Herein, novel linear block copolymers have been synthesized for use as a drug-eluting coating material in vascular grafts. Poly(ethylene glycol-block-L-lactide-block-N-isopropylacrylamide) triblock copolymers were prepared by stepwise polymerization from methoxy-terminated polyethylene glycol, i.e., anionic ring-opening polymerization of L-lactide followed by quasi-living polymerization of N-isopropylacrylamide. The chemical structures of the triblock copolymers were analyzed by FT-IR spectroscopy, ¹H-NMR spectroscopy, and WAXD. The surface adhesion of triblock copolymers was evaluated for the substrate and model proteins. The drug release behavior of antiproliferative methotrexate was investigated according to the block ratio of the triblock copolymers. Viscosity increased significantly with increasing proportion of poly(N-isopropylacrylamide) block, whereas protein adhesion decreased with decreasing proportion of poly(L-lactide) block. Furthermore, methotrexate release increased with decreasing proportion of poly(L-lactide) block, and both the initial and sustained release increased with increasing proportion of poly(N-isopropyl acrylamide) block. This triblock copolymer can adjust the ratio of blocks to design effective drug release for specific applications.

The durability and performance of air purification filters are typically improved through post processing. Post processing of air purification filters is mainly performed using the dipping process, which causes problems such as deformation of the filter media and decreased uniformity because of the increasing tension and mass of the filter media. To resolve these problems, we devised a tension-free post processing method and compared its performance with that of the dipping process. In our method, a resin tube is placed horizontally above a mangle roller, enabling resin to flow down the mangle roller, allowing it to be easily absorbed by the filter media. Owing to the horizontal placement of the resin tube, the tension applied to the filter media can be minimized. The basic physical performance such as tensile strength and initial pressure drop, of the filter media produced using our method improved evidently. Intensive research and development of the postprocessing technique are required to further improve the overall efficiency and durability of air purification filters.

Silk microfibers (MSFs) prepared directly from silk fibroin fibers (SFFs) have advantages over those prepared from regenerated silk fibroin. These advantages include a simple process and high crystallinity. This study provides preliminary results on preparing MSFs and their application as reinforcing fillers for hydrogels. Compared to previous methods using only NaOH, we suggest more mild conditions by lowering the concentration of NaOH and adding Na₂CO₃. In our study, the length of the MSFs was less than 200 ㎛ after 6 h of immersion of SFFs in the NaOH/Na₂CO₃ solution. X-ray diffraction results revealed that MSFs have a similar crystallinity to that of SFFs. When MSFs were added to the alginate solution, the solution exhibited increased viscosity and shear thinning behavior. The alginate/MSF hydrogel had enhanced compressive properties as compared to the alginate hydrogel, and the reinforcing effect was affected by the length of the MSFs.

This study was conducted to impart flame retardancy to cotton fabrics while maintaining their mechanical properties and appearance under environmentally friendly and room-temperature conditions. Anionic functional groups were prepared by adding polyacrylic acid to the cotton fabric. Calcium phosphate was grafted to polyacrylic acid by inducing a reaction between calcium ions and ammonium phosphate. In this layer-by-layer (LBL) deposition, 20 layers were formed. The results of a vertical flammability test revealed that the combustion of the multilayered fabrics was delayed and that the fabric structures were maintained, even after the combustion process. Thermogravimetric analysis showed that the residues of the multilayered cotton increased to 17% at temperatures above 500 ℃. X-ray photoelectron spectroscopy confirmed the production of calcium phosphate. These results indicate that calcium ions reacted with and were grafted to the carboxyl groups of polyacrylic acid, and that the grafted calcium ions reacted with ammonium phosphate to generate calcium phosphate. These findings suggest that LBL deposition can be performed with calcium phosphate to produce cotton fabrics with improved flame retardancy in an environmentally friendly manner.

Nonwoven fabrics are widely used as filter bags in dust collection facilities, which are industrial air pollution prevention facilities with high dust collection efficiency. The filter bag media is the most important factor that determines the performance of the pulse-jettype dust collection facility. In general, the materials used for filter bag media are polyester, nylon, and polypropylene fibers. Because of the effects of the operating temperature, meta-aramids and polyphenylene sulfide are used at a high temperature of around 200 ℃, while glass fiber, polyimide, and polytetrafluoroethylene (PTFE) are used at an ultra-high temperature of approximately 260 ℃. Among these, PTFE membranes show/exhibit excellent heat resistance, chemical resistance, non-adhesiveness, and filtration efficiency. Despite the advantages of these fibers, there are no studies on the preparation and properties of filter bag media mixed with meta-aramid staple and PTFE fibers. Therefore, in this study, expanded PTFE filaments were processed into staple fibers to enable carding; mixed with meta-aramid staple fibers by ratio to form the upper and lower webs; and then applied with a PTFE and aramid scrim. The filter bag media was manufactured through a needle punching process and finishing. The air permeability, pore size, tensile strength, filtration performance, and durability of the prepared mixed filter bag media were evaluated. The results show that the prepared low differential pressure filter bag media had improved heat resistance and durability, while maintaining the 100% dust collection efficiency of the existing aramid medium.

This study aims to investigate the application of perylenetetracarboxylic dianhydride (PTCDA), which is also known as C.I. Pigment Red 224 (PR224), as a carbon precursor. PTCDA has a stacking structure and planarity, thereby forming a crystal structure and good thermal stability. Moreover, PTCDA has a very high theoretical elemental carbon content of 73.47%, which suggests that its maximum theoretical carbon yield is more than 70%. Therefore, PTCDA was selected as a carbon precursor and compared with coal-tar pitch and petroleum pitch, which are carbon precursors with high carbon yield and excellent carbon crystallinity after carbonization. The initial decomposition temperature of PTCDA was 240-328 ℃ higher than that of the pitches, suggesting that the thermal stability of PTCDA is better than that of the other pithces. After carbonization, the graphite (002) interplanar distance (d₀₀₂) of carbonized PTCDA (C-PTCDA) was 3.54 Å, which was similar to that of the pitch-based carbons. The crystal size (Lc) was the largest among the prepared carbons with 30.03 Å. The I_D/I_G ratio of C-PTCDA was 2.12, which was the lowest value among the prepared carbons. The 2D peak of C-PTCDA was observed at 2720 cm^-1, suggesting the least disordered graphite structure. Therefore, we believe that PTCDA has excellent potential for use as a carbon precursor for highly ordered carbon materials.

In this study, we investigated the effects of weight loss ratio and tensile strength under various alkali hydrolysis conditions and NaOH concentrations (10-30% omf). We obtained the optimal weight loss ratio of 24.26% under the alkali hydrolysis conditions of 25% omf NaOH at 110 ℃ for 60 min. To obtain the optimal dyeing condition for a gray color in reduced sea-island polyethylene terephthalate ultramicrofiber tricot fabric, we conducted the dyeing process under the following conditions; dyeing temperature (95-135 ℃), dyeing time (20-60 min), blue dye content (0.1-0.5% omf), and UV-absorbent content (1-9% omf). The optimal dyeing conditions of the alkali-reduced fabric were 1 g/l dispersant, 1 g/l pH buffer solution, and 3% omf UV-absorbent at 135 ℃ for 40 min and a goods-to-liquor ratio of 1:10. Under these conditions, the dyed fabrics showed excellent color fastness against washing, rubbing, and light with grades of 4-5.

Herein, a facile method of catalytic chemical oxidation was reported to produce the micro-flower NiCoMnO₂ superstructures. FE-SEM confirmed the uniform NiCoMnO₂ flower-like morphologies with an averaged diameter of 1-2 ㎛, composed of the nanosheets with the thickness of 10 ± 2 nm, could provide the pathways for efficient and fast transport of both electrolyte ions and electrons due to higher electroactive surface areas and enhanced electrical conductivity. As an anode material, nanorod-like β-FeOOH with the average diameter of 139 ± 30 nm and the length of 796 ± 140 nm was obtained by a hydrothermal method. The NiCoMnO₂ and β-FeOOH electrode materials showed the good electrochemical performance with maximum specific capacitances of 726 F g^-1 and 276 F g^-1 at 1 A g^-1, respectively. Furthermore, the fabricated asymmetric supercapacitor (ASC) NiCoMnO₂//β-FeOOH device exhibited excellent specific capacitance of 110 F g^-1 at 1 A g^-1, cycle stability of 84.5% after 2000 charge/discharge cycles and high energy density of 34.38 Wh kg^-1 at the power density of 750 W kg^-1.

Environmental issues have led to a growing demand for eco-friendly functional materials and their biodegradable ability. One of the best way to design eco-friendly materials is to utilize bio-mimetic process to mimic their physical structures and chemical characteristics of naturally abundant materials. Here we develop lignocellulose-based composites for sustainable biodegradable materials, which mimic natural cellulose structures. Briefly, biodegradable PCL and stiff CNC crystals replace amorphous hemicellulose and cellulose fibroin, respectively, with enhanced mechanical strength and their facile fabrication. Indeed, electro-spinning with various applied voltage aided to manufacture nano-web structure to obtain definitely increased surface area. Importantly, the control of voltage affected the formation of agglomerates with different taylor cone structure, which could be attributed to the balance between spinning rate and charged constituents. The CNC reinforcement increased the mechanical strength (up to 3 MPa), and PCL increased the degradablity (up to 20% after 24 hrs), which confirms their aforementioned advantages.