Layer structures. 9. Poly(ester-imide)s with a four-layer or a six-layer repeat unit

Two isomeric poly(ester-imide)s, PEIs, were synthesized, consisting of two N-(4-oxyphenyl)trimellitimide moieties connected by 1,12-dodecane and tetra(ethylene oxide) spacers in an alternating sequence. Futhermore, two poly(ester-imide)s were prepared from two different mesogens and two different spacers, so that a repeating unit consisting of six subunits was obtained. Optical microscopy, DSC measurements, and WAXS powder patterns recorded with synchrotron radiation at variable temperature agree in that no poly(ester-imide) forms an enantiotropic LC phase. The WAXS powder patterns also prove, in agreement with the DSC measurements, that all poly(ester-imide)s form crystalline layer structures with an orthorhombic order of the imide moieties. The fiber patterns confirm for all four PEIs that the rigid building blocks (mesogens) are in upright position relative to the layer planes at ambient temperature.