Seok-Ho Hwang

Thermal and physical properties of poly(phenylene oxide) blends with glass fiber reinforced syndiotactic polystyrene

Abstract Melt blends of poly(phenylene oxide)(PPO) with glass fiber reinforced syndiotactic polystyrene(GFRsPS) were prepared using a single screw extruder. DSC and dynamic mechanical measurements indicate that the PPO/GFRsPS blends are miscible in amorphous state as shown by the existence of a single Tg whose values are blend composition-dependent. From the mechanical test results, it is shown that the tensile and flexural modulus increase, but the tensile and flexural strength do not improve as the GFRsPS content increases. An increase in the melt flow index (MFI) as GFRsPS contents increase implies that the processing problem of neat PPO is improved.

Thermal and mechanical properties of amorphous copolyester (PETG)/LCP blends

Abstract Blends of amorphous copolyester (PETG) having an aliphatic cyclic segment and liquid crystalline copolyester (LCP) were prepared in solution blending technique. Specimens for mechanical testing were prepared by a miniature injection molding machine. For PETG/LCP blends, the difference between the two Tgs was too small to define the resolution of two Tgs by DSC. Also, DSC study revealed that the crystallization of PETG was occurred by the addition of LCP in the matrix. The tensile and modulus mechanical behaviors of the PETG/LCP blends were improved with increasing LCP content, whereas the elongation-at-break showed reverse results for it. This result could be explained by that the interface adhesion of PETG and LCP was poor but LCP acted as a reinforcing agent in the blends. The fracture of the blends represents the incompatibility of the PETG/LCP blend.

Mechanical and thermal properties of syndiotactic polystyrene blends with poly(p-phenylene sulfide)

Abstract Melt blends of syndiotactic polystyrene (sPS) and poly(p-phenylene sulfide) (PPS) have been prepared by using an internal mixer at 300 °C. The thermal, mechanical and morphological properties of binary blends of sPS with PPS have been investigated in this paper. The thermal and morphological properties show the immiscible binary blend evidences, which have a clear phase separation between the components at all compositions and a lack of adhesion at the interface. According to the X-ray diffraction patterns of blends, the crystalline structure of sPS in the blend is not altered from α form to β form. Indeed, the results for tensile test reveal that there is no synergism of the modulus of elasticity for sPS/PPS blend system.

A novel organic bottom anti-reflective coating material for 193 nm excimer laser lithography

Abstract Bottom anti-reflective coatings (BARC) are useful to suppress the problems associated with reflection by the substrate during the lithographical processing. Now, we have proposed a new class of BARC material containing polyvinylphenol as a UV-absorber, poly(3,3′-dimethylpropene) (PDMP) as a crosslinker, and 2-hydroxycyclohexyl p -toluenesulfonate as a thermal acid generator. The PDMP was synthesized from acrolein by a two-step sequence reaction with a yield of 60%. The lithographic performance of photoresist with BARC that was proposed by us was evaluated and compared with those of photoresist without BARC.

The curing and decomposition kinetics for diglycidylether of bisphenol-A/di(4-aminobenzanilide)ether system

Abstract In order to prepare a high performance epoxy, we synthesized a di(4-aminobenzanilide)ether which has aromatic amide–ether–amide group in the main chain as epoxy curing agent by a two-step reaction sequence. The structure of the synthesized di(4-aminobenzanilide)ether was confirmed by fourier transform-infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, and elemental analyzer (EA). The glass transition temperature of cured epoxy resin was 162.4°C, and the thermal resistance was sustained below 330°C. The curing kinetics and decomposition kinetics of cured epoxy were elucidated by Ozawa equation and Flynn–Wall equation, respectively.

Synthesis of 5-substituted 1,3-[bis(2,2′:6′,2″-terpyridin-4′-ylethynyl)]benzene ligands and their coordination-driven self-assembly

The preparation of discrete 5-substituted 1,3-[bis(2,2′:6′,2″-terpyridin-4′-ylethynyl)] benzenes is described. A Pd-catalyzed cross-coupling procedure was employed to build these elongated, functionalized bis(terpyridine)-ligands, which readily self-assemble to afford the corresponding hexameric metallomacrocycle possessing an inner void diameter of 24Å.

Sensitized Solar Cells based on Hexagonal Dyes of Terpyridine-Ruthenium(II): Effect of the Electropolymerization of Dyes during their Performance in Solar Cells

Effect of the Electropolymerization of Dyes during their Performance in Solar Cells J. Manriquez, Seok-Ho Hwang, Tae Joo Cho, Charles N. Moorefield, George R. Newkome and Luis A. Godinez* a Department of Electrochemistry, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Sanfandila, Pedro Escobedo, Queretaro, 76700, Mexico; E-mail : lgodinez@cideteq.mx b Department of Polymer Science and c Maurice Morton Institute of Polymer Science, The University of Akron, Akron, OH, 44325, USA A study of the photovoltaic properties and performance for dyesensitized solar cells, using three hexagonal macrocycles based on terpyridine-ruthenium (II) is reported. Photoand electrochemical results suggest that the global conversion efficiencies for these devices were strongly dependent of the electropolymerization of dyes during the cells performance.

Preparation and Physical Properties of Poly(lactic acid) Bio-Composites using Surface Modified Microfibriled Celluloses

The surface modification of microfibriled cellulose (MFC) was carried out through the hydrolysis–condensation reaction using (3-aminopropyl)triethoxysilane (APS) and 3-glycidyloxypropyltriethoxysilane (GPS) and then the modified cellulose was compounded with bio-degradable poly(lactic acid) (PLA). Also, pristine MFC was compounded with PLA as a control groups. The confirmation of surface modification for the pristine MFC was characterized by FT-IR and SEM/ EDX. The thermal and mechanical properties of the PLA/MFC composites depended on the content of MFC and the type of silane coupling agents. From the thermal, morphological and mechanical behaviors of the PLA/MFC composites, it was found that GPS-MFC was more successful to improve the interface adhesion between PLA matrix and the surface of MFC than that of APS-MFC.

Miscibility of poly(1,4-cyclohexamethylene terephthalate) blends with Polyarylate

The miscibility of poly(1,4-cyclohexamethylene terephthalate) (PCT) having an aliphatic cyclic segment blended with Polyarylate (PAR) was investigated by means of calorimetric measurements. It was found that all the PCT/PAR blends are miscible and show a single, composition-dependent glass transition temperature (Tg). The Tg composition dependence has been analyzed by using the Gordon–Taylor equation and the values of Tg obtained experimentally agree quite well with those calculated theoretically by using that equation. Also, the melting point depression phenomenon that occurred in miscible polymer pairs was observed up to 40 wt % PCT content.

Synthesis and lithographic characterization of poly[(dihydrocarveol)‐co‐(1,1‐dimethylethyl bicyclo[2.2.1]hept‐5‐ene‐2‐carboxylate)‐co‐(maleic anhydride)]

A new ArF single-layer resist polymer, poly(dihydrocarveol-co-1,1-dimethylethyl bicyclo[2.2.1]hept-5-ene-2-carboxylate-co-maleic anhydride) has been synthesized by radical polymerization. The molar composition of synthesized resist polymer was confirmed by elemental analysis. The obtained molar composition was 0.25:0.35:0.40. This resist polymer was found to be stable up to 230 °C, but above 250 °C it underwent rapid thermal deprotection of the tert-butyl groups by releasing carbon dioxide and 2-methylpropene. The deprotection temperature was established by DSC and TGA. Using the resist, 0.14 µm L/S pattern was obtained at 26 mJ/cm−2 doses, using an ArF stepper and the developer of 2.38 wt% tetramethyl ammonium hydroxide aqueous solution. © 1999 Society of Chemical Industry