In this study, a facile strategy for the preparation of thermo- and pH-responsive nanogels through reversible addition–fragmentation transfer (RAFT) crosslinking copolymerization of ionic liquid-based monomers is demonstrated. The use of chain transfer agents (CTAs) containing carboxyl group in the RAFT polymerizations is the key to producing highly thermoresponsive nanogels. Experimental results demonstrate that the critical gelation temperature of the as-prepared nanogels can be tuned by adjusting the feed ratio of monomer and CTA. Variable temperature Fourier transform infrared measurements and control experiments indicate that hydrogen-bonding interactions between the carboxyl groups of CTAs are responsible for the thermoresponsive behaviors of poly(ionic liquid) (PIL)-based nanogels. Furthermore, PIL-based nanogels are also found to be pH-sensitive, and can be further decorated by poly(N-isopropylacrylamide) (PNIPAAm) via surface grafting polymerization. PNIPAAm-grafted nanogel aqueous solutions can be reversibly transformed into macrogels upon a change in temperature. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 169–178

The development of novel materials for carbon dioxide (CO₂) capture is of great importance in resource utilization and environmental preservation. In this study, imidazolium-based ionic liquids (ILs) with symmetrical ester and hydroxyl groups were prepared, and their corresponding polymer were synthesized by melt condensation polymerization. The structure and properties of the poly(ionic liquid)s (PILs) were characterized by proton nuclear magnetic resonance, gel permeation chromatograph, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. In addition, the CO₂ sorption behavior of the IL monomers and PILs were studied at a low pressure (648.4 mmHg CO₂) and under a temperature of 25°C using a thermogravimetric analyzer. The CO₂ sorption capacity of 1,3-bis(2-hydroxyl ethyl)-imidazolium hexafluorophosphate ([HHIm]PF₆, 10 mol%) was the highest among all the IL monomers and PILs studied. This capacity is also much higher than those reflected of previously reported ILs. Moreover, the sorption equilibrium of [HHIm]PF₆ was achieved within a short time. Copyright © 2011 John Wiley & Sons, Ltd.

Anhydrous conductive membranes composing of a composite of chitosan (CS) and ionic liquids with symmetrical carboxyl groups were explored. Scanning electron microscope images revealed that porous composite membranes could be obtained by combining CS with different amounts of 1,4-bis(3-carboxymethyl-imidazolium)-1-yl butane chloride ([CBIm]Cl). Fourier transform infrared and proton nuclear magnetic resonance confirmed that the formation of ammonium salts after CS was combined with [CBIm]Cl. The thermal property of CS–ionic liquid composite membranes was studied through thermogravimetric analysis. The anhydrous ionic conductivities of CS–[CBIm]X (X = Cl, Ac, BF₄, and I) composite membranes were measured using ac impedance spectroscopy at room temperature in N₂ atmosphere. The conductivities (0.4–0.7 × 10⁻⁴ Scm⁻¹), found to be in the same range as semiconductors, were significantly higher than those of pure CS membrane (<10⁻⁸ Scm⁻¹). In addition, the anhydrous conductivity of composite membrane based on CS–[CBIm]I at room temperature reached a level as high as 0.91 × 10⁻² Scm⁻¹ when iodine was doped. Copyright © 2011 John Wiley & Sons, Ltd.

Highly cross-linked polymeric nanoparticles were prepared via novel one-step synthesis by copolymerizing ethylene glycol dimethacrylate (EGDMA) and the ionic liquid, 1-vinyl-3-(2-methoxy-2-oxyl ethyl) imidazolium chloride ([VMIm]Cl). The results indicated that nanoparticles with the average size of about 350 nm could be obtained conveniently through the cross-linking copolymerization. The nanoparticles were characterized using scanning electron microscopy, atomic force microscopy, Fourier transform Infrared, thermo gravimetric analysis, element analysis, and X-ray diffraction techniques. Moreover, the cross-linked polymeric nanoparticles were highly active and selective catalysts for the cycloaddition reaction of carbon dioxide to epoxides. The influences of reaction time, reaction temperature, CO₂ pressure, and amount of catalyst on yield of the products were investigated. The results revealed that cyclic carbonates with high yield (98.4%) and selectivity (100%) could be produced on the condition of 0.1 g catalyst, 5 MPa CO₂, 160°C and 12 h. In addition, the nanocatalysts could be easily recovered by filtration, and reused several times with only slight loss of catalytic activity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012