Ionic Liquid-Doped Blue Phase Liquid Crystal Elastomer and Its Electric Field Response

Blue phase liquid crystal elastomers (BPLCEs) have significant advantages in the field of flexible optoelectronics due to their inherent flexibility and 3D optical property structure. However, there is currently insufficient research on the functional properties of BPLCEs, particularly regarding their electro-responsive characteristics. Herein, electro-responsive BPLCE was fabricated by introducing ionic liquid (IL) into the BPLC. It was systematically investigated for the influence of IL doping concentration on the self-assembly behavior and electro-responsive performance of BPLCEs. It was found that low concentrations (<2 mg_(IL)/100 mg_(BPLCE)) facilitated the achievement of the BPII → BPI transition; 2-3.5 mg_(IL)/100 mg_(BPLCE) doping is beneficial for directly generating uniform BPI phase in the system; excessive doping (>3.5 mg_(IL)/100 mg_(BPLCE)) disrupts the 3D orderliness. The optimal system (2 mg_(IL)/100 mg_(BPLCE)) contributes to the excellent optical quality of the sample. Its glass transition temperature (T_g) is as low as -28.78 °C, with a fracture elongation of 97.6%, allowing it to flexibly deform in cryogenic environments and overcome the limitations of low-temperature applications. Under an alternating current electric field, the as-prepared sample exhibits a lower response voltage and distinct response characteristics compared to the undoped sample, showing a trend of red shift followed by a blue shift in reflection wavelength at increased voltage, which provides novel design concepts for flexible optoelectronic materials.