Damage to Polystyrene Polymer Film by Shock Wave Induced Bubble Collapse.

Area of Science:

• Materials Science
• Surface Engineering
• Computational Physics

Background:

• Metallic surfaces are vulnerable to damage from shock wave-induced bubble collapse in various applications.
• Understanding polymer film behavior under such conditions is crucial for developing protective coatings.

Purpose of the Study:

• To investigate the damage mechanisms in polystyrene (PS) films coating a hard surface caused by collapsing nanobubbles and shock waves.
• To analyze the impact of a high-speed water jet generated by bubble collapse on the polymer film's structure.

Main Methods:

• Coarse-grained molecular dynamics simulations were employed to model the interaction between a collapsing nanobubble, an impinging shock wave, and a polystyrene film.
• Analysis of polymer molecule conformational changes and damage patterns (cavities/pits) in the film.

Main Results:

• A collapsing nanobubble interacting with a shock wave generates a high-speed water jet that causes significant damage to the polystyrene film.
• The water jet impact results in localized polymer chain extension perpendicular to the jet's motion and compression in other areas.
• The extent of film damage is demonstrably sensitive to the incident shock wave's strength.

Conclusions:

• Polymer films can be damaged by shock wave-induced bubble collapse, primarily through the generated water jet.
• The simulation provides insights into the molecular-level deformation and damage processes within the polymer film.
• Shock wave intensity is a critical parameter influencing the protective efficacy of polymer coatings against bubble collapse cavitation.