Dislocation mediated lattice bending in 1,6-di (N-carbazolyl)-2,4 hexadiyne (DCHD) polydiacetylene droplets

Droplets of 1,6–di (N-carbazolyl)-2,4 hexadiyne (DCHD) polydiacetylene were prepared by room temperature evaporation of dilute (0.01 wt. %) solution of the monomer in chloroform onto amorphous carbon-coated mica substrates. High Resolution Electron Microscopy (HREM) and Selected Area Electron Diffraction (SAED) revealed small crystallographically textured droplets (∼1 μm diameter) with cracks parallel to the [001] chain direction. The droplet geometry allowed us to investigate the organization of the polymer near surfaces. It was found that the curvature of the droplet edge caused a local bending of the polymer crystal lattice. Direct imaging of the molecular structure near the droplet surface revealed that the mechanism of lattice bending was by the formation of edge dislocations. Dislocations were etched in some droplets to gain information about perturbations in structure and reactivity near the core.