Cellulose‐Reinforced Programmable and Stretch‐Healable Actuators for Smart Packaging

Abstract

Biomimetic actuators are promising candidates for smart soft robotics. The applications of state‐of‐the‐art actuators require the combination of programmable stimuli‐responsiveness, excellent robustness, and efficient self‐healing ability in a wide‐range of working conditions. However, these properties may be mutually exclusive. Inspired by biological tissues, two kinds of polyelectrolytes including polyvinyl alcohol (PVA) and polystyrene sulfonate (PSS) are exploited as the fillers of cellulose nanofibrils (CNFs) for the fabrication of the CNF/PVA/PSS (CAS) film via the assembly of the physically‐crosslinked network through multiple H‐bonding and electrostatic interactions. Achieved by a casting‐evaporation strategy, internal stress is stored within the polymer matrix and transforms into reversible anisotropic bending deformations in response to a humidity gradient. The speed, direction, and pitch of the bending can be programmed by tailoring the internal stresses and geometry of the samples. Moreover, the H‐bonded network also contributes to the effective energy dissipation toward high toughness during tensile stretching, as well as self‐healing ability during moisture saturation of the CAS films. This enables the fabrication of a humidity‐sensitive flower‐shaped actuator and self‐healable packaging paper. This study presents a biomimetic strategy for the fabrication of multi‐functional soft robotics, which holds great promise for applications in the fields of biosensors and smart packaging.

Eco-Friendly Cellulose-Based Nonionic Antimicrobial Polymers with Excellent Biocompatibility, Nonleachability, and Polymer Miscibility

“…The tensile strengths of PVA-MIPA10, PVA-MIPA10, and PVA-MIPA20 were 31.31 ± 0.50, 42.01 ± 2.77, and 29.56 ± 1.76 MPa. The addition of MICA and MIPA can significantly improve the composite film's mechanical strength, 62 primarily due to strong intermolecular forces generated between MICA, MIPA, and PVA molecules to form a densely cross-linked network structure. Furthermore, the elongation at break of composite films with the addition of MICA and MIPA was significantly improved compared to that of pure PVA and increased with increasing MICA and MIPA contents.…”

Energy harvesting technology based on moisture-responsive actuators

“…It includes not only natural materials such as cotton, 88 cellulose, 89 rubber, 90 starch, 91 and protein, 92 but also synthetic materials such as poly(ethylene glycol), 93 Nafion, 94 polyethylene- co -acrylic acid, 95 polyamide, 96 and polyvinyl alcohol. 97 In addition to these organic materials, inorganic materials such as graphene oxide (GO), 98 carbon nanotubes, 99 montmorillonite clay, 100 MXene, 101 carbon nitride, 102 silica, 103 titanium oxide, 104 and MOFs 105 can also achieve hygroscopic swelling properties after reasonable design, and the hygroscopic swelling behavior of these materials is highly dependent on their hydrophilicity and water absorption.…”

Nanocellulose‐based soft actuators and their applications

“…For instance, Chen et al demonstrated a toughening and self-healing actuator composed of CNFs, polyvinyl alcohol (PVA) and polystyrene sulfonate (PSS). 51 The flexible CNF/PVA and rigid PVA/PSS networks contributed to the high toughness of the actuator due to the effective energy dissipation during stretching process. Self-healing properties of the actuators were achieved by soaking-evaporation treatment to repair intramolecular hydrogen bonds broken by an external force.…”