A new single-/two-photon sensitive monomer, (E)-5-(4-ethoxystyryl)-2-nitrobenzyl methacrylate (ENbMA), was synthesized and copolymerized with methyl methacrylate (MMA) to form a series of photosensitive copolymers P(ENbMA-MMA)s that were well characterized by H-1 NMR and GPC. The photochemical and photophysical properties of both photosensitive monomer and copolymers upon visible light irradiation were studied by UV-Vis, FTIR, and HPLC spectra, which confirmed that 5-(4-ethoxystyryl)-2-nitrobenzyl ester can be photolyzed effectively with generation of the corresponding 5-(4-ethoxystyryl)-2-nitrosobenzaldehyde and carboxylic acid groups. The successful photocleavage endowed the optimized copolymers with excellent micropatterning property due to the effective generation of alkaline-soluble carboxylic acid groups. Moreover, the high two-photon absorption cross-sections (over 20 GM at 800 nm) and the comparable photolysis upon two-photon NIR light irradiation of the chromophores provided the copolymers with significant application in two-photon microfabrication. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4099-4106, 2013