Nitruro di boro  (Boron nitride) è un composto chimico inorganico formato da atomi di boro e azoto. 

Materie prime utilizzate nella produzione.

Il nitruro di boro è prodotto principalmente da borace e composti azotati. Il borace è spesso estratto da miniere mentre l'azoto può essere derivato dall'aria attraverso processi di separazione.

Sintesi Chimica

• Preparazione del Borace. Il borace è estratto e purificato per essere utilizzato come materia prima.
• Produzione di Ammoniaca. L'azoto atmosferico è convertito in ammoniaca attraverso il processo Haber-Bosch.
• Reazione di Nitruro di Boro. Il borace e l'ammoniaca sono riscaldati a temperature elevate in un ambiente a bassa pressione o in atmosfera inerte per formare nitruro di boro.
• Purificazione. Il nitruro di boro prodotto è purificato attraverso metodi meccanici o chimici per rimuovere impurità.

Forma e Colore.

Il nitruro di boro può presentarsi in diverse forme, inclusi polveri bianche, cristalli e pellicole sottili, a seconda delle metodologie di produzione utilizzate.

A cosa serve e dove si usa

Cosmetica

Nell'industria cosmetica, il boron nitride è apprezzato per le sue proprietà lubrificanti e la sua capacità di diffondere la luce, che può aiutare a ridurre l'aspetto delle rughe e a creare un effetto opacizzante sulla pelle. Può essere utilizzato in vari prodotti cosmetici come polveri, fondotinta e ombretti per migliorare la scorrevolezza e la distribuzione del prodotto sulla pelle.

• Agente di carica. Regola il contenuto di acqua, diluisce altri solidi, può aumentare il volume di un prodotto per un miglior flusso, agisce come tampone contro gli acidi organici, aiuta a mantenere il pH della miscela entro un livello determinato.
• Slip modifier. Aumenta la spalmabilità di un prodotto aiutando altre sostanze a scorrere bene  e più agevolmente, senza reazione chimica.

Applicazioni Commerciali.

Il nitruro di boro è utilizzato in diverse applicazioni industriali a causa delle sue eccellenti proprietà termiche e di resistenza. Viene utilizzato in elettronica, materiali abrasivi, utensili di taglio, nonché come lubrificante solido e in applicazioni aero-spaziali.

Industria Cosmetica. Boron nitride è utilizzato nei cosmetici per le sue proprietà opacizzanti e la sua capacità di migliorare la scivolosità e l’aderenza dei prodotti cosmetici sulla pelle.

Prodotti per la Cura della Pelle. Utilizzato in polveri viso, fondotinta e altri prodotti per migliorare la texture e la distribuzione sul viso.

Prodotti Elettronici. Boron nitride trova applicazione come isolante termico in dispositivi elettronici.

Materiali Avanzati. Utilizzato nella produzione di ceramiche e compositi per la sua resistenza termica e stabilità chimica.

Industria Aerospaziale. Impiegato in applicazioni aerospaziali per la sua resistenza alle alte temperature e le sue proprietà isolanti.

Bibliografia__________________________________________________________________________

Goncu Y, Ay N. Boron Nitride's Morphological Role in the Design of Injectable Hyaluronic Acid Based Hybrid Artificial Synovial Fluid. ACS Biomater Sci Eng. 2023 Nov 13;9(11):6345-6356. doi: 10.1021/acsbiomaterials.3c01121. 

Abstract. The treatment process of osteoarthritis (OA) is challenging as it affects not only cartilage but also subchondral bone, ligament attachment capsules, synovium, and surrounding muscle tissue. Therefore, the search for preventive treatment or methods to slow the onset of the condition. Hexagonal boron nitride (hBN) has a graphite-like lamellar structure and is thought to facilitate cartilage movement for biomedical applications, just like in bearing systems. Hyaluronic acid (HA) is one of the natural polymers that can be used to transport boron nitride and maintain its presence in joints for a long time. In this study, hybrid hydrogels were formulated by using boron nitride nanoparticles and nanosheets. The rheological properties of the hydrogels were evaluated according to the structural differences of hBN. Characterizations have shown that hybrid hydrogels can be produced in injectable form, and the rheological properties are strongly related to the structural properties of the added particle. It has been determined that hBN added to the hydrogel structure reduces the dynamic viscosity of the zero-shear point and the deformation rate of the hydrogel and also changes the viscoelastic properties of the hydrogel depending on boron nitride's structural differences. The suggested mechanism is the hybrid hydrogel that exhibits lower viscosity as the layers detach from each other or disperses the agglomerates under applied shear stress. hBN, which has been proposed as a new strategy for joint injections, is thought to be a promising candidate for the treatment of OA due to its lamellar structures.

Merlo A , Mokkapati VRSS , Pandit S , Mijakovic I . Boron nitride nanomaterials: biocompatibility and bio-applications. Biomater Sci. 2018 Aug 21;6(9):2298-2311. doi: 10.1039/c8bm00516h. 

Abstract. Boron nitride has structural characteristics similar to carbon 2D materials (graphene and its derivatives) and its layered structure has been exploited to form different nanostructures such as nanohorns, nanotubes, nanoparticles and nanosheets. Unlike graphene and other carbon based 2D materials, boron nitride has a higher chemical stability. Owing to these properties, boron nitride has been used in different applications as a filler, lubricant and as a protective coating. Boron nitride has also been applied in the biomedical field to some extent, but far less than other 2D carbon materials. This review explores the potential of boron nitride for biomedical applications where the focus is on boron nitride biocompatibility in vivo and in vitro, its applicability as a coating material/composite and its anti-bacterial properties. Geometry, material processing and the type of biological analysis appear to be relevant parameters in assessing boron nitride bio-compatibility. Engineering of both these variables and the coating would open the door for some applications in the medical field for boron nitride, such as drug delivery, imaging and cell stimulation.

Golberg D, Bando Y, Huang Y, Terao T, Mitome M, Tang C, Zhi C. Boron nitride nanotubes and nanosheets. ACS Nano. 2010 Jun 22;4(6):2979-93. doi: 10.1021/nn1006495. 

Abstract. Hexagonal boron nitride (h-BN) is a layered material with a graphite-like structure in which planar networks of BN hexagons are regularly stacked. As the structural analogue of a carbon nanotube (CNT), a BN nanotube (BNNT) was first predicted in 1994; since then, it has become one of the most intriguing non-carbon nanotubes. Compared with metallic or semiconducting CNTs, a BNNT is an electrical insulator with a band gap of ca. 5 eV, basically independent of tube geometry. In addition, BNNTs possess a high chemical stability, excellent mechanical properties, and high thermal conductivity. The same advantages are likely applicable to a graphene analogue-a monatomic layer of a hexagonal BN. Such unique properties make BN nanotubes and nanosheets a promising nanomaterial in a variety of potential fields such as optoelectronic nanodevices, functional composites, hydrogen accumulators, electrically insulating substrates perfectly matching the CNT, and graphene lattices. This review gives an introduction to the rich BN nanotube/nanosheet field, including the latest achievements in the synthesis, structural analyses, and property evaluations, and presents the purpose and significance of this direction in the light of the general nanotube/nanosheet developments.

Lee CH, Bhandari S, Tiwari B, Yapici N, Zhang D, Yap YK. Boron Nitride Nanotubes: Recent Advances in Their Synthesis, Functionalization, and Applications. Molecules. 2016 Jul 15;21(7):922. doi: 10.3390/molecules21070922. 

Abstract. A comprehensive overview of current research progress on boron nitride nanotubes (BNNTs) is presented in this article. Particularly, recent advancements in controlled synthesis and large-scale production of BNNTs will first be summarized. While recent success in mass production of BNNTs has opened up new opportunities to implement the appealing properties in various applications, concerns about product purity and quality still remain. Secondly, we will summarize the progress in functionalization of BNNTs, which is the necessary step for their applications. Additionally, selected potential applications in structural composites and biomedicine will be highlighted.