Polyoxometalate-Containing Supramolecular Gels

Supramolecular gels are important soft materials with various applications, which are fabricated through hydrogen bonding, π-π stacking, electrostatic or host-guest interactions. Introducing functional groups, especially inorganic components, is an efficient strategy to obtain gels with robust architecture and high performance. Polyoxometalates (POMs), as a class of negatively-charged clusters, have defined structures and multiple interaction sites, resulting in their potential as building blocks for constructing POM-containing supramolecular gels. The introduction of POMs into gels not only provides strong driving forces for the formation of gels due to the characteristics of charged cluster and oxygen-rich surface, but also brings new properties sourcing from unique electronic structures of POMs. Though many POM-containing gels have been reported, a comprehensive review is still absent. Herein, the concept of POM-containing gels is discussed, following with the design strategies and driving forces. To better understand the results in the literature, detailed examples, which are classified into several categories based on the types of organic components, are presented to illustrate the gelation process and gel structures. Moreover, applications of POM-containing gels in energy chemistry, sustainable chemistry and other aspects are also reviewed, as well as the future developments of this field. This article is protected by copyright. All rights reserved.

Thermoreversible Polymer Gels in DMF Formed from Charge- and Crystallization-Induced Assembly

Polymer organogels formed through dynamic interactions are interesting for various applications. The fabrication of polymer organogels in polar solvents through ionic interaction is rare, although such organogels in non-polar organic solvents have been well studied. Herein, polymer organogels in a polar solvent N,N-dimethyl formamide (DMF) were fabricated from a triblock copolymer, poly(4-vinyl pyridine)-block-poly(ethylene glycol)-block-poly(4-vinyl pyridine) (4VPm-EGn-4VPm), and a fluorinated surfactant, perfluorooctanoic acid (PFOA), and their microphase separation and properties were studied. Ordered microphase separation and the crystalline structures were revealed by small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), respectively. All the 4VPm-EGn-4VPm/PFOA organogels are sensitive to temperature, and the ratio of PFOA to pyridine groups reversibly. The polymer organogels are also responsive to triethylamine and triethylammonium acetate.

Closed-cell and open-cell porous polymers from ionomer-stabilized high internal phase emulsions

We firstly present a strategy that enables fabrication of both closed-cell and open-cell porous polymers (polyHIPEs) from high internal phase emulsions (HIPEs) stabilized with an ionomer.