Processible polyazomethines and polyketanils: From aerospace to light-emitting diodes and other advanced applications

Conjugated polymers have attracted widespread interest during the last two decades, because of their useful electronic, optoelectronic, electrochemical and non-linear optical properties. In this paper we discuss synthetic routes (Section 2) and spectroscopic properties (Section 4) of the principal conjugated polymers with imine groups (C=N) in the main chain, such as polyazomethines (Schiff bases) and polyketanils (polyketimines). Special emphasis is put on the molecular and supramolecular engineering approach (Sections 3-7), which allows tuning of processibility and special desired properties of these polymers. Selected examples of possible technological applications of conjugated polymers containing imine groups are presented, such as their use as optical pH sensors, detectors, catalyst carriers or light-emitting diodes (Section 4). Additionally, the polyazomethines and polyketanils are thermally stable, making them potential candidate materials for aerospace applications (Section 4.1). Polyazomethines with liquid crystal properties are also considered (Section 5). The paper is completed by discussion of non-covalent interactions between dopant (Lewis and Brönsted acids) and conjugated polymers (polyazomethines and polyketanils) (Sections 3.2 and 7).