Engineering of molecular stacking arrangement via environmental stimuli is of particular interest in stimuli-responsive self-assembling architectures. A novel dual photo-functionalized diacetylene ((Z)-CNBE-DA) molecule was synthesized, in which photo-responsive cyanostilbene moieties exhibited interesting Z-E isomerization upon UV light irradiation and could be utilized to modulate mesomorphism, molecular stacking arrangement and resulting polymerization behavior. Rod-like (Z)-CNBE-DA could self-assemble into well-defined lamellar structures and the helical polydiacetylene (PDA) chains could be formed upon irradiation with circularly polarized ultraviolet light (CPUL). However, the bent-shaped (E)-CNBE-DA molecules only self-assembled into irregular loose packing, inhibiting the formation of ordered helical PDA chains upon CPUL irradiation. In this work, we established the links between chemical structures, molecular packing engineering and photophysical properties, which would be of great fundamental value for the rational design of smart soft materials. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2458-2466