Photoactivated Nano-Compatibilized Two-Phase Polymer Blends: An Approach for Determining Mechanical Behavior.

Light-activated polymers (LAPs) are shape-shifting materials capable of transforming their shapes in response to photoinduced chemical reactions, such as cis-trans isomerization and dimerization. Owing to the underlying photochemical reaction, these materials often exhibit behavior analogous to multicomponent/phase polymer blends. In this work, we present a free-energy-based theoretical framework to predict the mechanical behavior of nanoparticle-compatibilized elastic LAP blends that exhibit phase separation. In particular, we incorporate the impact of domain sizes and interfacial areas and establish a criterion for the materials' susceptibility to mechanical failure under various loading conditions, namely uniaxial and biaxial stretching. Our framework can also be adapted to high-entropy polymers and thermoresponsive or light-activated systems, with potential applications in soft robotics, biomedical devices, micromechanics, 4D printing, and material origami. Additionally, by integrating our model with physics-informed neural networks, we facilitate efficient analysis of complex domain geometries and enable comprehensive parametric studies.