In this article, we report on the formation of optically transparent photopolymer films from hexanediol diacrylate (HDDA) by inkjet printing, where droplets of monomer approximately 5 mu m in diameter were deposited onto a surface. The films were cured by irradiation with a UV-light-emitting-diode light source. It was found that the inkjet-printed HDDA films picked up a considerable amount of absorbed O-2 during printing. Exposure to increasing amounts of O-2 during photocuring severely restricted both the degree of conversion and the UV dose required for gelation in proportion to the O-2 concentration. Viscoelastic property data indicated that exposure to reduced oxygen concentrations during thermal postcuring (dark reaction) resulted in linear trends of increasing modulus above the glass-transition temperature (T-g) and increasing Tg itself. Thus, the final crosslink density was greater in fully cured samples that were exposed to atmospheres with increasing inert gas concentrations. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 2359-2370, 2011