2D boron nitride nanosheets (BNNS) prepared by high-pressure homogenisation: structure and morphology

Guerra, Valentina; Wan, Chaoying; Degirmenci, Volkan; Sloan, Jeremy; Presvytis, Dimitris; McNally, Tony

doi:10.1039/c8nr06429f

Cited by 101 publications

(69 citation statements)

References 42 publications

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“…As reported in our previous work, [16,17] BNNS and GNP agglomerates on the micrometre scale form layered structures. BNNS are round shaped platelets whereas GNP are more irregular square-shaped sheets see (insets in Figure 7a,b), respectively).…”

Section: (7 Of 9)supporting

confidence: 78%

“…Materials: BNNS and GNP were kindly provided by Thomas Swan & Co. Ltd. and thoroughly characterized in our previous work. [16,17] BNNS and GNP were treated by washing with ethanol (EtOH) and freeze-dried using the following procedure-(1) Washing with EtOH was completed by diluting BNNS/GNP into EtOH (BNNS (GNP)/EtOH = 1g per 5mL) using a beaker and magnetic stirring for ≈15min. The suspensions of BNNS-w-EtOH and GNP-w-EtOH were then vacuum filtered and dried in an oven at 100 °C for 3-4 h. (2) Freeze drying was realized using two procedures; FD-(i)-diluting BNNS (GNP) in water (≈1g BNNS (GNP)/5 mL water) under magnetic stirring and freezing in liquid nitrogen until solidification of the dispersion before freeze drying.…”

Section: Methodsmentioning

confidence: 99%

“…Almost without exception the top‐down production of 2D materials requires the use of surfactants or dispersants (e.g., water, ionic liquids) to assist the exfoliation of some bulk material. By way of example, the pretreatment of BNNS and exfoliated graphite nanoplatelets (GNP) studied here contain trace water and surfactant (sodium cholate, SC), [ 16,17 ] mainly introduced during the exfoliation of the corresponding bulk materials (i.e., boron nitride and graphite) in a high pressure homogenizer. [ 18 ] Specifically, three cleaning procedures were adopted in an attempt to remove impurities (i.e., water and SC) from the surfaces of BNNS and GNP, namely washing with ethanol, water assisted‐freeze drying, and freeze drying without addition of water.…”

Section: Introductionmentioning

confidence: 99%

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Surface Cleaning of 2D Materials: Boron Nitride Nanosheets (BNNS) and Exfoliated Graphite Nanoplatelets (GNP)

Guerra

McNally

2020

Adv Materials Inter

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and impurities using methodologies such as electrical current annealing, [5] thermal annealing/desorption, [6-12] washing with water, acids, bases, ethanol, [12-14] plasma treatment, [13] and etching of metals. [15] Electrical annealing is effective at cleaning the surfaces of 2D materials; however, it is very limited in that it can only treat small sample areas (few micrometer square). [5] Thermal annealing proved to be the most effective at removing the impurities from the surface of 2D materials; however, there are serious concerns with regard degradation of the 2D material as a function of time. Washing with acids/bases are not always desirable as they can alter surface chemistry and their use may negatively impact the environment. [15] The etching of metals procedure is too laborious and not readily suitable for large-scale applications. Almost without exception the top-down production of 2D materials requires the use of surfactants or dispersants (e.g., water, ionic liquids) to assist the exfoliation of some bulk material. By way of example, the pretreatment of BNNS and exfoliated graphite nanoplatelets (GNP) studied here contain trace water and surfactant (sodium cholate, SC), [16,17] mainly introduced during the exfoliation of the corresponding bulk materials (i.e., boron nitride and graphite) in a high pressure homogenizer. [18] Specifically, three cleaning procedures were adopted in an attempt to remove impurities (i.e., water and SC) from the surfaces of BNNS and GNP, namely washing with ethanol, water assisted-freeze drying, and freeze drying without addition of water. Ethanol (EtOH) was utilized as it can wash water away from the surface of the BNNS and GNP and interact with the ionic surfactant SC thus being removed. The freeze drying process was selected as the sublimation of iced-water from the surface of BNNS and GNP would ideally remove water and exfoliate the 2D material further. [19-23] Indeed, when ice sublimates, the layers and flakes surrounded by ice are pulled apart. Two specific procedures for freeze drying were realized; FD-(i)-freezing of a dispersion of BNNS or GNP in water in liquid nitrogen followed by freeze drying and FD-(ii)-freezing in liquid nitrogen of the as received BNNS or GNP powder followed by freeze drying. The latter was performed on the basis that the water present as impurity in the BNNS and GNP samples would be sufficient at creating an ice pattern cutting through the layered structure Surface impurities such as water and surfactants can significantly affect the properties of 2D materials. They disrupt the 2D material lattice structure and surface chemistry and also promote electron and phonon scattering. Strategies to clean the surfaces of 2D materials are therefore critical to achieving optimal properties. Boron nitride nanosheets (BNNS) and exfoliated graphite nanoplatelets (GNP) are treated using three procedures: washing with ethanol, water-assisted freeze-drying, and freeze-drying without addition of water in an attempt to remove two impurities-water and an ion...

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Section: (7 Of 9)supporting

confidence: 78%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Surface Cleaning of 2D Materials: Boron Nitride Nanosheets (BNNS) and Exfoliated Graphite Nanoplatelets (GNP)

Guerra

McNally

2020

Adv Materials Inter

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“…The thickness of αand β-spherulites within neat PP and its composites at different GNP loadings was calculated using Scherrer's equation [28]:…”

Section: Resultsmentioning

confidence: 99%

Nucleation of the β-polymorph in Composites of Poly(propylene) and Graphene Nanoplatelets

2019

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The effects of graphene nanoplatelets (GNPs) on the nucleation of the β-polymorph of polypropylene (PP) were studied when melt-mixed at loadings of 0.1–5 wt % using a laboratory scale twin-screw (conical) extruder and a twin-screw (parallel) extruder with L/D = 40. At low GNP loadings (i.e., ≤0.3 wt %), the mixing efficiency of the extruder used correlated with the β-nucleating activity of GNPs for PP. GNP agglomeration at low loadings (<0.5 wt %) resulted in an increase in the β-phase fraction (Kβ) of PP, as determined from X-ray diffraction measurements, up to 37% at 0.1 wt % GNPs for composites prepared using a laboratory scale twin-screw (conical) extruder. The level of GNP dispersion and distribution was better when the composites were prepared using a 16-mm twin-screw (parallel) extruder, giving a Kβ increase of 24% upon addition of 0.1 wt % GNPs to PP. For GNP loadings >0.5 wt %, the level of GNP dispersion in PP did not influence the growth of β-crystals, where Kβ reached a value of 24%, regardless of the type of extruder used. From differential scanning calorimetry (DSC) measurements, the addition of GNPs to PP increased the crystallization temperature (Tc) of PP by 14 °C and 10 °C for the laboratory scale extruder and 16-mm extruder, respectively, confirming the nucleation of PP by GNPs. The degree of crystallinity (Xc%) of PP increased slightly at low GNP additions (≤0.3 wt %), but then decreased with increasing GNP content.

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“…The same signal can be observed in the XRD pattern of the functionalized cellulose sample, indicating the successful functionalization of the cellulose fibers. Additional and much weaker peaks characteristic for h-BN nanostructures are located around 2θ ~ 41.8°; 43.9°; 55.1°; 76.0°, and 82.3° [ 30 ]. However these signals cannot be seen in the pattern of functionalized cellulose, because they are screened by high intensity of the (102) crystallographic plane of cellulose [ 31 ].…”

Section: Resultsmentioning

confidence: 99%

Few Layered Oxidized h-BN as Nanofiller of Cellulose-Based Paper with Superior Antibacterial Response and Enhanced Mechanical/Thermal Performance

Onyszko

Markowska‐Szczupak

Rakoczy

et al. 2020

IJMS

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In this study, hexagonal boron nitride nanosheets enriched with hydroxyl groups (h-BN-OH) were successfully grafted on the surface of cellulose fibers after the simple and effective exfoliation and oxidation of bulk h-BN. OH groups of h-BN-OH and the ones presented on the surface of cellulose fibers interacted via hydrogen bonding. Both spectroscopic (FT-IR, XRD) and microscopic (TEM, SEM, and atomic force microscopy (AFM)) methods results proved the successful functionalization of the cellulose fibers with the nanomaterial. Modified cellulose fibers were used to prepare paper sheets samples with different concentrations of the nanomaterial (1 wt %, 2 wt %, and 3 wt %). All the samples were tested for the antibacterial properties via the colony forming unit method and exhibited good performance against both Gram-negative (E. coli) and Gram-positive (S. epidermidis) model bacteria. Additionally, the influence of the volume of working bacterial suspension on the antibacterial efficiency of the obtained materials was examined. The results showed significantly better antibacterial performance when the volume of bacterial suspension was reduced. Mechanical properties of the paper samples with and without nanofiller were also characterized. Tensile strength, tearing strength, and bursting strength of the paper samples containing only 2 wt % of the nanofiller were improved by 60%, 61%, and 118% in comparison to the control paper samples, respectively. Furthermore, the nanofiller improved the thermal properties of the composite paper—the heat release rate decreased by up to 11.6%. Therefore, the composite paper can be further explored in a wide range of antibacterial materials, such as packaging or paper coatings

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2D boron nitride nanosheets (BNNS) prepared by high-pressure homogenisation: structure and morphology

Abstract: Polycrystalline boron nitride nano-sheets (BNNS) were prepared via a scalable high-pressure homogenization process.

Cited by 101 publications

References 42 publications

Surface Cleaning of 2D Materials: Boron Nitride Nanosheets (BNNS) and Exfoliated Graphite Nanoplatelets (GNP)

Surface Cleaning of 2D Materials: Boron Nitride Nanosheets (BNNS) and Exfoliated Graphite Nanoplatelets (GNP)

Nucleation of the β-polymorph in Composites of Poly(propylene) and Graphene Nanoplatelets

Few Layered Oxidized h-BN as Nanofiller of Cellulose-Based Paper with Superior Antibacterial Response and Enhanced Mechanical/Thermal Performance

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