Laser-induced Cavitation Dynamics of Polydimethylsiloxane with Varying Cross-Linking Density and Molecular Weight*

High-strain-rate mechanical properties of a cross-linked polymeric model system are relevant to understanding the dynamics and damage mechanisms of various biological tissues under HSR mechanical stimuli. We present the characterization of two material systems: 1) a commercially available polydimethylsiloxane (Sylgard 184) prepared with varying crosslinking times at fixed temperature; 2) a UV-curable polydimethylsiloxane having different controlled molecular weights. For high-strain-rate characterization, we performed laser-induced cavitation with ablation seeds. The ablation seed in a specimen was vaporized without dielectric breakdown, and produced a rapidly expanding cavity. The expansion dynamics of the laser-induced cavity was observed using ultrafast imaging. The dataset obtained from time-dependent radii of cavities was numerically analyzed, and the material's HSR mechanical parameters were identified. This study can lead us to establish a high-strain-rate mechanical characterization method for soft materials including various tissues.