On Going to a New Era of Microgel Exhibiting Volume Phase Transition

The discovery of phenomena of volume phase transition has had a great impact not only on bulk gels but also on the world of microgels. In particular, research on poly(N-isopropylacrylamide) (PNIPAM) microgels, whose transition temperature is close to body temperature, has made remarkable progress in almost 35 years. This review presents some breakthrough findings in microgels that exhibit volume phase transitions and outlines recent works on the synthesis, structural analysis, and research direction of microgels.

Chiral catalysts immobilized on achiral polymers: effect of the polymer support on the performance of the catalyst

Achiral polymeric supports can have important positive effects on the activity, stability and selectivity of supported chiral catalysts.

Polymer ionic liquid network: a highly effective reusable catalyst for one-pot synthesis of heterocyclic compounds

Significant efforts have been devoted to developing immobilized chiral catalysts with high activity, selectivity, and stability. In this present study, a new heterogeneous proline catalyst system was prepared based on strong noncovalent interactions between polymer ionic liquid (PIL) and l-proline. First, pyridine PILs, which can complex with l-proline monomers through noncovalent interactions, were synthesized using reversible addition–fragmentation chain transfer (RAFT) polymerization. The polymer network-supported chiral catalysts were obtained following further free radical polymerization. Different structures were formed in response to different ratios of PIL and chiral monomer, as well as different PIL anions, in the reactions. The new formed layer structures and synergic effects of PIL resulted in heterogeneous catalysts with high catalytic activity and enantioselectivity, thus endowing them with better catalytic performance for the one-pot synthesis of heterocyclic compounds compared to homogeneous catalytic systems. These catalytic systems were able to be reused and recycled five times with no discernible loss in catalytic activity and enantioselectivity. l-Proline was efficiently loaded onto the polymer network simply based on supramolecular interactions, providing a novel method of synthesizing high performance supported catalysts for organic reactions.

Significant efforts have been devoted to developing immobilized chiral catalysts with high activity, selectivity, and stability.

Poly(Ionic Liquid) Based Chemosensors for Detection of Basic Amino Acids in Aqueous Medium

Naked-eye detection of amino acids (AA) in water is of great significance in the field of bioanalytical applications. Herein, polymerized ionic liquids (PILs) with controlled chain length structures were synthesized via reversible addition–fragmentation chain-transfer (RAFT) polymerization and post-quaternization approach. The AA recognition performance of PILs with different alkyl chain lengths and molecular weights was evaluated by naked-eye color change and ultraviolet-visible (UV–vis) spectral studies. These PILs were successfully used for highly sensitive and selective detection of Arg, Lys, and His in water. The recognition performance was improved effectively with increased molecular weight of PILs. The biosensitivity of the PILs in water was strongly dependent on their aggregation effect and polarization effect. Highly sensitive and selective detection of AA was successfully accomplished by introducing positively charged pyridinium moieties and controlled RAFT radical polymerization.

Nanoparticle Based on Poly(Ionic Liquid) as an Efficient Solid Immobilization Catalyst for Aldol Reaction and Multicomponent Reaction in Water

An environmentally friendly nanoparticle-supported catalyst was successfully prepared via in situ ionic complexation between imidazolium-based polymer ionic liquid (PIL) and poly(l-prolinamide-co-MAA). The physical and chemical properties of the obtained nanoparticles were characterized by TEM, FTIR, XPS, and static water contact angle experiments. The surface properties of the nanoparticle were found to significantly affect the catalytic performance. The nanoparticle with PIL outer facilitated the adsorption of reaction substrate in it. As a result, the catalytic system catalyzed the asymmetric Aldol reaction and multicomponent reaction in pure water efficiently. The catalytic system was able to be reused and recycled five times, and with no discernible loss in catalytic activity and enantioselectivity. These findings suggest that nanoparticles based on PIL may provide a new approach for preparing high performance supported catalysts for organic reactions in water. This technology also addresses issues associated with mass transfer in pure water reactions.

A solution to achieve good reusability of MNPs Fe3O4-supported (S)-diphenylprolinoltrimethylsilyl ether catalysts in asymmetric Michael reactions

A PVP-modified MNPs Fe₃O₄-supported Jøgensen–Hayashi catalyst to achieved good reusability with high yields and unchangeable excellent stereoselectivities in the asymmetric Michael addition of propanal to nitroalkenes.

Magnetic Fe3O4 nanoparticles supporting Macmillan with controlled shell structure as an efficient and reusable catalyst for asymmetric reaction

Magnetic nanoparticles grafted with chiral polymer brushes offer an effective way to bridge the gap between heterogeneous and homogeneous catalysis.