Ti3C2Tx MXene-Based Light-Responsive Hydrogel Composite for Bendable Bilayer Photoactuator

Abstract

Soft actuators based on hydrogel materials, which can convert light energy directly into mechanical energy, are of the utmost importance, especially with enhancements in device development. However, the hunt for specific photothermal nanomaterials with distinct performance remains challenging. In this study, we successfully fabricated a bilayer hydrogel actuator consisting of an active photothermal layer from incorporated Ti3C2Tx MXene in poly(N-isopropylacrylamide) p(NIPAm)hydrogel structure and a passive layer from the N-(2-hydroxylethylpropyl)acrylamide (HEAA) hydrogel structure. The uniform and effective incorporation of MXene into the NIPAm hydrogel structures were characterized by a battery of techniques. The light responsive swelling properties of the MXene-embedded NIPAm-based hydrogel demonstrated fully reversible and repeatable behavior in the light on–off regime for up to ten consecutive cycles. The effect of MXene loading, the shape of the actuator, and the light source effects on the bilayer NIPAm-HEAA hydrogel structure were investigated. The bilayer hydrogel with MXene loading of 0.3% in the NIPAm hydrogel exhibited a 200% change of the bending angle in terms of its bidirectional shape/volume after 100 s exposure to white light at an intensity of 70 mW cm−2. Additionally, the bending behavior under real sunlight was evaluated, showing the material’s potential applicability in practical environments.

Functional Group Modification and Bonding Characteristics of Ti3C2 MXene‐Organic Composites from First‐Principles Calculations

“…[60][61][62] In the polymerization of organic molecules, monomer-monomer and monomer-substrate interaction are a competitive relationship, which affects the final structures of complex system. [42,43,63] On the surfaces of Ti 3 C 2 and Ti 3 C 2 (OH) 2 , the monomers tend to adsorb to the MXene surface first and then polymerize. However, for inert surfaces of Ti 3 C 2 F 2 and Ti 3 C 2 O 2 , the interaction of monomers is comparable with that between monomer and surfaces, which tends to aggregate while adsorbing.…”

“…In a composite system based on chemical adsorption, the functional groups of organic molecules play an important role in the entire adsorption process [60–62] . In the polymerization of organic molecules, monomer‐monomer and monomer‐substrate interaction are a competitive relationship, which affects the final structures of complex system [42,43,63] . On the surfaces of Ti 3 C 2 and Ti 3 C 2 (OH) 2 , the monomers tend to adsorb to the MXene surface first and then polymerize.…”

Soft Optomechanical Systems for Sensing, Modulation, and Actuation

“…[176] Following this trend, the high photothermal efficiency of MXene materials (e.g., Ti 3 C 2 T x ) has been used of to build sharp bilayer actuators. [177][178][179][180] For example, Luo et al reported multifunctional Ti 3 C 2 T x /polyethylene soft robots accurately driven by NIR, electricity, and heat. [181] In a different approach, a bimorph structure composed of an MXene-based asymmetric layered microstructure and polyethylene was reported, which demonstrated directional selflocomotion driven by natural sunlight (Figure 7d).…”

“…[ 176 ] Following this trend, the high photothermal efficiency of MXene materials (e.g., Ti 3 C 2 T x ) has been used of to build sharp bilayer actuators. [ 177–180 ] For example, Luo et al. reported multifunctional Ti 3 C 2 T x /polyethylene soft robots accurately driven by NIR, electricity, and heat.…”

Interface-Modified Ti3C2Tx MXene/1T-WSe2 Heterostructure for High-Capacitance Micro-Supercapacitors

“…The market demand for multi-functional and wearable electronics has continuously increased in recent years, and new efficient energy storage devices with features of flexibility, miniaturization, and integration are needed to be developed urgently. − Micro-supercapacitors (MSCs) with high power density, excellent circulating capacitance retention rate, and fast charging/discharging rate have attracted special attention in the important new energy field. − Especially, the interdigitated structure of on-chip MSCs shortens the electron diffusion distance and decreases the total internal resistance, resulting in a fast electron transfer rate and fast response capability. − In the past few decades, MSCs based on carbon composite structures, such as onion-like carbon, carbide-derived carbon, graphene, and relevant pseudocapacitive composite materials have been reported. − Nevertheless, these MSCs still suffer from complicated manufacturing processes, complex structures, and low substrate ductility, which hinder their wearable electronic applications. Designing and constructing new composite materials is the key to improving MSC energy storage performance and reliability.…”