Xupin Zhuang

Solution blowing of submicron-scale cellulose fibers.

Solution blowing is an innovative process for spinning micro-/nano-fibers from polymer solutions using high-velocity gas flow as fiber forming driving force. Submicron-scale cellulose fibers were successfully solution blown by two improvement measures. First, cellulose solution was directly blown to fibers of 260-1900 nm in diameter by raising the air temperature along the spinning line which was proved to accelerate the evaporation of solvent and fiber forming. Second, coaxial solution blowing technique was established with cellulose solution and polyethylene oxide (PEO) solution used as core and shell liquids, respectively. The core-shell structures of the fibers were examined by SEM and TEM. Cellulose fibers with diameter between 160 nm and 960 nm were further obtained after removing PEO shell. X-ray diffraction studies showed that the two kinds of submicron-scale cellulose fibers are mostly amorphous.

Solution blowing of chitosan/PVA hydrogel nanofiber mats

Both nanofiber mats and hydrogel have their own advantages in wound healing. In this study, a novel hydrogel nanofiber mats were fabricated via solution blowing of chitosan and PVA solution, with various content of ethylene glycol diglycidyl ether (EGDE) as cross-linker. SEM observation showed that the fibers were several hundred nanometers in diameter with smooth surface and distributed randomly forming three-dimensional mats. The structure of the chitosan/PVA nanofibers was examined by FTIR and XPS, and the results showed that the cross-linking reaction occurred between EGDE and the hydroxyl groups. The mats could quickly hydrate in an aqueous environment to form hydrogel. Their value of equilibrate water absorption varied from 680 to 459% various content of EGDE. The nanofiber mats showed good bactericidal activity against Escherichia coli. The chitosan/PVA hydrogel nanofiber mats showed the combination advantages of nanofibrous mats and hydrogel dressing, and were suggested as potential application in wound healing.

Solution blown sulfonated poly(ether ether ketone) nanofiber–Nafion composite membranes for proton exchange membrane fuel cells

In this study, a new type of modified Nafion membrane containing sulfonated poly(ether ether ketone) (SPEEK) nanofibers was fabricated for proton exchange membrane fuel cells. The solution blowing method was used for fabrication of SPEEK nanofibers, which were impregnated into Nafion solution to form pore-filled composite membranes with different contents of SPEEK nanofibers. The performance of the composite membranes as proton exchange membranes was investigated and compared with Nafion 117. The results showed that the introduction of SPEEK nanofibers into the Nafion matrix significantly improved its thermal stability, proton conductivity, swelling rate and selectivity. The maximum value of the proton conductivity of 0.09 S cm−1 was obtained when the nanofiber content was 10 wt% at 20 °C and 100% RH, higher than that for Nafion 117 (0.083 S cm−1). It is indicated that solution blown nanofibers are a kind of promising filler material for enhancing the performance of Nafion membranes, and the composite membrane containing SPEEK nanofibers can be considered as a novel proton exchange membrane for fuel cell applications.

Solution blowing of ZnO nanoflake-encapsulated carbon nanofibers as electrodes for supercapacitors

A facile spinning-based strategy is developed to fabricate zinc oxide nanoflake-encapsulated carbon nanofibers (ZnO/CNFs) as electrodes for supercapacitors. The zinc oxide/carbon nanofiber mats were solution blown with zinc acetate (Zn(Ac)2) and polyacrylonitrile (PAN) as the metal and carbon precursor to get Zn(Ac)2 core-enriched precursor nanofibers. After annealing under nitrogen, the precursor nanofibers were converted to ZnO/CNFs with ZnO nanoflakes encapsulated in the core of carbon nanofibers. In the constructed architecture, carbon nanofibers can avoid the direct exposure of ZnO to the electrolyte and preserve the structural and interfacial stabilization of ZnO nanoflakes. Meanwhile, the flexible entangled carbon nanofibers can accommodate temperate porosities thus providing the pore channel for electrolyte ions and maintain the structural and electrical integrity of the ZnO/CNF electrode during the charge–discharge processes. By loading different contents of ZnO, the microstructures of CNFs were changed, and the textural parameters significantly affected their electrochemical properties as electrodes. As a result, the ZnO/CNF electrodes exhibit high specific capacitance (216.3, 212.7, 208.8 and 172.5 F g−1 at 1, 5, 10, and 50 A g−1, respectively) and extremely excellent cycling performance at high current density (only 5.41% capacitance loss after 2000 cycles at a high rate of 10 A g−1), with promising energy densities of 29.76 kW h kg−1, over a power density range of 2.5–30 kW kg−1. The ZnO/CNFs simultaneously exhibit excellent capacity retention. These encouraging results indicate great potential applications of ZnO/CNFs in developing energy storage devices with high energy and power densities.

Solution blowing nylon 6 nanofiber mats for air filtration

Solution blowing process is a new nanofiber fabricating method with high productivity. In the present study, nylon 6 nanofiber mats were solution blown and the effects of spinning conditions on nanofibers morphology were investigated. The fiber diameter ranged from 150 to 750 nm which was affected by solution concentration, gas pressure and solution feeding rate. The solution blown fibers were three-dimensional curly which made loose construction in bulk. The filtration performance of solution blown mats was evaluated. The tested solution blown nanofiber mats showed high filtration efficiency of 83.10 % to 93.45 % for 0.3 µm particles filtration and extremely low pressure drop of 15.37 to 30.35 Pa. The results indicate the solution blown nanofiber mats will find potential application of high efficiency and low resistance filter.

A new method for preparing alumina nanofibers by electrospinning technology

A new method for synthesizing alumina (Al2O3) nanofibers through the electrospinning method was reported. The spinning solutions of anhydrous aluminium chloride/polyvinylpyrrolidone (AlCl3/PVP), wh...A new method for synthesizing alumina (Al2O3) nanofibers through the electrospinning method was reported. The spinning solutions of anhydrous aluminium chloride/polyvinylpyrrolidone (AlCl3/PVP), which were prepared by the sol-gel process of the mixture of AlCl3, PVP, ethanol and redistilled water, were electrospun to form AlCl3/PVP organic-inorganic hybrid fibers. Alumina nanofibers with average diameters of 100—800 nm were obtained by calcinations of the as-prepared fibers. The fibers were characterized by SEM, TG-DTA, FTIR, XPS and XRD. The results showed that with the increase of the concentration of spinning solution, the diameter of fibers also increased, and that the diameter of fibers decreased with the increase of the applied voltage and calcination temperature. The uncrystalline Al2O3, γ-Al 2O3 and α-Al2O3 were obtained after calcinations of about 5 h at 450, 900 and 1100°C, respectively.

Solution blowing of activated carbon nanofibers for phenol adsorption

An activated carbon nanofiber (ACNF) with high surface area and excellent phenol adsorption capacity has been successfully fabricated by solution blowing of polyacrylonitrile (PAN) into precursor nanofiber which was subsequently activated to ACNF via KOH activation process. The effects of impregnation ratio and activation temperature on the texture properties of ACNF were discussed. The texture properties were characterized by N2 adsorption–desorption isotherm. ACNF showed high value of special surface area and pore volume (2921.263 m2 g−1 and 2.714 cm3 g−1, respectively). The ACNF samples were used for phenol adsorption from aqueous solutions. Adsorption isotherms at 38 °C were fitted with Langmuir and Freundlich models. The relationship between texture properties and phenol adsorption behavior was investigated. As a result, ACNF sample with large surface area, high micropore volume and pore size close and above to 0.43 nm showed the maximum phenol adsorption capacity of 251.6 mg g−1.

Solution blowing of chitosan/PLA/PEG hydrogel nanofibers for wound dressing

In this study, a kind of hydrogel nanofibers were successfully fabricated via solution blowing of chitosan (CS) and polylactic acid (PLA) solutions mixed with various contents of polyethylene glycol (PEG) to offer hydration. The nanofibers with PEG content varying were average 341-376 nm in diameter with smooth surface and distributed randomly forming three-dimension (3D) mats. Glutaraldehyde (GA) vapor was then applied to impart stability, and the cross-linking reaction mainly occurred between GA and hydroxyl groups which was confirmed by XPS. The hydrogel nanofibers showed quick absorption behavior, high equilibrate water absorption and good air permeability which could help the mats absorbing excess exudates, creating a moist wound healing environment and oxygen exchanging in wound healing. The mats also exhibited good antibacterial activities against E. coil. The combination advantages of nanofibers mats and hydrogel will help it find promising application in wound healing.

Solution-blown core–shell hydrogel nanofibers for bovine serum albumin affinity adsorption

In this work, nylon 6 core–chitosan/poly(vinyl alcohol) (PVA) shell hydrogel nanofibers (NCNFs) were fabricated by coaxial solution blowing. The hydrogel fibers were 80–650 nm in diameter with smooth surfaces. These fibers were distributed randomly and formed three-dimensional mats. Cibacron Blue F3GA (CB) was then immobilized onto the membrane surfaces for subsequent protein affinity adsorption. The amount of PVA in the shell greatly influenced CB content and bovine serum albumin (BSA) adsorption. The highest BSA adsorption capacity achieved by the NCNF membranes with immobilized CB was 379.43 mg g−1. The results showed that NCNFs combine the large capacity of hydrogels and the high flux of nanofibrous mats for affinity adsorption.

Coaxial solution blown core-shell structure nanofibers for drug delivery

Abstract