Takeshi Ueki

Ionic liquids (ILs) are ambient temperature molten salts and have attracted considerable attention because of their unique properties such as nonflammability, negligible volatility, high ionic conductivity, and thermal stability. Here, we show that the combinations of macromolecules with ILs as solvents and additives could offer new progress, challenges, and opportunities in polymer materials science. Compatible binary systems, where ILs are solidified (gelled) by polymers, can be used as ion-co

Abstract In this paper, we review recent advances in the use of polymers in ionic liquids (ILs) from the view point of the “dawn of neoteric solvents and innovative materials.” The first part of this paper presents a brief review of the solubility parameters of ILs, which are expected to serve as a qualitative guide for predicting polymer solubility in ILs; however, this concept cannot be used to rationalize a number of cases in which strong Coulombic interactions dominate the solubility paramet

Poly(benzyl methacrylate) (PBzMA) and its copolymers exhibit lower critical solution temperature (LCST)-type phase separation in common hydrophobic ionic liquids (ILs) such as 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfone)imide ([C(2)mim][NTf2]). The turbidity measurements for PBzMA/IL mixed systems reveal that the LCST-type phase separation temperatures change significantly with the changes in the chemical structures of polymers and ILs. Moreover, cross-linked PBzMA gels show reversi

Abstract Poly(N-isopropylacrylamide) and its gels exhibited upper critical solution temperature behavior in a hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfone)imide, which may be utilized to prepare stimuli-sensitive polymer systems without the problem of solvent evaporation.

Highly stretchable and self-healing polymer gels formed solely by physical entanglements of ultrahigh-molecular weight (UHMW) polymers were fabricated through a facile one-step process. Radical polymerization of vinyl monomers in ionic liquids under very low initiator concentration conditions produced UHMW polymers of more than 10⁶ g/mol with nearly 100% yield, resulting in the formation of physically entangled transparent polymer gels. The UHMW gels showed excellent properties, such

We describe the doubly thermosensitive micellization-unimer-inverse micellization self-assembly of diblock copolymers in ionic liquids (ILs). Well-defined diblock copolymers (PBnMA(11)-b-PNIPAm and PBnMA(22)-b-P(NIPAm-r-AAm)) were prepared by reversible addition−fragmentation transfer (RAFT) polymerization, where BnMA, NIPAm, and AAm refer to benzyl methacrylate, N-isopropyl acrylamide, and acrylamide, respectively. The typical hydrophobic ILs 1-ethyl-3-methylimidazolium bis(trifluoromethane sul

Biomimetic cross-linked polymersomes that exhibit a self-beating motion without any on-off switching are developed. The polymersomes are made from a well-defined synthetic thermoresponsive diblock copolymer, and the thermoresponsive segment includes ruthenium catalysts for the oscillatory chemical reaction and vinylidene groups to cross-link the polymersomes. Autonomous volume and shape oscillations of the cross-linked polymersomes are realized following redox changes of the catalysts.

We present azobenzene-containing random copolymers exhibiting upper critical solution temperature (UCST) phase separation in an ionic liquid (IL). A series of well-defined random copolymers comprising N-isopropylacrylamide (NIPAm) and 4-phenylazophenyl methacrylate (AzoMA) were successfully prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization, using S-1-dodecyl-S′-(α, α′-dimethyl-α″-acetic acid)trithiocarbonate as a RAFT agent. The UCST phase separation temperature

The reversible micellization and sol-gel transition of block copolymer solutions in an ionic liquid (IL) triggered by a photostimulus is described. The ABA triblock copolymer employed, denoted P(AzoMA-r-NIPAm)-b-PEO-b-P(AzoMA-r-NIPAm)), has a B block composed of an IL-soluble poly(ethylene oxide) (PEO). The A block consists of a random copolymer including thermosensitive N-isopropylacrylamide (NIPAm) units and a methacrylate with an azobenzene chromophore in the side chain (AzoMA). A phototrigge

We report the reversible photoinduced self-assembly of a diblock copolymer in a typical hydrophobic ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim]PF6). A series of random copolymers consisting of 4-phenylazophenyl methacrylate and N-isopropylacrylamide (P(AzoMA-r-NIPAm)) show both photoresponsive solubility changes and upper critical solution temperature (UCST) phase transitions in [C4mim]PF6. The UCST phase transition temperature of the random copolymer depends strongly

Rhythmic oscillation of the scattering intensity and hydrodynamic radii of a block copolymer solution driven by the Belousov-Zhabotinsky (BZ) reaction was demonstrated without any on-off switching of external stimuli. This is the first report on a synthetic block copolymer that realizes the novel concept of self-assembly assisted by a dissipative structure.

In the field of polymer science, many kinds of polymeric material systems that show a sol-gel transition have been created. However, most systems are unidirectional stimuli-responsive systems that require physical signals such as a change in temperature. Here, we report on the design of a block copolymer solution that undergoes autonomous and periodic sol-gel transition under constant conditions without any on-off switching through external stimuli. The amplitude of this self-oscillation of the

We describe a functional soft material that can spontaneously repair damage by straightforward application of light illumination. The composite material is composed of a common ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim]PF6), and a well-defined ABA triblock copolymer consisting of the IL-compatible poly(ethylene oxide) (PEO) middle block with thermo- and photosensitive random copolymers combining N-isopropylacrylamide (NIPAm) and 4-phenylazophenyl methacrylate (Az