Origins of Electromechanical Behavior in Surface-Localized Nanocomposites: Insights into Crack Network Dynamics and...

Area of Science:

• Materials Science
• Nanotechnology
• Space Engineering

Background:

• Advanced materials are crucial for lunar and Martian exploration.
• Electrically conductive thin films are vital for space applications like structural monitoring and dust shielding.
• Surface-localized nanocomposites (SLNCs) present a flexible, durable alternative to traditional films.

Purpose of the Study:

• To investigate the electromechanical properties of SLNCs under tensile and bending stress.
• To evaluate the influence of different polymer substrates on SLNC performance.
• To identify failure mechanisms and their impact on conductivity.

Main Methods:

• Melt infiltration of chemically modified reduced graphene oxide (CMrGO) into polymer substrates (OBC, HDPE, PVDF).
• Monotonic electromechanical tensile testing and static bending tests.
• In situ microscopy and optical profilometry during deformation.

Main Results:

• SLNCs exhibited a linear piezoresistive response in the elastic regime and a substrate-dependent nonlinear response beyond yield.
• Substrate ductility significantly impacted the gauge factor (GF), with OBC and HDPE showing higher GFs (20-100) than PVDF (2).
• Small resistance changes were observed during sharp bending, and crack network development was identified as a key mechanism for nonlinear response.

Conclusions:

• SLNCs demonstrate tunable electromechanical properties influenced by polymer substrate choice.
• The observed low GF in the elastic regime and during bending is advantageous for flexible electronics in space structures.
• Crack formation, closure, and particle network rearrangement are critical to the piezoresistive behavior of these nanocomposites.