Researchers use 3D printing to assemble nanoparticles into robust macrostructures

China3D printingNet, June 11, researchers from the Technical University of Hamburg (TUHH) and the Massachusetts Institute of Technology (MIT) have cooperated with the University of Bremen and the University of Bremen and have used3D printingAssemble the nanoparticles into a strong macrostructure.

The research team developed a direct-write self-assembly technology, which is fully enhanced by cross-linking, so that the structural strength of the microstructure can be reflected in the macrostructure.will3D printingCombined with this colloidal assembly method, it can enable the development of stronger mechanical properties, multi-functional 3D structures, and open new application areas for the materials obtained in the aerospace industry.
” 3D printingIt provides a fast and controllable way for the development of new materials.Earlier3D printingThe particle-based materials are generally weaker because their particles are held together mainly by weak forces. In our case, a tightly packed network of covalently bonded nanoparticles is formed throughout the material. “Said Dr. Berta Domènech of TUHH, who is in charge of this research.


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Schematic diagram of the column and the corresponding porosity assessment” alt=”
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Schematic diagram of the column and the corresponding porosity assessment” />

3D printingSchematic diagram of the column, and the corresponding porosity assessment. The picture comes from advanced engineering materials.

Utilize the strength of microstructures

Macrostructures usually contain many cracks or defects, which may cause them to fail when placed under higher loads. On the other hand, nanomaterials have few defects, so the potential to incorporate the advantages of microstructures into their macroscopic equivalents can provide the latter with higher strength. In order to achieve this integration, a manufacturing method that can precisely control the composition and assembly of nanoparticles (NP) needs to be developed.

The researchers proposed that NPs can be assembled into larger structures by using and further controlling their inherent intermolecular and surface forces. Using these short-range forces, colloidal self-assembly becomes a feasible method, which can specifically design nano-blocks and adjust the properties of the resulting materials.Although colloidal self-assembly is usually used to create 1D or 2D structures, the use of3D printingThe 3D material system can be tailored across multiple length scales.

In order to effectively use this direct writing3D printingTechnology, the research team will need to use shear-thinning ink, which flows through pinholes under pressure and has the ability to maintain shape when deposited. As a result, the successful bridging of several length scales depends on the inherent mechanical strength of the synthesized nanocomposite. Although the theoretical strength of NP is extremely strong, the bonding force between NPs needs to reach hundreds of MPa to work, so the team needs a new method.In response, the researchers devised a way to write directly3D printingThe method combined with the colloidal self-assembly of iron oxide NP to create a strong free-standing macrostructure.



The sample is subjected to a bending test (image B), and the obtained column surface is retained in image D. Images obtained through Advanced Engineering Materials.

3D printingHigh-strength macro structure

The direct writing colloidal components were built using a custom desktop direct writing system, which was originally developed by the Massachusetts Institute of Technology. To create the structure, a toluene-based suspension of OA-functionalized Fe3O4-NP was dispensed from a high-precision needle onto the substrate to form a liquid bridge. During the colloid assembly process, the bridge provides a limit for the NPs that gather at the bottom and forms a self-assembled solid column. The process can be controlled by moving the substrate down at a rate that matches the vertical growth rate of the self-assembled printed column. The strength is enhanced by heat treatment in an inert atmosphere at 325°C, thereby forming new bonds (or crosslinks) between the organic molecules of adjacent nanoparticles. The resulting organic parts are harder and more resistant to higher loads, and the curing effect is similar to the curing process on ordinary epoxy resins.

Using this new technology, the researchers produced a free-standing millimeter-sized column with a supercrystalline structure. It was found that the surface of micro-pillars composed of an ordered arrangement (supercrystalline) of spherical iron oxide nanoparticles was covered with short organic molecules (oleic acid). It was found that this surface functionalization is responsible for the enhanced mechanical properties of the material. The binding force allows the nanoparticles to be controllably assembled into tightly packed, ordered arrangements, and organic molecules act as active sites for further enhancement of the material.
To evaluate possible changes in the superlattice, synchrotron-based small-angle X-ray scattering (SAXS) analysis was performed at different points along the cylinder axis. The scan determined that a superlattice was formed, and no significant differences in the lattice parameters as a function of column position were detected.Apply abstract X-ray microscope (XRM) to3D printingA part of the column with a total length of 460 μm. The scan detected asymmetrically distributed internal voids and pores inside the 41 311 μm3 chromatographic column, which is equivalent to 0.6% of the total estimated volume of the sample.
The research team successfully proved that colloidal assembly and3D printingThe combination of, you can easily and quickly create a sturdy and durable chromatographic column, bridging almost five different length ranges together.According to the researchers, they will now try to gain more control over the process parameters, expand the scope of research to other nanoparticle systems, and eventually create different geometries3D printingpart. This new technology may lead to the integration of nano-scale building blocks into a variety of macro-multifunctional materials, from photonic devices to new structural materials.
3D printingHigh-durability macrostructure
Researchers from various government departments and academic institutions have designed new3D printingMethods, these methods have produced more durable metals in recent years.
Researchers at Texas A&M University established a set of guidelines and parameters to allow low-alloy additive manufacturing as defect-free parts in March 2020. The team developed a standard that can accurately determine the maximum distance between shadow lines, so as to avoid the lack of fusion between defective layers.
The U.S. Air Force Institute of Technology (AFIT) developed a3D printingHigh-performance Air Force AF-9628 steel method for weapon applications. Innovated a new type of powder bed fusion (PBF) technology, which can produce metals that exhibit higher tensile strength than traditional AM alloys.
In October 2019, the Marshall Space Flight Center (MSFC) of the National Aeronautics and Space Administration (NASA) became HRL Laboratory 7A77 Aluminum3D printingFan’s first commercial customer. This material is a developed version of Al-7075, which has good ductility, high strength, toughness and excellent corrosion resistance.

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