Yubing Xiong

One‐Step Synthesis of Thermosensitive Nanogels Based on Highly Cross‐Linked Poly(ionic liquid)s

A gel for all seasons: Thermosensitive nanogels based on highly cross-linked poly(ionic liquid)s (CLPNs) were prepared in one step by the copolymerization of imidazolium-based monomers with cross-linkers in selective solvents. Reversible nanogel-macrogel transitions of CLPNs in methanol could be achieved by changing the temperature.

A facile one-step synthesis to ionic liquid-based cross-linked polymeric nanoparticles and their application for CO2 fixation

Highly cross-linked polymeric nanoparticles (CLPNs) were prepared via a facile one-step synthesis, and these nanoparticles are effective catalysts for CO2 cycloaddition with epoxides. In this study, CLPNs were synthesized by radical copolymerization of 4-vinylbenzyl-tributylphosphorous chloride (PIL) and ethylene glycol dimethacrylate (EGDMA) in selective solvent, such as C1∼C5 alcohols. The results revealed that spherical nanoparticles with the mean diameter range of 10–100 nm could be prepared in these alcohols, and the size of the CLPNs could be facilely tuned by the feed ratio of EGDMA to PIL. The CLPNs were characterized using dynamic light scattering, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, thermogravimetric analysis, atom absorbance spectrometry, and Fourier transform infrared spectroscopy techniques. In addition, CLPNs can be exploited as highly active and selective catalyst for the cycloaddition of CO2 to epoxides. The effects of parameters, such as reaction temperature, pressure, reaction time, and catalyst amount, on the cycloaddition reaction were investigated. As a result, excellent yield (100%) and selectivity (100%) of cyclic carbonates could be achieved under mild conditions (0.1 g CLPNs, 3.0 MPa CO2, 140 °C and 3 h) without the addition of any solvents or co-catalysts. Unexpectedly, the CLPNs could be dispersed in the products homogeneously, which resulted in the extremely high activity and selectivity. At the same time, the CLPNs could be easily separated by filtration after pouring the reaction mixture into toluene. CLPNs could be recycled six times with less than 1.5% loss of catalytic activity.

Poly(ionic liquid)-based nanogels and their reversible photo-mediated association and dissociation

Controlling the association and dissociation of polymers and nanoparticles has attracted tremendous interest in the past few decades. In this study, we reported a novel poly(ionic liquid) (PIL)-based nanogel that could undergo reversible photo-mediated association and dissociation through the trans–cis isomerizatioin of azobenzene (Azo) or host–guest interactions between the Azo group and β-cyclodextrin (β-CD) dimer. PIL nanogels were fabricated via the one-step cross-linking copolymerization of ionic liquid (IL) monomers and cross-linkers in a selective solvent, and characterized using dynamic light scattering (DLS), UV-vis spectroscopy, solid state carbon nuclear magnetic resonance (13C NMR), elementary analyses, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analyses (TGA), and scanning electron microscopy (SEM). The results demonstrated that the sizes of PIL nanogels containing Azo units could be facilely tuned through the feed ratio of IL monomers to cross-linkers, and their polarity could also be mediated through anion exchange. Moreover, due to the presence of Azo units, PIL nanogels in water could associate and dissociate reversibly under the alternative irradiation of UV and visible light. Additionally, by using PIL nanogels as the building blocks, supramolecular aggregates could be achieved via the host–guest interaction of Azo and β-CD dimers. The assembly process was testified by UV-vis spectroscopy, DLS, 2D nuclear Overhauser effect spectroscopy (NOESY), and SEM measurements. Therefore, our findings provided a feasible strategy for the photo-induced association and dissociation of polymer nanoparticles.