Matter latest research: so simple, flexible polymeric pull it becomes rigid actuator
Brake means a mechanical stress or strain in the device external stimulation chemical, electromagnetic, air / water pressure, temperature, humidity, light, pH, etc., with the soft (flexible brake) and hardware (rigid brake) Robotics important potential applications and research value. Most polymer-based flexible actuator due to the low modulus material (> 1%) characteristics, is mainly applied in the field of robotics software, hardware and difficult to prepare a robot. Hardware required rigidity of the robot actuators require ultra-high modulus (>> 1GPa) a base material, and prior studies have shown that only the metal material to meet this characteristic, but a higher density of hard metal material is difficult to meet future development trend of body weight of the robot, and because the properties of the material, a metal material is now the driving force of the brake is generally rigid electrical stimulation. Thus to find a material having a lower density and other stimulation (e.g. light) instead of the metallic material suitable for the preparation of rigid hardware robot actuator is a major problem in the field! Based on this, Professor Albertus PHJSchenning Eindhoven University of TF having a light – heat conversion effect azobenzene derivative is added to the ultra high molecular weight polyethylene (UHMWPE) matrix highly stretched (stretch ratio DR = 60) was obtained having a low density (975kg / m-3), high mechanical strength (modulus ≈100GPa) and having a light fast (<1 S) responsive classes at low strain (<1%) a rigid metal material film actuator. The results show that the use of short-chain azobenzene derivative (C78-OH-AZO, and C78-AZO) after PE modified with good dispersibility in UHMWPE matrix, after a substantial increase in height stretched composite film crystallinity, therefore greatly enhance the mechanical properties, to meet the strength and modulus of rigidity required of the actuator, while the added amount of the micro (<0.22mol%) azobenzene derivative after highly stretched mainly dispersed in the amorphous phase region in, after being subjected to external light, due to the conformation of the bound substrate is applied, cis-trans photoisomerization of the azobenzene structure process has been limited, and the trans-cis-trans isomerization process can be conducted smoothly releases heat , the heat is transferred to a highly oriented UHMWPE chain causes an increase of the stress. Test results show that a composite film having a light fast – mechanical response capability (<1s), An LED light at 405nm and ultra-low strain (~ 0.06%) conditions, the light-induced stress C78-OH-AZO composite film containing 0.22mol% reinforcing reaches 60MPa, the driving efficiency of more than 6 × 104Pa / ( kg m-3), and may be obtained through stress driving the light after 2600 cycles enhancement effect remains good, and thus desired in the art lightweight rigid actuation hardware on the robot actuator having prepared important potential applications. The research paper entitled \"Fast, Light-Responsive, Metal-Like Polymer Actuators Generating High Stresses at Low Strain\" hair on \"Matter\" journal (attached description link).
investigated the molecular azobenzene two structures (C78-OH-aZO, and C78-aZO) on UHMWPE reinforced optical film stress driving performance, in order to improve dispersibility in a nonpolars UHMWPE matrix, the first ends of the azobenzene molecules grafted PE short-chain [FIG. 1 (a)] to give an even nitrogen benzene derivatives, the isotropic film into UHMWPE after high temperature which is miscible with, and then further stretched at a height 120 ℃ (DR = 60) to obtain an anisotropic [FIG. 1 (b), (c )], high crystallinity and high strength composite film.
Analysis of azobenzene derivatives with different structures and different composite film strength under stress lighting conditions – relaxation mechanical test, the results shown in FIG. Test strain was found at less than 1%, the composite film exhibits a typical linear elastic mechanical behavior sticky, thus maintaining the 1% strain ofThe effect of light on the composite film (containing 0.06 mol% azobenzene derivative) under stress conditions. The results show that the composite film stress light has a very rapid response, in the time elastic modulus of about <1s 100GPa membrane stress is increased 10 ~ 30MPa, and with enhanced light stress may also be further improved, showing excellent light induced stress enhanced features. The authors found that while the reinforcing effect of light-induced stress can also be added as an azobenzene derivative in an increased amount of the composite film is increased [FIG. 2 (E) (F)] – 406nm in an LED lighting conditions, containing 0.22mol % of C78-OH-AZO complex photo film stress can be enhanced more than the maximum 60MPa.
- FIG 3. (A) composite film in the spectrum change after light irradiation, showing the change of cis trans azobenzene structure; linear-rotary irradiating light (B) the stress wave oscillation generated in the composite film; (C) containing 0.22 mol% of C78-OH-aZO thin film composite photo enhanced cyclic stress test
the results show that UHMWPE composite film structure containing a photochromic azobenzene stress enhanced features derived from azobenzene light – heat transfer characteristics, azobenzene in UHMWPE matrix restricted in highly crystalline structure to promote the transition of the cis-trans configuration, heat is released so that the composite reinforcing film stress. Since the composite film comprising a high modulus, stress and rapid response to light illumination greatly enhanced properties, thus is an ideal material for preparing rigid brake. Test results show that a stable oscillation can be generated stress wave linear illumination light is rotated by the actuator rigidity of the composite film prepared under and exhibit excellent cyclability test in a long time. Summary: The study used processing methods and high tensile strength prepared by adding the cis and trans configuration of the variable structure of the molecule azobenzene (light-triggered), the polymerization density, excellent light-induced stress and to enhance fast optical response characteristics group was a rigid actuator, the traditional rigid electrically driven brake and advantages of the flexible light-driven brake combination, have important potential applications in the future field of robotics hardware lightweight, but also to develop a low-density rigid material brake Preparation. Original link: https: //www.sciencedirect.com/ Science / article / pii / S2590238520301144