Direct Imaging of the Diacetylene Solid-State Monomer-Polymer Phase Transformation

The solid-state phase transformation from 1,6-di(N-carbazolyl)-2-4-hexadiyne (DCHD) diacetylene monomer to polymer has been studied dynamically by low-dose selected area electron diffraction and high-resolution electron microscopy. The total exposure required to induce polymerization is five orders of magnitude smaller than the critical dose for electron beam damage. The phase transformation is quasi-homogeneous, with the lattice parameters changing continuously as a function of beam dose. Characteristic streaking that develops in the selected area electron diffraction patterns in the [200] reciprocal directions during the intermediate stages of the transformation provides information about the defect-mediated mechanisms of this reaction.