Polydimethylsiloxane Polymerized Emulsions for Acoustic Materials Prepared Using Reactive Triblock Copolymer...

Area of Science:

• Materials Science
• Polymer Chemistry
• Acoustics

Background:

• Porous polymers exhibit valuable acoustic properties like wave dampening and impedance matching.
• Applications include acoustic waveguiding and cloaking.
• Controlled porosity and mechanical properties are crucial for optimizing sound dampening.

Purpose of the Study:

• To synthesize acoustic materials with independently controllable porosity and mechanical properties.
• To investigate the use of emulsion-templated polymerizations for creating these materials.
• To explore the role of reactive surfactants in tailoring material characteristics.

Main Methods:

• Synthesis of polydimethylsiloxane-based ABA triblock copolymer surfactants via reversible addition-fragmentation chain transfer polymerization.
• Utilizing these surfactants in emulsion-templated polymerizations to form porous polymer networks.
• Characterization of material porosity, mechanical properties (storage modulus), and acoustic properties (sound speed).

Main Results:

• Acoustic materials prepared with reactive surfactants showed a storage modulus of ~300 kPa at 71% porosity.
• Materials from nonreactive surfactants had a storage modulus of ~150 kPa at similar porosities.
• Achieved very low longitudinal sound speeds of ~35 m/s at ultrasonic frequencies.

Conclusions:

• Emulsion-templated polymerization with reactive surfactants enables independent control over porosity and mechanical properties.
• The synthesized porous polymers demonstrate significant potential for acoustic applications.
• These materials are excellent candidates for acoustic devices such as metasurfaces and lenses.