Surface Polymerization of Poly( <scp>l</scp> -lactide) on Iron for the Development of a Non-Hormonal Intrauterine Device

The copper intrauterine device (Cu-IUD) is the only reversible, long-acting, and nonhormonal form of contraceptive available. However, similarly to hormonal IUDs, the Cu-IUD causes adverse side effects for many of its users. This motivates the development of alternative nonhormonal IUDs, including those based on other metals such as Fe. However, despite the contraceptive efficacy of Fe ions, the rapid corrosion of Fe under biological conditions has limited its use as a nonhormonal IUD material. In this study, we explore the polymerization of poly(l-lactide) (PLLA) directly from the surface of Fe substrates and examine the properties of coated samples in the context of their use as nonhormonal IUDs. By utilizing a reductive electrografting technique, 4-(2-hydroxyethyl)benzene was bound electrochemically to the Fe surface, and uniquely, the hydroxy group enabled the initiation of PLLA polymerization. The resulting PLLA-coated Fe surfaces were characterized using optical microscopy, atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy to demonstrate that the polymer was successfully attached to the Fe surface. Additionally, the corrosion rate of the PLLA-coated Fe was evaluated using potentiodynamic polarization and compared to uncoated Fe exposed to the same experimental conditions, showing a decrease by a factor of 4 in degradation rate comparable to that of Cu under similar conditions. These results demonstrate the potential of PLLA as an effective, biodegradable coating material for enhancing the corrosion resistance of Fe-based IUDs.