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.