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For some binary systems, an extended Flory–Huggins equation is applicable to both vaporliquid equilibria (VLE) and liquid–liquid equilibria (LLE) using the same adjustable parameters. New LLE and VLE data are reported for polystyrene (PS) (MW = 100,000)/cyclohexane and for poly(ethylene glycol) (PEG) (MW = 8,000)/water. Experimental results for the PS/cyclohexane system agree well with the semiempirical model, whereas those for PEG/water do not, probably because, for PEG/water, the temperature range of the VLE data is about 55°C lower than that of the LLE data. Excellent fits were obtained for our previously published experimental results for PS/cyclohexane (upper critical solution temperature, UCST), PS/ethyl acetate (lower critical solution temperature, LCST), PS/tert‐butyl acetate and PS/methyl acetate (both UCST and LCST), and PEG/water (closed‐loop). The semiempirical model also fits well with new data obtained for the polymer blend PS/poly(vinyl methyl ether). © 1993 John Wiley & Sons, Inc.

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Submicrometer-sized N-isopropylacrylamide(NIPA) gel particles with various composition of cross-linker are prepared by precipitation polymerization and their swelling behaviors are examined by using photon correlation spectroscopy(PCS) technique. Theoretically, Hu et al.'s double-lattice model has been modified by introducing a new universal constant and simplifying the expression of the Helmholtz energy of mixing. The modified double-lattice model(MDL) describes very well the lower critical solution temperature (LCST) behavior of linear PNIPA/water system. For cross-linked NIPA gel particles in water, we have combined MDL theory with Flory and Erman's theory of elasticity, which takes into account the nonaffine displacements of network junctions under high degree of swelling. Energy parameters obtained from the linear PNIPA/water system were directly used to predict swelling equilibria for the NIPA gel/ water system. Our results represented that an affine network model explained the swelling behavior at high swelling ratio more accurately than that of the phantom network model. To correct the deviation of the continuous volume transition temperature, we have considered the interaction energy parameter between cross-linker segment and solvent molecule. The corrected model was applied to the swelling equilibria of gel particles with various cross-linking density and agreed well with their experimental data with no adjustable model parameters.

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We have successfully synthesized a spherical core-shell structure based on Li[(Ni0.8Co0.2)0.8(Ni0.5Mn0.5)0.2]O2 via a coprecipitation route. According to the careful examination by scanning electron microscopy (SEM), transmission electron microscopy energy-dispersive spectroscopy (TEM-EDS), and X-ray diffraction (XRD), it was found that the core-shell particle consisted of Li[Ni0.8Co0.2]O2 as the core and Li[Ni0.5Mn0.5]O2 as the shell, of which the thickness was estimated to be 1 to approximately 1.5 microm. Both the core and shell were dense as confirmed by SEM. Though the core-shell-structured Li[(Ni0.8Co0.2)0.8(Ni0.5Mn0.5)0.2]O2 delivered a slightly reduced initial discharge capacity, the capacity retention and thermal stability were significantly improved relative to those of the Li[Ni0.8Co0.2]O2 electrode without the Li[Ni0.5Mn0.5]O2 shell. The carbon/Li[Ni0.8Co0.2]O2 pouch cell underwent an explosive ignition during the nail penetration test, whereas the carbon/Li[(Ni0.8Co0.2)0.8(Ni0.5Mn0.5)0.2]O2 cell remained stable, demonstrating the superior thermal stability of the core-shell electrode. As a new positive electrode material, the core-shell-structured Li[(Ni0.8Co0.2)0.8(Ni0.5Mn0.5)0.2]O2 is a significant breakthrough in the development of high-capacity lithium secondary batteries.

Plasma based transfer of photoresist (PR) patterns into underlying films and substrates is basic to micro- and nanofabrication but can suffer from excessive surface and line edge roughness in the photoresist and resulting features. The authors have studied the interaction of a set of adamantyl methacrylate-based model polymers with fluorocarbon∕Ar discharges and energetic Ar+ ion beams. Through systematic variation of the polymer structure, the authors were able to clarify the contributions of several critical polymer components on the chemical and morphological modifications in the plasma environment. Etching rates and surface chemical and morphological changes for the model polymers and fully formulated 193 and 248nm photoresists were determined by ellipsometry, atomic force microscopy, time of flight static secondary ion mass spectrometry, and x-ray photoelectron spectroscopy. The polymer structure in the near surface region (∼10nm) of all materials is destroyed within the first seconds of exposure to a fluorocarbon∕Ar plasma. The plasma-induced changes include destruction of polymeric structure in the near surface region and oxygen and hydrogen loss along with fluorination. For the 193nm PR material, the initial densification of the near surface region was followed by the introduction of pronounced surface roughness. This change was not seen for 248nm PR processed under identical conditions. When comparing the responses of different polymer materials, the authors observed a strong dependence of plasma-induced surface chemical and morphological changes on polymer structure. In particular, the adamantane group of 193nm PR showed poor stability under plasma exposure. On the other hand, the plasma-induced changes for polymer resins with or without the low molecular weight chemicals required to make the photoresist system photoactive did not differ significantly. The behavior of the same materials during energetic argon ion beam bombardment was also investigated. No significant differences in etch yield and surface roughness evolution for the different materials were seen in that case.