Relaxation of the stress produced by photopolymerization of a diacetylene crystal

A single crystal of diacetylene monomer, 1,6-di(N-carbazolyl)-2,4-hexadiyne (DCHD), is polymerized by photo-irradiation keeping the b-axis of polymer crystals parallel to that of monomer crystals on which some amount of stres s is introduced in the lattice of polymer crystals. In the present study, m orphological changes on the surfaces of DCHD polymer crystal were observed by atomic force microscopy in order to examine the relaxation mechanism of such stress. On polymerization, nodule-like structures were formed on the s urface, aligning along the direction of nearly 60 degrees with respect to t he b-axis of monomer crystal. The alignment of nodules is concluded to corr espond to a mechanical slip direction in the monomer crystal.