Preparation And Properties Of Electro-Spiral Polymer Composites

As the end-executing mechanism of space robots,space robot claw is an important part of space robots when performing delicate and complex tasks.Due to the relatively simple structure,the traditional space robot claw can only finish the routine missions including the capture and transportation of large target objects.It is still a challeng to develop a new type of flexible space robot claw to capture space debris and other micro targets.Liquid crystal elastomers(LCE)and polyolefin materials are typical stimuli-responsive flexible polymer materials with shape memory capacity.These materials can undergo reversible macroscopic deformation in response to external stimulus,and have been widely used in software actuators,smart wearable devices and other fields.Inspired by the spiral growth of the Boston Ivy,we designed two preparation strategies based on LCE and polyolefin polymer materials to obtain flexible three-dimensional warped claws for space robots.Finally,an electro-driven flexible robot claw with a sandwich structure was made from polyethylene,polypropylene and carbon nanotube materials.Under 20 V direct-current(DC)power,the flexible robot claw realized several movement modes including winding,grasping and transferring of the target object.Nowadays,some challenges still remain in the fabrication of electro-driven polymer soft actuators.One main problem was that traditional electro-driven polymer materials are prepared by doping polymer materials with inorganic conductive materials.Inorganic conductive materials can effectively improve the conductivity of whole polymer materials but will inevitably sacrifice the mechanical properties and increase the costs and complexities of preparation protocols.Besides,a nonnegligible technique limitation was that to maintain good electrical contacts,the electro-driven polymer soft actuators are all directly connected with wires.Most of previous electro-response polymer soft actuators could only perform simple in-situ deformations,such as shrinking and bending.The wires inevitably hindered the sophisticated actuations of the polymer materials.Herein,we present a novel electro-driven cylindric actuator system composed of a bilayered liquid crystal elastomer/carbon black(LCE/CB)electro-driven soft actuator and a conductive track.The bilayered LCE/CB electro-driven actuator consists of an inner LCE circular band and 4 U-shaped CB conductive regions stuck on the outer surface of the LCE ring.Benefited from the effective Joule heating of CB powder and the consequent inhomogeneous stress inside the bilayered LCE/CB film,the cylindric actuator can roll forward with a rate of 1.6 mm/s along a stationary copper conductive track powered by a 50 V direct current supply.The dynamic connection between the rolling actuator and the conductive track effectively eliminate the limitation of electric wires in the complicated actuation set-ups of the LCE materials.