Photo Actuation Performance of Nanotube Sheet Incorporated Azobenzene Crosslinked Liquid Crystalline Polymer Nanocomposite

Abstract

Crosslinked liquid crystalline polymers (CLCPs) containing azobenzene (AZO-CLCPs) are a type of promising material due to their significance in the design of light-driven smart actuators. Developing AZO-CLCP composites by incorporating AZO-CLCPs with other materials is an effective way of enhancing their practicability. Herein, we report an AZO-CLCP/CNT nanocomposite prepared by the in situ polymerization of diacrylates containing azobenzene chromophores on carbon nanotube (CNT) sheets. The liquid crystal phase structure of CLCP matrix was evidenced by the two-dimensional X-ray scattering. The prepared pure AZO-CLCP films and AZO-CLCP/CNT nanocomposite films demonstrated strong reversible photo-triggered deformation under the irradiation of UV light at 366 nm of wavelength, as a result of photo-induced isomerization of azobenzene moieties in the polymer network. But compared to pure AZO-CLCP films, the AZO-CLCP/CNT nanocomposite films could much more rapidly return to their initial shapes after the UV light irradiation was removed due to the elasticity effect of CNT sheets. The deformation behavior of AZO-CLCP/CNT nanocomposite films under the light irradiation was also different from that of the pure AZO-CLCP films due to the interfacial interaction between a polymer network and CNT sheet. Furthermore, incorporation of a CNT sheet remarkably increased the mechanical strength and robustness of the material. We also used this AZO-CLCP/CNT nanocomposite as a microvalve membrane actuator, which can be controlled by light, for a conceptual device of a microfluidic system. The results showed that this AZO-CLCP/CNT nanocomposite may have great potential in smart actuator applications for biological engineering, medical treatment, environment detection and microelectromechanical systems (MEMS), etc.

Actuation performance of a liquid crystalline elastomer composite reinforced by eiderdown fibers

“…The conjunction of the self-organization characteristic of long-range-order LC systems and the flexibility/elasticity of polymer networks enables large, reversible and programmable anisotropic shape changes of LCE materials induced by the order–disorder transition upon being subjected to applied stimuli. 5–7 The dramatic performances of stimuli-responsive shape change and actuation together with the other advantages of polymer materials give LCE materials potential in many applications, such as smart actuators, 8–22 artificial muscles, 23–27 biomimetic devices, 28–36 soft robots, 37–45 etc.…”

“…On the other hand, the stiff continuous hetero-phases in LCE matrices will impede the shape change performance of LCE materials. LCE composites incorporated with 2-dimensional elastic continuous phase hetero-materials, such as carbon nanotube sheets, 18,26,27,52 etc. , can only perform asymmetric deformations, such as bending or distortion, due to nonuniform strain through the composites.…”

Bio-Inspired Soft Robotics: Tunable Photo-Actuation Behavior of Azo Chromophore Containing Liquid Crystalline Elastomers

“…Most importantly, the photochemical phase transition of azobenzene chromophore (azotolane) containing CLCPs has a great influence on the photo-actuation (See Figure 3a-c.) [44][45][46][47][48][49][50]. In addition to azotolane moieties in the CLCP film, authors used other components such as platinum(II) tetraphenyltetrabenzoporphyrin (sensitizer) and 9,10-bis(diphenylphosphoryl)anthracene (annihilator) in order to trigger the trans-cis photoisomerization with 635-nm laser at a low power density of 200 mW cm −2 .…”

Ethanol Phase Change Actuator Based on Thermally Conductive Material for Fast Cycle Actuation

“…Commonly used artificial muscles are mechanically driven, including pneumatic and hydraulic [ 3 , 4 , 5 , 6 ]. Various materials have been adopted to prepare the artificial muscles, which involves electroactive polymers [ 7 , 8 , 9 , 10 , 11 , 12 ], shape memory materials [ 13 , 14 , 15 , 16 ], hydrogels [ 17 , 18 , 19 , 20 ], and polymers driven by photothermal or humidity [ 21 , 22 , 23 , 24 , 25 , 26 ]. There are also biogenic actuators that rely on animal muscle cells [ 27 , 28 ].…”