Light‐Fueled Climbing of Monolithic Torsional Soft Robots via Molecular Engineering

摘要

Azobenzene‐functionalized liquid crystalline polymer networks (azo‐LCNs) are promising candidates for light‐fueled contactless manipulation of miniaturized soft robots through embedding photoactive molecular switches into alignment‐programmable LCNs. In particular, the 3D helical geometry of azo‐LCNs is reported to achieve rapid photomotility by introducing rolling resistance. However, the maximum height of the obstacle that soft robot can overcome is limited by the helix diameter and the stress–strain responsivity. Herein, the helical diameter per unit length and photogenerated stress through molecular engineering of photoactive molecular switches are maximized. The carbon number of aliphatic spacers in the photoactive molecular switches is varied from two to eight to systematically investigate the structure–property–performance relations by studying the molecular geometry, physical properties of polymers, and photomotility of polymers. Furthermore, a finite‐element analysis simulation is presented to understand the rolling locomotion of helical torsional soft robots. Through molecular engineering, the helix diameter per unit length of 0.2 mg soft robots is maximized, demonstrating high Young's modulus (≈2 GPa) and photogenerated stress (>1 MPa), as well as large velocity per body length, compared with the previously reported soft robots. Finally, the molecularly engineered soft robots successfully climb stairs, which is a key task in robotic systems.