract

tails of this procedure have been published previously [18]. An aqueous solution of PBDT has a LC nature above 2.8 wt.-% (C * LC ). DMA-PAA-Q (Kohjin Co. Ltd.) was used as the monomer without further purification. MBAA (Junsei Chemical Co. Ltd.) was recrystallized with ethanol and used as a crosslinker. Acrylamide (AAm) (Junsei Chemical Co. Ltd.) was recrystallized with chloroform and used as the neutral monomer. Potassium persulfate (KPS) (Wako Pure Chemical Industries Ltd.) was recrystallized with water and used as the initiator. Water was deionized and purified with 0.22 lm and 5 lm membrane filters before use. 2 wt.-% PBDT, 2 mol L -1 DMAPAA-Q (or AAm), 0.5, 1, or 2 mol-% (to DMAPAA-Q) MBAA, and 0.1 mol-% KPS were dissolved in water. These solutions were poured into reaction cells consisting of a pair of glass plates with a 2 mm spacing. Radical polymerization was performed at 60°C. After gelation, the products were immersed in a large amount of water and allowed to reach an equilibrium state for a week.Measurements: The swelling degree of the gels, Q, is defined here as the weight ratio of a swollen to a dried gel [23]. The dried gels were obtained by keeping them in a desiccator for 12 h and in a vacuum oven at 60°C for 6 h.Optical-microscopy observation was performed using a crossed polarizing microscope (Olympus, BH-2) at room temperature. Sample gels were placed on glass plates and the upper free surfaces were observed. Birefringence, Dn, was measured by a crossed polarizing microscope with a Berek compensator [20]. In the measurement, many microscopic domains randomly oriented in the bulk were observed. Thus, we chose one of large domains and selected the orientation direction by turning the sample under the crossed polarizing microscope. Under these conditions, Dn was measured from the retardation. Average Dn was determined by measuring Dn several times for each sample.

Nanofibers Fabricated Using Triaxial Electrospinning as Zero Order Drug Delivery Systems

“…19 The creation of core-sheath nanostructures using a concentric spinneret has been widely reported, but there is a deficit of knowledge regarding other more complex structure types. [20][21][22][23] There are very few investigations into side-by-side electrospinning to generate Janus nanofibers, [24][25][26][27][28][29] and even fewer reports on multiple-layer nanofibers. [30][31][32][33][34][35] The slow development of multiple-fluid electrospinning processes is related to their difficulty of implementation.…”

Microfluidic electrospinning of biphasic nanofibers with Janus morphology

“…Syringe pumps ͑11 Plus, Harvard Apparatus͒ are used to provide a constant flow source for the solutions. Unlike the single spinnerette microfluidic manifold of Lin et al, 19 in which colaminar flow was exploited to segregate the precursor solutions in the microchannel prior to electrospinning at the outlet, the polymeric solutions in our device combine only at the outlet, minimizing dispersion between the two fluids. Advantages of this approach include ease of fabrication, flexible control over channel dimensions and geometry, and the potential for multiplexed, multijet electrospinning within a single microfluidic device.…”

“…Advantages of this approach include ease of fabrication, flexible control over channel dimensions and geometry, and the potential for multiplexed, multijet electrospinning within a single microfluidic device. 19,25,27 The multilayer microfluidic electrospinning devices used in this study were molded from two-part ͑A:B͒ Sylgard 184 PDMS rubber ͑Dow Corning͒. Positive-relief photoresist molds, used as masters for the microchannel networks, were fabricated using standard lithographic procedures.…”

“…Liu et al reported on the fabrication of TiO 2 / SnO 2 nanofibers by electrospinning using two syringes for the source materials arranged in a side-by-side configuration, 20 while Gupta and Wilkes used a similar side-by-side set-up to electrospin bicomponent fibers of polyvinylchloride/polyurethane and polyvinylchloride/polyvinylidiene fluoride, 18 Recently, Lin et al reported side-by-side electrospinnning of self-crimping bicomponent nanofibers using a microfluidic source. 19 While the spinning nozzle in their report was a microfluidic device, it was fabricated using a negative template made out of stainless steel tubes glued to each other. The microfluidic source had single outlet for spinning, leading to single jet spinning of bicomponent nanofibers.…”

“…11 Several research groups have reported the synthesis of core-sheath bicomponent nanofibers using coaxial electrospinning. [12][13][14][15][16][17] Although there are a few reports on side-by-side spinning of bicomponent polymer nanofibers, [18][19][20] they are mainly restricted to either syringe, needle-based electrospinning or microfluidic single jet spinning. Liu et al reported on the fabrication of TiO 2 / SnO 2 nanofibers by electrospinning using two syringes for the source materials arranged in a side-by-side configuration, 20 while Gupta and Wilkes used a similar side-by-side set-up to electrospin bicomponent fibers of polyvinylchloride/polyurethane and polyvinylchloride/polyvinylidiene fluoride, 18 Recently, Lin et al reported side-by-side electrospinnning of self-crimping bicomponent nanofibers using a microfluidic source.…”