PilHo Huh

Fabrication of poly(ethylene oxide) hydrogels for wound dressing application using E-beam

AbstractCross-linked poly(ethylene oxide) (PEO) hydrogel was developed for application to wound dressings. To determine the optimum conditions for wound dressing materials, PEO with different molecular weights and various PEO/poly(ethylene glycol) diacrylate (PEGDA) compositions were irradiated in order to obtain cross-linked hydrogels using an electron beam with various beam intensities. The contents of the PEGDA influenced the gel fraction, swelling ratio, mechanical properties, and water vapor transmission rate. To evaluate the healing effect of PEO/ PEGDA cross-linked hydrogel for wound dressing, wounds on the backs of mice were covered with PEO/PEGDA hydrogel films. Healing under the wet environment of the hydrogel dressing was faster than with a gauze control and a commercial reference. The results demonstrate the possibility of the facile production of mechanically robust and transparent wound dressing materials with improved wound healing characteristics.

Effect of various encapsulants for frameless glass to glass Cu(In,Ga)(Se,S)2 photovoltaic module

Cu(In,Ga)(Se,S)2 (CIGSS) modules with a frameless glass to glass (G2G) structure were successfully fabricated by replacing the currently used ethylene vinyl acetate (EVA) with new encapsulants such as polyolefins (POE), ionomer (IO) and liquid silicon (LSI), and their characteristics including optical, mechanical, and reliability properties were investigated. Most of the solid films for encapsulation except POE exhibit similar light transmittance in the visible-infrared wavelength range, while LSI shows the highest light transmittance with a difference of more than 2% in the overall wavelength range. The G2G structure encapsulated with IO exhibits superior values for the adhesion strength at which interface failure occurs (about 7.5 MPa) compared to other encapsulants. Water vapor transmittance ratio (WVTR) values of the encapsulants were evaluated to determine their suitability as water-resistant materials in terms of the CIGSS G2G structure. The IO encapsulant had the lowest WVTR value of about 1.75 g per m2 per day. Changes of cell-to-module (CTM) conversion ratio in the CIGSS G2G structure using various encapsulants were investigated using I–V measurements. The CIGSS G2G structure encapsulated by LSI shows the best CTM conversion ratio, since the module process occurs at the lowest temperature as compared with other encapsulants, therefore the module has a smaller thermal transient effect. Finally, the long-term reliability of the CIGSS modules based on various encapsulants was also evaluated by damp heat testing.

Water-Soluble Polyaniline/Polystyrene Sulfonate Synthesized Using Dialysis Membrane

ABSTRACT Relatively narrow molecular weight distribution polyaniline/poly(4-styrene sulfonate) were synthesized by aqueous chemical oxidation polymerization using a dialysis membrane as the key to controlling the diffusion speed of the initiator. The optical, electrochemical, and electrical properties of the resulting polyaniline/poly(4-styrene sulfonate) were estimated by ultraviolet–visible–near infrared spectroscopy, cyclic voltammetry, and four-point probe. Compared to a bulk polyaniline/poly(4-styrene sulfonate), the resulting polyaniline/poly(4-styrene sulfonate) showed relatively high crystallinity according to X-ray diffraction, and their polydispersity indices ranged from 1.6 to 2.0 as a function of the reaction time. The electrical conductivities of the resulting polyaniline/poly(4-styrene sulfonates) were also enhanced gradually with increasing reaction time. GRAPHICAL ABSTRACT

Synthesis and characterization of novel polypyrrole hybrid nanotubules incorporated with polyaniline spots

Novel hybrid nanostructures composed of the polypyrrole (PPy) as the void nanotubules and the polyaniline (PANi) as the spots were fabricated using a successive synthetic process. Unique phase-separated morphological properties of PPy-PANi hybrid nano-tubules might be caused by the PANi spots distributed randomly in the PPy matrix.

Ladder-Type Poly(3,4-ethylenedioxythiophene)-poly (Ethylene Glycol)-polyurethane Supramolecular Network for Gel Polymer Electrolyte

ABSTRACT A ladder-type poly(3,4-ethylenedioxythiophene)–poly(ethylene glycol)–polyurethane (PEDOT–PEG–PU) supramolecular network was successfully synthesized using graft copolymerization of hydroxymethyl-EDOT with isocyanate-terminated PEG–PU prepolymer. PEDOT functionalized as the frame for a ladder-type supramolecular structure and PEG–PU as the rung. The successful formation of supramolecular network was confirmed by analyzing the Fourier transform infrared spectroscopy. A series of PEDOT–PEG–PU gel polymer electrolytes by linking the LiClO4 were prepared as a function of [O/Li+] ratios. The pH effect of their electrical capacitances was investigated using cyclic voltammetry. Ionic conductivities of different PEDOT–PEG–PU/Li+ complexes at a fixed pH were also evaluated through impedance analysis. GRAPHICAL ABSTRACT

Synthesis of β-hydroxyalkylamide by using microwave and its performance for powder coating

ABSTRACT Among the curing hardeners for powder coating, β-hydroxyalkylamide is widely used due to its easy handling, excellent exterior durability, good mixing with other chemicals, flexibility, hardness, and especially non-toxic property. In this study, β-hydroxyalkylamide which is normally produced by oil bath heating was synthesized by microwave heating system. For synthesis, it takes 300 min of reaction time for heating system of oil bath but the microwave heating requires only 100 min of reaction time because of the internal heating. Performances of products obtained by both heating systems showed very similar properties. These results suggest that the microwave as a heating source is an effective tool for the reaction of β-hydroxyalkylamide.

Nanoporous polyimide film from poly(ethylene glycol-co-imide) using a one-step heat calcination process

ABSTRACT Polyamic acid (PAA) made from 3,3, 4,4-biphenyltetracarboxylic dianhydride and 4,4-diaminodiphenyl ether was synthesized and used as the backbone of nanoporous polyimide. Thermally labile polyethylene glycol (PEG) at 10, 20 or 30 wt% was introduced to the end group of PAA. Self-assembled PAA-b-PEG micelle-like nanoparticles could be formed as a result of amphiphilic characteristics of hydrophobic PAA and hydrophilic PEG. Thermal imidization and degradation of spin-coated amphiphilic PAA-b-PEG film were performed sequentially through one-step heat treatment to obtain polyimide film with nanopores. Pore sizes decreased with increasing amount of PEG block and their dielectric constants decreased from 2.71 ± 0.13 to 2.38 ± 0.11.

Solid Polymer Electrolyte Based on Peg-Co-Ppg-Pu/Liclo 4

With a view to enhancing the ionic conductivity via the control of chain mobility of solid polymer electrolyte(SPE)based on poly(ether urethane)(PEU), polyurethane(PU)matrix containing polyethylene glycol(PEG)and polypropylene glycol(PPG)randomly distributed within matrix was synthesized from the simultaneous polymerization of PEG-PU and PPG-PU prepolymers. The efficacy of PEG-co-PPG-PU complexed with LiClO4salt as a SPE is discussed and compared with that of PEG-PU/LiClO4.