Photoinitiator-grafted polymer chains for integrating hydrogels with various materials

Hydrogels are commonly integrated with other materials. In the one-pot synthesis of a hydrogel coating, polymerization, crosslink, and interlink are concurrent. This concurrency, however, is often inapplicable for integrating hydrogels to other materials. For example, a permeable substrate will absorb small molecules in the solution, causing side reactions and even toxicity. Here, we report a method to break the concurrency by using photoinitiator-grafted polymer chains (PGPCs). A type of photoinitiator is copolymerized with various monomers. The PGPCs are uncrosslinked during synthesis, have long shelf lives in dark storage, and can be applied to a substrate by brush, cast, spin, dip, spray, or print. Under ultraviolet light, the polymer chains crosslink into a network and interlink with the substrate. The cured PGPC hydrogels are characterized by mechanical tests. Furthermore, the PGPCs are demonstrated to adhere wet materials, form hydrophilic coatings on hydrophobic substrates, and pattern functional groups on permeable substrates.