Advances in 4D Printed Shape Memory Polymers: From 3D Printing, Smart Excitation, and Response to Applications

Abstract

The most common SMP is the one-way double SMP under thermal excitation, where thermal excitation specifically refers to the assignment of a temporary shape to the material in a thermal environment and triggers the return of a permanent shape under thermal stimulation. One-way indicates that the deformation of the temporary shape to the permanent shape is one-way irreversible and cannot be reversed spontaneously. Double indicates that the SMP can only remember one temporary shape during the deformation process. However, the single stimulus-response model of the thermal response dual SMP and its sensitivity to temperature change conditions have greatly limited its application, and this shortcoming has largely affected the continued development of SMP. To meet the adaptation needs of SMP in various fields, conventional solutions focus on the design of SMP material modification, such as enriching the SMP response deformation mode by adding functional fillers. Recently, with the emergence of 4D printing, it provides a new idea for the design and manufacturing of efficient, intelligently deformed, and multifunctionally integrated prototypes. [10][11][12] And SMPs have become one of the most widely used material types in 4D printing research due to their superior material properties and printability. [13] And they show great potential for applications in biomedicine, intelligent robotics, aerospace and other fields. [14][15][16][17] Therefore, this review provides an overview of the 3D printing processes commonly used in 4D printing SMP and the shape deformation patterns of SMP, an analysis of novel 4D deformation patterns realized with the unique molding principles of 3D printing, and 4D printing strategies for integrated structure-material-function manufacturing, as shown in Figure 1, providing a research basis for next-generation biomedical implants, smart devices, and origami structures.

3D and 4D Printing in the Fight against Breast Cancer

“…Among them, PLA showed to be a promising candidate for 4DP applications, in particular to produce vascular stents [ 63 , 64 ] and bone tissue scaffolds [ 65 , 66 ], allowing minimal invasive surgery. However, some drawbacks limit the use of polymers in 4DP, for instance, the strength and stiffness [ 67 ]. For this reason, combinations of materials can sometimes represent an opportunity to improve materials’ properties; alternatively, newly synthesized materials should be investigated.…”

3D‐Printable Shape‐Memory Polymers Based on Halogen Bond Interactions

“…The 3D-printing of polymers and, in particular, of SMPs gets more and more popular based on the ability to obtain defined and individualized 3D-shapes applying a rather simple processing method. [52][53][54][55] As the last part of this study, it was investigated whether it is possible to 3D-print this type of shape-memory polymers, further named P 3D (see Figure 4). For this reason, a mixture of the four monomers was prepared.…”

Multi-material and Multi-dimensional 3D Printing for Biomedical Materials and Devices

“…Cartilage construct with combined mechanical and biological properties [55] Hybrid AM -Embryoid body-laden GelMA -PCL Tubular scaffold directing neural differentiation for spinal cord repair [56] path along the time dimension of the 'spacetime continuum' upon a stimulation from an external energy. Smart material is just one implementation of the 4D printing concept, even though many smart material-based biomedical devices have been 4D printed as extensively discussed in several reviews [62][63][64][65][66][67][68].…”