High-Contrast Visualization and Differentiation of Microphase Separation in Polymer Blends by Fluorescent AIE Probes

The visualization of microphase separation in immiscible polymer blends is of great academic and industrial significance as the phase-separated structures are directly associated with the properties and performances of the blend materials and ultimately influence the corresponding product quality. However, conventional techniques for detecting microphase separation are generally expensive and time-consuming with troublesome and even destructive sample preparation procedures. Complicated and highly material-dependent chemical reactions or interactions are often involved in some characterization approaches. In this work, we demonstrated a simple, fast, and powerful method for high-contrast visualization and differentiation of micrometer-sized phase separation in polymer blends using luminogens with aggregation-induced emission characteristics (AIEgens) as fluorescent probes. This method relies on the sensitive fluorescence response of AIEgens to the change of environmental rigidity and polarity and operates based on the mechanisms of “restriction of intramolecular motions” and “twisted intramolecular charge transfer”. The working principle indicates that this visualization strategy is applicable to a wide scope of polymer blends comprised of components with different rigidities and/or polarities.