Three‐dimensional (3D) printing has emerged as a versatile and powerful technology allowing the fabrication of structures with complex geometries. It has significantly impacted engineering and manufacturing processes across multiple sectors, including automobiles, aerospace, healthcare, construction, and consumer products.1 The cost-effectiveness and high speed of 3D printing can accelerate the transition to a digital world.2
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Integrating nanotechnology with 3D printing expands its application potential to intelligent designs and smart structures. Nanomaterials like boron nitride (BN) offer exceptional mechanical, electrical, and thermal properties. With flexible designing and product manufacturing through 3D printing, BN is a promising material for energy storage, medical devices, and flexible electronics.1
This article explores the role of BN in enhancing 3D printing processes and applications.
Properties and Advantages of Boron Nitride
BN is a well-known electrical insulator with a wide band gap of about 5.97 eV. It has a coated plane surface and a highly stable structure. Its extraordinary interface properties and low coulomb scattering exhibit synergistic effects with other nanomaterials. BN’s exceptional thermal, electrical, and mechanical reliability enables its incorporation as a dielectric, substrate, and filler in nanocomposites.1
The hexagonal form of BN has a structure similar to graphite (honeycomb configuration) with strong covalent bonds between boron and nitrogen and weak van der Waals forces between interlayers.2,3 This results in high k anisotropy, making BN an excellent thermally conductive material. Thus, it is ideal for thermal regulation in applications with phonon-dominated thermal transport.2
The strong B-N bonds also make BN mechanically and chemically stable, exhibiting great resistance to wear and chemical processes like oxidation. BN also has good biocompatibility, expanding its application in the medical field.3
Applications in 3D Printing
BN can enhance the quality and performance of 3D-printed structures and is incorporated into various composite materials for specialized 3D printing applications. For instance, BN-polymer composites can help 3D-print mechanically robust, self-sustaining constructions. Such structures with a high BN content exhibit high physical tractability and elasticity and require minimal post-treatment.1
Thermally conductive BN-based composites are critically important in microelectronic devices requiring controlled heat transfer and dissipation.2 Apart from thermal management applications, these composites are appropriate for 3D bioprinting due to their cytocompatibility.1
BN-incorporated poly(vinyl alcohol) (PVA) fibers are explored for thermal control textiles in personal cooling applications. BN ensures the fibers’ compact structure, even distribution, and appropriate orientation, enhancing tensile strength, thermal conductivity, and uniform heat distribution.
Textiles 3D printed from BN-PVA composites exhibit heat conduction over 1.5 times that of PVA textiles and twice that of cotton fabrics. Additionally, BN-PVA fabrics have about 55 % greater cooling capabilities than conventional cotton materials.1
BN has also been demonstrated in the 3D printing of scaffolds by combining it with photosensitive polymers (PSPs). The resultant scaffolds perform well in microhardness, damping, and compressive strength tests due to effective interfacial interactions between BN and PSP resin. The good energy dissipation qualities of BN and the viscoelasticity of polymers enhance the damping capacities of 3D-printed scaffolds.1
Two-dimensional hexagonal BN (hBN) nanoplatelets combined with ionic liquids produce aerosol‐jet‐printable ionogels with excellent ionic conductivities and mechanical properties. These ionogels can be used to print thin film transistors (TFTs), which exhibit exceptional transfer and output characteristics and mechanical bending tolerance by utilizing hBN as the dielectric. Such 3D-printed transistors are promising electroanalytical sensing platforms.1
Challenges and Limitations
Despite several advantageous properties of BN, its utilization in 3D printing is mostly limited to research and development. This is primarily due to the technical challenges in processing BN for 3D printing. The strong B-N bonds responsible for the robustness of BN make its functionalization challenging.3
Incorporating BN and other nanomaterials in 3D printing technologies is in an early stage, requiring further research. For instance, incorporating high amounts of BN in a composite enhances its thermal conductivity but reduces ductility. Consequently, the processability of the composite is negatively impacted, especially for applications requiring mechanically robust structures, such as medical device encapsulation.3
Printing of high-resolution structures with a greater degree of freedom requires careful optimization of various technical parameters. Additionally, comprehending the synergy of BN with other advanced 3D printing materials (mainly polymers) can help tailor the geometry of the structures into unique designs.1
BN incorporation in nanocomposites for 3D printing provides better manufacturing process control. However, its distribution, dispersion, and interaction with other components are challenging, with practical results distant from theoretical predictions.
Better printability can be achieved by investigating the BN properties as a filler, including chemical structure and cure kinetics.4 This will also help reduce the costs of BN-based 3D printing for commercial applications.3
Apart from the limitations of BN as a printing material in terms of availability and costs, the 3D printing technique also faces challenges regarding the environmental effects of the printing materials, high equipment costs, and difficult customization.1
Future Outlook
Significant efforts are being made to address the above limitations and expand the use of BN in 3D printing applications. For instance, a recent study in Polymers examined the impact of BN as a reinforcement material in polylactic acid (PLA) to enhance its mechanical and wear properties. BN (5 % and 10 % by weight) was incorporated into the PLA matrix to create composite filaments with 1.75 mm diameter.5
The 3D-printed specimens from these filaments exhibited enhanced tensile strength, dimensional accuracy, and wear characteristics with low surface roughness. Thus, the optimized incorporation of BN into polymer matrices allows for enhanced polymer composites, which are the building blocks of 3D printing.5
Another recent study in ACS Applied Nano Materials demonstrated the incorporation of hBN into cellulose, a natural polymer, to produce 3D-printed nanosheets for energy harvesting applications. Mechanically exfoliated hBN was used as a rheology modifier in the cellulose matrix. The 3D-printed hBN-cellulose film exhibited high strength, flexibility, and maximum apparent viscosity.6
A flexoelectric energy harvester was fabricated using the prepared hBN-cellulose film and examined for strain-induced charge production. The application of load resistance and pressure resulted in a voltage and current flow through the device.
Charge state fluctuations and spontaneous polarization were also observed in the hBN-cellulose nanosheets. Density functional theory calculations also supported these experimental results.6
Overall, 3D printing technology is rapidly advancing toward industrialization, and this growth can be further accelerated by using high-functionality materials like BN.1
More from AZoNano: Nanoimprint Lithography: Advantages and Disadvantages
References and Further Reading
1. Mubarak, S., Divakaran, N., Raghavan, A., Ramachandran, SK., Wang, J. (2022). Advanced 2D Nanomaterials for Additive Manufacturing. Nanotechnology-Based Additive Manufacturing. DOI: 10.1002/9783527835478.ch12
2. Bondareva, JV. et al. (2023). Thermal and Electrical Properties of Additively Manufactured Polymer–Boron Nitride Composite. Polymers. DOI: 10.3390/polym15051214
3. Do, NBD., Imenes, K., Aasmundtveit, KE., Nguyen, H.-V., Andreassen, E. (2023). Thermal Conductivity and Mechanical Properties of Polymer Composites with Hexagonal Boron Nitride-A Comparison of Three Processing Methods: Injection Moulding, Powder Bed Fusion and Casting. Polymers. DOI: 10.3390/polym15061552
4. Behera, A., Nguyen, T. A., & Gupta, R. K. (2022). Smart 3D Nanoprinting. CRC Press. ISBN: 9781003189404. DOI: 10.1201/9781003189404
5. Keshavamurthy, R., Tambrallimath, V., Patil, S., Rajhi, AA., Duhduh, AA., Khan, T. M. Y. (2023). Mechanical and Wear Studies of Boron Nitride-Reinforced Polymer Composites Developed via 3D Printing Technology. Polymers. DOI: 10.3390/polym15224368
6. Jayakumar, A., et al. (2023). Energy Harvesting Using High-Strength and Flexible 3D-Printed Cellulose/Hexagonal Boron Nitride Nanosheet Composites. ACS Applied Nano Materials. DOI: 10.1021/acsanm.3c0223
