Preparation of Highly Efficient Electromagnetic Interference Shielding Polylactic Acid/Graphene Nanocomposites for Fused Deposition Modeling Three-Dimensional Printing

3D Printed Graphene and Graphene/Polymer Composites for Multifunctional Applications

Three-dimensional (3D) printing, alternatively known as additive manufacturing, is a transformative technology enabling precise, customized, and efficient manufacturing of components with complex structures. It revolutionizes traditional processes, allowing rapid prototyping, cost-effective production, and intricate designs. The 3D printed graphene-based materials combine graphene's exceptional properties with additive manufacturing's versatility, offering precise control over intricate structures with enhanced functionalities. To gain comprehensive insights into the development of 3D printed graphene and graphene/polymer composites, this review delves into their intricate fabrication methods, unique structural attributes, and multifaceted applications across various domains. Recent advances in printable materials, apparatus characteristics, and printed structures of typical 3D printing techniques for graphene and graphene/polymer composites are addressed, including extrusion methods (direct ink writing and fused deposition modeling), photopolymerization strategies (stereolithography and digital light processing) and powder-based techniques. Multifunctional applications in energy storage, physical sensor, stretchable conductor, electromagnetic interference shielding and wave absorption, as well as bio-applications are highlighted. Despite significant advancements in 3D printed graphene and its polymer composites, innovative studies are still necessary to fully unlock their inherent capabilities.

Combining Solid-State Shear Milling and FFF 3D-Printing Strategy to Fabricate High-Performance Biomimetic Wearable Fish-Scale PVDF-Based Piezoelectric Energy Harvesters

High-performance flexible piezoelectric polymer-ceramic composites are in high demand for increasing wearable energy-harvesting applications. In this work, a strategy combining solid-state shear milling (S³M) and fused filament fabrication (FFF) 3D-printing technology is proposed for the fabrication of high-performance biomimetic wearable piezoelectric poly(vinylidene fluoride) (PVDF)/tetraphenylphosphonium chloride (TPPC)/barium titanate (BaTiO₃) nanocomposite energy harvesters with a biomimetic fish-scale-like metamaterial. The S³M technology could greatly improve the dispersion of BaTiO₃ sub-micrometer particles and the interfacial compatibility, resulting in better processability and piezoelectric performance of the nanocomposites. Typically, the FFF 3D printed energy harvester incorporating 30 wt % BaTiO₃ showed the highest piezoelectric outputs with an open-circuit voltage of 11.5 V and a short-circuit current of 220 nA. It could hence drive nine green LEDs to work normally. In addition, a 3D-printed biomimetic wearable energy harvester inspired by an environmentally adaptive fish-scale-like metamaterial was further fabricated. The fish-scale-like energy harvester could harvest energy through different deformation motions and successfully recharge a 4.7 μF capacitor by being mounted on a bicycle tire and the tire's rolling. This work not only provides a 3D printing strategy for designing diversified and complex geometric structures but also paves the way for further applications in flexible, wearable, self-powered electromechanical energy harvesters.

Bioplastics and Carbon-Based Sustainable Materials, Components, and Devices: Toward Green Electronics

The continuously growing number of short-life electronics equipment inherently results in a massive amount of problematic waste, which poses risks of environmental pollution, endangers human health, and causes socioeconomic problems. Hence, to mitigate these negative impacts, it is our common interest to substitute conventional materials (polymers and metals) used in electronics devices with their environmentally benign renewable counterparts, wherever possible, while considering the aspects of functionality, manufacturability, and cost. To support such an effort, in this study, we explore the use of biodegradable bioplastics, such as polylactic acid (PLA), its blends with polyhydroxybutyrate (PHB) and composites with pyrolyzed lignin (PL), and multiwalled carbon nanotubes (MWCNTs), in conjunction with processes typical in the fabrication of electronics components, including plasma treatment, dip coating, inkjet and screen printing, as well as hot mixing, extrusion, and molding. We show that after a short argon plasma treatment of the surface of hot-blown PLA-PHB blend films, percolating networks of single-walled carbon nanotubes (SWCNTs) having sheet resistance well below 1 kΩ/□ can be deposited by dip coating to make electrode plates of capacitive touch sensors. We also demonstrate that the bioplastic films, as flexible dielectric substrates, are suitable for depositing conductive micropatterns of SWCNTs and Ag (1 kΩ/□ and 1 Ω/□, respectively) by means of inkjet and screen printing, with potential in printed circuit board applications. In addition, we exemplify compounded and molded composites of PLA with PL and MWCNTs as excellent candidates for electromagnetic interference shielding materials in the K-band radio frequencies (18.0-26.5 GHz) with shielding effectiveness of up to 40 and 46 dB, respectively.

Design and Synthesis Strategies: 2D Materials for Electromagnetic Shielding/Absorbing

Two-dimensional (2D) materials possess special physical and chemical properties. They have been proved to have potential application advantage in the microwave absorption (MA) and electromagnetic interference (EMI) shielding. Particularly, they exhibit positive shielding and absorbing response to EMI. Here, the research progress of preparation, electromagnetic performance and microwave shielding/absorbing mechanisms of 2D composite materials are introduced. Effective preparation routes including introducing heteroatoms, constructing unique structures and 2D composite materials are described. Furthermore, the application prospects and challenges for the development of novel EMI materials are expatiated.

Improvement of Interlayer Adhesion and Heat Resistance of Biodegradable Ternary Blend Composite 3D Printing

Poly(lactic acid) (PLA) filaments have been the most used in fused deposition modeling (FDM) 3D printing. The filaments, based on PLA, are continuing to be developed to overcome brittleness, low heat resistance, and obtain superior mechanical performance in 3D printing. From our previous study, the binary blend composites from PLA and poly(butylene adipate-co-terephthalate) (PBAT) with nano talc (PLA/PBAT/nano talc) at 70/30/10 showed an improvement in toughness and printability in FDM 3D printing. Nevertheless, interlayer adhesion, anisotropic characteristics, and heat resistance have been promoted for further application in FDM 3D printing. In this study, binary and ternary blend composites from PLA/PBAT and poly(butylene succinate) (PBS) with nano talc were prepared at a ratio of PLA 70 wt. % and blending with PBAT or PBS at 30 wt. % and nano talc at 10 wt. %. The materials were compounded via a twin-screw extruder and applied to the filament using a capillary rheometer. PLA/PBAT/PBS/nano talc blend composites were printed using FDM 3D printing. Thermal analysis, viscosity, interlayer adhesion, mechanical properties, and dimensional accuracy of binary and ternary blend composite 3D prints were investigated. The incorporation of of PBS-enhanced crystallinity of the blend composite 3D prints resulted in an improvement to mechanical properties, heat resistance, and anisotropic characteristics. Flexibility of the blend composites was obtained by presentation of PBAT. It should be noted that the core-shell morphology of the ternary blend influenced the reduction of volume shrinkage, which obtained good surface roughness and dimensional accuracy in the ternary blend composite 3D printing.