Macromolecules, Vol.32, No.11, 3565-3573, 1999
Influence of hydroxy functionalization and metal cross-linking on fiber properties of liquid-crystalline polyazomethines
A number of semiflexible liquid-crystalline polyazomethines have been synthesized by condensation of two dialdehyde monomers (1,10-bis[(4-formyl-3-hydroxyphenyl)oxy] or 1,10-bis[(4-formylphenyl)oxy]decane) with two diamines (2-methyl-1,4-phenylenediamine or 3,3'-dimethoxybenzidine). Polyazomethines having a hydroxyl group at the ortho position of the imine bond have higher degrees of polymerization and a remarkable tendency to show an increase in their molecular weight upon postpolymerization thermal treatments. These hydroxy-functionalized polymers have been coordinated with copper(II) ions to give rise to metallomesogenic cross-linked polymers. Fiber spinning of both organic and copper(II)-complexed polymers has been carried out, and the structure, orientation, and morphology of the fibers have been studied by X-ray diffraction, electron paramagnetic resonance, and scanning electron microscopy. The mechanical properties have also been evaluated. Hydroxy functionalization and copper(II) complexation are the key strategies to obtain highly oriented fibers with good mechanical properties and strong intermolecular cohesive forces. A highly oriented crystalline phase with improved mechanical properties could be developed by thermal annealing of "as-spun fibers".