Well-defined ABA-triblock copolymers, polystyreneblock-poly(methyl methacrylate)-block-polystyrene (SMS), which have two different polystyrene (PSt) weight fractions (f PSt ), were synthesized by successive atom-transfer radical polymerizations. Ion gels consisting of SMS and an ionic liquid, (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide [C 2 mim][NTf 2 ]), were prepared using the cosolvent evaporation method with tetrahydrofuran. Atomic force microscope images of the ion gels indicated that PSt is phase-separated to form sphere domains that serve as physical cross-linking points because PSt is not compatible with [C 2 mim][NTf 2 ], while a continuous poly(methyl methacrylate) (PMMA) phase with dissolved [C 2 mim][NTf 2 ] is formed to serve as ion conduction paths. Accordingly, the ion gels are formed by the self-assembly of SMS and the preferential dissolution of [C 2 mim]-[NTf 2 ] into the PMMA phase. The viscoelastic properties of the gels can be easily controlled by changing f PSt in SMS and [C 2 mim][NTf 2 ] concentration in the ion gels. The ion gels that exhibit high ionic conductivities (>10 −3 S cm −1 ) at room temperature were used as an electrolyte of an ionic polymer actuator, which has a trilaminar structure consisting of the ion-gel electrolyte sandwiched between two composite carbon electrodes containing high-surface-area activated carbon powders. By applying low voltages (<3.0 V) to the electrodes, the actuator exhibited a soft bending motion toward the anodic side.
We present a new series of polymer-ionic liquid solutions exhibiting LCST-type liquid-liquid phase separation behaviour, and reveal their phase behaviour and intermolecular interactions based on phase diagrams and NMR analysis.
The solubility and phase behavior of linear polymethacrylate polymers, primarily poly(phenylalkyl methacrylate)s, in imidazolium-based ionic liquids (ILs) were systematically studied by changing the structure of each component. Solutions of polymethacrylates in 1-alkyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([C(n)mim] [NTf2]) showed lower critical solution temperature (LCST) phase behavior, and the phase separation temperature (T(c)) could be varied by selecting an appropriate combination of a polymer and an IL. An increase in alkyl chain length between the phenyl and ester groups in the polymer side chain decreased the T(c); alternatively, substitution of the imidazolium cation with a longer alkyl chain increased the T(c). When the same anion was used, the miscibility of the polymer/IL system was mainly determined by the alkyl chain length. T(c) could also be varied by mixing two ILs in an appropriate ratio. In addition, the kinetics of the reversible phase transition phenomena exhibited by these polymers were examined. Redissolution kinetics were largely controlled by the magnitude of the difference between T(c) and the glass transition temperature (T(g)) of the polymer (T(c) - T(g)), in addition to the mutual affinity between the polymer and the IL.
The solubility and phase behavior of five polyethers (poly(ethylene oxide), poly(glycidyl methyl ether), poly(ethyl glycidyl ether), poly(ethoxyethyl glycidyl ether) and poly(propylene oxide)) in 14 different room-temperature ionic liquids (ILs) were studied by changing the structures of polyethers and the cations and anions in the ILs. Certain combinations of a polyether and an IL binary mixture exhibited lower critical solution temperature (LCST) phase behavior. For ILs containing the same anions, the polyethers were highly soluble in imidazolium-or pyridinium-based ILs, whereas they were insoluble in ammonium-or phosphonium-based ILs. An increase in length of the alkyl chain in the imidazolium cation and an increase in polarity of the polyethers resulted in a higher LCST phase separation temperature, whereas substitution of the hydrogen atoms on the imidazolium ring by methyl groups resulted in a lower LCST phase separation temperature. The hydrogen bonding interaction between the oxygen atoms in the polyethers and the aromatic hydrogen atoms on the cations in the ILs had an important role in the LCST phase behavior of the mixtures. Miscibility of the mixtures was also affected by the Lewis basicity of the anions in the ILs.
Palladium-catalyzed polycondensation between 2,5-dibromo-4-alkylthiazoles (alkyl ) butyl thorough nonyl) and 2,5-bis(trimethylstannyl)thiophene gave charge-transferred-type alternating polymers, PTz(R)Th's. PTz(R)Th's had a high regioregularity as judged from their 1 H NMR and X-ray diffraction (XRD) data, and the head-to-tail content was estimated to be higher than 90% from the 1 H NMR data. The polymer forms a stacked structure, and the stacked structure is proposed based on the XRD data. The tendency of the polymer to form the stacked structure is considered to contribute to the regioregulation in the polymerization. The polymer was susceptible to both electrochemical oxidation (or p-doping) and reduction (or n-doping).
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