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A series of porous poly(ionic liquid)s (PILs) were synthesized using an innovative method which involves the synthesis of a non-ionic co-polymer of divinylbenzene and vinylimidazole, followed by an alkylation step to introduce the Io nic Liquid functionality in the polymeric matrix. This synthetic strategy allowed to obtain tuneable imidazolium type PILs having simultaneously high surface area and exposed ionic moieties. A set of PILs was obtained changing systematically the alkyl chains, the anions and the cross-link degree. This approach allowed to elucidate the effect of each synthetic variable on the catalytic performances of PILs towards carbon dioxide cycloaddition reaction in very mild conditions (room temperature and low pressure). Finally, in-situ FTIR spectroscopy allowed to establish a relation between structure of PILs and their catalytic properties.

Imidazolium based porous cationic polymers were synthesized using an innovative and facile approach, which takes advantage of the Debus-Radziszewski reaction to obtain meso-/microporous polymers following click-chemistry principles. In the obtained set of materials, click based-porous cationic polymers have the same cationic backbone whereas they bear the commonly used anions of imidazolium poly(ionic liquid)s. These materials show hierarchical porosity and good specific surface area. Furthermore, their chemical structure was extensively characterized using ATR-FTIR and SS-NMR spectroscopies, and HR-MS. These polymers show good performance towards carbon dioxide sorption, especially those possessing the acetate anion. This polymer can uptake 2 mmol/g of CO2 at 1 bar and 273 K, a value which is among the highest recorded for imidazolium poly(ionic liquid)s. These polymers were also modified in order to introduce N-heterocyclic carbene along the backbone. Carbon dioxide loading in the carbene containing polymer is in the same range of the non-modified versions, but the nature of the interaction is substantially different. Combined use of in-situ FTIR spectroscopy and micro-calorimetry evidenced a chemisorption phenomenon that brings to the formation of an imidazolium carboxylate zwitterion

Porous poly(ionic liquid) membranes that were prepared via electrostatic cross-linking were subsequently covalently cross-linked via formation of a 1,3,5-triazine network. The additional covalent cross-links do not affect the pore size and pore size distribution of the membranes and stabilize them towards salt solutions of high ionic strength, enabling the membranes to work in a broader environmental window.Porous polymer membranes are a field of growing interest both in academia and industry. [1][2][3][4][5][6][7] Such membranes are composed of polyelectrolytes, where the charge character of the polymer affords a wide range of applications such as sensing, separation and catalysis. [8][9][10][11][12][13][14][15][16][17][18][19] From a structural point of view, the porous morphology of the membrane is important, especially considering the pore size, pore size distribution, and pore stability that dictate the transport behaviour of the membranes. 20In order to generate porosity inside polyelectrolyte membranes, there have been several strategies developed, such as layer-by-layer deposition, templating, etc. It is also possible to take advantage of interpolyelectrolyte complexation between two oppositely charged polyelectrolytes (or a polyelectrolyte and an oppositely charged species) to construct porous polyelectrolyte membranes if a phaseseparation process can arise simultaneously. 8,21 Our group previously exploited this complexation technique to create porous membranes based on two components, (i.e. an imidazolium poly(ionic liquid) (PIL), which is a polyelectrolyte built up from ionic liquid (IL) monomers, 22 and a multiacid compound that is usually organic compounds with multiple carboxylic acid units or poly(acrylic acid)). [23][24][25] These PIL membranes are versatile because by changing the IL moiety, its polymer characteristics, or the multiacid type that electrostatically cross-links the PIL, it is possible to confer different pore size to target different separation or transport applications. [25][26][27][28][29] Nevertheless, the first generation of porous PIL membranes suffered from a stability issue, as the interpolyelectrolyte complex membrane is ionic in nature and in a highly ionic environment undergoes partial, if not full, dissociation. This instability issue restricts the porous PIL membranes to be used in the absence of liquid electrolytes either in aqueous or organic solution. To address this issue, an easy strategy is to introduce covalent cross-links in addition to the existing electrostatic, noncovalent ones. This concept has already been exploited in covalently cross-linked amino-and carboxylat-containing polymer chains, forming an amide linkage for a better control over the swelling properties of the resulting membranes. [30][31][32] Taking advantage of the "click-"chemistry represents another way to covalently cross-link membranes forming a 1,2,3-triazole ring.33 Moreover, diols have been proven to be able to covalently cross-link carboxylate groups upon ester formation. 34...

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Palladium nanoparticles in vinylimidazolium-based polymers and poly­(ionic liquid)­s (PIL)­s have been synthesized, systematically characterized, and preliminarily tested in the selective hydrogenation of p-chloronitrobenzene to p-chloroaniline. In both nonionic polymers and PILs the palladium nanoparticles were found to be extremely small (below 2 nm) and hardly detectable by means of transmission electron microscopy (TEM) and X-ray powder diffraction (XRPD), but they have been successfully detected by Fourier transform infrared (FT-IR) spectroscopy of adsorbed CO, which indicated that the available metal surface was approximately the same, as well as the types of exposed sites. In nonionic polymers palladium nanoparticles are stabilized mainly by the interaction with the nitrogen atoms of the imidazole ring, which act as electron donors. In contrast, in absence of available nitrogen species inside PILs, palladium nanoparticles are mainly stabilized by the iodide anions, which determine important electronic effects at the palladium surface. PILs/Pd samples were tested in the selective reduction of p-chloronitrobenzene to p-chloroaniline, under remarkably mild conditions (room temperature, absence of solvents, gaseous H2 below 1 atm). The reaction was followed by FT-IR spectroscopy in operando. All the PILs/Pd samples display an excellent chemoselectivity, whereas nonionic polymers/Pd samples are not selective. Since the morphology and size of the palladium nanoparticles is the same in all the catalysts, it is concluded that the driving force for chemoselectivity is the ionicity of the environment provided by the PIL scaffolds.

An imidazolium-based poly(ionic liquid) is covalently crosslinked via UV-light-induced thiol-ene click chemistry to yield a stable porous polyelectrolyte membrane, which carries gradients of crosslink density and pore size distribution along its cross-section from top to bottom.

Porous ionic liquid materials are a well-established reality in the field of functional porous materials. The combination of porosity with ionic liquid functionality gives rise to a large variety of materials useful for a broad range of applications, ranging from gas adsorption/separation to catalysis. This chapter gives an overview of all kinds of porous materials that bear an ionic liquid functionality ranging from porous poly(ionic liquid)s, to porous cationic polymers and ionic liquids supported or grafted on several kinds of pre-formed porous inorganic or hybrid materials. In particular, in hybrid materials, the ionic liquid moiety is an integrated part of the organic–inorganic hybrid structure, as in the case of metal–organic frameworks (MOFs), and periodic mesoporous organosilicas (PMOs). The porous materials described in this chapter bear the common ionic liquid functionalities, such as imidazolium, pyridinium and ammonium. A brief discussion is given on the synthetic approaches and on the evaluation of the porosity in terms of surface area and pore size distribution, distinguishing between microporous and mesoporous materials.