Development of Sustainable Hydrophilic Azadirachta indica Loaded PVA Nanomembranes for Cosmetic Facemask Applications

Nanofiber-based facial masks have attracted the attention of modern cosmetic applications due to their controlled drug release, biocompatibility, and better efficiency. In this work, Azadirachta indica extract (AI) incorporated electrospun polyvinyl alcohol (PVA) nanofiber membrane was prepared to obtain a sustainable and hydrophilic facial mask. The electrospun AI incorporated PVA nanofiber membranes were characterized by scanning electron microscope, Ultraviolet-visible spectroscopy (UV-Vis) drug release, water absorption analysis, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, and antibacterial activity (qualitative and quantitative) at different PVA and AI concentrations. The optimized nanofiber of 376 ± 75 nm diameter was obtained at 8 wt/wt% PVA concentration and 100% AI extract. The AI nanoparticles of size range 50~250 nm in the extract were examined through a zeta sizer. The water absorption rate of ~660% and 17.24° water contact angle shows good hydrophilic nature and water absorbency of the nanofiber membrane. The UV-Vis also analyzed fast drug release of >70% in 5 min. The prepared membrane also exhibits 99.9% antibacterial activity against Staphylococcus aureus and has 79% antioxidant activity. Moreover, the membrane also had good mechanical properties (tensile strength 1.67 N, elongation 48%) and breathability (air permeability 15.24 mm/s). AI-incorporated nanofiber membrane can effectively be used for facial mask application.

Nonwoven/Nanomembrane Composite Functional Sweat Pads

Sweat is a natural body excretion produced by skin glands, and the body cools itself by releasing salty sweat. Wetness in the underarms and feet for long durations causes itchiness and an unpleasant smell. Skin-friendly reusable sweat pads could be used to absorb sweat. Transportation of moisture and functionality is the current challenge that many researchers are working on. This study aims to develop a functional and breathable sweat pad with antimicrobial and quick drying performance. Three layered functional sweat pads (FSP) are prepared in which the inner layer is made of an optimized needle-punched coolmax/polypropylene nonwoven blend. This layer is then dipped in antimicrobial ZnO solution (2, 4, and 6 wt.%), and super absorbent polymer (SAP) is embedded, and this is called a functional nonwoven (FNW1) sheet. Electrospun nanofiber-based nanomembranes of polyamide-6 are optimized for bead-free fibers. They are used as a middle layer to enhance the pad's functionality, and the third layer is again made of needle-punched optimized coolmax/polypropylene nonwoven sheets. A simple nonwoven-based sweat pad (SSP) is also prepared for comparison purposes. Nonwoven sheets are optimized based on better comfort properties, including air/water vapor permeability and moisture management (MMT). Nonwoven webs having a higher proportion of coolmax show better air permeability and moisture transfer from the inner to the outer layer. Antimicrobial activity of the functional nonwoven layer showed 8 mm of bacterial growth, but SSP and FSP showed only 6 mm of growth against Staphylococcus aureus. FSP showed superior comfort and antibacterial properties. This study could be a footstone toward highly functional sweat pads with remarkable comfort properties.

Electrospun Nanofiber/Textile Supported Composite Membranes with Improved Mechanical Performance for Biomedical Applications

Textile-supported nanocomposite as a scaffold has been extensively used in the medical field, mainly to give support to weak or harmed tissues. However, there are some challenges in fabricating the nanofiber/textile composite, i.e., suitable porous structure with defined pore size, less skin contact area, biocompatibility, and availability of degradable materials. Herein, polyamide-6 (PA) nanofibers were synthesized using needleless electrospinning with the toothed wheel as a spinneret. The electrospinning process was optimized using different process and solution parameters. In the next phase, optimized PA nanofiber membranes of optimum fiber diameter with uniform distribution and thickness were used in making nanofiber membrane-textile composite. Different textile fabrics (woven, non-woven, knitted) were developed. The optimized nanofiber membranes were combined with non-woven, woven, and knitted fabrics to make fabric-supported nanocomposite. The nanofiber/fabric composites were compared with available market woven and knitted meshes for mechanical properties, morphology, structure, and chemical interaction analysis. It was found that the tear strength of the nanofiber/woven composite was three times higher than market woven mesh, and the nanofiber/knitted composite was 2.5 times higher than market knitted mesh. The developed composite structures with woven and knitted fabric exhibited improved bursting strength (613.1 and 751.1 Kpa), tensile strength (195.76 and 227.85 N), and puncture resistance (68.76 and 57.47 N), respectively, than market available meshes. All these properties showed that PA nanofibers/textile structures could be utilized as a composite with multifunctional properties.

Novel Dispersion of 1D Nanofiber Fillers for Fast Ion-Conducting Nanocomposite Polymer Blend Quasi-Solid Electrolytes for Dye-Sensitized Solar Cells

Electrospun nanocomposite polymer blend poly(vinylidene difluoride-co-hexafluoropropylene) (PVDF-HFP)/poly(methyl methacrylate) (PMMA) membranes with a novel dispersion of x wt % of one-dimensional (1D) TiO₂ nanofiber fillers (x = 0.0-0.8 in steps of 0.2) were developed using the electrospinning technique. The developed nanocomposite polymer membranes were activated using various redox agents such as LiI, NaI, KI, and tetrabutyl ammonium iodide (TBAI). Introduction of the 1D TiO₂ nanofiber fillers improves the amorphous nature of the blended polymer membrane, as confirmed through X-ray diffraction (XRD) and Fourier transform infrared (FTIR), and yielded an electrolyte uptake of over 480% for a 6 wt % TiO₂ nanofiber filler-dispersed sample. PVDF-HFP/PMMA-1D 6 wt % TiO₂ nanofiber fillers with the LiI-based redox electrolyte provided a high conductivity of 2.80 × 10^-2 S cm^-1 and a power conversion efficiency (PCE) of 8.08% to their fabricated dye-sensitized solar cells (DSSCs). The observed better ionic conductivity and efficiency of the fabricated DSSCs could be due to the faster movement of the smaller-ionic-radius (Li) ions entrapped inside the amorphous polymer. This enhanced mobility of ions in the quasi-solid electrolyte leads to faster regeneration of the depleting electrons in the photoanode, resulting in improved efficiency. Further, the achieved high conductivity was analyzed in terms of the dynamics and relaxation mechanisms involved by the ionic charge carriers with complex impedance spectroscopy using a random barrier model and Havriliak-Negami formulation. It was observed that the high-conducting PVDF-HFP/PMMA-1D 6 wt % TiO₂ nanofiber fillers with LiI-based redox electrolyte show better ac conductivity parameters such as a σ of 5.82 × 10^-2 S cm^-1, ω_e (12685 rad s^-1), τ_e (0.909 × 10^-4 s), and n (0.578). Also, dielectric studies revealed that the high-conducting sample has a higher dielectric constant and subsequently high loss. The J-V characteristics were studied using the equivalent circuit of a single-diode model, and the parameters influencing the photovoltaic performance were determined by Symbiotic Organisms Search (SOS) algorithm. The results suggest that the high-efficient sample possesses a minimum series resistance of 1.33 Ω and a maximum shunt resistance of 997 Ω. Hence, the highest-conducting electrospun-blended polymeric nanocomposite (PVDF-HFP-PMMA-6 wt % TiO₂ nanofiber fillers) with LiI-based redox agent and tert-butyl pyridine (TBP) additive as the polymer quasi-solid electrolyte nanofibrous membrane can be a better electrolyte for high-performance dye-sensitized solar cell applications.

Preparation and Characterization of Novel Polymer-Based Gel Electrolyte for Dye-Sensitized Solar Cells Based on poly(vinylidene fluoride-co-hexafluoropropylene) and poly(acrylonitrile-co-butadiene) or poly(dimethylsiloxane) bis(3-aminopropyl) Copolymers

Polymer gel electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and poly(acrylonitrile-co-butadiene) (PAB) or poly(dimethylsiloxane) bis(3-aminopropyl)-terminated (PDES-bAP) copolymers were prepared and investigated in dye-sensitized solar cells (DSSCs). Selected optical and electrochemical properties of all compositions with various ratio from 9:1 to 6:4 were investigated towards DSSC applications. The highest value of power conversion efficiency equal to 5.07% was found for DSSCs containing a PVDF-HPF:PAB (9:1) gel electrolyte. Compositions of electrolytes were additionally tested by electrochemical impedance spectroscopy. The influence of the ratio and type of polymers used as an additive to PVDF-HPF on absorption wavelengths, energy gap, and Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) levels were investigated. Individual components of DSSCs, such as the TiO₂ layer and platinum nanoparticles, were imaged by scanning electron microscope. Finally, a DSSC module with six electrically separated solar cells with a 7 × 80 mm² active area was constructed based on gel electrolytes and tested.

Specific Ion Effects in Polyampholyte Hydrogels Dialyzed in Aqueous Electrolytic Solutions

Polyampholyte hydrogels (PAHs) constitute a class of physical gels with cross-linking originating from inter- and intrachain ionic cross-linking between countercharged functional groups. In our previous report, we have shown that PAH has the potential to be a gel electrolyte in electrochemical energy storage devices. In this work, we further our understanding of charge-balanced PAH as a host material for gel electrolytes by studying the effect of dialysis on the mechanical properties and ionic conductivities of PAHs, whereas these properties are compared with those of poly(vinyl alcohol) (PVA)-based gel electrolytes. Here, various electrolyte solutions were investigated as dialyzing agents. The ionic species in the electrolytes form ion pairs with countercharged functional groups in PAH, whereas such interactions govern the ionic conductivity and mechanical strength of PAH in various electrolytes. For anions, the trend in ionic interactions follows the Hofmeister series in an exact manner, whereas some anomaly is observed among cations. We anticipate that our study provides a design criterion for fabricating gel electrolytes. In a broader context, this work can shed light on understanding the behavior of PAHs in various operational environments, such as under physiological conditions and in antifouling coatings for biomedical and maritime applications, respectively.