(649h) Computational Modeling of Interfaces and Self-Healing in Multilayers of Immiscible Dynamic Polymers

Self-healing soft electronic and robotic devices, like human skin, can recover autonomously from some forms of damage. Existing multilayered devices generally employ a single type of dynamic polymer embedded with different functional nano–micro materials for each layer, to provide a cohesive interface between layers. In such devices, successful healing from damage requires precise manual alignment and re-contacting of the fractured interfaces, limiting functional recovery from diverse forms of damage, such as processes leading to imperfect registry of device layers. To overcome these limitations, we have recently designed a pair of dynamic polymers, which have immiscible polymer backbones, but similar dynamic bonding units to maintain interlayer adhesion while providing selectively self-healing layers with similar viscoelastic behavior (and thus self-healing dynamics) over a convenient range of temperatures. Upon lamination, these dynamic polymers exhibit a weakly interpenetrating and adhesive interface, whose width and toughness are tunable with processing temperature. When multilayered polymer films are misaligned after damage, these structures autonomously realign during the healing process through a process which we hypothesize to be governed by the diffusion-mediated minimization of interfacial free energy. This presentation will focus on the computational modeling of these phenomenona using both coarse-grained molecular dynamics simulations and continuum phase field simulations. We use these models to investigate the interplay between the degree of immiscibility (interfacial width), diffusion kinetics of individual polymer chains, and the rate of alignment during self-healing of multilayered systems. These simulations demonstrate the generality of our experimental observations towards different dynamic polymer chemistries and provide a framework for guiding the design of multilayer dynamic polymer systems with improved self-healing efficacy.

Cooper, C.^†; Root, S. E.^†; Michalek, L.; Wu, S.; Lai, J-C.; Khatib, M.; Oyakhire, S.; Zhao, R.; Qin, J.; Bao, Z.*; Autonomous alignment and self-healing in multilayer soft electronics using dynamic polymers with immiscible backbones. Science, 2023