Designing sustainable and high-strain rate energy dissipating materials using lipoic acid derivatives

Shock wave is a powerful and nonlinear acoustic pressure wave generated by high-energy explosion. Its potential to cause severe damage from buildings to human organs emphasizes the critical need for shock wave energy dissipation materials. Dynamic covalent bonds possess intermediate bond energy, allowing selective breaking and energy dissipation in response to external forces. These dynamic motifs are introduced into covalent polymer networks to enhance strain at break and toughness. Recent research highlights the effectiveness of these dynamic motifs in dissipating high-strain rate energy, particularly in shock waves. Herein, we investigate how polymer architectures and rates of dynamic covalent exchange reactions influence the dissipation of shock wave. Lipoic acid (LA)-derived polymers are chosen as the model system due to their tunable side chains and disulfide-rich main chain backbones. To control the aliphatic chain length and the presence of hydrogen bonding in LAs, we employ esterification or amidification of their carboxylic acid end groups. The exchange reaction of disulfides is accelerated at room temperature by adjusting the amount of a strong base. Employing a laser-induced shock wave technique, we demonstrate the superior energy dissipation in dynamic poly(disulfide)s characterized by optimal side chain length and rapid disulfide exchange rate. Furthermore, these polymers exhibit fast self-healing and efficient chemical recycling, which presents a promising route for designing sustainable materials with superior energy-dissipating capabilities.