Light-induced mechanical response in crosslinked liquid-crystalline polymers with photoswitchable glass transition temperatures.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30104602.
- Also identified by DOI 10.1038/s41467-018-05744-x and PMC identifier 6089925.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Energy conversion of light into mechanical work is of fundamental interest in applications. In particular, diligent molecular design on nanoscale, in order to achieve efficient photomechanical effects on macroscopic scale, has become one of the most interesting study topics. Here, by incorporating a "photomelting" azobenzene monomer crosslinked into liquid crystalline (LC) networks, we generate photoresponsive polymer films that exhibit reversible photoswitchable glass transition temperatures (T<sub>g</sub>) at room temperature (~20 °C) and photomechanical actuations under the stimulus of UV/visible light. The trans-to-cis isomerization of azo chromophores results in a change in T<sub>g</sub> of the crosslinked LC polymers. The T<sub>g</sub> of the polymer network is higher than room temperature in the trans-form and lower than room temperature in the cis-form. We demonstrate the photoswitchable T<sub>g</sub> contribute to the photomechanical bending and a new mechanism for photomechanical bending that attributes the process to an inhomogeneous change in T<sub>g</sub> of the film is proposed.