Preparation of Nanofiber Bundles via Electrospinning Immiscible Polymer Blend for Oil/Water Separation and Air Filtration.

Nanofiber bundles with specific areas bring a new opportunity for selective adsorption and oil/water or air separation. In this work, nanofiber bundles were prepared by the electrospinning of immiscible polystyrene (PS)/N-trifluoroacetylated polyamide 6 (PA6-TFAA) blends via the introduction of carbon nanotubes (CNTs) or a copolymer of styrene and 3-isopropenyl-α, α'-dimethylbenzene isocyanate (TMI), which was denoted as PS-co-TMI. Herein, CNT was used to increase the conductivity of the precursor for enhancing the stretch of PS droplets under the same electric field, and PS-co-TMI was used as a reactive compatibilizer to improve the compatibility of a PS/PA6-TFAA blend system for promoting the deformation. Those obtained nanofiber bundle membranes showed an increase in tensile strength and high hydrophobicity with a water contact angle of about 145.0 ± 0.5°. Owing to the special structure, the membranes also possessed a high oil adsorption capacity of 31.0 to 61.3 g/g for different oils. Moreover, it exhibits a high potential for gravity-driven oil/water separation. For example, those membranes had above 99% separation efficiency for silicon oil/water and paraffin wax/water. Furthermore, the air filtration efficiency of nanofiber bundle membranes could reach above 96%, which might be two to six times higher than the filtration efficiency of neat PS membranes.

PLLA/POSS Nanofibers Loaded with Multitargeted pANG Composite Nanoparticles for Promotion of Vascularization in Shear Flow.

In vitro prevascularization is particularly important for the clinical application of tissue engineering scaffolds that require vascularization. The principal challenge is simulating the dynamic in vivo environment to promote the continuous growth of blood vessels. In this study, two targeting polypeptides are linked to the two ends of an amphiphilic block copolymer, polyethyleneimine-b-poly(lactide-co-3(S)-methyl-morpholine-2,5-dione)-b-polyethyleneimine (PEI-PLMD-PEI), and self-assembled to form positively charged nanoparticles (NPs), which can bind to negatively charged pANG through electrostatic interactions; the polypeptides are finally loaded into PLLA/polyhedral oligomeric silsesquioxane (POSS) porous fibers to prepare untargeted nanofibers (unTFs), targeted porous nanofibers (TFBs), and targeted nanofiber bundles. The effects of the porous nanofibers on human umbilical vein endothelial cell (HUVEC) transfection, spreading, proliferation, morphology, and expression of related factors are investigated under the action of shear flow force. The results show that the PLLA/POSS nanofibers can maintain stable release of multitargeted NPs for nearly 45 days. Both the dual-targeted porous NPs and shear flow improve the pANG transfection efficiency and promote cell proliferation, and they have a good synergistic effect. These results provide a potential strategy for designing HUVEC-specific gene carriers and using shear flow to enhance endothelialization.

Statistical Optimization of the Sol-Gel Electrospinning Process Conditions for Preparation of Polyamide 6/66 Nanofiber Bundles.

Polymeric nanofibers are widely studied in the textile industry since with them, it is possible to get a great variety of functionalities. In this paper, polyamide 6/66 (PA 6/66) solutions at different concentrations (12, 17, and 22% wt.) were made, to get nanofibers through the basic electrospinning process which were characterized by scanning electron microscope (SEM) and productivity. Afterwards, nanofiber bundles were produced using the electrospinning sol-gel process, which were characterized by SEM and tensile test. From the results of statistical optimization based on one-way analysis of variance (ANOVA) with post hoc Tukey HSD, it was found that nanofiber bundles with higher productivity (1.39 ± 0.15 mg/min), draw ratio (9.0 ± 1.2), and tensile strength (29.64 ± 7.40 MPa) were obtained with a 17% concentration. Finally, a thermal characterization through differential scanning calorimetry (DSC) was done, finding evidence of a Tg and Tm reduction in the nanofibers in relation to PA 6/66 pellets and nanofiber bundles.