Polyaniline films electrodeposited from acidified nonaqueous organic media were investigated for their electropolymerization behavior and charge-discharge characteristics. The solution system used for the electropolymerization of polyaniline film was CF3COOH acidified propylene carbonate, which was previously found to be the best system for the preparation of a highly electroactive conducting polymer film. Electroactive polyaniline films only form in solutions where the mole ratio of acid (CF3COOH) to aniline monomer is greater than one. As the acidity is increased, the resultant polyaniline film exhibits greater electroactivity and better charge-discharge performance of Li/polyaniline cathode cell. This effect may be ascribed to the high current efficiency in electro-oxidative polymerization and high redox reversibility of PAn films prepared in the high acid content solutions.
Electroactive polyaniline (PAn) films were deposited from PC (propylene carbonate)‐EC (ethylene carbonate) and PC‐DME (1,2‐dimethoxyethane) mixed polymerization solutions containing aniline,
CF3COOH
, and
LiClO4
. Higher dielectric constant solvents are necessary to deposit the PAn film where protons, dissociated from the acid, initiate the polymerization of aniline. Various PAn films deposited in the PC, the PC‐EC (50 mole percent), and the PC‐DME (50 volume percent) solutions were used for the cathode materials of the rechargeable lithium batteries. Charge capacity and discharge ability of the Li/PAn batteries in the
PC‐LiClO4
electrolyte solution are almost the same, regardless of the polymerization solvents, such as
PC≈PC‐EC≥PC‐DME
and
PC‐EC≥PC‐DME≈PC
. The mixed solvent electrolyte solution effect on the Li/PAn (polymerized in the PC solution) batteries becomes much larger such as
PC‐DME>PC‐EC>PC
. Moreover, the electrochemical kinetic factors of the PAn films deposited in the various mixed polymerization solutions and also in the different electrolytes were experimentally determined by measuring the ac impedance. The results of the ac impedance analysis of each PAn film correlate well with the battery performances of Li/PAn cells.
γ-Cyclodextrin-based metal−organic framework (CD-MOF) particles were prepared using poor solvent crystallization and spray-drying methods in order to advance conventional engineering processes. Particles were characterized in terms of their morphology, size, surface area, surface elemental composition, crystallinity, and drug content. CD-MOFs prepared by the poor solvent crystallization method exhibit similar morphologies and crystallinities to those fabricated by vapor diffusion. In contrast to the development of the (γ-CD) 6 cubic array, the rapid evaporation of the solvent during spray-drying promoted the formation of hollow CD-MOF particles with low crystallinity. The CD-MOF structure in spray-dried particles reformed into the well-known (γ-CD) 6 cubic array following contact with ethanol. In terms of their spherical shape, low density, and geometric median particle size (D 50 ) that is lower than 5 μm, the potential application of spray-dried CD-MOF for dry powder inhaler formulation was affirmed. Thus, the spray-drying process was further enhanced using a modified procedure. Modified spray-dried particles achieved an outstanding aerosolization performance by initiating crystal growth using an ethanolic spray-drying precursor. The successful design of this crystal structure grants CD-MOF products a high potential for use in inhalable formulation carriers and likely for other applications in the future.
An electrochemical and Raman spectroscopic study on polyaniline consisting of 1,4iminophenylene (IP, -NHC6H4-) and nitrilo-2,5-cyclohexadiene-l,4-diylidenenitrilo-l,4-phenylene (NP, -N= CeH4=NCeH4-) units has proved that the NP part is electrochemically inactive in nonaqueous electrolytes in spite of its conjugated structure of single and double bonds. The IP part can be doped but the doped regions of polyaniline with more NP content are less uniform and have larger bond orders. Increase in the NP content decreases electrical conductivity and discharged capacity of polyaniline. Hence, polyaniline containing the NP structure is not suitable for the positive electrode material of a rechargeable lithium battery.
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