The electro-spinnability of poly(vinylidne fluoride) (PVDF) solutions vary based on the characteristics of the blended additives and solutions. In this study, we prepared PVDF-based polymer blends comprising of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), thermoplastic polyurethane (TPU), and carbon black nanoparticles. The electro-spinnability of PVDF nanofibers at different polymer concentrations was analyzed using the storage to loss moduli ratio known as the Cole-Cole plot. In addition, the van Gurp-Palmen plot, comprising of the complex modulus and phase angle, was used to describe the polymer network behavior in the PVDF solutions.

This study aims to determine a conductive fabric suitable for wearable smart devices. The effect of the introduction of conductive particles on the fabric characteristics based on yarn thickness was compared and analyzed. The surface structure of cotton fabrics made of 20 s, 30 s, and 40 s, was observed under a microscope at 400x magnification, and their contact angles were measured. To provide conductivity, the fabric was dipcoated with water-dispersed SWCNTs, and its average line and sheet resistance were measured. The ratio of the apparent area occupied by the yarn increased as the yarn became thinner, and the contact angle were largest and smallest for Fabrics B and C, respectively. Accordingly, the surface properties were confirmed to be determined not only by the component and thickness of the yarn, but also by the microstructure and energy of the fabric surface and the size and spacing of irregularities. Upon measuring the resistance, Fabrics B and A were confirmed to have the highest and lowest resistance, respectively. Therefore, we propose a method of fabric selection by conducting such experiments before conductive fabric manufacturing.

Lyocell fiber, with its elasticity and excellent touch, is ideal for use in clothing and sanitary products. Additionally, unlike viscose rayon, solvent recovery and carbon neutrality is possible, making it environmentally friendly. Research to activate lint on the surface of the fibers by chemically treating lyocell long fiber nonwoven fabric has been underway. As a chemical treatment method, after immersing the lyocell long fiber nonwoven fabric in an alkali solution, the degree of lint generation on the surface of the long fiber nonwoven fabric was analyzed, and its chemical and physical properties were analyzed upon alkali treatment. A 3D model was generated using the physical properties of the chemically treated lyocell nonwoven fabric, and a filtration performance simulation study was conducted subsequently. Alkali treatment activated the lint on the surface of the fabric with the NaOH-treated specimen producing the most lint. Further, simulation results showed that the pressure loss value was the lowest as the specific surface area of the specimen treated with NaOH was the largest. It's value also reduced by more than 23.2% compared to the specimen without chemical treatment.

Ambulatory and real-time electrocardiography (ECG) enable the modified monitoring of cardiovascular diseases and more precise patient condition diagnosis. Although the Holter monitor is widely used to record cardiograms due to its wireless nature, an ideal ECG monitoring system must be lightweight, soft, and accessibility without discomfort. Therefore, smart electronic clothing including conductive electrodes and circuits is an ideal platform to monitor ECG for addressing the suggested requirements. Accordingly, in this study, we have developed an ECG monitoring system on conventional textiles via screen printing, which is ideal for readily fabricating the desired conductive patterns onto the fabric. An affordable silver paste was used to prepare an electronic surface on the fabric, and this fabric was integrated into daily clothing for accessibility. We demonstrated that the screen-printed Ag paste showed lower electrical resistance than conventional circuits. Furthermore, the printed circuits exhibited electrical stretchability when elongated completely. Additionally, the electrical properties of the circuits displayed little difference with 500x stretching deformation, which restored completely after 24 h. The washing durability results showed that the screen-printed circuits were reusable, implying affordable and sustainable technologies. Lastly, the ECG monitoring performance of the smart textile prototype (Ag paste printed fabric integrated daily clothing) was compared with that of traditional wet-type Ag/AgCl electrodes. The result demonstrated that the smart textile prototype could record higher quality ECG signals than the conventional electrode. Consequently, this study opens the possibility of comfortable, affordable, and wearable physiologic signal monitoring system.

This study fabricated a sulfur blue dye/graphite composite (SBLG) as an anode to enhance the electrochemical performance of lithium-ion batteries. Nitrogen and sulfur atoms from a sulfur dye were doped into a carbon microstructure via facile high-energy ball milling. The anode materials with a 5:5 (SBLG50) sulfur dye/graphite composite ratio generated a specific capacity of 801.2 mAh g^-1 after 100 cycles with Coulombic efficiency of over 99%. The enhanced electrochemical performance of SBLG50 was attributed to the N and S-doped carbon microstructure that provided additional active sites for lithium-ion storage.

In this study, the effect of chitin nanofiber (ChNF) on the physical behaviors of cellulose nanocrystal (CNC) in suspension and solid states was investigated using polarized optical microscopy, rotational rheometry, and wide-angle X-ray scattering system. ChNF showed a significant effect on the cholesteric phase of CNC suspension, mainly owing to the electrostatic attraction and hydrogen bonding between ChNF and CNC. In turn, the increase of ChNF content reduced the size of the cholesteric domain. The applied shear force on the suspension changed the cholesteric phase to a nematic structure that was maintained after the solidification. This improved the mechanical strength of the resulted film along the shear direction.

Herein, double-network (DN) hydrogel beads of calcium alginate/polyacrylamide (PAAm) were synthesized, and their dye adsorption and mechanical performances were enhanced by incorporating cellulose nanocrystal (CNC). The DN hydrogel beads were prepared via two-step procedures: free-radical polymerization of AAm in oil bath at 90 ℃ and ionotropic crosslinking of alginate in calcium chloride solution. The nanocomposite DN beads were fabricated at the CNC contents of 0.5-2 wt% with respect to the polymer amount. Whereas CNC had insignificant effect on the bead structure, it significantly improved both mechanical properties and dye adsorption capacity. Neat and nanocomposite beads exhibited the diameter, weight, and water content of approximately 3.3 mm, 0.04 g, and 88%, respectively, irrespective of the CNC amount. In the dye adsorption, whereas neat hydrogel beads exhibited 19.7% dye removal for the immersion time of 180 min, nanocomposite beads with 1.5 wt% CNC exhibited a 1.8-fold increased dye removal efficiency (35.3%). In addition, nanocomposite beads with 1.0 wt% CNC exhibited 1.8- and 3.8-fold increased compressive modulus and strength (9.0 and 3.0 MPa) compared with those of neat beads (4.9 and 0.8 MPa). Consequently, the DN hydrogel beads with the highest performances were obtained at the CNC content of 1.0-1.5 wt%.

Wearable biosignal monitoring systems are being developed in various fields such as healthcare, fitness, and military industries. Due to its convenience, the leg sleeve-integrated with embedded sEMG electrodes can be worn unconsciously in daily life, enabling continuous measurement and collection of biological signals. In this study, the knitting structure, electrode diameter, the amount of conductive yarn required, the coefficient of friction, the electrical resistance, the skin-electrode impedance, and the signal to noise(SNR) were measured to optimize the knit based sEMG electrodes in the sleeve. The results indicated that plain stitch was confirmed to be an economically efficient knitting process because the production time is shorter and the amount of conductive yarn per unit area is smaller than other stitch structures. In addition, the biosignal collection performance of the knitted electrode was slightly lower than that of the conventional Ag-Ag/Cl disposable wet electrode, and an electrode with a plain stitch diameter of 20 mm showed the highest value of 0.31±0.02 mV in the state of muscle activation. It suggests that it is possible to develop knitted electrodes for biosignal monitoring system.

Cotton fabrics with improved flame retardancy were manufactured by introducing calcium phosphate groups into cotton fabrics using the LBL (Layer-by-layer deposition) method in which polyacrylic acid is used as one layer, and the flame retardant mechanism was studied. As a result of scanning electron microscopy, the shape of the fabrics and cotton fiber not treated with LBL was destroyed, but the shape of the fabrics and the shape of the fibers were maintained in the LBL-treated cotton fabric. In the flame retardancy test of the LBL-treated fabrics, it was observed that numerous nanoparticles with a size of 40-60 nm were formed on the surface of the cotton fiber. In XPS (X-ray photoelectron spectroscopy) analysis, it can be confirmed that nanoparticles of calcium phosphate are generated by the reaction between phosphoric acid and calcium. This result shows that flame retardancy was improved by a mechanism in which an incombustible calcium phosphate layer is formed by a reaction between phosphoric acid and a calcium metal salt, as well as an increase in char formation of cellulose by phosphoric acid. XRD (X-ray diffraction analysis) confirmed that the nanoparticles produced were hydroxyapatite calcium phosphate. This result is significant in suggesting a new method for preparing hydroxyapatite nanoparticles by an environmentally friendly LBL method.

This study investigated the effect of spinning and heat treatment conditions on the cellulose carbon hollow fiber membrane. A cellulose-based asymmetric carbon hollow fiber membrane has been prepared by wet spinning process and heat treatment. Cellulose was dissolved using EmimAc/DMSO and discharged in a coagulation bath at 60℃ to form asymmetric pores. To maintain the formed asymmetric pores even after the drying process, there was a stepped exchange process of solvent for the elimination of water in the fiber. The formed asymmetric pores are composed of a selective layer with dense pores and a support layer with finger-like pores. These asymmetric pores are important structures for increasing the selectivity and permeability of the carbon hollow fiber membrane. The pore structure according to the heat treatment temperature was analyzed. Because the pore size and micropores are controlled by the heat treatment condition, we applied different temperatures (550-850℃) in the heat treatment process. It was confirmed by BET that the surface area and pore size distribution improved 18.5%. As a result, it was confirmed that the structure and pore size of the cellulose carbon hollow fiber membrane were significantly affected by the spinning, solvent exchange, and heat treatment process conditions.