Reliable Nanoparticle Dispersion for Industrial Applications
High power ultrasonication can efficient and reliably break-up particle agglomerates and even disintegrate primary particles. Due to its high-performance dispersion performance, probe-type ultrasonicators are used as preferred method to create homogeneous nanoparticle suspensions.
Reliable Nanoparticle Dispersion by Ultrasonication
Many industries require the preparation of suspensions, which are loaded nanoparticles. Nanoparticles are solids with a particle size less than 100nm. Due to the minute particle size, nanoparticle express unique properties such as exceptional strength, hardness, optical features, ductility, UV resistance, conductivity, electrical and electromagnetic (EM) properties, anti-corrosiveness, scratch resistance, and other extraordinary characteristics.
High-intensity, low-frequency ultrasound creates intense acoustic cavitation, which is characterized by extreme conditions such as shear forces, very high pressure and temperature differentials, and turbulences. These cavitational forces accelerate particles causing inter-particle collisions and consequently shattering of the particles. Consequently, nanostructured materials with a narrow particle size curve and a uniform distribution are obtained.
Ultrasonic dispersing equipment is suitable to treat any kind of nanomaterials in water and organic solvents, with low to very high viscosities.
- ultrafine particles
- quantum dots
- nanoplatelets, nanosheets
- nanorods, nanowires
- 2D and 3D nanostructures
Ultrasonic Dispersion of Carbon Nanotubes
Ultrasonic dispersers are widely used for the purpose of dispersing carbon nanotubes (CNTs). Sonication is a reliable method to detangle and disperse single-walled carbon nanotubes (SWCNTs) as well as multi-walled carbon nanotubes (MWCNTs). For instance, in order to produce a highly conductive thermoplastic polymer, high-purity (> 95%) Nanocyl® 3100 (MWCNTs; external diameter 9.5 nm; purity 95 +%) have been ultrasonically dispersed with the Hielscher UP200S for 30min. at room temperature. The ultrasonically dispersed Nanocyl® 3100 MWCNTs at a concentration of 1% w/w in the epoxy resin showed superior conductivity of approx. 1.5 × 10-2 S /m.
Ultrasonic Dispersion of Nickel Nanoparticles
Nickel nanoparticles can be successfully produced via ultrasonically-assited hydrazine reduction synthesis. The hydrazine reduction synthesis route enables tp prepare pure metallic nickel nanoparticle with spherical shape by the chemical reduction of nickel chloride with hydrazine. The research group of Adám demonstrated that ultrasonication – using the Hielscher UP200HT (200W, 26kHz) – was able to maintain an average primary crystallite size (7–8 nm) independently from the applied temperature, while the use of intense and shorter sonication periods could reduce the solvodynamic diameters of the secondary, aggregated particles from 710 nm to 190 nm in the absence of any surfactant. The highest acidity and catalytic activity were measured for the nanoparticles prepared by mild (30 W output power) and continuous ultrasound treatment. The catalytic behaviour of the nanoparticles was tested in a Suzuki-Miyaura cross-coupling reaction over five samples prepared in the conventional as well as the ultrasonic ways. The ultrasonically prepared catalysts usually performed better, and the highest catalytic activity was measured over the nanoparticles prepared under low-power (30 W) continuous sonication.
The ultrasound treatment had crucial effects on the aggregation tendency of the nanoparticles: the defragmentation influence of the destroyed cavitation voids with the vigorous mass transfer could overcome the attractive electrostatic of the destroyed cavitation voids with the vigorous mass transfer could overcome the attractive electrostatic and van der Waals forces between the particles.
(cf. Adám et al. 2020)
Ultrasonic Synthesis of Wollastonite Nanoparticles
Wollastonite is a calcium inosilicate mineral with the chemical formula CaSiO3 Wollastonite is widely used as component for the production of cement, glass, brick, and tile in the construction industry, as flux in the casting of steel as well as an additive in the manufacturing of coatings and paints. For instance, wollastonite provides reinforcement, hardening, low oil absorption, and other improvements. In order to obtain excellent reinforcing properties of wollastonite, nano-scale deagglomeration and uniform dispersion are essential.
Dordane and Doroodmand (2021) demonstrated in their studies that ultrasonic dispersion is a very important factor that infliuences the size and morphology of wollastonite nanoparticles significantly. To evaluate the contribution of sonication on wollastonite nano-dispersion, the research team synthesized wollastonite nanoparticles with and without the application of high-power ultrasonics. For their sonication trials, the researchers used the ultrasonic processor UP200H (Hielscher Ultrasonics) with a frequency of 24 kHz for 45.0 min. The results of ultrasonic nano-dispersion are shown in the high-resolution SEM below. The SEM image shows clearly that the wollastonite sample before ultrasonic treatment is agglomerated and aggregated; after the sonication with the UP200H ultrasonicator the average size of the wollastonite particles is approx. 10nm. The study demonstrates that ultrasonic dispersion is a reliable and efficient technique to synthesize wollastonite nanoparticles. The average nanoparticle size can be controlled by adjusting the ultrasonic processing parameters.
(cf. Dordane and Doroodmand, 2021)
Ultrasonic Nanofiller Dispersion
Sonication is a versatile method to disperse and deagglomerate nanofillers in the liquids and slurries, e.g. polymers, epoxy resins, hardeners, thermoplastics etc. Therefore, sonification is widely used as an highly efficient dispersion method in R&D and industrial production.
Zanghellini et al. (2021) investigated the ultrasonic dispersion technique for nanofillers in epoxy resin. He could demonstrate that sonication was able to disperse small and high concentrations of nanofillers into a polymer matrix.
Comparing various formulations, the 0.5 wt% oxidized CNT showed the best results of all sonicated samples, revealing size distributions of most of the agglomerates in a comparable range to three roll mill-produced samples, a good binding to the hardener, the formation of a percolation network inside the dispersion, which points towards stability against sedimentation and thus a proper long-term stability. Higher filler amounts showed similar good results, but also the formation of more pronounced internal networks as well as somewhat larger agglomerates. Even carbon nanofibres (CNF) could be dispersed successfully via sonication. Direct US dispersion of nanofillers in the hardener systems without additional solvents was successfully achieved, and thus can be seen as an applicable method for a simple and straight-forward dispersion with the potential for industrial use. (cf. Zanghellini et al., 2021)
Ultrasonic Dispersion of Nanoparticles – Scientifically Proven for Superiority
Research shows in numerous sophisticated studies that ultrasonic dispersion is one of the superior techniques to deagglomerate and distribute nanoparticles even at high concentration in liquids. For instance, Vikash (2020) investigated the dispersion of high loads of nano-silica in viscous liquids using the Hielscher ultrasonic disperser UP400S. In his study, he comes to conclusion that “the stable and uniform dispersion of nanoparticles can be achieved using an ultra-sonication device at high solid loading in viscous liquids.” [Vikash, 2020]
- Disintegration / Milling
- Particle size reduction
- Nanoparticle synthesis and precipitation
- Surface functionalization
- Particle modification
High-Performance Ultrasonic Processors for Nanoparticle Dispersion
Hielscher Ultrasonics is your trustworthy supplier for reliable high-performance ultrasonic equipment from lab and pilot to full-industrial systems. Hielscher Ultrasonics’ devices feature sophisticated hardware, smart software and outstanding user-friendliness – designed and manufactured in Germany. Hielscher’s robust ultrasonic machines for dispersion, deagglomeration, nanoparticle synthesis and functionalization can be operated 24/7/365 under full load. Depending on your process and your production facility, our ultrasonicators can be run in batch or continuous in-line mode. Various accessories such as sonotrodes (ultrasonic probes), booster horns, flow cells and reactors are readily available.
Contact us now to get more technical information, scientific studies, protocols and a quotation for our ultrasonic nano-dispersion systems! Our well-trained, long-experienced staff will be glad to discuss your nano-application with you!
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The table below gives you an indication of the approximate processing capacity of our ultrasonicators:
Literature / References
- Adám, Adele Anna; Szabados, M.; Varga, G.; Papp, Á.; Musza, K.; Kónya, Z.; Kukovecz, Á.; Sipos, P.; Pálinkó, I. (2020): Ultrasound-Assisted Hydrazine Reduction Method for the Preparation of Nickel Nanoparticles, Physicochemical Characterization and Catalytic Application in Suzuki-Miyaura Cross-Coupling Reaction. Nanomaterials 10(4), 2020.
- Siti Hajar Othman, Suraya Abdul Rashid, Tinia Idaty Mohd Ghazi, Norhafizah Abdullah (2012): Dispersion and Stabilization of Photocatalytic TiO2 Nanoparticles in Aqueous Suspension for Coatings Applications. Journal of Nanomaterials, Vol. 2012.
- Vikash, Vimal Kumar (2020): Ultrasonic-assisted de-agglomeration and power draw characterization of silica nanoparticles. Ultrasonics Sonochemistry, Volume 65, 2020.
- Zanghellini,B.; Knaack,P.; Schörpf, S.; Semlitsch, K.-H.; Lichtenegger, H.C.; Praher, B.; Omastova, M.; Rennhofer, H. (2021): Solvent-Free Ultrasonic Dispersion of Nanofillers in Epoxy Matrix. Polymers 2021, 13, 308.
- Jeevanandam J., Barhoum A., Chan Y.S., Dufresne A., Danquah M.K. (2918): Review on nanoparticles and nanostructured materials: history, sources, toxicity and regulations. Beilstein Journal of Nanotechnology Vol. 9, 2018. 1050-1074.
- Guadagno, Liberata; Raimondo, Marialuigia; Lafdi, Khalid; Fierro, Annalisa; Rosolia, Salvatore; and Nobile, Maria Rossella (2014): Influence of Nanofiller Morphology on the Viscoelastic Properties of CNF/Epoxy Resins. Chemical and Materials Engineering Faculty Publications 9, 2014.
Facts Worth Knowing
What are Nanostructured Materials?
A nanostructure is defined when at least one dimension of a system is less than 100nm. With other words, a nanostructure is a structure characterized by its intermediate size between microscopic and molecular scale. In order to describe an differentiate nanostructures properly, it is necessary to differentiate between the number of dimensions in the volume of an object which are on the nanoscale.
Below, you can find a few important terms which reflect specific characteristics of nano-structured materials:
Nanoscale: Approximately 1 to 100 nm size range.
Nanomaterial: Material with any internal or external structures on the nanoscale dimension. The terms nanoparticle and ultrafine particle (UFP) are often used synonymously although ultrafine particles may have a particles size that reaches into the micrometre range.
Nano-object: Material that possesses one or more peripheral nanoscale dimensions.
Nanoparticle: Nano-object with three external nanoscale dimensions
Nanofiber: When two similar exterior nanoscale dimensions and a third larger dimension are present in a nanomaterial, it is referred to as nanofiber.
Nanocomposite: Multiphase structure with at least one phase on the nanoscale dimension.
Nanostructure: Composition of interconnected constituent parts in the nanoscale region.
Nanostructured materials: Materials containing internal or surface nanostructure.
(cf. Jeevanandam et al., 2018)