Recently, the research team led by Professor Haifeng Yu from College of Engineering of Peking University has made an important progress in the full-band wavelength light-responsive liquid crystal and micro/nano composite materials. The results titled “NIR-VIS-UV Light-Responsive Actuator Films of Polymer-Dispersed Liquid Crystal/Graphene Oxide Nanocomposites” have been published in the famous journal ACS Applied Materials & Interfaces  2015,7, 27494-27501. http://pubs.acs.org/doi/abs/10.1021/acsami.5b09676

To take full advantage of sunlight for photomechanical materials, NIR-VIS-UV light-responsive actuator films of polymer-dispersed liquid crystal (PDLC)/graphene oxide (GO) nanocomposites were fabricated. The strategy is based on phase transition of LCs from nematic to isotropic phase induced by combination of photochemical and photothermal processes in the PDLC/GO nanocomposites. Upon mechanical stretching of the film, both topological shape change and mesogenic alignment occurred in the separated LC domains, enabling the film to respond to NIR-VIS-UV light. The homo-dispersed GO flakes act as photo-absorbent and nanoscale heat source to transfer NIR or VIS light into thermal energy, heating the film and photothermally inducing phase transition of LC microdomains. By utilizing photochemical phase transition of LCs upon UV-light irradiation, one azobenzene dye was incorporated into the LC domains, endowing the nanocomposite films with UV-responsive property. Moreover, the light-responsive behaviors can be well controlled by adjusting the elongation ratio upon mechanical treatment. The NIR-VIS-UV light-responsive PDLC/GO nanocomposite films exhibit excellent properties of easy fabrication, low cost, good film-forming and mechanical features, promising their numerous applications in the field of soft actuators and optomechanical systems driven directly by sunlight.

This work was supported by the National Natural Science Foundation of China.

Video 1.  Photoresponsive behavior of liquid crystal and micro/nano composite materials upon NIR irradiation.

Video 2.  Photoresponsive behavior of liquid crystal and micro/nano composite materials under natural sunlight. (The video was taken in October at the gate of No. 1 Building, College of Engineering of Peking University)