Preparation of needle-like poly(azomethine) crystals by means of reaction-induced crystallization of oligomers

Needle-like poly(azomethine) crystals were successfully prepared by the polycondensation of 1,4-phenylenediamine and 1,4-terephthalaldehyde in liquid paraffin at 180 °C. The favorable polymerization concentration for the preparation of the well-defined needle-like crystals was 2.0×10−2 mol l−1. The average length and width of the needle-like crystals were 7.7 and 0.6 μm, respectively. These crystals possessed high crystallinity and good thermal stability. The extended polymer chains were aligned along the long axis of the needle-like crystal. The morphological observations indicated that the needle-like crystals were formed through the spiral growth of the oligomer lamellae caused by the screw dislocation.