Skeletal Muscle Fibers Inspired Polymeric Actuator by Assembly of Triblock Polymers

Abstract

Inspired by the striated structure of skeletal muscle fibers, a polymeric actuator by assembling two symmetric triblock copolymers, namely, polystyrene-b-poly(acrylic acid)-b-polystyrene (SAS) and polystyrene-b-poly(ethylene oxide)-b-polystyrene (SES) is developed. Owing to the microphase separation of the triblock copolymers and hydrogen-bonding complexation of their middle segments, the SAS/SES assembly forms a lamellar structure with alternating vitrified S and hydrogen-bonded A/E association layers. The SAS/SES strip can be actuated and operate in response to environmental pH. The contraction ratio and working density of the SAS/SES actuator are approximately 50% and 90 kJ m −3 , respectively; these values are higher than those of skeletal muscle fibers. In addition, the SAS/SES actuator shows a "catch-state", that is, it can maintain force without energy consumption, which is a feature of mollusc muscle but not skeletal muscle. This study provides a biomimetic approach for the development of artificial polymeric actuators with outstanding performance.

Bioinspired Liquid Crystalline Spinning Enables Scalable Fabrication of High‐Performing Fibrous Artificial Muscles

“…By changing the light intensity, the actuation strain and stress of microfibers can be regulated, and the maximum stress can exceed 3.8 MPa (Figure 3b), which is at least an order of magnitude higher than that of human skeletal muscle (0.35 MPa). [3,41,42] It was observed that the thinner the LCE microfiber, the higher the actuation stress. A finer microfiber with a diameter of ≈3 µm can generate actuation stress up to 5.3 MPa in 0.1 s (Figure S14, Supporting Information).…”

“…Muscles are one of the most important functional components for living organisms, which offer deformation and strength for a broad range of movements. [41,54,59] Skeletal muscles are made up of a bundle of muscle fibers enabling rapid, reversible, and highly controllable drives. We demonstrate that our LCE microfibers can serve as fibrous artificial muscles to achieve diverse motion patterns (Movie S7, Supporting Information).…”

Polymer Complex Fiber: Property, Functionality, and Applications

“…Actuators are devices that can transform various input energies into mechanical energy for operation. , For instance, steam engines, combustion engines, and electric motors are classical actuators that drove the industrial revolution and shaped modern society. Nowadays, much of chemistry and physics have been combined to realize miniaturized actuators at micro and nanoscale, essential for drug delivery and soft robotic systems.…”

Precisely Controllable Artificial Muscle with Continuous Morphing based on “Breathing” of Supramolecular Columns

“…[14] By sharing the anisotropic characteristics with skeletal muscles at both molecular and self-organization levels to some extent, liquid crystal polymers (LCPs) have been favored in constructing stimuli-responsive soft actuators, in addition to their light weight, adjustable modulus, and highly tunable chemical compositions. Wide ranges of artificial muscles are produced when mesogenic moieties are embedded into networks of chemical crosslinks, resulting in liquid crystal elastomers (LCEs) or liquid crystal networks, which can be actuated by numerous external stimuli such as heat, [3,9,10,15] light, [16][17][18][19][20][21][22] electric field, [23,24] magnetic field, [25,26] pH values, [27] or humidity. [28] The macroscopic deformation of these LCPs is primarily dependent on drastic changes in molecular conformation and orientation, which can be triggered by the phase transition between LC and isotropic state.…”