Ohzono Takuya, Norikane Yasuo, Saed Mohand O, Terentjev Eugene M
Research Institute for Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan.
Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, U.K.
ACS Appl Mater Interfaces. 2020 Jul 15;12(28):31992-31997. doi: 10.1021/acsami.0c08289. Epub 2020 Jul 1.
In liquid crystal elastomers (LCEs), the internal mechanical loss increases around the nematic-isotropic phase transition and remains high all through the nematic phase, originating from the internal orientational relaxation related to the so-called "soft elasticity". Because the viscoelastic dissipation of the materials affects their adhesion properties, the nematic-isotropic phase transition can cause dramatic changes in the adhesion strength. Although the phase transitions can generally be induced by heat, here, we demonstrate the light-driven transition in dynamic adhesion in dye-doped nematic LCE. The special dye is chosen to efficiently generate local heat on light absorption. The adhesion strength is lowered with fine tunability depending on the light power, which governs the effective local temperature and through that the viscoelastic damping of the system. We demonstrate the light-assisted dynamic control of adhesion in a 90°-peel test and in pick-and-release of objects, which may lead to the development of stimuli-responsive adhesive systems with fine spatio-temporal controls.
在液晶弹性体（LCEs）中，内部机械损耗在向列相-各向同性相转变附近增加，并在整个向列相中保持较高水平，这源于与所谓“软弹性”相关的内部取向弛豫。由于材料的粘弹性耗散会影响其粘附性能，向列相-各向同性相转变会导致粘附强度发生显著变化。虽然相变通常可由热引发，但在此我们展示了掺杂染料的向列相LCE中光驱动的动态粘附转变。所选的特殊染料在吸收光时能有效产生局部热量。粘附强度可根据光功率进行精细调节而降低，光功率控制着有效局部温度，进而控制体系的粘弹性阻尼。我们在90°剥离试验以及物体的拾取和释放过程中展示了光辅助的粘附动态控制，这可能会推动具有精细时空控制的刺激响应型粘附系统的发展。
