Drastically different morphological anisotropy was induced by linear photopolymerization in thin amorphous films of poly(vinyl 4-methoxy-cinnamate) (PVMC) and Langmuir-Blodgett films of 12-8(poly)diacetylene (PDA) deposited on glass substrates. Examination of these films by x-ray reflectivity reveals that the PVMC films became rough while PDA thin films became smooth along the direction of polarization of uv light. The elongated x-ray coherence area inherent to the reflectivity technique allowed quantitative determination of changes in the film morphology and structure.