Surface energy gradient surfaces created by latent alpha-particle tracks in SSNTDs

Surface energy gradient surfaces with changes in the ratio of the polar component (γ_s^p) to the dispersive component (γ_s^d) of the surface energy γ_s have been successfully fabricated by irradiating CR-39 solid-state nuclear track detectors (SSNTDs) with 3 MeV alpha particles with different fluence followed by irradiation with ultraviolet photons with 257 nm. The alpha-particle source has an activity of 0.1 μ Ci and the irradiation time ranges from 1 to 7 d. The contact angles for doubly distilled water, glycerin and ethylene glycol, as well as γ_s do not vary significantly with the alpha-particle irradiation. In contrast, γ_s^p decreases steadily while γ_s^d increases steadily, and the ratio γ_s^p / γ_s^d decreases significantly with the alpha-particle fluence. Such surface energy gradient surfaces are of particular interest for establishing the relationship between the γ_s^p / γ_s^d ratio and the biocompatibility. © 2008 Elsevier Ltd. All rights reserved.