Polymer-Based Smart Material in 4D Printing Applications

4D printing: Pragmatic progression in biofabrication

Hybrid hinge structure with elastic hinge on self-folding of 4D printing using a fused deposition modeling 3D printer

6 - 4D printing of autonomously controlled soft actuators for tremor vibration suppression

Four-dimensional (4D) printing is used to describe three-dimensional (3D)-printed objects with properties that change over time. Shape memory polymers (SMPs) are representative materials for 4D printing technologies. The ability to print geometrically complex, free-standing forms with SMPs is crucial for successful 4D printing. In this study, an SMP capable of frontal polymerization featuring exothermic self-propagation was synthesized by adding cyclooctene to a poly(dicyclopentadiene) network, resulting in switching segments. The rheological properties of this SMP were controlled by adjusting incubation time. A nozzle system was designed such that the SMP could be printed with simultaneous polymerization to yield a free-standing structure. The printing speed was set to 3 cm min−1 according to the frontal polymerization speed. A free-standing, hexagonal spiral was successfully printed and printed spiral structure showed excellent shape memory performance with a fixity ratio of about 98% and a recovery ratio of 100%, thereby demonstrating the 3D printability and shape memory performance of frontally polymerizable SMPs.

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.

In the past decade, 3D/4D printing has emerged as a novel and acceptable approach to manufacturing cost-effective industrial products, sensors, and actuators for various devices. The 4D printing of polymers is now being explored widely for advanced space exploration and biomedical and structural applications by utilizing smart materials that possess shape-memory or programming properties. Commercially available smart materials (ceramics and composite-based) are reportedly costly for the desired applications. Nevertheless, little has been reported on the in-house development of smart materials for such 4D printing applications. The present study highlights the material processing route to prepare smart polymer-based composite materials in lab-scale environments that possess good shape-recovery features (piezoelectric capabilities) and self-alignment capabilities for non-structural engineering-based 4D printing applications. The proposed material processing route may be adopted for self-expansion and self-contraction properties of thermoplastic composites for the replacement of hip joints. Finally, a framework for fabrication of smart/rapid tooling to be used in total hip arthroplasty (THA) (having 4D capabilities) has been detailed in this work.

4 - 4D-printed low-voltage electroactive polymers modeling and fabrication

4D printed and multi-stimulus responsive shape memory polymer nanocomposites developed on hydrogen bonding–metal-phenolic sacrificial network: Application for hazardous chemical operations soft robots

Four-dimensional (4D) printing is regarded as a methodology that links 3D printing to time, which is characterized by the evolution of predetermined structures or functions for the printed object after applying stimulation. This dynamic feature endows 4D printing the potential to be intelligent, attracting wide attention from academia and industry. The transformation of shape and function is both obtained from the programming of the object endowed by the intrinsic characteristics of the material or by the manufacturing technology. Therefore, it is necessary to understand 4D printing from the perspective of both mechanism and manufacturing. Here, the state-of-the-art 4D printing polymer was summarized, beginning with the classifications, and leading to the mechanisms, stimulations, and technologies. The links and differences between 4D printing polymer and shape memory polymer, between 4D printing and 3D printing were highlighted. Finally, the biomedical applications were outlined and the perspectives were discussed.

3D printing technology has revolutionized the way products are manufactured, and it has opened up new possibilities in the field of smart materials. Smart materials are materials that can change their properties in response to external stimuli, such as temperature, pressure, or light. By combining 3D printing technology with smart materials, highly customizable and responsive products are created. The addition of the time dimension to 3D printing has introduced 4D printing technology, which has gained considerable attention in different fields such as medical, art, and engineering. To bridge the gap in knowledge of 4D, this paper assessed the revolution in healthcare with 3D/4D printing and smart materials. Data was generated as part of a broader empirical study which sought to explore healthcare personnel and electrical engineers’ perception on the practices around the use of 3D/4D printing technology and smart materials. The main method used was structured interviews. 12 participant were purposively selected and interviewed including healthcare personnel and electrical engineers form Philippines and Nigeria. The findings reveal an array of activities undertaken using both 3D and 4D. Furthermore, the study revealed that 4D printing is a new generation of 3D printing. Another aspect of the 3D usage is the integration of electrical stimulation and smart implant as a new area of study in healthcare. 3D could also be used to monitoring the smart implant performance. The study also evaluate the possibility of using Internet of things (IoT) in the smart implant as some device embeds smart materials. Smart implant commonly used includes orthopedic applications, such as knee and hip replacement, spine fusion, and fracture fixation. The smart materials used in this technology are important because 3D printing allows printed structures to be dynamic. The paper highpoints is that 4D printing has great potential for the future.

The rapid development and advancements in field of shape memory alloys (SMAA) has tremendously increased the progress in four-dimensional (4D) printing. The conventional 4D printing will require skilled manpower but utilization of reversibility aspect achieved using self adjusting external stimuli will eliminate the necessity of sophisticated devices and human intervention in 4D printing. The components created using reversible 4D printing can be reused after each recovery cycle that suits the current industry requirements. This review is divided into three sections: The first section starts with a detailed illustration of different mechanisms associated with SMAA and shape memory polymers SMPP along with an illustration of realistic 3D-printed SMAA and SMPP. The second section of this paper deals with the different methods of manufacture with the advantages and disadvantages of different types of SMAA. The third section deals with the mechanisms associated with SMPP, namely (1) Thermo-responsive mechanism, (2) Chemo-responsive mechanism, and (3) Photo-responsive mechanism along with a detailed insight into the aspect of repeatability and reversibility. The fourth section presents an exhaustive review of the application of SMAA and SMPP in civil engineering. The last section of this work throws light on the challenges faced in 4D reversible printing of SMAA and SMPP along with the potential solutions and presents directions for future research.

In the traditional 4D printing method using Shape Memory Polymer (SMP), the design process and preparation of 4d printing are complex. In this research, we proposed a design method of a temperature-driven SMP smart structure and made Realization. This smart structure also a bilayer structure use an SMP material in one printing process to realize the deformation in 4D printing. The design of the smart structure is mainly realized by parameter allocation in the printing process, such as print line width, print line height, print temperature, simulation temperature, and fill the form in Fused Deposition Modelling (FDM). Through experimental determination and analysis of statics and thermodynamics, our method fitting out the model relationship between process parameters and the curvature and strain of smart structure. This bilayer smart structure widely applied to the self-folding. In the example stage, this paper mainly uses PLA as an SMP material for the preparation of structure. Observing that the motion behaviors of the smart structure conformed to the model measured in this paper, the average accuracy of the strategy reaches 95%.

Three-dimensional (3D) bioprinting is a versatile technique for biomedical applications, and includes organ printing, 3D disease model development, and drug delivery. The bioprintable materials combined with live cells have been utilized as bioinks in 3D bioprinter to fabricate versatile 3D printed structures. The 3D structures developed with smart and responsive materials can change their dimension, a technique similar to self-assembly, unfolding a new branch termed as four-dimensional (4D) printing. This manuscript reviews the details of various bioprintable materials and 3D printers, the application of 3D printing in biomedicine, smart materials, and stimulations for 4D printing. Further, this article also summarizes the regulatory issues and the limitations involved with the bioprinting. The advancements in 3D and 4D printing technology have significantly contributed to the medical field, and adequate research and amalgamation of engineering and science ideas will strengthen the application of this technology and bring solution for the existing problems.Graphical abstract

Despite great progress in four-dimensional (4D) printing, i.e. three-dimensional (3D) printing of active (stimuli-responsive) materials, the relatively low actuation force of the 4D printed structures often impedes their engineering applications. In this study, we use multimaterial inkjet 3D printing technology to fabricate shape memory structures, including a morphing wing flap and a deployable structure, which consist of active and flexible hinges joining rigid (non-active) parts. The active hinges, printed from a shape memory polymer (SMP), lock the structure into a second temporary shape during a thermomechanical programming process, while the flexible hinges, printed from an elastomer, effectively increase the actuation force and the load-bearing capacity of the printed structure as reflected in the recovery ratio. A broad range of mechanical properties such as modulus and failure strain can be achieved for both active and flexible hinges by varying the composition of the two base materials, i.e. the SMP and the elastomer, to accommodate large deformation induced during programming step, and enhance the recovery in the actuating step. To find the important design parameters, including local deformation, shape fixity and recovery ratio, we conduct high fidelity finite element simulations, which are able to accurately predict the nonlinear deformation of the printed structures. In addition, a coupled thermal-electrical finite element analysis was performed to model the heat transfer within the active hinges during the localized Joule heating process. The model predictions showed good agreement with the measured temperature data and were used to find the major parameters affecting temperature distribution including the applied voltage and the convection rate.

Although several force application concepts are known that can be used to deform shape memory polymers (SMPs) within the scope of programming, controlled deformation is challenging in the case of samples with a cylinder-like shape, which need to be homogeneously compressed starting from the lateral surface. To solve this problem, this contribution follows a material approach that takes advantage of four-dimensional (4D) printing. Fused filament fabrication (FFF) was used as an additive manufacturing (AM) technique to produce a thermoresponsive tool in a cylindrical shape from a polyether urethane (PEU) having a glass transition temperature (Tg) close to 55 °C, as determined by differential scanning calorimetry (DSC). Once it was 4D-printed, a sample of laser cut polyester urethane urea (PEUU) foam with a cylindrical wall was placed inside of it. Subsequent heating to 75 °C and keeping that temperature constant for 15 min resulted in the compression of the foam, because the internal stresses of the PEU were transferred to the PEUU, whose soft segments were completely molten at 65 °C as verified by DSC. Upon cooling to -15 °C and thus below the offset temperature of the soft segment crystallization transition of the PEUU, the foam was fixed in its new shape. After 900 days of storage at temperatures close to 23 °C, the foam recovered its original shape upon reheating to 75 °C. In another experiment, a 4D-printed cylinder was put into hibernation for 900 days before its thermoresponsiveness was investigated. In the future, 4D-printed tools may be produced in many geometries, which fit well to the shapes of the SMPs to be programmed. Beyond programming SMP foams, transferring the forces released by 4D-printed tools to other programmable materials can further expand technical possibilities.