Light-matter interactions revealing load-induced phase mobility in elastomers.

Elastomers with segmental microstructure are fascinating class of shock-tolerant and impact-resistant materials. However, their technological potential remains untapped due to a vague understanding of the molecular contributions to their superior mechanical behavior. Here, we leverage in-situ light-matter interactions to reveal the extent of microstructural mobility by temporally exploiting molecular processes during creep response. The segmental microstructure comprises of aromatic hard domains embedded within an aliphatic soft matrix. High-resolution digital image correlation reveals the development of strain striations, mild-anisotropy, and the mechanisms responsible for domain mobility, where the rate of hard segment mobility is found to be 60% slower than that of the soft segment. Terahertz spectral analyses pinpoint the contributions of interchain hydrogen bonding of the hard segments and their significant conformational changes by observing spectral features at ∼1.2THz and ∼1.67THz. Moreover, the domain mobility is examined using experimental and computational light scattering approaches, uncovering dynamic scattering and elucidating the difference in the complex refractive index of the soft and hard segments. Our study unlocks the pathway for quantitative measurements of elusive molecular mobility and conformational changes during mechanical loading and sheds light on the origin of the shock tolerance in some elastomeric polymers with segmental microstructure. This article is protected by copyright. All rights reserved.