Advances in additive manufacturing of shape memory polymer composites

Abstract

Purpose A review on additive manufacturing (AM) of shape memory polymer composites (SMPCs) is put forward to highlight the progress made up to date, conduct a critical review and show the limitations and possible improvements in the different research areas within the different AM techniques. The purpose of this study is to identify academic and industrial opportunities. Design/methodology/approach This paper introduces the reader to three-dimensional (3 D) and four-dimensional printing of shape memory polymers (SMPs). Specifically, this review centres on manufacturing technologies based on material extrusion, photopolymerization, powder-based and lamination manufacturing processes. AM of SMPC was classified according to the nature of the filler material: particle dispersed, i.e. carbon, metallic and ceramic and long fibre reinforced materials, i.e. carbon fibres. This paper makes a distinction for multi-material printing with SMPs, as multi-functionality and exciting applications can be proposed through this method. Manufacturing strategies and technologies for SMPC are addressed in this review and opportunities in the research are highlighted. Findings This paper denotes the existing limitations in the current AM technologies and proposes several directions that will contribute to better use and improvements in the production of additive manufactured SMPC. With advances in AM technologies, gradient changes in material properties can open diverse applications of SMPC. Because of multi-material printing, co-manufacturing sensors to 3D printed smart structures can bring this technology a step closer to obtain full control of the shape memory effect and its characteristics. This paper discusses the novel developments in device and functional part design using SMPC, which should be aided with simple first stage design models followed by complex simulations for iterative and optimized design. A change in paradigm for designing complex structures is still to be made from engineers to exploit the full potential of additive manufactured SMPC structures. Originality/value Advances in AM have opened the gateway to the potential design and fabrication of functional parts with SMPs and their composites. There have been many publications and reviews conducted in this area; yet, many mainly focus on SMPs and reserve a small section to SMPC. This paper presents a comprehensive review directed solely on the AM of SMPC while highlighting the research opportunities.

DLP 4D‐Printing of Remotely, Modularly, and Selectively Controllable Shape Memory Polymer Nanocomposites Embedding Carbon Nanotubes

“…Conversely, carbon-based materials (e.g., carbon black, carbon nanotubes (CNTs), carbon nanofibers, and graphene) provide excellent mechanical properties and electrical conductivity at much lower concentrations due to their outstanding specific surface area and aspect ratio, which makes them the most attractive fillers for the development of conductive SMPCs. [16,24] The fabrication of electro-activated SMPCs embedding carbon-based fillers have been explored by means of different 3D-Printing technologies, [25] ranging from Spray Deposition Modeling, [26] solvent-cast 3D-Printing, [27] Direct Ink Writing (DIW) [28,29] to Fused Deposition Modeling (FDM). [17,[30][31][32] Nevertheless, just one study has been found on 3D printed selectively electro-activated SMPCs embedding carbon-based fillers.…”

“…[33] In this regard, the lack of photocurable SMP, the high viscosity of the doped formulations, and the light scattering induced by the filler are the main limitations to the fabrication of SMPCs via SLA/DLP processes. [25] Trying to fill this gap, we report in this study the development of novel electro-activated SMPCs consisting of a photocurable and DLP printable SMP matrix embedding multi-walled CNTs. The optimization of the formulation and the study of its printability, together with the analysis of the electro-thermal properties of the material, enabled the preparation of electrically controllable DLP printed SMPCs.…”

“…The fabrication of electro‐activated SMPCs embedding carbon‐based fillers have been explored by means of different 3D‐Printing technologies, [ 25 ] ranging from Spray Deposition Modeling, [ 26 ] solvent‐cast 3D‐Printing, [ 27 ] Direct Ink Writing (DIW) [ 28,29 ] to Fused Deposition Modeling (FDM). [ 17,30–32 ] Nevertheless, just one study has been found on 3D printed selectively electro‐activated SMPCs embedding carbon‐based fillers.…”

“…[ 33 ] In this regard, the lack of photocurable SMP, the high viscosity of the doped formulations, and the light scattering induced by the filler are the main limitations to the fabrication of SMPCs via SLA/DLP processes. [ 25 ]…”

Programming the microstructure of magnetic nanocomposites in DLP 3D printing

“…4D printing is expected to bring breakthrough improvements in several domains, such as robotics, sensors, and biomedicine [21][22][23]. In polymeric 4D printing, smart materials, either neat polymers or composites, must possess one or more functions that can be activated by physicochemical stimuli including, solvents [24,25], light [26][27][28], temperature [29][30][31][32][33],…”