Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding

Shape memory polymers: Past, present and future developments

The formation of 3D objects composed of shape memory polymers for flexible electronics is described. Layer-by-layer photopolymerization of methacrylated semicrystalline molten macromonomers by a 3D digital light processing printer enables rapid fabrication of complex objects and imparts shape memory functionality for electrical circuits.

3D Printing of Shape Memory Polymers for Flexible Electronic Devices

Over the past decades, interest in shape memory polymers (SMPs) has persisted, and immense efforts have been dedicated to developing SMPs and their multifunctional composites. As a class of stimuli-responsive polymers, SMPs can return to their initial shape from a programmed temporary shape under external stimuli, such as light, heat, magnetism, and electricity. The introduction of functional materials and nanostructures results in shape memory polymer composites (SMPCs) with large recoverable deformation, enhanced mechanical properties, and controllable remote actuation. Because of these unique features, SMPCs have a broad application prospect in many fields covering aerospace engineering, biomedical devices, flexible electronics, soft robotics, shape memory arrays, and 4D printing. Herein, a comprehensive analysis of the shape recovery mechanisms, multifunctionality, applications, and recent advances in SMPs and SMPCs is presented. Specifically, the combination of functional, reversible, multiple, and controllable shape recovery processes is discussed. Further, established products from such materials are highlighted. Finally, potential directions for the future advancement of SMPs are proposed.

A Review of Shape Memory Polymers and Composites: Mechanisms, Materials, and Applications

Four-dimensional (4D) active shape-changing structures based on shape memory polymers (SMPs) and shape memory nanocomposites (SMNCs) are able to be controlled in both space and time and have attracted increasing attention worldwide. However, conventional processing approaches have restricted the design space of such smart structures. Herein, 4D active shape-changing architectures in custom-defined geometries exhibiting thermally and remotely actuated behaviors are achieved by direct-write printing of ultraviolet (UV) cross-linking poly(lactic acid)-based inks. The results reveal that, by the introduction of a UV cross-linking agent, the printed objects present excellent shape memory behavior, which enables three-dimensional (3D)–one-dimensional (1D)–3D, 3D–two-dimensional (2D)–3D, and 3D–3D–3D configuration transformations. More importantly, the addition of iron oxide successfully integrates 4D shape-changing objects with fast remotely actuated and magnetically guidable properties. This research realizes ...

Direct-Write Fabrication of 4D Active Shape-Changing Structures Based on a Shape Memory Polymer and Its Nanocomposite

As a new class of smart materials, shape memory polymers and their composites (SMPs and SMPCs) can respond to specific external stimulus and remember the original shape. There are many types of stimulus methods to actuate the deformation of SMPs and SMPCs, of which the thermal- and electro-responsive components and structures are common. In this review, the general mechanism of SMPs and SMPCs are first introduced, the stimulus methods are then discussed to demonstrate the shape recovery effect, and finally, the applications of SMPs and SMPCs that are reinforced with fiber materials in aerospace are reviewed. SMPC hinges and booms are discussed in the part on components; the booms can be divided again into foldable SMPC truss booms, coilable SMPC truss booms and storable tubular extendible member (STEM) booms. In terms of SMPC structures, the solar array and deployable panel, reflector antenna and morphing wing are introduced in detail. Considering the factors of weight, recovery force and shock effect, SMPCs are expected to have great potential applications in aerospace.

https://iopscience.iop.org/article/10.1088/0964-1726/23/2/023001/pdf

Shape memory polymers and their composites in aerospace applications: a review

A segmented styrene-based shape memory polymer (SMP) comprising two types of SMP materials (S1-SMP and S2-SMP) was fabricated by using a two-step curing method to exhibit the triple shape memory effect (triple-SME). The material properties of S1-SMP and S2-SMP parts were explored using dynamic mechanical analysis, multi-frequency scan testing, thermal expansion measurements, static tensile testing and shape memory testing, respectively. Meanwhile, the triple-SME of segmented SMP was also characterized by shape memory testing with continue heating step. These experimentally determined material properties were incorporated into the theoretical model for the triple-SME based on a phase transition model and Generalized Maxwell model. Experimental verification was obtained by observing the triple-SME behavior under uniaxial tensile strain of 20%. Finally, the triple-SME behavior of SMP was assessed in two engineered implementations; a programmable self-deployed structure model and double bottle-shaped smart mandrel. Good agreement was demonstrated between experimental result and a finite-element model (FEM) simulation during the continue heating recovery step.

Triple-shape memory effect in a styrene-based shape memory polymer: Characterization, theory and application

Based on the thermomechanical mechanism of shape memory polymers (SMPs), the three-dimensional thermomechanical constitutive equation that can be used in the ABAQUS finite element simulation was derived. Then this paper compiled UMAT subroutine and simulated the thermomechanical behaviors of SMP smart mandrels. In addition, the properties of shape fixity and shape recovery ratio of SMP were considered in detail. Finally, filament winding experiments were proceeded on bottle-shaped and air duct-shaped mandrels and the simple and efficient demoulding of SMP mandrels were verified. The results showed the feasibility of SMP as the smart mandrels from practical application in the future.

Haiyang Du

Papers

Shape memory polymers and their composites in aerospace applications: a review

Triple-shape memory effect in a styrene-based shape memory polymer: Characterization, theory and application

Analysis and design of smart mandrels using shape memory polymers

Design and analysis of smart release devices based on shape memory polymer composites

Thermal-mechanical behavior of styrene-based shape memory polymer tubes