Interfacial nanoconnections and enhanced mechanistic studies of metallic coatings for molecular gluing on polymer surfaces

Interfacial adhesion has been identified as being key for realizing flexible devices. Here, strong interfacial nanoconnections involving metallic patterns on polymer surfaces were fabricated via a molecular bonding approach, which includes UV-assisted grafting and molecular self-assembly. The interfacial characteristics of conductive patterns on liquid crystal polymer substrates were observed via transmission electron microscopy and atomic force microscopy infrared spectroscopy. The interfacial molecular layers have a thickness of 10 nm. Due to the successful molecular bonding modifications, interfacial adhesion has been sufficiently improved; in particular, the peel-related breakage sites will be located in the modified layers on the plastic surface beneath the interface after the metallic coatings are peeled off. Integrating X-ray photoelectron spectroscopy, infrared spectroscopy, and scanning electron microscopy results, the molecular bonding mechanism has been revealed: UV-assisted grafting and self-assembly result in the construction of interfacial molecular architectures, which provide nanosized connecting bridges between the metallic patterns and polymer surfaces. Such in-depth interfacial studies can offer insight into interfacial adhesion, which will impact on the development of metal/polymer composite systems and continue to push the improvement of flexible devices.