Aluminum Diethylphosphinate-Incorporated Flame-Retardant Polyacrylonitrile Separators for Safety of Lithium-Ion Batteries.

Herein, we developed polyacrylonitrile (PAN)-based nanoporous composite membranes incorporating aluminum diethylphosphinate (ADEP) for use as a heat-resistant and flame-retardant separator in high-performance and safe lithium-ion batteries (LIBs). ADEP is phosphorus-rich, thermally stable, and flame retardant, and it can effectively suppress the combustibility of PAN nanofibers. Nanofibrous membranes were obtained by electrospinning, and the content of ADEP varied from 0 to 20 wt%. From the vertical burning test, it was demonstrated that the flame retardancy of the composite membranes was enhanced when more than 5 wt% of ADEP was added to PAN, potentially increasing the safety level of LIBs. Moreover, the composite membrane showed higher ionic conductivity and electrolyte uptake (0.83 mS/cm and 137%) compared to those of commercial polypropylene (PP) membranes (Celgard 2400: 0.65 mS/cm and 63%), resulting from interconnected pores and the polar chemical composition in the composite membranes. In terms of battery performance, the composite membrane showed highly stable electrochemical and heat-resistant properties, including superior discharge capacity when compared to Celgard 2400, indicating that the PAN/ADEP composite membrane has the potential to be used as a heat-resistant and flame-retardant separator for safe and high-power LIBs.

Photothermal Fabrics for Efficient Oil-Spill Remediation via Solar-Driven Evaporation Combined with Adsorption.

Oil spill rapidly destroys aquatic system and threatens humans, requiring fast and efficient remedy for removal of oil. The conventional remedy employs water-floating oil adsorbents whose volume should be large enough to accommodate all oil ingredients. Here, we suggest a new concept for efficient oil-spill remediation, which combines solar-driven evaporation of light oil components and simultaneous adsorption of heavy oil components, namely, solar-driven evaporation of oil combined with adsorption (SEOA). To design photothermal oil absorbents for the efficient SEOA, we designed carbonaceous fabrics with high photothermal heating performance and oil-adsorption capacity by carbonizing nonwoven cotton fabrics. For three model organic solvents of octane, decane, and dodecane floating on water, the fabrics, respectively, accelerated the evaporation in factors of 2.0, 4.4, and 2.3 through photothermal heating under simulated sunlight condition. For the 1.18 mm thick crude oil floating on water, 70 and 77 wt % of crude oil were evaporated within 2 and 16 h, respectively, with the photothermal fabrics, whereas only 22 and 34 wt % was evaporated in the absence of the fabrics, indicating the dramatic enhancement of oil removal by solar-driven evaporation. The remaining heavy oil components were accommodated in the pores of the fabrics, removal of which showed an additional 18 wt % reduction; that is, a total 95 wt % of the crude oil was removed. The oil-treatment capacity is as high as 110 g g-1, which has never been achieved with conventional oil adsorbents to the best of our knowledge. We believe that our combinatorial SEOA approach potentially contributes to minimizing the environmental disaster through a fast and efficient oil-spill remediation.

Improved pretreatment process using an electron beam for optimization of glucose yield with high selectivity.

In this study, electron beam irradiation (EBI) assisted by a dilute acid pretreatment process was investigated to improve the glucose yield and show high selectivity in the enzymatic hydrolysis of rice straw. In the first step, EBI of rice straw was performed at various doses ranging from 50 to 500 kGy. The electron beam-irradiated rice straw was then autoclaved with 3 % dilute acid at 120 °C for 1 h. The pretreated rice straw was finally subjected to enzymatic hydrolysis at 50 °C for 24, 48, and 72 h by 70 filter paper units (FPU)/mL cellulase and 40 cellobiose units (CbU)/mL glucosidase. Glucose was obtained with a very high selectivity of 92.7 % and a total sugar yield of 80 % from pretreated rice straw after 72 h of enzymatic hydrolysis.

Patterning of polymer nanocomposite resists containing metal nanoparticles by electron beam lithography.

Poly(vinyl pyrrolidone) (PVP)-stabilized silver nanoparticles (NPs) were used as a new nanocomposite resist for electron beam lithography. A nanocomposite resist prepared by reducing silver nitrate in an alcoholic PVP solution was patterned by using a scanning electron microscope equipped with a nanometer pattern generation system. Well-defined negative tone patterns with a good sensitivity of 200 microC/cm2 and a contrast of 2.83 were obtained using the prepared nanocomposite resist. In addition, the changes in the morphology and structure of the resist patterns with a thermal treatment temperature were investigated by a FE-SEM with an EDX. The results revealed that the patterns of Ag NPs were formed through sintering the formed resist patterns at above 300 degrees C.

Micropatterning of polymer-embedded metal nanoparticles by an ion beam contact lithography.

A convenient and effective method to pattern polymer-embedded metal nanoparticles by ion irradiation has been developed. The thin Pluronic films containing silver nitrate as a precursor of silver nanoparticles were irradiated through a pattern mask with accelerated proton (H+) ions. It was found from the UV-Vis measurement that the formation of silver nanoparticles in the Pluronic matrix was dependant on the amount of silver nitrate. The 50 microm line (pitch 150 microm) patterns of the Pluronic containing silver nanoparticles were obtained with the thin film irradiated to 1 x 10(16) ions/cm2. The heat treatment effect on the morphology of the patterns was investigated by using a scanning electron microscope with an energy dispersive X-ray spectrometer. The results confirmed that the silver nanoparticles were successfully embedded in the Pluronic patterns and the patterns were changed into large silver particles by a heat treatment above 350 degrees C.

Micropatterning of poly(vinyl pyrrolidone)/silver nanoparticle thin films by ion irradiation.

This study describes a new patterning method of poly(vinyl pyrrolidone) (PVP) containing silver nanoparticles by using ion irradiation. The thin films prepared from PVP/silver nanoparticle solutions were irradiated through a mask with accelerated H+ ions. Well-defined 50 microm line (pitch 150 microm) patterns were generated from the film irradiated at 1 x 10(16) ions/cm2. The heat treatment effect on the morphology of the patterns was investigated by using a scanning electron microscope with an energy dispersive X-ray spectrometer. The results confirmed that the silver nanoparticles were successfully immobilized in the PVP patterns and the patterns were changed into silver particles by heat treatment above 300 degrees C.

Influence of atmospheric fluorine plasma treatment on thermal and dielectric properties of polyimide film.

Plasma treatment of polyimide surfaces not only causes structural modification during the plasma exposure, but also leaves active sites on the surfaces that are subject to post-reaction. In this work, the effects of atmospheric fluorine plasma treatment on the surface properties and dielectric properties of polyimide thin film were investigated by using X-ray photoelectron spectroscopy (XPS), Fourier transform-IR (FT-IR) spectroscopy, and contact angle measurement. The results indicated that plasma treatment successfully introduced fluorine functional groups on the polyimide surfaces. The polyimides also exhibited good thermal stability and a lower dielectric constant. It appears that the replacement of fluorine led to the decrease of the local electronic polarizability of polyimide. Consequently, it was found that the atmospheric fluorine plasma-treated polyimides possessed lower dielectric characteristics than the untreated polyimides.

Release behaviors of porous poly(butylene succinate)/poly(epsilon-caprolactone) microcapsules containing indomethacin.

The biodegradable poly(butylene succinate)/poly(epsilon-caprolactone) (PBS/PCL) microcapsules containing indomethacin were prepared by emulsion solvent evaporation method. The morphologies, thermal properties, and release behaviors of PBS/PCL microcapsules were investigated. As a result, the microcapsules exhibited porous and spherical form in the presence of gelatin as a surfactant. From the DSC result, the PBS/PCL microcapsules showed the two exothermic peaks meaning the melting points of PCL and PBS. The results of FT-IR and DSC proved that the PBS and PCL were mixed so that the PBS/PCL microcapsules were composed of two wall-forming materials. And the release rate of indomethacin from the microcapsules was decreased with increasing the PCL content. It was noted that an addition of PCL on the PBS led to the decrease of pore size in the PBS/PCL microcapsules.

Thermal and mechanical interfacial properties of the DGEBA/PMR-15 blend system.

In this work, the blend system of diglycidyl ether of bisphenol A and PMR-15 polyimide is investigated in terms of thermal and dynamic mechanical interfacial properties of the casting specimens. The thermal stabilities are studied by thermogravimetric and thermomechanical analyses, and the dynamic mechanical properties are carried out by dynamic mechanical analysis. The results show that the thermal stabilities based on the initial decomposition temperature, the integral procedural decomposition temperature, and the glass transition temperature are increased with increasing PMR-15 content. The crosslinking density (rho) of the blend system is increased at 10 phr of PMR-15, compared with that of neat epoxy. Mechanical interfacial properties measured in the context of critical stress intensity factor and critical strain energy release rate show similar behaviors with E(a) and rho, probably due to the increase in intermolecular interactions or hydrogen bondings in polymer chains.