Effects of silicone acrylate on morphology, kinetics, and surface composition of photopolymerized acrylate mixtures

Films (ca. 150 microm thick) of twelve acrylate mixtures, which contained various proportions of hydrocarbon acrylates [mainly oligo(ethylene glycol) diacrylate, (OEGDA)] and small amounts of a silicone hexaacrylate (in proportion of 5% or less), were cured on a nickel substrate, and X-ray photoelectron spectroscopy analysis of the nickel-side surface compositions showed that for formulations with and without the silicone hexaacrylate, this surface was enriched with OEGDA and saturated (up to 50%) with the silicone hexaacrylate, respectively. The silicone hexaacrylate phase-separated and formed micelles which migrated to the resin-nickel interface. Silicone hexaacrylate, inherently less reactive, also significantly slowed the photopolymerization of the mixtures. The sequential homopolymerization of OEGDA and silicone hexaacrylate in a formulation was elicited using real-time Fourier transform infrared spectroscopy. The design-of-experiment approach was used to quantify the influence of the components on gelation time and the nickel-side surface composition as well as provide the statistical models to predict these two properties for new compositions.