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Traditionally, shape transformation using implicit functions is performed in two distinct steps: 1) creating two implicit functions, and 2) interpolating between these two functions. We present a new shape transformation method that combines these two tasks into a single step. We create a transformation between two N-dimensional objects by casting this as a scattered data interpolation problem in N + 1 dimensions. For the case of 2D shapes, we place all of our data constraints within two planes, one for each shape. These planes are placed parallel to one another in 3D. Zero-valued constraints specify the locations of shape boundaries and positive-valued constraints are placed along the normal direction in towards the center of the shape. We then invoke a variational interpolation technique (the 3D generalization of thin-plate interpolation), and this yields a single implicit function in 3D. Intermediate shapes are simply the zero-valued contours of 2D slices through this 3D function. Shape transformation between 3D shapes can be performed similarly by solving a 4D interpolation problem. To our knowledge, ours is the first shape transformation method to unify the tasks of implicit function creation and interpolation. The transformations produced by this method appear smooth and natural, even between objects of differing topologies. If desired, one or more additional shapes may be introduced that influence the intermediate shapes in a sequence. Our method can also reconstruct surfaces from multiple slices that are not restricted to being parallel to one another., 8 pages, 8 figures. Also available at: http://graphics.berkeley.edu/papers/Turk-STU-1999-08

Three-dimensional (3D) printing enables the fabrication of complex, highly customizable structures, which are difficult to fabricate using conventional fabrication methods. Recently, the concept of four-dimensional (4D) printing has emerged, which adds active and responsive functions to 3D-printed structures. Deployable or adaptive structures with desired structural and functional changes can be fabricated using 4D printing; thus, 4D printing can be applied to actuators, soft robots, sensors, medical devices, and active and reconfigurable photonic devices. The shape of 3D-printed structures can be transformed in response to external stimuli, such as heat, light, electric and magnetic fields, and humidity. Light has unique advantages as a stimulus for active devices because it can remotely and selectively induce structural changes. There have been studies on the light activation of nanomaterial composites, but they were limited to rather simple planar structures. Recently, the light activation of 3D-printed complex structures has attracted increasing attention. However, there has been no comprehensive review of this emerging topic yet. In this paper, we present a comprehensive review of the light activation of 3D-printed structures. First, we introduce representative smart materials and general shape-changing mechanisms in 4D printing. Then, we focus on the design and recent demonstration of remote light activation, particularly detailing photothermal activations based on nanomaterial composites. We explain the light activation of 3D-printed structures from the millimeter to sub-micrometer scale.

Soft untethered microswimmers have recently been demonstrated to be capable of transporting and delivering cargos by external control while maintaining biocompatibility and safety. However, such microswimmers still suffer from complex and inconvenient fabrication processes and control methods, which impedes their clinical translation. In this paper, an easy‐to‐fabricate, magnetic‐driven and IR‐induced shape transformative microswimmer is presented. This microswimmer can be fabricated in a fast, low‐cost and high‐throughput manner. Besides, the soft body of the microswimmer can provide an inherent friendly contact with the biological environment, and its components are biocompatible and biodegradable. Being magnetically‐drivable allows the microswimmer to provide untethered movement and targeted therapy in the human body, and its IR‐induced shape transformability enables penetrable regulation of the movement and function. Furthermore, the shape of the untethered microswimmer can be transformed due to its combination of low melting behaviours and multi‐response materials, suggesting that other materials with similar properties can also be adopted in a similar method. The proposed method validates the feasibility to integrate polymers for fabricating magnetic‐driven, infrared‐responsive and shape transformative microswimmers.

Caricature is an artistic drawing created to abstract or exaggerate facial features of a person. Rendering visually pleasing caricatures is a difficult task that requires professional skills, and thus it is of great interest to design a method to automatically generate such drawings. To deal with large shape changes, we propose an algorithm based on a semantic shape transform to produce diverse and plausible shape exaggerations. Specifically, we predict pixel-wise semantic correspondences and perform image warping on the input photo to achieve dense shape transformation. We show that the proposed framework is able to render visually pleasing shape exaggerations while maintaining their facial structures. In addition, our model allows users to manipulate the shape via the semantic map. We demonstrate the effectiveness of our approach on a large photograph-caricature benchmark dataset with comparisons to the state-of-the-art methods.

Confined self-assembly of block copolymers (BCPs) is effective to manipulate various shapes of particles. In emulsion confined self-assembly, reversibly light-trigged switchable BCP particles are extremely expected, yet rarely reported. Herein, a novel strategy is developed to realize reversibly light-responsive shape-transformation of BCP particles by constructing functional surfactants with light-active azobenzene (azo) groups in the confined self-assembly of BCPs within emulsion droplet. Ultraviolet and visible lights can reversibly modulate the amphiphilicity and interfacial affinity of the surfactants to different blocks, triggering the reversible microphase structure transformation of BCP particles with high temporal-spatial resolution. We can realize shape and morphological transitions of BCP particles from onion-shaped spherical particles to striped ellipsoids and, ultimately, to inverse onion-like particles by ultraviolet irradiation. More importantly, this shape transformation is reversible by the irradiation of visible light, attributed to the reversible

Geometrical representation method plays a fundamental role in aerodynamic design in that it makes preparation for design space. A good design space should be composed of design variables that are more likely to attain the solution to the problem than others. This study finds that due to the characteristics of Bernstein polynomials, a conventional class-shape transformation (CST) geometrical representation method is insufficiently focused on the leading-edge region of airfoils/wings. However, more aerodynamic attention is required there because it has strong relationship with the aerodynamic performance of whole geometry. The lack of design variables assigned to the leading-edge region is likely to compromise the effort in finding better optimization results in design space. While maintaining the convenience and accuracy of conventional CST, this study proposes two types of modifications to add more aerodynamic insights into the leading-edge region: (1) an approach of supplementary vertical CST aiming to describe the leading-edge region upon the fitting result of conventional CST; (2) an approach of globally transforming airfoil surfaces into a single-value function with respect to x-direction so that the leading-edge region avoids being split up into two separate parts. With those two modifications, the leading edge can be put to the center of geometric description by rotating the local coordinate system after tackling some other issues that come with the operation. Modification 1 is intuitive, although it requires additional attention to some parameters for the continuity between the leading-edge region and other regions of the airfoil. Modification 2 is convenient to implement, but has limitations on accuracy control because the result of shape error has to account for the introduction global transforming function. Two modifications are illustrated, and their applications are discussed in the study, showing the perspective of being utilized in aerodynamic design that involves delicate difference of aerodynamic performance brought by variations of leading-edge shape.

A number of deformation models are considered for a wear coating. They are used as a basis to perform the calculations of coating wear kinetics within the two-dimensional formulation of the wear contact problem. It is shown that the use of refined deformation models for a coating with consideration for its shape transformation may have a significant effect on the results of calculating the coating wear kinetics.

Shape transformable materials that can respond to external environments have attracted widespread interest over the fields of soft robotics, flexible electronics, and tissue engineering. Among stimuli-responsive materials, liquid metals exhibit rather unique characteristics of versatile morphological changes upon diverse stimuli, including chemicals, electrical field, and mechanical force, etc. Herein, a superfast (few milliseconds), large-scaled (13.8% deformation increase), and fierce (cracks formation) transformation of liquid metal microdroplets (LMMs) with strong impulse expanded force due to liquid-solid phase transition in a dual fluid system composed of LMMs and aqueous solution is reported. When subject to low-temperature stimulus, LMM would transform from ellipsoidal shape to amorphous shape induced by thermal stress, driving the shape morphing. Furthermore, the phase changes of LMMs as well as the formation of surrounding ice crystals are proven to be responsible for this phenomenal behavior. The densification of ice crystals is demonstrated to play a significant role in the transformable behavior. In particular, these nonconductive LMMs in aqueous solutions are discovered to turn into conducive materials with an impedance change of about 10

We synthesized fullerene-terminated polymethyl methacrylates (PMMAs), linear ditopic calix[5]arene host, and branched tritopic calix[5]arene host. The calix[5]arene hosts bound to the fullerene moi...

Plasmon-mediated shape transformation from quasi-spherical silver nanoparticles (AgNPs) to silver nanoprisms (AgNPrs) and decahedral silver nanoparticles (D-AgNPs) under irradiation of blue LEDs (λ = 456 ± 12 nm, 80 mW/cm2) was studied at temperatures ranging between 60, 40, 30, 20, 10, and 0 °C. It was found that reaction temperature affected transformation rates and influenced the morphology distribution of final products. The major products synthesized at temperatures between 60 °C and 0 °C were AgNPrs and D-AgNPs, respectively. The D-AgNPs synthesized at such low temperatures are unstable and become blunt when light irradiation is removed after the photochemical synthesis. These blunt nanoparticles with pentagonal multiple-twinned structures can be further used as the seeds to reconstruct complete D-AgNPs after irradiating blue LEDs at various bath temperatures. Our results showed that these rebuilt D-AgNPs are much more stable when at higher bath temperatures. Furthermore, the rebuilt D-AgNPs (edge lengths ~41 nm) can grow into larger D-AgNPs (edge lengths ~53 nm) after the irradiation of green LEDs. Surface-enhanced Raman spectra of CV in AgNP colloids showed that D-AgNP colloids have better SERS enhancements factors than AgNPrs.

The aim of our research was to investigate and optimise the main 3D printing process parameters that directly or indirectly affect the shape transformation capability and to determine the optimal transformation conditions to achieve predicted extent, and accurate and reproducible transformations of 3D printed, shape-changing two-material structures based on PLA and TPU. The shape-changing structures were printed using the FDM technology. The influence of each printing parameter that affects the final printability of shape-changing structures is presented and studied. After optimising the 3D printing process parameters, the extent, accuracy and reproducibility of the shape transformation performance for four-layer structures were analysed. The shape transformation was performed in hot water at different activation temperatures. Through a careful selection of 3D printing process parameters and transformation conditions, the predicted extent, accuracy and good reproducibility of shape transformation for 3D printed structures were achieved. The accurate deposition of filaments in the layers was achieved by adjusting the printing speed, flow rate and cooling conditions of extruded filaments. The shape transformation capability of 3D printed structures with a defined shape and defined active segment dimensions was influenced by the relaxation of compressive and tensile residual stresses in deposited filaments in the printed layers of the active material and different activation temperatures of the transformation.

Light-triggered unique shape transformation of calcein-loaded giant polymersomes with tubular protrusions, which serve as a reservoir membrane area during the shape transformation, is reported here. Under irradiation at the excitation wavelength of calcein, the tubular protrusions form strings of budded vesicles and then reintegrate into the mother vesicle. The initial giant polymersomes transform to two connected spherical vesicles via two pathways to alleviate the osmotic pressure imbalance across the vesicle membrane. The two connected spherical vesicles further transform to a mother vesicle with an inner daughter vesicle after switching off the light to relieve the bending energy. The finding provides a promising platform to mimic cell morphology changes.

Here we report the shape transformation of poly(ethylene glycol)-polystyrene (PEG-PS) polymersomes into ordered inverse morphologies, directed by the salt concentration of the medium and the presence of azide groups on the polymersome surface. The azide moieties introduced at the chain ends of the PEG blocks induce a difference in hydrodynamic volume of the hydrophilic domains at the inner and outer side of the vesicular membrane, allowing control over its spontaneous curvature and hence the pathway of shape deformation. This simple modification enables access to intricate morphologies which are traditionally only accessible via the application of complex polymer building blocks.

The design of materials that can mimic encoded shape evolution in nature is important but challenging. Here we present a simple yet versatile strategy for programming the sequential deformation of hydrogel sheets to acquire desired actuation motions and geometric shapes. The method relies on the dual-gradient structure-enabled snapping deformation of hydrogels through the accumulation and burst release of elastic energy, as well as the patterning of the prestored energy in gels. Pretreating distinct regions of the hydrogel sheets with different durations of the same stimulus (or with different stimuli) allows for locally prestoring chemical energy that can be converted to temporospatially patterned elastic energy and abruptly released to drive the successive snapping of different regions of hydrogels in predefined onset sequences. The sequence of energy release (i.e., the sequence of snapping deformation) of the local regions for hydrogels can be reprogrammed by different local prestimulation methods, which allows one gel to deform into various defined geometric configurations. The general mathematic criteria are developed to predict the energy release and snapping of the hydrogels. This work can provide guidance for the design of new-generation actuators and soft robotics.

Shape transformation of thin two-dimensional sheets into three-dimensional structures using light is of great interest for remotely controlled fabrication, surface modulation, and actuation. Over the last few decades, significant efforts have been made to develop material systems incorporating photochemical or photothermal elements to drive deformation in response to illumination. However, the full extent of the interplay between chemistry, optics, and mechanics in these materials is poorly understood. In this review, we introduce principles of shape morphing in these systems by considering the underlying physics of photoinduced stresses and how these have been used in recent literature. In addition, we provide a critical overview of the important design characteristics of both photochemical and photothermal system and offer our view on the open opportunities and challenges in this rapidly growing field.

The ability to optically reconfigure an existing actuator of a liquid crystal polymer network (LCN) so that it can display a new actuation behavior or function is highly desired in developing materials for soft robotics applications. Demonstrated here is a powerful approach relying on selective polymer chain decrosslinking in a LCN actuator with uniaxial LC alignment. Using an anthracene-containing LCN, spatially controlled optical decrosslinking can be realized through photocleavage of anthracene dimers under 254 nm UV light, which alters the distribution of actuation (crosslinked) and non-actuation (decrosslinked) domains and thus determines the actuation behavior upon order-disorder phase transitions. Based on this mechanism, a single actuator having a flat shape can be reconfigured in an on-demand manner to exhibit reversible shape transformation such as self-folding into origami three-dimensional structures. Moreover, using a dye-doped LCN actuator, a light-fueled microwalker can be optically reconfigured to adopt different locomotion behaviors, changing from moving in the laser scanning direction to moving in the opposite direction.

Significance Liquid crystal (LC) research is rapidly expanding to include studies of curved and topologically nontrivial structures. Here, we explore the role of the bulk LC elasticity and interfacial free energy under weak thermal stimuli to achieve structural transformations in LC emulsions using two different surfactants. Our method is universal and could be used for any LC material or phase. A theoretical model for transforming LC emulsions into uniform fibers and vice versa is presented. We also show the self-shaping of smectic vesicle structures and monodispersed droplet formation at the nematic–smectic transition, utilizing the LC bulk elasticity. This work shows the potential to obtain the controllable shape of complex curved structures for a constant volume of different LCs and other soft materials., The shape diversity and controlled reconfigurability of closed surfaces and filamentous structures, universally found in cellular colonies and living tissues, are challenging to reproduce. Here, we demonstrate a method for the self-shaping of liquid crystal (LC) droplets into anisotropic and three-dimensional superstructures, such as LC fibers, LC helices, and differently shaped LC vesicles. The method is based on two surfactants: one dissolved in the LC dispersed phase and the other in the aqueous continuous phase. We use thermal stimuli to tune the bulk LC elasticity and interfacial energy, thereby transforming an emulsion of polydispersed, spherical nematic droplets into numerous, uniform-diameter fibers with multiple branches and vice versa. Furthermore, when the nematic LC is cooled to the smectic-A LC phase, we produce monodispersed microdroplets with a tunable diameter dictated by the cooling rate. Utilizing this temperature-controlled self-shaping of LCs, we demonstrate life-like smectic LC vesicle structures analogous to the biomembranes in living systems. Our experimental findings are supported by a theoretical model of equilibrium interface shapes. The shape transformation is induced by negative interfacial energy, which promotes a spontaneous increase of the interfacial area at a fixed LC volume. The method was successfully applied to many different LC materials and phases, demonstrating a universal mechanism for shape transformation in complex fluids.

Dynamic DNA origami has been employed for generating a rich repository of molecular nanomachines that are capable of sensing various cues and changing their conformations accordingly. The common design principle of the existing DNA origami nanomachines is that each dynamic DNA origami is programmed to transform in a specific manner, and the nanomachine needs to be redesigned to achieve a different form of transformation. However, it remains challenging to enable a multitude of controlled transformations in a single design of dynamic DNA nanomachine. Here we report a modular design method to programmatically tune the shapes of a DNA origami nanomachine. The DNA origami consists of small, modular DNA units, and the length of each unit can be selectively changed by toehold-mediated strand displacement. By use of different combinations of trigger DNA strands, modular DNA units can be selectively transformed, leading to the programmable reconfiguration of the overall dimensions and curvatures of DNA origami. The modular design of programmable shape transformation of DNA origami can find potential applications in more sophisticated molecular nanorobots and smart drug delivery nanocarriers.

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London This research reviews the state-of-the-art literature on the two-emerging material-driven Additive Manufacturing (AM) strategies, Functionally Graded Additive Manufacturing (FGAM) and 4D Printing (4DP) to recognise, select and implement the appropriate materials, design and fabrication methods to produce shape-changing thermo-responsive textiles. Shapememory polymers (SMPs) are required to provide the active properties required to sense and self-actuate when subjected to an appropriate stimulus over time. The current availability of SMPs for AM in the commercial market is limited and expensive. To ensure a wider uptake of 4DP, the aim of this research is to develop a material selection framework to discover, define and select commercially available thermoplastics as potential SMPs for use in material extrusion (ME) 4DP. The theoretical and practical knowledge to create a thermally actuated dual-state mechanism (DSM) active structure is described at a feasible level for users with different backgrounds and knowledge levels in 4DP. The experiments showed that commercial AM filaments could be used for 4DP, but not all materials exhibit shape memory properties despite belonging to the same material type. The shape recovery performance and repeatability of an SMP would also vary according to the programming condition. The next stage of this research details the development and testing of polymertextile composites using direct ME of PLA filaments on synthetic mesh fabrics. T-peel test results revealed that the compatibility between the printing material and the textile substrate fibre type has a dominant effect on the peel resistance of ME polymer-textile composite. The research demonstrated the use of 4DP as an alternative and novel technique for the 3D manipulation of textile fabrics. The shape transformation studies presented a proof-ofconcept that the accuracy of deformation and the shape-shifting patterns of the thermoresponsive textiles can be controlled by the geometrical dimensions and structural arrangement of the printed SMP structure on the textile substrate. The findings will enable researchers and designers to take advantage of the optimum parameters to discover new shape transformations and to create potential applications in the AM fashion and textile industry.

4D printing is a pioneer field to produce functional smart devices. The combination of 3D printing and smart material is called as 4D printing. The extra dimension refers to time in order to shape transformation of the printed part during time. FDM is a universal process to 3D printing of thermoplastic polymers. Therefore, for successful and typical 4D printing a deep understanding of every aspect of shape memory polymers especially thermoplastic polymers is necessary. So, in this chapter, shape memory polymers, printing preparation such as filament production and FDM printing parameters, finally applications, previous finding and functional printed parts by FDM have been studied detailed.

Polymeric self-assembled structures have been a topic of interest in the last few decades, specifically for the use of biomedical applications, such as drug delivery. It is exciting to investigate the formation of various shapes and sizes of such structures, as the morphology is crucial for their function. In this manuscript the important factors to control the morphology during self-assembly and subsequent shape transformation processes are discussed. We describe the main parameters to control and show the practical application of these parameters on biodegradable amphiphilic PEG-PDLLA block-copolymers. Thereby a variety of different morphologies, including micelles, worms, LCVs, discs, rods, stomatocytes, nested vesicles, and spherical vesicles of various sizes are created using only four diblock-copolymers and with careful tuning of two organic solvents. Further advances will lead to formation of more complex structures.

Hybrid stimuli-responsive soft robots have been extensively developed by incorporating multi-functional materials, such as carbon-based nanoparticles, nanowires, low-dimensional materials, and liquid crystals. In addition to the general functions of conventional soft robots, hybrid stimuli-responsive soft robots have displayed significantly advanced multi-mechanical, electrical, or/and optical properties accompanied with smart shape transformation in response to external stimuli, such as heat, light, and even biomaterials. This review surveys the current enhanced scientific methods to synthesize the integration of multi-functional materials within stimuli-responsive soft robots. Furthermore, this review focuses on the applications of hybrid stimuli-responsive soft robots in the forms of actuators and sensors that display multi-responsive and highly sensitive properties. Finally, it highlights the current challenges of stimuli-responsive soft robots and suggests perspectives on future directions for achieving intelligent hybrid stimuli-responsive soft robots applicable in real environments.

While living organisms have mastered the dynamic control of residual stresses within sheets to induce shape transformation and locomotion, man-made implementations are rudimentary. We present the first autonomously shape-shifting sheets made of a gel that shrinks and swells in response to the phase of an oscillatory chemical (Belousov-Zhabotinsky) reaction. Propagating reaction-diffusion fronts induce localized deformation of the gel. We show that these localized deformations prescribe a spatiotemporal pattern of Gaussian curvature, leading to time-periodic global shape changes. We present the computational tools and experimental protocols needed to control this system, principally the relationship between the Gaussian curvature and the reaction phase, and optical imprinting of the wave pattern. Together, our results demonstrate a route for developing fully autonomous soft machines mimicking some of the locomotive capabilities of living organisms.

We report two different formation mechanisms of a triangular Au nanoplate through the transformation of a truncated octahedron and the direct formation of a triangular seed using liquid-cell TEM. This work stresses the great significance of thermodynamics and kinetics in the formation and later shape transformation of a triangular nanoplate.

We present the shape transformation of a single layer of Au nanoparticles (NPs) when embedded in, and at the interface of, amorphous $\mathrm{Si}{\mathrm{N}}_{\mathrm{x}}$ and $\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$ ($\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{N}}_{\mathrm{x}}$ and $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$) thin films upon irradiation with 185-MeV Au ions to fluences ranging from 0.3 to $30\ifmmode\times\else\texttimes\fi{}{10}^{13}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}2}$. Transmission electron microscopy (TEM) and high angular annular dark field microscopy were used to study the ion-shaping process. The former allows us to follow the overall change in geometry, size, and structure, while the latter reveals information about the relative position with respect to the interface. For Au NPs embedded in a single material, a lower elongation rate for $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{N}}_{\mathrm{x}}$ was found in comparison to $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$. When at the interface of the two materials, TEM reveals a preferential elongation towards $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$. The latter demonstrates the use of $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{N}}_{\mathrm{x}}$ for confining the ion-shaping process within an intermediate $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$ layer. The simulation of the temperature evolution during a single-ion impact was used to understand the difference in elongation rates between $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{N}}_{\mathrm{x}}$ and $\mathrm{a}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{\mathrm{x}}$, as well as the asymmetric behavior when located at the interface using the three-dimensional inelastic thermal spike model with bulk thermophysical properties. The calculations show good agreement with the experimental observations and reveal a correlation between the thermal profile and the resulting NP geometry.

Inspired by the unusual shapes of the titration curve observed for many surfactants and mixed colloidal systems, we decided to extend the analysis to isothermal titration calorimetric curves (ITC) by paying special attention to potential structural changes in micellar aggregates. In this paper, we used isothermal titration calorimetry in conjunction with Scanning Transmission Electron Microscopy (STEM), Small-Angle Neutron Scattering (SANS) and X-ray Scattering (SAXS) methods support by Monte Carlo and semiempirical quantum chemistry simulations to confirm if the isothermal calorimetric curve shape can reflect micelle transition phenomena. For that purpose, we analysed, from the thermodynamic point of view, a group of cationic gemini surfactants, alkanediyl-&alpha, &omega, bis(dimethylalkylammonium) bromides. We proposed the shape of aggregates created by surfactant molecules in aqueous solutions and changes thereof within a wide temperature range. The results provide evidence for the reorganization processes and the relationship (dependence) between the morphology of the created aggregates and the conditions such as temperature, surfactant concentration and spacer chain length which affect the processes.

Herein, through the active-peptide-functionalization, we developed a nanoscale micelles system (named HEKM) which consists of tumor microenvironment-regulated shape-changing with specific recognition abilities for enhanced cellular targeting, internalization and therapy of heterogeneic tumors. As a result, HEKMs could recognize and bind the tumor heterogeneity marker EGFR-HER2 complex, which led to an enhanced tumor targeting effect. In particular, HEKMs could self-assemble into nanorods under normal physiological conditions while transform into nanospheres in the tumor extracellular microenvironment by a sensitive response to matrix metalloproteinase-2 (MMP-2). The nanorods could prolong the blood circulation time while the nanospheres could accelerate tissue penetration in tumors. In vivo dual-modal targeted imaging was realized by FRET-fluorophore conjugation and gadolinium loading in HEKMs. Tumor cell apoptosis was achieved by proapoptotic element integration. The in vitro and in vivo studies both demonstrated that these rationally designed, shape-changing and targeting micelles could achieve maximized drug efficacy and minimum side effects.

Nature offers a plethora of astonishing examples of shapes and functions from the aspects of both simplicity and complexity. The creation of synthetic systems that can morph in a controlled manner as seen in nature is of paramount importance in many fields of fundamental and applied sciences. The tremendous interest in self-shaping materials stems from a wide range of applications for these materials, ranging from biomedical devices to aircraft design. This review article highlights recent advances in understanding and designing thin, sheet-like soft materials that can transform into complex three-dimensional structures in a controlled manner by modulating the internal stresses. We review the general principles underlying shape transformation phenomena in natural and synthetic systems, and the significant achievements in fabricating self-shaping of soft materials via representative examples. We conclude with a discussion on the challenges facing the field, and future directions from the perspective of theoretical and experimental methodology and interdisciplinary applications.

Topology and defects are of fundamental importance for ordered structures on all length scales. Despite extensive research on block copolymer self-assembly in solution, knowledge about topological defects and their effect on nanostructure formation has remained limited. Here, we report on the self-assembly of block copolymer discs and polymersomes with a cylinder line pattern on the surface that develops specific combinations of topological defects to satisfy the Euler characteristics for closed spheres as described by Gauss-Bonnet theorem. The dimension of the line pattern allows the direct visualization of defect emergence, evolution, and annihilation. On discs, cylinders either form end-caps that coincide with λ+1/2 disclinations or they bend around τ+1/2 disclinations in 180° turns (hairpin loops). On polymersomes, two λ+1/2 defects connect into three-dimensional (3D) Archimedean spirals, while two τ+1/2 defects form 3D Fermat spirals. Electron tomography reveals two complementary line patterns on the inside and outside of the polymersome membrane, where λ+1/2 and τ+1/2 disclinations always eclipse on opposing sides ("defect communication"). Attractive defects are able to annihilate with each other into +1 disclinations and stabilize anisotropic polymersomes with sharp tips through screening of high-energy curvature. This study fosters our understanding of the behavior of topological defects in self-assembled polymer materials and aids in the design of polymersomes with preprogrammed shapes governed by synthetic block length and topological rules.

Intense investigations have been attracted to the development of materials which can reconfigure into 3D structures in response to external stimuli. Herein we report on the design and self-folding behaviors of hydrogels composed of poly(ethylene glycol) methyl ether methacrylate (OEGMA) and 2-(2-methoxyethoxy) ethyl methacrylate (MEO $_{2}$ MA). Upon immersion into a variety of solvents at room temperature, the resulting P(MEO $_{2}$ MA-co-OEGMA) hydrogel sheets self-fold into 3D morphologies, and the observed transformation in shape is reversible. We further show that composition of the gel, gaseous environment, and preparation procedure play important roles in the self-folding behavior of the resulting hydrogels. This work provides a facile approach for fabricating self-folding hydrogels.

Since smart materials and structures that holds the capability of automatically conducting shape transformation or functional variation upon environmental condition changes are critical in developing advanced components for intelligent devices and apparatus, such as sensors, actuators, self-recovery and self-healing systems. Generally, either physical or chemical approach would be applied to meet the stimulus-response modes for realizing smart shape or functional changes. In the present contribution, novel mechano-hydro-dielectric coupled graphene oxide hybrid sponges are proposed to integrate the physical and chemical approach into a smart material. Based on investigation on the decoupled features from mechano-dielectric (physical approach) and hydro-dielectric (chemical approach) modes, the mechano-hydro-dielectric coupled features suggest that integration of physical and chemical approaches would substantially promote the change ratios of each single approach, which implies both hydro-enhanced mechano-dielectric and mechano-enhanced hydro-dielectric coupled stimulus-response modes. According to the mechanism discussion from effective medium theory, the results from indicate that such mechano-hydro-dielectric coupled hybrid sponges promise a great stage to establish multifunctional sensors (both mechanical and humidity sensors) based on various physical-chemical coupled modes.

Container stacking is a common activity in various industries. At a large scale, the shipping industry stacks cargo containers, while at a smaller scale the home and office storage providers stack paper or plastic boxes. An interesting question behind container stacking is how to efficiently move containers from one stack to another. In this paper, we investigate a remotely related question: shape transformation between LEGO models. While many computational algorithms have been developed to construct LEGO models, the problem of constructing a LEGO model using bricks from an existing model has not been explored in open literature. We propose two objectives to optimize the transformation: the movement cost and the reuse rate of LEGO bricks. Two basic approaches coupled with three strategies are implemented to achieve shape transformation. Experiments and analysis reveal the efficiency of different algorithms under several metrics of evaluation.

Actuators are a kind of energy-conversion devices which can perceive external stimulus and undergo reversible deformation or motion to produce a mechanical response. Developing actuators with advanced structures rather than typical bilayer configuration is essential for stable actuations, and installing reprogrammability into actuators for on-demand complex shape transformation within the same piece of material is more convenient and cost-effective for new actuation modes. However, actuators that satisfy these requirements have rarely been reported yet. Herein, a facile and low-cost design strategy for a transparent, gradient cross-linked, patternable and reprogrammable humidity-responsive actuator based on commercial available poly (vinyl alcohol) (PVA) is presented. The actuator is fabricated by grafting PVA with 9-anthracenecarboxylic acid (9-AN) via esterification and then blending with a UV-screening agent 2,2′,4,4′-tetrahydroxybenzophenone (THBP) followed by photo-crosslinking. In such design, the abundant hydroxyl groups in grafted PVA endow the actuator with humidity-responsive ability, the THBP enables the gradient cross-linking of actuator due to the attenuated UV intensity through the film thickness, and the photo-controlled reversible cross-linking of anthracene groups allows the patterning and reprogramming of the actuator. The chemical structure, gradient morphology, and humidity-responsiveness of actuators are thoroughly investigated. The fast actuation speed and large actuation amplitude, the realization of complex shape deformation by photo-controlled programming/reprogramming, and the biomimetic applications such as the soft walking robot are also demonstrated. This study is expected to provide new opportunity for facilely developing high-performance, stable and reprogrammable actuators.

In this study, we designed a dual colorimetric and fluorometric sensor by using nitrogen and phosphor doped carbon dots (N, P-CDs) and Ag nanoprisms (AgNPrs) to detect 6-mercaptopurine (6-MP). For this purpose, we applied the AgNPrs/I- mixture to establish a shape transformation based colorimetric method for the detection of 6-MP. The assay mechanism of colorimetric method was based on etching and protecting effect of I- and 6-MP on the AgNPrs. In the presence of I-, as an etching agent, the solution color altered from blue to purple and the position of AgNPrs' local surface plasmon resonance (LSPR) peak shifted to the blue wavelengths. This phenomenon was assigned to the morphological change of AgNPrs. In the presence of 6-MP, AgNPrs were protected from etching by I-, so the LSPR peak position and solution color of AgNPrs remained unchangeable. Furthermore, the fluorescence intensity of N, P-CDs decreased with adding AgNPrs/I- due to the spectral overlap between etched AgNPrs and N, P-CDs. The CDs' quenched fluorescence was restored in the presence of 6-MP, as a result of the protecting effect of 6-MP on the AgNPrs. These facts have been applied to develop a dual sensor for the determination of 6-MP at the range of 10–500 nM and 30–500 nM by colorimetric and fluorometric detection methods. The detection limits were obtained 10 and 4 nM for fluorometric and colorimetric methods, respectively. The developed sensor was utilized for dual signal analysis of 6-MP in human serum samples with satisfactory results.

We report a new type of responsive polymer film which is composed of pure poly(vinylidene fluoride) (PVDF) and is prepared using a simple solution-casting method. This responsive PVDF film possesses an anisotropic spatial distribution of the α phase and β phase, resulting in a fast response rate, high sensitivity, and robust responsiveness to organic vapors. Experimental and computational studies illustrate that α-phase PVDF exhibits a much stronger swelling ability in acetone vapor than β-phase PVDF. Anisotropic swelling induces internal stresses, offering a driving force for macroscopic shape transformation. This newly unveiled mechanism endows the material with new functionalities for fabricating devices such as a magnetically controlled soft tumbler and a chemi-mechanical sensor. Furthermore, crystal phase anisotropy in the PVDF film can be easily programmed into origami patterns by direct laser writing (DLW) for driving reversible three-dimensional (3D) shape transformation of the film.

Shape transformation of Au crystals from a {111}-bounded octahedron to a {730}-bounded tetrahexahedron (THH) and then to a {310}-bounded truncated ditetragonal prism (TDP) was achieved by a one pot synthesis method. The transformation of the crystal morphology is the result of the synergistic effect of Ag+ and O2/Cl-. This work not only provides a way to prepare high-index faceted Au micro/nanocrystals, but also provides new insights into the crystal growth habit.

Shape transformation of flat (two-dimensional) substances into complicated (three-dimensional) structures is a new concept that can be investigated to tailor materials with appealing attributes while lessening package space. The purpose of this research is to create root-based xerogel, investigate their application as a flat 2D food product capable of transforming into a 3D shape, and quantify their hydro and oleomorphic behavior. By drying (29 °C and 75% RH) tapioca hydrogel (5%) using the sessile drop method, flat tapioca xerogels were developed. Tapioca xerogel's topside was characterized as smooth whereas the bottom side was noted to be porous in nature. There is no difference in the chemical characteristics of tapioca flour during the xerogel design process. Cold plasma-treated tapioca xerogel with and without constraint material was engineered into a flower shape (3D) through stimuli (water and oil). Because of its interconnected arrangement of particles, tapioca xerogel swells/absorbs oil in various directions when exposed to water/oil. Anisotropic nature causes a stress gradient in tapioca xerogel, causing it to self-bend. The effect of shape change was quantified by bending angle, curvature, end-end distance, and curve height. This work discusses the new approach for designing attractive pasta/chips from 2D tapioca xerogel using water/oil-actuated shape change.

Magnetic soft materials (MSMs) and magnetic shape memory polymers (MSMPs) have been some of the most intensely investigated newly developed material types in the last decade, thanks to the great and versatile potential of their innovative characteristic behaviors such as remote and nearly heatless shape transformation in the case of MSMs. With regard to a number of properties such as shape recovery ratio, manufacturability, cost or programming potential, MSMs and MSMPs may exceed conventional shape memory materials such as shape memory alloys or shape memory polymers. Nevertheless, MSMs and MSMPs have not yet fully touched their scientific-industrial potential, basically due to the lack of detailed knowledge on various aspects of their constitutive response. Therefore, MSMs and MSMPs have been developed slowly but their importance will undoubtedly increase in the near future. This review emphasizes the development of MSMs and MSMPs with a specific focus on the role of the magnetic particles which affect the shape memory recovery and programming behavior of these materials. In addition, the synthesis and application of these materials are addressed.

Because of the continuous variability of the ambient environment, all aircraft would benefit from an in situ optimized wing. This paper proposes a method for preliminary design of feasible morphing wing configurations that provide benefits under disparate flight conditions but are also each structurally attainable via localized active shape change operations. The controlled reconfiguration is accomplished in a novel manner through the use of shape memory alloy embedded skin components. To address this coupled optimization problem, multiple sub-optimizations are required. In this work, the optimized cruise and landing airfoil configurations are determined in addition to the shape memory alloy actuator configuration required to morph between the two. Thus, three chained optimization problems are addressed via a common genetic algorithm. Each analysis-driven optimization considers the effects of both the deformable structure and the aerodynamic loading experienced by the wing. Aerodynamic considerations are addressed via a two-dimensional panel method and each airfoil shape is generated by the so-called class/shape transformation methodology. It is shown that structurally and aerodynamically feasible morphing of a modern high-performance sailplane wing produces a 22% decrease in weight and significantly increases stall angle of attack and lift at the same landing velocity when compared to a baseline design that employs traditional control surfaces.

Tailoring the driving force of shape revolution for Au nanoparticles is proposed, and faceted single crystalline Au nanoparticles are prepared by a magnetron sputtering and post thermal annealing route. Theoretical investigation demonstrates that the grain boundary migration is driven by thermal stress at the annealing temperature lower than 600 °C, and in the higher temperature range till up to 900 °C, the shape transformation is driven by minimizing the formation energy. The experimental results successfully replicate the shape revolution of Au films to faceted single crystalline Au nanoparticles, demonstrating that in the first annealing temperature range from 400 to 600 °C, the nanoparticles change more easily from polycrystal grains into single-crystal grains as the annealing temperature increases. While, for the higher temperature range from 700 to 900 °C, the nanoparticles tend to form nanoprisms with regular hexagonal shape when the annealing temperature increasing.

The paper presents an innovative approach to solving interdisciplinary problems emerging in the design process of building free forms roofed with elastically transformed corrugated shells. The effectiveness and rationality of shaping such free forms and the creativeness in searching for the parametric forms require the application of their regular and symmetric models which have to be derived from the geometric and mechanical properties of the rationally transformed subsequent folds of these shells. Simplified smooth models used for engineering developments and accurate folded models implemented for scientific research have to be created by means of unconventional methods different from those presented in classical courses. Owing to the variety of the forms of the proposed innovative reference tetrahedrons and their parametric description, the algorithms developed by the authors have to be implemented in computer programs. The rationality of the transformed roof shells, revealed in the limitation of the level of the fold&rsquo, s initial stresses resulting from the shape transformation, and the attractiveness of these forms are achieved by the axial symmetry and contraction of each shell fold at its half-length. The symmetries adopted in the process of modeling such roof shells are also exploited by the discussed new method to obtain coherent unconventional general forms of entire buildings.