(336e) Quantifying Interfaces and Multilayer Self-Healing of Periodic Dynamic Polymers with Identical Backbones and Distinct Dynamic Bonds

Dynamic polymers offer a promising platform for the design of multifunctional soft electronic devices due to their highly tunable chemical structures. Incorporating periodic dynamic bonding motifs with low binding energies (~10–150 kJ/mol) into flexible polymer backbones promotes a reconfigurable network topology, enabling thermoplastic elastomers with efficient self-healing behavior at readily accessible temperatures. These advances have led to the development of self-healing polymer-based devices, including field-effect transistors, light-emitting capacitors, battery-based sensors, and advanced multifunctional sensing platforms. Despite progress, achieving robust adhesion between distinct layers, and improving efficacy of functional healing upon damage and potential misalignment of these multilayer composite devices remains a challenge. It is important to investigate how molecular architecture dictates bulk rheology, self-healing dynamics and interfacial properties such as adhesion and the potential for multilayer autonomous alignment. Here we show how a pair of self-healing polymers with identical flexible backbone (polydimethylsiloxane, PDMS) but different dynamic bonding interactions (i.e. hydrogen bonding (HB) vs. metal-ligand coordination (ML)) exhibit thermodynamic immiscibility via physically crosslinked structures formed by each distinct network. To achieve relatively matching thermo-rheological behavior, and thus similar self-healing dynamics, mixed strength dynamic bonding interactions of specific ratios were incorporated for both the HB and ML motifs. We evaluated the self-healing behavior of each polymer, and interfacial adhesion between the pair using a modified rheometer technique, revealing a 20% reduction in work per unit area required to separate the welded interface when compared to self-healing case. To quantify the width of the interface, polymer bilayers were annealed at different temperatures and cross-sections were characterized using atomic force microscopy. These experiments showed how immiscibility in bilayer system persists up to 130°C, demonstrating the impact of dynamic bond-driven interphase separation. On-going experiments have demonstrated preliminary evidence of autonomous alignment behavior in damaged, misaligned multilayers annealed at elevated temperatures. These findings provide insights into the interface behavior of dynamic polymer networks, and further increase the comprehension of alignment potential and supporting the integration of dynamic polymers in smart multifunctional self-healing multilayer devices.