Dual‐Fluorophore Labeling for Polymer Blending Differentiation and Visualization

ABSTRACT The visualization of phase separation in immiscible polymer blends holds significant industrial and academic relevance, as the resultant phase architecture governs the macroscopic properties and ultimate performance of blended materials. To address this challenge, a dual‐fluorophore labeling strategy is introduced, enabling high‐contrast differentiation of polymeric phases. By covalently tethering two spectrally orthogonal fluorophores to their respective polymer components, unambiguous spatial resolution of blend morphologies is achieved through laser scanning confocal microscopy (LSCM). When compatibilizers are incorporated, LSCM imaging reveals fundamentally reconfigured phase architectures compared to uncompatibilized systems. This fluorescence‐based approach permits direct assessment of blend compatibility through quantitative evaluation of interfacial domain coherence and phase dispersion homogeneity. The methodology demonstrates exceptional versatility, successfully resolving phase boundaries in both chemically dissimilar systems (e.g., polylactic acid [PLA]/poly (butylene adipate‐ co ‐terephthalate) [PBAT] blends with pronounced polarity disparities) and structurally congruent polymers (e.g., polyethylene [PE]/polypropylene [PP] variants). The universal applicability stems from the substantial spectral distinction between fluorophore‐labeled polymers, independent of variations in polymer polarity or structural configurations.