The polymerized ionic liquid (IL) shows great promise for diverse applications. Some polymerization methods have already been oriented toward specific applications. Polymerized ILs are useful in polar environments or where there are ion species for transport in the matrix. Amphoteric polymers that contain no carrier ions are being considered for several porposes in polymer electrolytes. Zwitterionic liquids (ZILs) were introduced in Chapter 20 as ILs in which component ions cannot move with the potential gradient. ZILs can provide ion conductive paths upon addition of salt to the matrix. It is therefore possible to realize selective ion transport in an IL matrix. If the resulting matrix can form solid film over a wide temperature range, many useful ionic devices can be realized. This chapter focuses on the preparation and characteristics of amphoteric IL polymers.
Amphoteric IL polymers contain no carrier ions, since the migration of component ions is completely excluded by fixing them on the polymer chain. They can therefore transport only added target ions in the matrix. Research into solid polymer electrolytes has so far mainly involved the use of polyether matrices, since these polyethers can dissolve salts and transport the dissociated ions along with intraand intermolecular motion of these polyether chains [1,2]. Polymer matrices having both high polarity and low glass transition temperature are rare. However, the ionic conductivity of certain polyether systems is about 10 ร4 S cm ร1 at room temperature [3], and it is difficult to improve cationic conductivity. This is a consequence of the ion-dipole interaction of polyethers to target ions, known as strong solvation of polyethers to cations. Alternative matrices have therefore been sought in order to overcome the problem. Some polyampholytes, in which both Electrochemical Aspects of Ionic Liquids Edited by Hiroyuki Ohno