Photoreversible Bond-Based Shape Memory Polyurethanes with Light-Induced Self-Healing, Recyclability, and 3D Fluorescence Encryption

Mimosa-Inspired Body Temperature-Responsive Shape Memory Polymer Networks: High Energy Densities and Multi-Recyclability

Inspired by the Mimosa plant, this study herein develops a unique dynamic shape memory polymer (SMP) network capable of transitioning from hard to pliable with heat, featuring reversible actuation, self-healing, recyclability, and degradability. This material is adept at simulating the functionalities of artificial muscles for a variety of tasks, with a remarkable specific energy density of 1.8 J g-1-≈46 times higher than that of human skeletal muscle. As an intelligent manipulator, it demonstrates remarkable proficiency in identifying and handling items at high temperatures. Its suitable rate of shape recovery around human body temperature indicates its promising utility as an implant material for addressing acute obstructions. The dynamic covalent bonding within the network structure not only provides excellent resistance to solvents but also bestows remarkable abilities for self-healing, reprocessing, and degradation. These attributes significantly boost its practicality and environmental sustainability. Anticipated to promote advancements in the sectors of biomedical devices, soft robotics, and smart actuators, this SMP network represents a forward leap in simulating artificial muscles, marking a stride toward the future of adaptive and sustainable technology.

Self-Healing Polymers Coupling Shape Memory Effect

In recent years, shape memory polymers (SMPs) and self-healing polymers (SHPs) have been research hotspots in the field of smart polymers owing to their unique stimulus response mechanisms. Previous research on SHPs has primarily focused on contact repair. However, in instances where substantial cracks occur during practical use, autonomous closure becomes challenging, impeding effective repair. By integration of the shape memory effect (SME) with SHPs, physical wound closure can be achieved via the SME, facilitating subsequent chemical/physical repair processes and enhancing self-healing effectiveness. This article reviews key findings from previous research on shape memory-assisted self-healing (SMASH) materials and addresses the challenges and opportunities for future investigation.

Multistimuli-Responsive Shape-Memory Composites with a Water-Assisted Self-Healing Function Based on Sodium Carboxymethyl Cellulose/Poly(vinyl alcohol)/MXene

Recent advancements in artificial intelligence have propelled the development of shape-memory polymers (SMPs) with sophisticated, environment-sensitive capabilities. Despite the progress, most of the existing SMPs are limited to responding to a single stimulus and show poor functionality, which has severely hindered their future applications. Herein, we report a high-performance multistimuli-responsive shape-memory and self-healing composite film fabricated by embedding MXene nanosheets into a conventional shape-memory sodium carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) matrix. The incorporation of photothermal MXene nanosheets not only enhances the composite films' mechanical strength but also provides efficient solar-thermal conversion and robust light-actuated shape-memory properties. The resultant composite films exhibit an exceptional shape-memory response to various stimuli including heat, light, and water. Meanwhile, the interfacial interactions can be modulated by adjusting the MXene content, thereby enabling precise manipulation of the shape-memory performance. Moreover, thanks to the intrinsic hydrophilicity of the components and the unique physically cross-linked network, the composite films also demonstrate an effective water-assisted self-healing capability with an impressive healing efficiency of 85.7%. This work offers insights into the development of multifunctional, multistimuli-responsive shape-memory composites, opening up new possibilities for future applications in smart technologies.

The effect of Pluronic P123 on shape memory of cross-linked polyurethane/poly(l-lactide) biocomposite

Polyurethane (PU) and poly(l-lactide) (PLLA) have attracted increasing attention in the development of shape memory polymers (SMPs) due to their good biocompatibility and degradability. Although Pluronic P123 can be used to tune polymeric surface hydrophilicity, its effect on SM performance is a mystery. In this study, a soluble cross-linked PU is synthesized as the switching phase and combined with PLLA and P123 to construct a hydrothermally responsive SM composite. The water contact angle of PU/PLLA/P123 decreases from 22.7° to 5.1° within 2 min. PU and P123 form the switching group, which enhances the SM behavior of the composite. The shape fixity (Rf) and shape recovery (Rr) of PU/PLLA/P123 are 94.4 % and 98 % in 55 °C water, respectively, and the shape recovery time is only 10 s. P123 plays the role of "turbine" in the SM process. PU/PLLA/P123 exhibits a balance between stiffness and elasticity, and good degradability. Furthermore, PU/PLLA/P123 is also biocompatible and beneficial to cell proliferation and growth. Therefore, it offers an alternative approach to developing hydrothermally responsive SM biocomposites based on P123, PU and PLLA for biomedical applications.

Fundamental properties of smart hydrogels for tissue engineering applications: A review

Tissue engineering is an advanced and potential biomedical approach to treat patients suffering from lost or failed an organ or tissue to repair and regenerate damaged tissues that increase life expectancy. The biopolymers have been used to fabricate smart hydrogels to repair damaged tissue as they imitate the extracellular matrix (ECM) with intricate structural and functional characteristics. These hydrogels offer desired and controllable qualities, such as tunable mechanical stiffness and strength, inherent adaptability and biocompatibility, swellability, and biodegradability, all crucial for tissue engineering. Smart hydrogels provide a superior cellular environment for tissue engineering, enabling the generation of cutting-edge synthetic tissues due to their special qualities, such as stimuli sensitivity and reactivity. Numerous review articles have presented the exceptional potential of hydrogels for various biomedical applications, including drug delivery, regenerative medicine, and tissue engineering. Still, it is essential to write a comprehensive review article on smart hydrogels that successfully addresses the essential challenging issues in tissue engineering. Hence, the recent development on smart hydrogel for state-of-the-art tissue engineering conferred progress, highlighting significant challenges and future perspectives. This review discusses recent advances in smart hydrogels fabricated from biological macromolecules and their use for advanced tissue engineering. It also provides critical insight, emphasizing future research directions and progress in tissue engineering.

Recent Advances in Tailored Fabrication and Properties of Biobased Self-Healing Polyurethane

With the emergence of challenges in the environmental degradation and resource scarcity fields, the research of biobased self-healing polyurethane (BSPU) has become a prevailing trend in the technology of the polyurethane industry and a promising direction for developing biomass resources. Here, the production of BSPU from lignocellulose, vegetable oil, chitosan, collagen, and coumarin is classified, and the principles of designing polyurethane based on compelling examples using the latest methods and current research are summarized. Moreover, the impact of biomass materials on self-healing and mechanical properties, as well as the tailored performance method, are presented in detail. Finally, the applications of BSPU in biomedicine, sensors, coatings, etc. are also summarized, and the possible challenges and development prospects are explored to helpfully make progress in the development of BSPU. These findings demonstrate valuable references and practical significance for future BSPU research.

Mechanochromic Self-Healing Materials with Good Stretchability, Shape Memory Behavior, Cyclability, and Reversibility Based on Multiple Hydrogen Bonds

It is challenging to develop materials with room-temperature self-healing ability and mechanochromic response from mechanical stimuli to optical signals by a facile and simple preparation process. Herein, novel mechanochromic self-healing materials were designed by a simple synthesis procedure, balancing the mechanical properties, self-healing, stretchability, and mechanochromic response. Moreover, we designed and prepared the mechanochromic self-healing materials with different soft and hard segments by introducing multiple hydrogen bonds into the network, improving the mechanical properties and self-healing efficiency. In addition, the optimized sample exhibited good shape memory behavior (shape recovery ratio of 94.4%), self-healing properties (healed by pressing during stretching process), high tensile strength (17.6 MPa), superior stretchability (893%), fast mechanochromic response (strain of 272%), and great cyclic stretching-relaxing properties (higher than 10 times at strain of 300%). Above all, mechanochromic self-healing materials have promising potential in various fields, such as stress sensing, inkless writing, damage warning, deformation detection, and damage distribution.

Thermal/Near-Infrared Light Dual-Responsive Reconfigurable and Recyclable Polythiourethane/CNT Composite with Simultaneously Enhanced Strength and Toughness

Thermoset polymers cross-linked by dynamic covalent bonds are recyclable and reconfigurable based on solid-state plasticity, resulting in less waste and environmental pollution. However, most thermoset polymers previously reported show thermal-responsive solid-state plasticity, depending much on external conditions and not allowing for local shape modulation. Here, the isocyanate modified carbon nanotubes (CNTs-NCO) are introduced into the polythiourethane (PCTU) network with multiple dynamic covalent bonds by in situ polymerization to prepare the composite with thermal/light dual-responsive solid-state plasticity, reconfigurability, and recyclability. The introduction of CNTs-NCO simultaneously strengthens and toughens the PCTU composite. Moreover, based on the photothermal properties and light-responsive solid-state plasticity, the PCTU/CNTs composite or bilayer sample could achieve complex permanent shape by locally precise shape regulation without affecting other parts. This work provides a simple and reliable method for preparing high-performance polymer composite with light-responsive solid-state plasticity, which may be applied in the fields of sensing and flexible electronics.

A wear-resistant, self-healing and recyclable multifunctional waterborne polyurethane coating with mechanical tunability based on hydrogen bonding and an aromatic disulfide structure

Considering a sustainable society, it is highly desirable to develop coatings that combine excellent wear-resistance, healing and recovery capabilities with tunable mechanical properties.