Xianlin Xu

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 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.

Hierarchical fibrous microfiltration membrane by self-assembling DBS nanofibrils in solution-blown nanofibers.

A novel hierarchical nanofibrous membrane was demonstrated via in situ self-assembly of 1,3:2,4-dibenzylidene-d-sorbitol (DBS) supramolecular fibrils in solution-blown polyacrylonitrile (PAN) nanofibers. The formed DBS fibrils were interconnected into networks and anchored onto the PAN nanofibers, which decreased the pore sizes and enhanced the mechanical properties, the filtration efficiency, and particularly the flux.

Self-Assembly DBS Nanofibrils on Solution-Blown Nanofibers as Hierarchical Ion-Conducting Pathway for Direct Methanol Fuel Cells

In this work, we reported a novel proton exchange membrane (PEM) with an ion-conducting pathway. The hierarchical nanofiber structure was prepared via in situ self-assembling 1,3:2,4-dibenzylidene-d-sorbitol (DBS) supramolecular fibrils on solution-blown, sulfonated poly (ether sulfone) (SPES) nanofiber, after which the composite PEM was prepared by incorporating hierarchical nanofiber into the chitosan polymer matrix. Then, the effects of incorporating the hierarchical nanofiber structure on the thermal stability, water uptake, dimensional stability, proton conductivity, and methanol permeability of the composite membranes were investigated. The results show that incorporation of hierarchical nanofiber improves the water uptake, proton conductivity, and methanol permeability of the membranes. Furthermore, the composite membrane with 50% hierarchical nanofibers exhibited the highest proton conductivity of 0.115 S cm−1 (80 °C), which was 69.12% higher than the values of pure chitosan membrane. The self-assembly allows us to generate hierarchical nanofiber among the interfiber voids, and this structure can provide potential benefits for the preparation of high-performance PEMs.

Preparation and BSA Adsorption Behavior of Chitosan-arginine Based Nanofiber Membranes

In this work, an affinity nanofiber membrane was successfully prepared by solution blowing of arginine-modified chitosan (CS-Arg) for bovine serum albumin (BSA) adsorption. CS-Arg was firstly synthesized by coupling L-arginine onto chitosan backbone. Then, CS-Arg nanofiber membranes (CANFs) were fabricated using solution blowing process with Polylactide (PLA) as assistant polymer. The results showed that CANFs effectively adsorbed BSA, and the adsorption capacities were influenced by the degrees of substitution (DS) of arginine in CS, pH value, contact time, and initial protein concentration. The highest adsorption capacity of 445.19 mg/g was achieved uvnder the following conditions: DS of 43.7 %, pH of 7.14, and initial concentration of 3.0 mg/ml. BSA adsorbed on the CANFs membrane conformed to Langmuir model, and the adsorption rate was consistent with the second-order kinetics model. This work implies that an arginine-modified chitosan nanofiber-based novel biomaterial has a potential application in adsorption of BSA.

Solution Blowing of Polyacrylonitrile Nanofiber Mats Containing Fluoropolymer for Protective Applications

A new type of hydrophobic polyacrylonitrile (PAN) nanofiber is fabricated by solution blowing of a blend solution of fluorine-containing polyacrylate (FPA) and PAN. The nanofibers’ surface composition, hydrophobicity, and protection ability were evaluated to clarify the effects of FPA addition. Results revealed that FPA addition increased the nanofiber diameter, as well as enhanced the hydrophobicity and transport properties of the nanofiber mats. The mats had average water contact angles of 123.44°, 132.11°, and 137.11° for FPA contents of 0.66 wt%, 1.98 wt%, and 3.30 wt%, respectively. All these results suggested the potential of the solution blowing nanofiber mats as protection materials.

Cellulose nanofiber-embedded sulfonated poly (ether sulfone) membranes for proton exchange membrane fuel cells

Cellulose nanofibers were embedded into sulfonated poly (ether sulfone) matrix to heighten the water retention and proton conductivity of proton exchange membranes (PEMs). Cellulose nanofibers were obtained by hydrolyzing cellulose acetate nanofibers, which were prepared via electrostatic-induction-assisted solution blow spinning. Morphology, thermal stability, and mechanical properties of the PEMs were investigated. The results showed that proton conductivity, water uptake, and methanol permeability of the composite membranes were improved. Hydrophilicity of the composite membranes was gradually improved with the addition of nanofibers. When the content of nanofibers was 5 wt%, the highest proton conductivity was 0.13 S/cm (80 °C, 100% RH). Therefore, the cellulose nanofiber could be used as support materials to enhance the performance of proton exchange membranes, the composite membranes have potential application in Direct methanol fuel cells (DMFCs).

Development of amino acid-modified PET/PA6 segmented pie bicomponent spunbonded microfiber nonwoven for bilirubin affinity adsorption

A novel affinity membrane based on PET/PA6 segmented pie bicomponent spunbonded microfiber nonwoven (PET/PA6 SBSNW) was developed for bilirubin adsorption. PET/PA6 SBSNW was initially fabricated as microfiber nonwoven fabric, and was then ammoniated with ethylenediamine (ETDA). Finally, amino acids as affinity ligands were immobilized on the ammoniated PET/PA6 SBSNW. The amino acid-modified PET/PA6 SBSNW was applied to adsorb bilirubin, and the effects of pH, temperature, species of affinity ligands, and time were investigated. The results showed that amino acid-modified PET/PA6 SBSNW has decent adsorption performance, and adsorption capacity of PET/PA6 SBSNW-Lys peaked at 388.35 mg/g.