STUDY ON THERMOTROPIC LIQUID-CRYSTALLINE POLYMERS .1. SYNTHESIS AND PROPERTIES OF POLY(AZOMETHINE-URETHANE)S

A series of novel azomethinediols, benzene 1,4-di(4-iminohydroxyphenox y-n-alkanol)s was prepared from 4-[4-(4-hydroxybenzylideneamino)phenyl iminomethyl] phenol with 2-chloroethanol, 3-bromopropanol, 6-bromohexa nol, respectively. A series of poly(azomethine-urethane)s was prepared by condensation of benzene 1,4-di(4-iminohydroxyphenoxy-n-alkanol) wi th hexamethylene-diisocyanate (HMDI), isophorone-diisocyanate (IPDI), 4,4'-methylene-di(phenyl-diisocyanate) (MDI) and 2,4-toluylene-diisocy anate (2,4 TDI), respectively. Thermotropic liquid crystalline propert ies of these synthesized poly(azomethine-urethane)s were examined by d ifferential scanning calorimetry (DSC), optical photomicroscopic obser vation, X-ray diffraction and thermogravimetric analysis (TGA). All of the polymers, except polymers P2, P3 and P7, exhibit thermotropic liq uid crystalline properties.