SYNTHESIS AND CHARACTERIZATION OF CRYSTALLINE POLY(ETHYLENEIMINE)S WITH MESOGENIC SIDE-CHAINS FORMING LIQUID-CRYSTALS ON QUATERNIZATION

The synthesis and thermal properties of a new type of side-chain liquid-crystalline polysalts are described. The polymers are first obtained by partial or complete alkylation of a linear poly(ethyleneimine) with 6-(4-methoxy-4'-biphenylyloxy)hexyl bromide or 12-(4-methoxy-4'-biphenylyloxy)dodecyl bromide. In a second step, polysalts are prepared by partial or complete quaternization with acyl bromide or dimethyl sulfate. Differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction experiments show that the polymers and copolymers alkylated with the mesogenic groups are all crystalline. When quaternized, they exhibit thermotropic smectic A phases. This behaviour confirms the smectogenic function of the ammonium units located in the backbone, as already observed with poly(4-vinylpyridinium) salts.