The Polymer Society of Korea

Abstract

Metastable stress states in soft polymers arise from viscoelastic deformation and delayed stress relaxation but are difficult to visualize directly. Here, non-close-packed photonic crystals are fabricated by melt-shear assembly of core-shell colloidal particles within a soft polymer matrix, where shear-induced ordering defines the photonic structure. Unlike close-packed crystals, the non-close-packed architecture allows stress-induced deformation without lattice locking, enabling continuous optical responses to mechanical history. The resulting films exhibit mechanochromic color changes under external mechanical loading. By tuning the core-shell architecture to impart shape memory behavior, metastable stress states can be optically visualized through time-dependent structural color relaxation.