Efficient Shockwave Energy Dissipation in Dynamic PDMS Networks

Polymer networks containing dynamic bonds have received increasing attention over the past decade. Depending on the specific bond, a certain amount of energy is required for the bonds 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 energy, in particular from a shockwave. The density of dynamic bonds can be controlled which controls the modulus while the network Tg is unchanged. Using a classical laser induced shockwave technique, superior energy dissipation is observed in a PDMS dynamic rubber compared to the benchmark polyurea. The dynamic PDMS also outperforms covalently crosslinked PDMS and shows a monotonic improvement in dissipation performance 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. The dynamic networks can be shocked multiple times with invariant performance suggesting the mechanism is non-destructive and related to bond exchange rather than breakage.