Multiple hydrogen-bonded cross-linked photo-responsive liquid crystal elastomers with photo-responsive fluorescence

Luminescent liquid crystal elastomers (LCEs) have wide application prospect in fluorescent soft actuators and dynamic display devices. alpha-Cyanostilbene shows a rigid rod structure, aggregation-induced emission enhancement (AIEE) characteristic and photo-induced trans-cis isomerization, which can be used as multifunctional building block to prepare stimulus responsive luminescent LCEs. In this paper, a series of physically cross-linked luminescent LCEs showing photo-induced deformation behavior and photo-responsive fluorescence are obtained (named as LCE-M(x)-L(y), x and y denote the feed mole fraction of M6PVPC10 and ME6UPy respectively, x + y = 1, y = 0.04, 0.06, 0.08, 0.10, 0.12). The photo-induced deformation, luminescent property, and the intrinsic relationship between the luminescent behavior and the photo-induced bending behavior of LCEs were studied in particular. Under the irradiation of 365 nm ultraviolet light, the prepared uniaxially oriented LCEs bent toward the direction of light. The deformation rate, the maximum bending angle of polymers are sensitive to crosslinking agent content, and increase with increasing crosslinking agent content. All the prepared LCEs also behave AIEE characteristic and can emit strong fluorescence in solid state. Meanwhile, LCE-M(x)-L(y) presents stimuli-sensitive fluorescence, and the emission intensity decreases with increasing of 365 nm UV light irradiation time. The emission intensity variation with 365 nm UV irradiation is proved to be related to the photo-induced deformation, which can be used to monitor the deformation of LCEs.

Automated summary

This study focuses on a series of luminescent liquid crystal elastomers with photo-induced deformation behavior and photo-responsive fluorescence. By adjusting the crosslinking agent content, the deformation rate and maximum bending angle of the polymers can be controlled. All prepared LCEs exhibit aggregation-induced emission enhancement (AIEE) characteristic and emit strong fluorescence in solid state.