Polymers with Ionic Liquid Fragments as Potential Conducting Materials for Advanced Applications

Abstract

During the last decades, the use of ionic liquids (ILs) has become one of the most useful techniques for the development of green chemistry tools.1 The potential use of liquid salts based on delocalized organic cations (ammonium or phosphonium) as designer green solvents represents one of the most significant contributions to modern chemistry. Thus, the high modularity of the structures of the ILs based on the proper selection of the cation and anion moieties has allowed the development of an almost infinite number of compounds well suited for each specific application. Nevertheless, in recent years, the application of ILs also needs to confront some important challenges in order to be able to develop the expected practical applications.2 Thus, some important drawbacks are limiting the general application of ILs in scientific and technological applications. First of all, the cost of ILs is clearly much higher than that for traditional solvents. Additionally, the benefits of the use of ILs as media for different chemical reactions and other applications is counterbalanced by the need of using traditional “non-green” solvents for the extraction of the desired products from the IL phase. Finally, recent studies have shown that, although ILs have been considered traditionally as environmentally friendly solvents because of the lack of any appreciable vapor pressure, some of the most usual ILs present some environmental concerns in particular in terms of their contact with aqueous media.3 Many of those drawbacks can be drastically reduced by the use of supported ILs. The immobilization of ILs onto a solid support provides a simple way for reducing the amount of IL required for a given application, reducing accordingly the associated cost; facilitates their handling and manipulation decreasing the need of using traditional solvents in the corresponding process, and finally, greatly reduces the potential leaching to the environment of the ILs.4 In order to accomplish this target two main approaches have been studied: 1. Non-covalent support of IL phases on the surface of inorganic or organic supports (SILPs). 2. Covalent attachment of IL-like phases on the surface of inorganic or organic supports (SILLPs).