Digital light processing-stereolithography three-dimensional printing of yttria-stabilized zirconia

Digital light processing (DLP)-stereolithography three-dimensional (3D) printing is a well known technique for fabricating components with complex geometries. However, the application of DLP 3D printing to functional ceramics such as 8 mol% yttria-stabilized zirconia (8YSZ), which is one of the most extensively used electrolyte materials for solid oxide fuel cells, is still a great challenge. Therefore, the fabrication of fully 8YSZ monoliths via DLP 3D printing was attempted herein, including the preparation of UV-curable ceramic suspensions, shaping of green bodies, and debinding and sintering. The results show that intact green bodies printed using a 30 vol% 8YSZ-photosensitive resin suspension with 0.1 wt% oleic acid as the dispersant under the optimized printing conditions was sufficiently dense without connected pores after vacuum debinding and sintering in air. The successful fabrication of 8YSZ monoliths with design flexibility via 3D printing provides a simple method for preparing functional ceramic components and may expand the application of 3D printing technology to the energy field.     

Comparing digital light processing and stereolithography vat polymerization Technologies for antimicrobial 3D printing using silver oxide as an antimicrobial filler

Vat polymerization technology allows filler particles to be incorporated into photosensitive 3D printing resin to improve the properties of the printed material. This method can be used to produce medical devices with an antimicrobial effect that can reduce biofilm formation and reduce infections due to indwelling devices. Metal oxides have the potential to combat antibiotic-resistant bacteria, further lowering the risk of hospital-acquired infections. The antimicrobial agent in this study, silver oxide, was evaluated for its antimicrobial effect against gram-positive bacteria (Staphylococcus epidermidis) as these are the main cause of biofilm formation. The 3D printed samples demonstrated a strong antimicrobial effect at low concentrations of 1 wt.%. Two vat polymerization technologies, stereolithography (SLA) and digital light processing (DLP), were compared for their suitability for producing 3D printed samples with an antimicrobial effect. DLP successfully produced samples with mechanical properties comparable to the base resin, whereas SLA samples had reduced mechanical strength at higher concentrations of silver oxide filler. Neither printing technology nor silver oxide concentration had a statistically significant effect on the mechanical properties of the printed materials.     

Thiol-yne 3D Printable Polymeric Resins for the Efficient Removal of a Model Pollutant from Waters

A new 3D printable resin formulation is developed and optimized from commercially available thiol (pentaerythritol tetrakis(3-mercaptopropionate); PETMP) and alkyne (3-butyn-1-ol; BA) monomers. Printed objects are characterized by Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The extraction efficiency of the printed thiol-yne device is then investigated using a model dye – malachite green (MG). The results displayed excellent dye removal efficiency with > 95% MG removed within 5 min. The 3D-printed devices are reusable and show 100% removal over six cycles after washing with deionized water and methanol. The presence of surface hydroxyl groups derived from the BA monomer is shown to enhance dye adsorption in comparison to control materials. The printing procedure and resin formulation are robust and consistent when devices from different resin batches are compared for MG dye removal. The thiol-yne 3D printed devices demonstrated excellent dye removal (> 99%) from water samples collected from a tap and a nearby river source. The successful development of this resin provides a new thiol-yne-based resin system for stereolithography (SLA) 3D printing for the removal of organic dyes from wastewater and presents a potential for broad applications in water treatment.     

Effect of print path process on sintering behavior and thermal shock resistance of Al2O3 ceramics fabricated by 3D inkjet-printing

In this study, Al₂O₃ ceramics parts were printed by inkjet printing technology with different printed paths distributions, such as the spiral printed path, round trip straight printed path and ladder lap printed path. The influences of inkjet printed paths on sintering performance and thermal shock resistance of the Al₂O₃ green bodies were investigated. The sintering performance of the green sample with the ladder lap printed path is the highest among the three samples. Sintered at 1550?℃, its bulk density and porosity reached 3.73?g/cm³ and 10.80%, respectively. In addition, the thermal shock resistance of the sample with the step print path reached 11 times. The results suggest that the optimization of the printed path provides an effective way to print 3D ceramics with good performances through 3D inkjet-printing technology.     

3D printing of shape memory poly(d,l-lactide-co-trimethylene carbonate) by direct ink writing for shape-changing structures

Four-dimensional (4D) printing of shape memory materials has attracted increasing interests for personalized structures. In this study, a biocompatible poly(d ,l -lactide-co-trimethylene carbonate) (PLMC) is utilized to fabricate 4D shape-changing structures with customized geometries through direct ink writing. The printed objects show shape transformations at different dimensions under thermal programming. The influence of the printing parameters on the properties including rheological, solvent evaporation, and static mechanical behavior are systematically investigated. A printing map is further depicted to achieve high-quality printing with high viscous ink flowed from micronozzle to construct various structures. The printed structures in one-dimensional, two-dimensional, and three-dimensional (3D) exhibit shape-changing behavior with fast response around body temperature. The fast responsive time shows potential in the field of surgical suture (4 s), nonwoven fabric (3 s), and self-expandable stent (35 s). The feasibility of 3D printing of PLMC opens the way for applications in shape-changing devices with small diameter. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48177.     

3D-Structured Monoliths of Nanoporous Polymers by Additive Manufacturing

Recent advances in 3D printing provide great opportunities for the utilization of functional materials in chemical engineering and heterogeneous catalysis. In this work cylindrical monoliths with varying geometries of transport channels are designed and printed by a fused deposition modeling (FDM) 3D printer from thermoplastic polymers. Their hydrodynamic characteristics are investigated. For a proof of concept composite monoliths of microporous hyper-crosslinked polymers (HCP) are printed. They contain up to 40 wt % of HCP with an accessible specific surface area of up to 171 m²g⁻¹.     

Fused deposition fabrication of high-quality zirconia ceramics using granular feedstock

Benefiting from the mature technology of ceramic injection molding, Fused deposition modeling based on highly-filled ceramic-polymer granular feedstocks has been showing great potential and advantage for fabricating 3D ceramics. Herein, 3D zirconia ceramics using granular feedstock were fabricated, and typical morphology, surface quality, and effect of the thermal accumulation on 3D structure were clarified. Typical morphology of printing steps on the surface were quantitatively characterized, and determined by the surface curvature and layer height of the printed structure. Aligned triangular pores were confirmed at the junction of the deposited filaments with elliptical cross-section morphology. Simple square plates with different size were used to illustrate the influence of thermal accumulation on the morphology of 3D structure. Small printing size increased the thermal accumulation during deposition, resulting in decreased printing quality caused by the secondary over-melting of former deposited layers. Except for the pores at the junctions, dense zirconia ceramics with uniform structure and smooth surface could be achieved. A low-cost and high-quality route for the preparation of 3D ceramics was demonstrated via FDM of highly-filled granular feedstocks.     

3D polymer composite filament development from post-consumer polypropylene and disposable chopstick fillers

This study focused on the development of three-dimensional (3D) polymer composite filament made of disposable chopstick (DC) and post-consumer polypropylene (PPP). The PPP/DC composite parts were printed via fused filament fabrication (FFF) process. The effect of the printing temperature and different DC fiber content on the properties of the 3D printed parts were investigated. The printing temperature of 200–220°C was suitable for these filaments because the printing temperature did not show any thermal degradation, as proven by thermogravimetric analysis. Furthermore, the thermal stability of the 3D filament increased with DC content. The chemical modification with sodium hydroxide (NaOH) was carried out on DC to remove the unwanted organic components by showing changes in peak intensity in the Fourier transform infrared analysis. Moreover, the melt flow index of the composite filaments decreased with increasing of the DC content and caused the composites' viscosity increased. The results show that the optimum printing temperature of 210°C would reduce the warping and gave better tensile properties to the 3D printed parts. Nevertheless, the tensile strength and elongation at break of the 3D printed PPP/DC parts reduced as the DC content increased because the presence of some air gap and fiber pull out on the fracture surface of 3D printed parts, which are in line with the results observed from scanning electron microscopy. However, the tensile strength and elongation at break percentage of all 3D printed PPP/DC composite parts were higher in comparison with the 3D parts printed by commercial wood plastic composite filament.     

3D Printed Tooling for Injection Molded Microfluidics

Microfluidics have been used for several decades to conduct a wide range of research in chemistry and the life sciences. The reduced dimensions of these devices give them advantages over classical analysis techniques such as increased sensitivity, shorter analysis times, and lower reagent consumption. However, current manufacturing processes for microfluidic chips either limit them to materials with unwanted properties, or are not cost-effective for rapid-prototyping approaches. Here the authors show that inlays for injection moulding can be 3D printed, thus reducing the skills, cost, and time required for tool fabrication. They demonstrate the importance of orientation of the part during 3D printing so that features as small as 100 × 200 µm can be printed. They also demonstrate that the 3D printed inlay is durable enough to fabricate at least 500 parts. Furthermore, devices can be designed, manufactured, and tested within one working day. Finally, as demonstrators they design and mould a microfluidic chip to house a plasmonic biosensor as well as a device to house liver organoids showing how such chips can be used in organ-on-a-chip applications. This new fabrication technique bridges the gap between small production and industrial scale manufacturing, while making microfluidics cheaper, and more widely accessible.     

反应喷墨打印技术及其在功能材料领域的研究进展

反应喷墨打印技术作为喷墨打印电子技术的重要分支,因其可以在沉积材料的同时可得到器件而受到人们的广泛关注.本文详细阐述了反应喷墨打印技术在功能材料制备领域,特别是在金属材料、高分子材料、无机材料等方面的研究进展,说明了反应喷墨打印用墨水是未来喷墨印刷电子研究的关键技术之一,简要介绍了反应喷墨打印技术与三维打印的联系,指出其在金属电路、有机发光二极管等印刷电子产业领域有广阔的应用前景.     

Mild functionalization of carbon nanotubes filled epoxy composites: Effect on electromagnetic interferences shielding effectiveness

The effect of nitric acid mild functionalized multiwalled carbon nanotubes (MWCNTs) on electromagnetic interference (EMI) shielding effectiveness (SE) of epoxy composites was examined. MWCNTs were oxidized by concentrated nitric acid under reflux conditions, with different reaction times. The dispersion of MWCNTs after functionalization was improved due to the presence of oxygen functional groups on the nanotubes surface. Functionalization at 2 h exhibits the highest EMI SE and electrical conductivity of MWCNTs filled epoxy composites. However, EMI shielding performance of MWCNTs filled epoxy composite declined when the functionalization reaction time was prolonged. This was due to extensive damage on the MWCNT structure, as verified by a Raman spectroscope. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42557.     

Tough thiourethane thermoplastics for fused filament fabrication

Fused filament fabrication (FFF) is the most common form of additive manufacturing. Most FFF materials are variants of commercially available engineering plastics. Their performance when printed can widely vary, thus there is an increasing volume of research on alternative materials with thermal and mechanical performance optimized for FFF. In this work, thiol–isocyanate polymerization is used for the development of a one‐pot synthesis for polythiourethane thermoplastics for tough three‐dimensional (3D) printing applications. The thiol–isocyanate reaction mechanism allows for rapid polymer synthesis with minimal byproduct formation and few limitations on reaction conditions. The resulting elastomer has high toughness and a low melting point, making it favorable for use as a 3D printing filament. The elastomer outperforms commercial filaments in tension when printed. Considering the rapid advancement of additive manufacturing and the limitations of many engineering polymers with the 3D printing process, these results are encouraging for the development of bespoke 3D printing thermoplastics. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45574.     

3D-printed polymer packing structures: Uniformity of morphology and mechanical properties via microprocessing conditions

Three-dimensional (3D) printing is an attractive approach to fabricate highly porous extremely lightweight structures for architecture antivibrational packaging. We report 3D printing processing of model packaging structures using biodegradable poly(lactic acid) (PLA) as a source material, with acrylonitrile butadiene styrene (ABS) utilized as a common 3D printing source material as a traditional benchmarked material. The effects of printing temperature, speed, and layer morphology on the layer-by-layer 3D-printed structures and their mechanical properties were considered. Three different characteristic morphologies were identified based on printing temperature; the microscopic surface roughness was dependent on the printing speed and layer height. We demonstrate that the mechanical performances and surface properties of 3D-printed PLA structures could be improved by optimization of printing conditions. Specifically, we evaluate that these PLA-based 3D structures printed exhibited better surface qualities and enhanced mechanical performance than traditional ABS-based structures. Results showed that the PLA-based 3D structures possessed the favorable mechanical performance with 34% higher Young's modulus and 23% higher tensile strength in comparison to the ABS-based 3D structures. This study provides guidelines for achieving high-quality 3D-printed lightweight structures, including smooth surfaces and durable mechanical properties, and serves as a framework to create biodegradable 3D-printed parts for human use.     

Photocurable pentaerythritol triacrylate/lithium phenyl-2,4,6-trimethylbenzoylphosphinate-based ink for extrusion-based 3D printing of magneto-responsive materials

Recent advances in additive manufacturing made it feasible to fabricate products with desired shapes and features. Herein, a new, photocurable 3D printer ink mainly based on pentaerythritol triacrylate (PETA) is reported. To achieve rapid curing needed for 3D printing process, high performance water-soluble photoinitiator, lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), was emulsified in PETA monomers and this suspension was evaluated for its polymerization kinetics by exposing to 395 nm UV-light. The distinct influences of LAP and triethanolamine (TEA) concentrations on photo-polymerization and printability were examined and an optimum concentration for extrusion-based 3D printing was found to be 10 mM and 1.62 M for LAP and TEA, respectively. Synthesized PETA-based 3D printer ink was functionalized by dispersing magnetic particles/flakes into the mixture, and consequently, a magneto responsive ink was obtained to be used in specialized applications. A ring-shaped structure embedded with micron sized iron flakes was printed as a prototype. This study presents a versatile photo-curable polymer formulation with possible translation to high performance 3D printing of customizable shapes that can be utilized in a wide range of areas such as micro-robotics and medical science.     

SLA 3D printing of high quality spine shaped β-TCP bioceramics for the hard tissue repair applications

β-TCP has excellent biodegradability and bioabsorption properties, and is regarded as an ideal hard tissue repair material. In the present study, 3D printing β-TCP green bodies was realized using the stereo lithography apparatus (SLA) technology. The effects of the KH-560 dispersant and solid loading on the slurry properties were investigated systematically. The optimized KH-560 addition amount and the solid loading of the slurry were 2.0 wt% and 48 wt%, respectively, and the corresponding slurry for the subsequent SLA 3D printing exhibited good fluidity, uniform dispersion and good stability. The sintering schedule of the printed β-TCP green bodies was optimized by the DSC-TG analysis. By sintering the green bodies at 1050 °C for 8 h, high quality β-TCP bioceramics without crack or deformation were fabricated. It was found that increasing the solid loading of the slurry would decrease the porosity while reducing the shrinkage degree of the β-TCP ceramics. However, the slurry could hardly be printed when its solid loading was higher than 50 wt%.     

4D Printing of Polyvinyl Chloride (PVC): A Detailed Analysis of Microstructure,Programming, and Shape Memory Performance

In this research, polyvinyl chloride (PVC) with excellent shape-memory effects is 4D printed via fused deposition modeling (FDM) technology. An experimental procedure for successful 3D printing of lab-made filament from PVC granules is introduced. Macro- and microstructural features of 3D printed PVC are investigated by means of wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), and dynamic mechanical thermal analysis (DMTA) techniques. A promising shape-memory feature of PVC is hypothesized from the presence of small close imperfect thermodynamically stable crystallites as physical crosslinks, which are further reinforced by mesomorphs and possibly molecular entanglement. A detailed analysis of shape fixity and shape recovery performance of 3D printed PVC is carried out considering three programming scenarios of cold (T_g −45 °C), warm (T_g −15 °C), and hot (T_g +15 °C) and two load holding times of 0 s, and 600 s under three-point bending and compression modes. Extensive insightful discussions are presented, and in conclusion, shape-memory effects are promising,ranging from 83.24% to 100%. Due to the absence of similar results in the specialized literature, this paper is likely to fill a gap in the state-of-the-art shape-memory materials library for 4D printing, and provide pertinent results that are instrumental in the 3D printing of shape-memory PVC-based structures.     

3D Printing Conductive Composites with Poly(ionic liquid) as a Noncovalent Intermedia to Fabricate Carbon Circuits

In this study, a kind of imidazole type poly(ionic liquid) ([PEP-MIM]Cl) is synthesized, which can disperse carbon effectively. [PEP-MIM]Cl is used as an intermediate to coat carbon on the poly(acrylic acid)(PAA-co-MBA) via ion exchange to obtain conductive polymer composite (CPC). A series of characterizations are performed. Experiments show that carbon can be coated on the PAA-co-MBA uniformly, and compared with using carbon as filler, this method requires less carbon to achieve good conductive performance. The carbon layer on the polymer's surface is enriched via the swelling-shrinking properties of PAA-co-MBA according to the SEM images. Furthermore, in combination with 3D printing technology, PAA-co-MBA can be designed into different shapes to achieve various functions such as pressure-sensing element. Finally, a new type of CPC named carbon clad polymeric laminate (CCPL) is prepared by using the carbon coating method and 3D printing technology. It has the potential to replace copper clad laminate (CCL) and printed circuit board (PCB), to a certain extent. This technology expands the preparation method and application of the CPC such as flexible and wearable conductive fabrics.     

Nanogrooved carbon microtubes for wet three‐dimensional printing of conductive composite structures

Recent advances in three‐dimensional (3D) printing have enabled the fabrication of interesting structures which are not achievable using traditional fabrication approaches. The 3D printing of carbon microtube composite inks allows fabrication of conductive structures for practical applications in soft robotics and tissue engineering. However, it is challenging to achieve 3D printed structures from solution‐based composite inks, which requires an additional process to solidify the ink. Here, we introduce a wet 3D printing technique which uses a coagulation bath to fabricate carbon microtube composite structures. We show that through a facile nanogrooving approach which introduces cavitation and channels on carbon microtubes, enhanced interfacial interactions with a chitosan polymer matrix are achieved. Consequently, the mechanical properties of the 3D printed composites improve when nanogrooved carbon microtubes are used, compared to untreated microtubes. We show that by carefully controlling the coagulation bath, extrusion pressure, printing distance and printed line distance, we can 3D print composite lattices which are composed of well‐defined and separated printed lines. The conductive composite 3D structures with highly customised design presented in this work provide a suitable platform for applications ranging from soft robotics to smart tissue engineering scaffolds. © 2019 Society of Chemical Industry     

3D打印技术用于不规则骨缺损的重建与修复

为研究3D打印技术对不规则形状骨缺损模型的重建程度,和3D打印的可降解生物材料对脊椎骨缺损在12周内的修复的效果,本文随机选取一名病人,用其电子计算机断层扫描（computed tomography, CT）数据构建出不规则的三维脊柱缺损模型,选用聚己内酯（polycaprolactone, PCL）作为支架材料,运用3D打印技术打印出高度符合该病人骨缺损部位的人工骨支架。同时建立一个简单的兔子脊椎缺损模型,运用3D打印技术打印缺损尺寸的支架移植兔子体内,术后观察3个月,将兔子处死取出缺损部位,制作切片进行苏木素和伊红（Hematoxylin and Eosin, H&E）染色,染色结果表明缺损部位修复良好。     

Sustainable functionalization and modification of materials via multicomponent reactions in water

In materials chemistry, green chemistry has established firm ground providing essential design criteria to develop advanced tools for efficient functionalization and modification of materials. Particularly, the combination of multicomponent reactions in water and aqueous media with materials chemistry unlocks a new sustainable way for constructing multi-functionalized structures with unique features, playing significant roles in the plethora of applications. Multicomponent reactions have received significant consideration from the community of material chemistry because of their great efficiency, simple operations, intrinsic molecular diversity, and an atom and a pot economy. Also, by rational design of multicomponent reactions in water and aqueous media, the performance of some multicomponent reactions could be enhanced by the contributing “natural” form of water-soluble materials, the exclusive solvating features of water, and simple separating and recovering materials. To date, there is no exclusive review to report the sustainable functionalization and modification of materials in water. This critical review highlights the utility of various kinds of multicomponent reactions in water and aqueous media as green methods for functionalization and modification of siliceous, magnetic, and carbonaceous materials, oligosaccharides, polysaccharides, peptides, proteins, and synthetic polymers. The detailed discussion of synthetic procedures, properties, and related applicability of each functionalized/modified material is fully deliberated in this review.