Polymer networks can be crosslinked via permanent covalent bonds. Polymer networks can include super-soft hydrogels that mimic human tissue , protective ultra-hard coatings , and highly bonded adhesives . Highly crosslinked lightweight networks, such as those formed with epoxide, are crucial in industrial applications like transportation, where reducing vehicle weight improves passenger safety and reduces harmful greenhouse gas emissions. The process of crosslinking or "curing" polymers is typically accomplished via a) mixing, b) heat, or c) high energy light. Heat and light are popular routes, as they facilitate curing on-demand, allowing liquid application to a substrate. However, light and heat are not always feasible, as light cannot pass through opaque materials, and heat can damage delicate or flammable substrates.