Efficient Shockwave Energy Dissipation in Dynamic Covalent PDMS Rubber

Polymer networks containing transient bonds require some amount of energy to undergo an exchange process. We hypothesize and demonstrate that dynamic bonds in polydimethylsiloxane (PDMS) networks can be used as an effective mechanism for dissipating shockwave energy. By controlling the diol molecular weight, the density of dynamic boronic ester linkages can be controlled while the network chemistry is invariant. Using a classical laser induced shockwave technique, we demonstrate superior energy dissipation in a PDMS boronic ester dynamic rubber (PDMS-B-DR) compared to the benchmark polyurea and covalent PDMS (cured via thiol-ene click chemistry). A monotonic improvement in dissipation performance (monitored as a reduced peak pressure of the shockwave) is observed with increasing density of dynamic boronic ester bonds. In all cases, the Tg is invariant in the different networks (-125 °C) implying a minimal role of segmental dynamics on dissipation in these specific networks. Our results indicate that dynamic networks are a promising route to engineering improved SWED materials which are lightweight, flexible, and able to withstand repeated shocks. X-ray scattering and rheology have also been performed to relate dissipation performance to structure and relaxation of the material.