Preparation and properties of side chain liquid crystalline polymers with aggregation-induced emission enhancement characteristics

In this article, novel side chain liquid crystalline polymers (SCLCPs) based on cyanostilbene were synthesized to obtain luminescent liquid crystalline materials. The fluorescent luminescence behavior and liquid crystallinity of SCLCPs were evaluated and characterized by differential scanning calorimetry (DSC), polarized optical microscopy (POM), X-ray diffraction (XRD), ultraviolet spectroscopy (UV) and photoluminescence (PL) measurements. Testing results showed that all polymers exhibited good thermo-stability and stable double-layer smectic A phase below the clearing point temperature. The liquid crystalline properties of polymers were affected by the spacer length. The clearing point temperature (Ti) of SCLCPs decreased with increasing spacer length. All polymers were weakly emissive in good solvent but emitted stronger fluorescence in the aggregation state, showing aggregation-induced emission enhancement (AIEE) behavior. The fluorescent luminescence behavior of polymers was closely linked with chemical structure and the fluorescence quantum yield of polymers in solid phase, which increased with increasing spacer length.