Water-responsive shape memory hybrid: Design concept and demonstration

Chapter 14 reviews shape memory polymers (SMPs). Shape memory polymers belong to the family of shape memory materials (SMMs), which can be deformed into a predetermined shape under some imposed specific conditions such as temperature, electric or magnetic field, as well as strain and stress. These shapes can be relaxed back to their original field-free shapes under thermal, electrical, magnetic, strain, stress, temperature, laser, or environmental stimuli. These transformations are essentially due to the elastic energy stored in SMMs during initial deformation. As a member of SMMs, SMPs are stimuli-sensitive polymers. Shape memory polymers normally use either heat or laser light energy as a stimulant to change shape. The thermally-induced shape memory effect can be observed by irradiation with infrared light, exposure to alternating magnetic fields, application of an electric field or immersion in water.

Shape memory polymers (SMPs) possess the remarkable ability to recover their original shape after being severely deformed, triggered by the right stimulus. This chapter reviews recent progress in shape memory materials, focusing on traditional types like shape memory alloys (SMAs) and SMPs, as well as emerging shape memory hybrids, which enable customizable properties for specific applications in a “do-it-yourself” manner. SMPs, in particular, show great promise for morphing aircraft applications due to their temperature- and time-dependent mechanical properties. Tests on SMPs under monotonic loading in high shear demonstrate their ability to recover original shapes while resisting large loads. Advances in SMP composites (SMPCs), which incorporate functional materials and nanostructures, further enhance their deformation recovery, mechanical properties, and controllable actuation. SMPs have broad applications across aerospace, biomedical devices, flexible electronics, and more. This chapter also provides an in-depth analysis of the shape recovery mechanisms, multifunctionality, and potential future directions for SMP development.

Shape memory materials and 4D printing in pharmaceutics.

Shape memory materials (SMMs) recover their original shape as an external stimulus is applied. To meet the growing needs for complicated applications, it is imperative to design advanced SMMs with more functions and better performance. This paper reports a new design of liquid-based SMMs, i.e. liquid nanofoam (LN) system, by controlling the extent of liquid outflow from hydrophobic nanopores. The liquid outflow behavior is dominated by the thermoresponsive sensitive bubble nucleation process in the confined nanoenvironment. As temperature increases, the extent of liquid outflow is promoted, and the system volume is recovered. Thus, the LN system exhibits an instant volume memory behavior. As temperature decreases, the volume memory behavior is reversed. A constitutive model for the shape memory LN material has also been developed and validated. The thermoresponsive nanoconfined liquid outflow opens up new avenues for the design of advanced SMM.

It is proposed to develop a small spacecraft for an experiment using high-temperature superconductors (HTS) and shape memory materials. The purpose of the experiment is to test a technological capability of creating a strong magnetic field on the small spacecraft using HTS and shape memory materials for deployed large-area structures, and study the magnetic field interaction with the solar wind plasma and the resulting force impact on the small spacecraft. This article is of a polemical character and makes it possible to take a fresh look at the applicability of new technologies in space-system engineering. Key words: high-temperature superconductors, shape memory materials, solar wind, spacecraft.

In this study, we developed a variable-stiffness and deformable link using shape-memory material and the jamming transition phenomenon. Above its glass transition temperature (Tg), a shape-memory polymer (SMP) can be deformed by applying a small load. SMPs maintain the deformed shape after they have been cooled below Tg, and they return to their original shape when heated above Tg. The reversible change in the elastic modulus between the glassy and rubbery states of SMPs can be on the order of 100–1000 times. We exploited the characteristics of SMPs to develop robot components with variable stiffness and sensitivity. The jamming transition phenomenon for granular material has been widely used as a method to change the stiffness of robots. This phenomenon is the change from fluid-like to solid-like conditions by removing air from a space containing particles. In this study, we developed a variable-stiffness link by combining the SMP and the jamming transition phenomenon. Moreover, by replacing the SMP with shape-memory alloys (SMAs), whose recovery force and elastic modulus are larger than those of SMPs, we prepared a second prototype with variable stiffness. We evaluated the performance of both prototypes, using the SMP or the SMA, with experiments and confirmed the motion principle of the proposed link (e.g., shape recovery and shape fixity). Moreover, it was confirmed that the stiffness of these links can be changed among four states.

The temperature and field dependence of the magnetization in a Ni2MnGa single crystal was measured using a magnetometer with an applied field oriented in the [001] and [011] directions, respectively, of the parent cubic phase. It was found that the magnetic field magnitude and direction could be used to determine the magnetization of the sample during a thermal transformation from the austenitic phase to the martensite phase. This is explained in terms of a magnetic field induced growth of the twin variant having a favorable orientation to the external magnetic field. A model to interpret the magnetic response in terms of aligned twin variants in the shape memory material is discussed.

This chapter investigates the tribological behavior of shape memory material (SMM) thin films, a critical aspect of their successful implementation in diverse applications such as microelectromechanical systems (MEMS), biomedical devices, and smart coatings. SMMs, encompassing shape memory alloys (SMAs) like NiTi and shape memory polymers (SMPs), exhibit unique shape recovery capabilities, enabling innovative functionalities. The chapter begins by reviewing common fabrication techniques for SMM thin films, including PVD, CVD, sol-gel methods, electrospinning, and spin coating. Subsequently, it discusses key tribological testing and characterization methods, encompassing friction and wear tests (e.g., pin-on-disk, ball-on-disk, and scratch tests) and characterization techniques. The core of the chapter delves into the tribological properties of SMM films, analyzing factors influencing friction (e.g., surface roughness, and phase transformations) and wear (e.g., hardness, and elastic recovery). Strategies for mitigating wear and friction, such as solid lubrication, self-lubricating coatings, and surface texturing, are explored. This chapter includes the critical role of wear resistance in MEMS devices, the importance of biocompatibility and minimal wear debris in biomedical implants, and the potential of SMM-based smart coatings for adaptive friction control in various industrial settings.

Smart textiles are one of the areas that provides added value to textile materials. It is a sector that has been developed with new technologies, new fibers, and textile materials. The production of smart or intelligent textiles cooperate with other branches of science like nanotechnology, materials science, design, electronics, and computer engineering, etc. Smart textiles are classified into three groups as passive smart textiles, active smart textiles and ultra smart textiles according to their performance characteristics. Passive smart textiles are the first generation of smart textiles and sense the external conditions; for instance, UV protecting clothing, conductive fibers, etc. As active smart textiles respond to external conditions, ultra smart textiles sense, react, and adopt themselves to conditions. Shape memory materials, chromic materials, heat storage, and thermo-regulated fabrics are the typical applications of active smart textiles.

Shape memory properties provide a very attractive insight into materials science, opening unexplored horizons and giving access to unconventional functions in every material class (metals, polymers, and ceramics). In this regard, the biomedical field, forever in search of materials that display unconventional properties able to satisfy the severe specifications required by their implantation, is now showing great interest in shape memory materials, whose mechanical properties make them extremely attractive for many biomedical applications. However, their biocompatibility, particularly for long-term and permanent applications, has not yet been fully established and is therefore the object of controversy. On the other hand, shape memory polymers (SMPs) show promise, although thus far, their biomedical applications have been limited to the exploration. This paper will first review the most common biomedical applications of shape memory alloys and SMPs and address their critical biocompatibility concerns. Finally, some engineering implications of their use as biomaterials will be examined.

Due to a simpler calculation process and better precision, the rotating-angle softened-truss model is often used to predict behaviours of reinforced concrete shell or panel structures. In the current algorithm of the rotating-angle softened-truss model, the calculation process is from strains to stresses, which needs a trial and error procedure. A new algorithm of the rotating-angle softened-truss model is proposed in this paper. The Poisson effect is included in the new algorithm. Its calculation process is from stresses to strains. The trial and error procedure is avoided, which simplifies the calculation process significantly. The reliability of the new algorithm is verified by test data of six panels.

It is proposed to develop a small spacecraft for an experiment using high-temperature superconductors (HTS) and shape memory materials. The purpose of the experiment is to test a technological capability of creating a strong magnetic field on the small spacecraft using HTS and shape memory materials for deployed large-area structures, and study the magnetic field interaction with the solar wind plasma and the resulting force impact on the small spacecraft. This article is of a polemical character and makes it possible to take a fresh look at the applicability of new technologies in space-system engineering.

Jewelry is a passion of a large segment of children, especially females, which inspires the jewelry designer to direct this passion to raise a generation of young jewelry designers, using the combination of the arts of jewelry design and formulation and the science of smart materials. Smart materials are one of the most important fruits of technological development, and they vary between shape memory materials, color-changing materials, light-sensitive materials, and others sensitive to electricity. Given that jewelry design is one of the most important fields that affect the culture and thinking of the recipient, and based on the major role of shaping processes in enriching jewelry design, the interest in this research was in studying smart materials as a result of advanced technological developments and the possibility of employing them in simulating some jewelry shaping processes, so that this simulation would be the nucleus of a project to raise the young designer. The problem of the research is the scarcity of the use of smart materials in children's jewelry, and the lack of diversity of shaping methods in jewelry crafting collections directed at children. The research aims to build a knowledge base about smart materials, and employ these materials in simulating jewelry shaping processes. The importance of the research lies in its attempt to benefit from smart materials as a result of advanced technological developments in simulating some jewelry forming processes, with the aim of raising the child practicing this simulation as a young designer. Through the descriptive analytical approach, the research concluded that there are multiple types of smart materials, including shape memory materials, color changing materials, and materials sensitive to pressure and electricity. Through the experimental approach, the research concluded that some smart materials can be developed to suit children's practices. Main Results: 1-.sing smart materials to simulate some jewelry formation processes. 2. Using smart materials leads to diversifying the forming methods in jewelry collections directed at children. 3. Shape memory polymer can be employed to simulate the process of forming ceramic jewelry. 4. Simulating the process of forming jewelry with wires using nitinol wires. 5. Simulating the process of inlaying jewelry with micromosaics using glow-in-the-dark lobes and (UV Resin) 6. The possibility of simulating the process of thermal forming glass jewelry through luminous thermal beads 7. Employing smart materials to simulate some jewelry forming processes makes them suitable for children's practices in middle childhood. 8. The high flexibility of nitinol wires weakens the stability of their formations. 9. Developing nitinol wire by combining it with another aluminum wire of the same thickness. 10. Nitinol wires combined with colored aluminum wires have an attractive surface appearance for children in addition to the ability to stabilize the formation.

Electrospinning with sequential layer deposition has been reported for various applications such as tissue scaffolds, shape memory materials, and separations. However, the effect of layering on the mechanical properties is not fully understood. In this work, layered structures of thermoplastic polyurethane (TPU) and nylon were selected as a model system to investigate the effect of sequential layer deposition on mechanical properties. Evidence of the layered structure was indicated by scanning electron microscopy (SEM) and Fourier Transform Infrared spectroscopy (FTIR) experiments. Layering TPU with nylon resulted in a 60-fold increase in the Young's modulus. The Young's modulus of the layered structure was reasonably predicted by the Voigt rule of mixtures. Furthermore, the Young's modulus changes without any statistically significant change in elongation at break compared to a single layer of nylon. Thus, the elongation at break was dictated by the stiffer material, despite being present at a lower volume fraction. Overall, electrospinning with sequential layer deposition electrospinning is an effective approach for tuning the mechanical properties and surface chemistry of electrospun materials independently, which may be of interest for applications in tissue engineering and separations.

This paper introduced the mainly application of intelligent materials in fashion and clothing, summarized three operating types of intelligent materials: passive intelligent materials, active intelligent materials and advanced intelligent materials. Including temperature control material of clothing, shape memory material, photosensitive, thermal, humidity and pressure sensitive and other color changing materials. Meanwhile, four directions towards the future development of intelligent clothing are summarized, including high performance, high precision, information and data security as well as commercial popularity.