POLY QUINOLINES AND DERIVATIVES

This class of polymers possesses properties similar to those of the ladder polymers, in that their syntheses were known much before the advent of the field of CPs, they are thermally more stable and more easily processible into films and fibers than more conventional CPs, and they can be doped to appreciable conductivity and do possess some semblance of a x-conjugated structure that qualifies them as CPs. Some examples are given in Fig. 14-25. In the early preparations, e.g. that of Stille [676], an acid-catalyzed Friedlander synthesis was employed. 

14-25 Structural units of some poly(quinolines) and derivatives. 

These polymers may also be chemically or electrochemically doped, with both n- and p-doping found. Conductivities as high as 50 S/cm have been claimed [677, 678] for Bu4N -doping (n-type) of the first polymer shown in the schematic above. Methane-sulfonate doping (p-type) of the second polymer above yields a conductivity of ca. 1 S/cm. 

The facile processibility and thermal stability of this class of polymers has also led to increased interest in potential applications. Thus, Agrawal and Jenekhe have studied rigid-rod poly(quinolines) for 3rd-order NLO applications [679], whilst Cai et al. [523] have looked at poled guest-host poly(quinoline) thin films for 2nd-order NLO applications. Wolf et al. [619] documented the use of poly(quinolines) in electrochromic devices. Chandrasekhar et al. [293b,c] have synthesized a series of unique poly(amino quinolines) (below) and demonstrated significant 3rd-order NLO effects in them. 

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