A series of diacetylene compounds containing b-alanine ethyl ester and di-b-alanine ethyl ester groups
were synthesized and dip-coated on paper for colorimetric UV sensing study. The white-to-blue-to-red
colorimetric responses of the sensor strips were recorded by a photo scanner. The color images are
analyzed based on the RGB color system to determine the color transition points and sensitivity. Coarse
and fine tuning of the UV sensitivity was achieved by varying the head group and aliphatic chain length
of the diacetylene lipids. Comparison of the UV sensitivity trends with the thermochromic sensitivity
trends revealed that not only the photo-induced thermochromism but also photo-induced mechanical
strain of the polydiacetylene backbone contributed to the color transition upon the UV irradiation.