Multi-Stimuli Responsive and Electrically Conducting rGO patterned azo-LCN for Enhanced Mechanical Stiffness Simultaneously with High Deformablility

초록

The traditional trade-off relationship between stiffness and deformability of liquid crystalline polymers results in a great limitation about application validity for mechanically strong but flexible electronic devices. Herein, a patterned structure is introduced through the lamination of reduced graphene oxide (rGO) on azo-functionalized liquid crystal polymer networks (azo-LCN) for enhanced mechanical and electrical properties without sacrificing shape reconfigurability. The storage modulus of the azo-LCN/rGO nanocomposites is enhanced as 4.9 times (6.4 GPa) compared to the neat azo-LCN (1.3 GPa) and the electrical conductivity is measured as 340 S/cm. Remarkably, in-plane bending is improved as 2.4 times in forward direction and 12 times in backward direction under UV exposure despite of enhanced modulus. Twisted actuations are also demonstrated by applying various cutting angle of the patterned azo-LCN/rGO nanocomposites. In addition, multi-stimuli sensitivity is demonstrated by introducing various stimuli including photothermal and direct heating. Photothermally driven bending actuation is performed by absorption of near infrared (NIR) light. The selective and reversible actuation is also performed by spatially concentrated solar ray. In addition, rapid bending actuation is induced by direct heat transfer operating a portable lighter. Finally, the concept of kirigami is applied to azo-LCN/rGO nanocomposites for further enhanced functionality. The azo-LCN/rGO nanocomposites is a great candidate for on-demand programmable electronic devices operated as untethered system.