In this paper, we briefly review the recent progress in comfort fitting using elastic polymeric shape memory materials (SMMs). First, the required features on elastic SMMs for comfort fitting are ...discussed. A few types of polymeric SMMs (including some commercially available ones), which have these features, are presented. A number of prototypes made of these SMMs are used to demonstrate the feasibility to achieve the concept of comfort fitting in a one-for-all manner, i.e., one sized product to comfort fit any individuals.
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•Available elastic polymeric shape memory polymers at present are revealed.•Potential applications in comfort fitting are demonstrated.•We may utilize the shape memory effect to realize one size-for-all in a cost effective manner.
Electrically triggered shape memory polymers efficiency has been proven by numerous studies making them promising novel structural materials for high-end applications. In this field, ...poly(ε-caprolactone) covalent adaptable networks (PCL-CAN) are particularly appealing since they benefit from excellent shape memory (SM) properties combined with network reconfiguration making easy the design of self-actuated devices of complex shape. Preparation of conducting PCL-CAN networks by melt blending multi-walled carbon nanotubes (MWCNTs) with four-arm star-shaped PCL end-capped with maleimide and furan groups is here investigated. The conventional tensile tester and dynamic mechanical analysis demonstrated the reinforcement of the composite mechanical properties paired with excellent shape memory properties (recovery and fixity ratios about 99%). The simultaneous measurement of the sample resistivity was also integrated to these experiments allowing to follow its evolution during the SM cycles. Rheological measurements highlighted the impact of MWCNTs on the recyclability and self-healing properties of the composite. Electrical triggering of the shape recovery through Joule resistive heating is also deeply studied. The combination of all these properties in the developed material offers unique opportunities to design self-folding multi-materials which is illustrated through the design of smart multi-layered composites. This high-performance composite is especially attractive for reconfiguration of the permanent shape of complex geometry self-deploying devices and their thermal and electrical triggering.
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•Recyclable composite based on star shaped PCL covalent adaptable network based on Diels Alder reaction.•MWCNT composite shows excellent shape memory properties.•Sequentially actuated systems by easy welding of the dynamic network with and without fillers.•Electrical actuation of the shape recovery and self-healing thanks to conducting MWCNTs.
Additive Manufacturing or 3D Printing has a great potential to develop significant advances in materials, printers' technology, and processes. Thus, the layer by layer manufacturing has existed for ...three decades and new developments recently appeared in smart materials. Laboratories discovered ways to design and manufacture advanced structured materials and responsive materials used in multi-functional and high-performance products. The current research and development efforts will have an impact on the traditional design and manufacturing process. 4D Printing announces a major modification in the product design and manufacturing process from static structures to dynamic structures like Shape Memory Material (SMM) with integrated functionalities. This article presents a review of smart materials based on a classification of advanced structured materials and responsive materials before beginning a description of current applications. The use of multi-materials and the study of predictive models to simulate the responsive materials behaviour accelerate the smart materials development.
The emerging 4D printing techniques open new horizons for fabricating self-actuated deformable objects by combing strength of 3D printing and stimuli-responsive shape memory materials. This article ...focuses on designing self-actuated deformable solids for 4D printing such that a solid can be programmed into a temporary shape and later recovers to its original shape after heating. To avoid a high material cost, we choose a dual-material strategy that mixes an expensive thermo-responsive shape memory polymer (SMP) material with a common elastic material, which however leads to undesired deformation at the shape programming stage. We model this shape programming process as two elastic models with different parameters linked by a median shape based on customizing a constitutive model of thermo-responsive SMPs. Taking this material modeling as a foundation, we formulate our design problem as a nonconvex optimization to find the distribution of SMP materials over the whole object as well as the median shape, and develop an efficient and parallelizable method to solve it. We show that our proposed approach is able to design self-actuated deformable objects that cannot be achieved by state of the art approaches, and demonstrate their usefulness with three example applications.
In this brief review, an introduction of the underlying mechanisms for the shape memory effect (SME) and various shape memory phenomena in polymers is presented first. After that, a summary of ...typical applications in sensors based on either heating or wetting activated shape recovery using largely commercial engineering polymers, which are programmed by means of in-plane pre-deformation (load applied in the length/width direction) or out-of-plane pre-deformation (load applied in the thickness direction), is presented. As demonstrated by a number of examples, many low-cost engineering polymers are well suited to, for instance, anti-counterfeit and over-heating/wetting monitoring applications via visual sensation and/or tactual sensation, and many existing technologies and products (e.g., holography, 3D printing, nano-imprinting, electro-spinning, lenticular lens, Fresnel lens, QR/bar code, Moiré pattern, FRID, structural coloring, etc.) can be integrated with the shape memory feature.
Recently, new developments in the design and performance optimization of smart mechanisms associated with natural and man-made hazards have progressed considerably. This is mainly owing to advances ...in smart sensing mechanisms including communication and data technologies. This work provides a detailed overview of existing improvements on smart hazard monitoring equipment and materials applied in textile sensing systems. Given that fire is one of the most common disasters in many countries such as Australia, and every year many firefighters are affected by these unfortunate incidents, the focus of this study is on firefighters' protective clothing Fire Fighter Protective clothing. This review provides a unique opportunity to study smart sensing systems in coating technologies, potentially provides more effective techniques for training and better safety protocols of fire fighters. It aims to revisit the existing advances and address recent challenges and opportunities for improvement in the domain of smart coating and fire protective wearables. The goal of this review is to provide information about smart coating in protective clothing for firefighters. The capability of some of these clothing in managing thermal stresses, responding to humid environment, monitoring some critical parameters and adapting to the size of the wearers (clothes fabricated with phase change and shape memory substances) made them attractive choice in adjusting specific design features of industrial textiles. Various types of phase change and shape memory substances are defined and a combination of these substances within the structure of fabrics are presented. This paper also provides a detailed review on the heat exposure and capability of the shape memory substances (SMM) and phase change materials (PCM) to delay the heat transfer through fire fighter protective clothing. Referring to the former research, several issues have been detected using such substances. For instance, combination of phase change and shape memory materials needs fundamental improvements with regards to assessment techniques and testing criteria. Additionally, recent improvements in the domain of PCM and SMM including modifying mechanical features, functionality, and durability under different conditions have been informed. It has been suggested that the major problem in developing fabric-Phase Change Materials (PCMs) and Shape memory material (SMM) systems is their usage methods. At last recent developments on wearable monitoring systems applied in the firefighters’ protective gear. Wearable sensors are usually used directly on the body or located on wearable items to monitor information related to firefighters’ safety.
Shape memory polymers (SMPs) are among the main groups of smart materials widely used in smart textiles and apparels, intelligent medical devices, sensors & actuators, high-performance water–vapor ...permeability materials, morphing applications, and self-deployable structures in spacecraft. However, SMPs have some limitations: comparatively low tensile strength and stiffness, relatively low recovery stress, low thermal conductivity, inertness to electrical, light, and electromagnetic stimuli accompanied by slow responsibility and low recovery time during actuation, which often limits SMPs potential applications in high-performance field. In recent years, researchers have focused more on shape memory polymer nanocomposites (SMPNCs) than the classical composites to overcome this limitation of the SMPs, as nanofillers have a large surface area and strong interaction with polymers. This review thoroughly examines the progress in SMPNCs, including the very recent past, with a particular focus on their structure–property relationship. Considering all the SMPs, the most commonly used SMPs like polyurethane, epoxy, polycaprolactam, polylactic acid, and polyvinyl alcohol along with carbon-based (i.e., CNTs, carbon black, graphene oxide, graphene nanoplatelets, graphene quantum dots, nano-diamonds), metal oxide-based (i.e., Fe
3
O
4
, TiO
2
), cellulose-based (i.e., cellulose nanocrystals, nano-cellulose gel), and other nanomaterials like nano-clay, TiN, AuNRs, organic nanoparticles, silica, sepiolite, silsesquioxane, and hydroxyapatite nanofillers are discussed. The future development of SMPNCs may enhance their performance under thermal, electric, light (UV/NIR), magnetic, and solvent (pH/water) stimuli, which may open the door to more advanced applications in the field of aerospace, robotics, sensing and actuation, and biomedical.
In this work, a novel sort of form-stable phase change materials (FSPCMs) which possesses simultaneously the shape memory function was designed and prepared. The FSPCMs consist of paraffin with ...melting point of approximately 53°C as a latent heat storage material and olefin block copolymer (OBC) as a supporting material. With mass percentage of paraffin up to 40wt%, the FSPCMs exhibit good shape stability until temperature approaches 90°C as shown by visual photographs, and this result is confirmed by dynamic mechanical analysis. At the same time, composites with 40wt% paraffin also maintain the excellent mechanical property of OBC and exhibit large elongation at break as well as similar tensile stress, insuring excellent tenacity and deformation ability. The results of shape memory testing demonstrate that the composites possess good shape memory property, with nearly complete shape fixing and recovery. Compared with other reported FSPCMs, this material can be both temperature-controlled and temperature-sensitive, and may show advantages in some advanced applications such as intelligent textile. The diversity of paraffin endows the composites with flexibility of design for applications with wide range of temperatures. Considering the inexpensive sources and easy processing, this work may open up opportunities to produce difunctional FSPCMs in the industrial field.
A fantastic sort of FSPCMs which possesses simultaneously the shape memory function is designed and prepared. As paraffin molecules are dispersed in the continuous phase of OBCs, they can be utilized as both PCMs and switch for shape changing in this material. The difunctional composites may show advantages in some advanced applications such as intelligent textile. Display omitted
•Form-stable phase change materials (FSPCM) with shape memory function are prepared.•The FSPCMs consist of paraffin and multi-block olefin copolymer.•This FSPCMs can be both temperature-controlled and temperature-sensitive.
Shape memory blends of polycaprolactone/thermoplastic polyurethane (PCL/TPU) were prepared by in situ ring‐opening polymerization (ROP) of ε‐caprolactone (CL) and thermoplastic polyurethane (TPU). ...Fourier infrared spectrometer and 1H‐NMR were used to characterize the chemical structure of PCL/TPU copolymers. The results show that TPU has been involved in the ROP of CL, leading to the formation of copolymers with homogeneous morphologies. Besides, pure PCL and all the blends exhibit an excellent shape fixation ratio of 100%, due to their high crystallinity. When a small amount of TPU is introduced, the crystallinity of PCL decreases, and as a result, the shape recovery ratio of the copolymer is enhanced compared with pure PCL. However, with the increased loading of TPU, the content of PCL as the reversible phase decreases and the storage modulus of the PCL/TPU blend declines, so the driving force for the blends to return from the temporary shape to the initial shape becomes smaller, leading to a decrease in the shape recovery ratio. Notably, when the amount of TPU is only 5%, the shape recovery ratio of the blend could reach 83.3%, which is 26% higher than that of pure PCL, and meanwhile, the tensile strength of the blend decreases slightly. This study provides a new strategy for the design of shape‐memory materials with high shape‐memory properties.
In situ preparation of PCL/TPU shape memory blends.
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