Gelation Of The Double Substituted Imidazolium Ionic Liquids And Fabrication And Characterization Of Their Composite Membranes

Ionic liquids normally have a low melting point, exhibit high conductivity, and are in liquid states at room temperature. Ionic liquids are usually immobilized in a polymer matrix to be used as electrolyte in such as proton exchange membrane fuel cells. During the operation of the fuel cells, water is generated. At temperatures below100℃, the presence of the liquid water in fuel cell will result in the loss of the ionic liquid from the composite membrane. In order to solve this problem, we can prepare the ionic liquid gelation. The ionic liquid gelation has low mobility without conspicuously lose its own excellent characteristics.In the present work, different ionic liquids of hydrophilic BMIMOH and hydrophobic BMIMPF6were synthesized by two steps. Aniline methyl triethoxysilane (ND-42) was used to prepare the ionic liquid gelation by the Sol-Gel method. Characterization of the gelations such as the structure, water solubility, and viscosity was made. The results indicated that the viscosity of two kinds of ionic liquids are getting higher and higher in the process of gelation. In addition, the BMIMOH loss due to high solubility in water was improved. The ionic liquids and their gelations were used to prepare composite membranes with polyvinylidene fluoride (PVDF) and poly ether ether ketone (SPEEK) with a45%of sulfonation degree, respectively. The loss rate of ionic liquids in water from the composite membranes and the conductivities of the membranes were investigated. The gelation of the ionic liquids benefits the maintaining of the ionic liquids but decreased the conductivity of the composite membranes as well.