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Light-Matter Interactions Revealing Load-Induced Phase Mobility in Elastomers
Nha Uyen Huynh1, Behrad Koohbor2, George Youssef1
1Experimental Mechanics Laboratory, Mechanical Engineering Department, San Diego State University, San Diego, CA, 92182, USA.
Macromolecular Rapid Communications
|February 4, 2023
Summary
This study reveals how molecular mobility in segmental elastomers dictates their shock tolerance. Understanding hard and soft segment movement explains their impact resistance, paving the way for advanced material design.
Area of Science:
- Materials Science
- Polymer Physics
Background:
- Segmental elastomers offer superior shock tolerance and impact resistance.
- Their full potential is limited by an incomplete understanding of molecular mechanisms.
- Key to their behavior are aromatic hard domains within an aliphatic soft matrix.
Purpose of the Study:
- To elucidate the molecular contributions to the mechanical behavior of elastomers.
- To quantify microstructural mobility and conformational changes during mechanical loading.
- To understand the origin of shock tolerance in segmental elastomers.
Main Methods:
- In situ light-matter interactions to probe molecular processes during creep.
- High-resolution digital image correlation to analyze strain development and domain mobility.
- Terahertz spectral analysis to investigate interchain hydrogen bonding and conformational changes.
- Experimental and computational light scattering to examine domain dynamics.
Main Results:
- Strain striations and mild anisotropy were observed, linked to domain mobility mechanisms.
- Hard segment mobility was found to be 60% slower than soft segment mobility.
- Terahertz spectra revealed significant conformational changes and interchain hydrogen bonding in hard segments.
- Light scattering elucidated differences in the complex refractive index and dynamics between soft and hard segments.
Conclusions:
- The study provides a quantitative method for measuring molecular mobility and conformational changes in elastomers under load.
- Findings illuminate the origin of shock tolerance in segmental elastomeric polymers.
- This research enables tailored design of high-performance elastomeric materials.
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