RO135651A2 - Surfaces coated with metal nanoparticles with hydrophobic properties and simple and clean method for preparing the same - Google Patents

Abstract

The invention relates to metal surfaces coated with metal nanoparticles with hydrophobic properties and to a method for preparing them, the surfaces being used in various applications, such as for the preparation of the next generation of lithium-ion batteries or soldering alloys for metal interconnections. According to the invention, the metal surfaces consist of a flat silicon substrate coated with a thin layer of silicon oxide and a coating of Sn metal nanoparticles with a particle size ranging between 180 and 240 nm and a surface density of nanoparticles ranging between 3...4 μ m2. The claimed preparation method consists of the following steps: a. dividing the SnSe powder as a vapour phase, by a thermal process, at a temperature ranging between 650...700°C, in an enclosure through which a gas stream consisting of a mixture of H2 and Ar passes, b. directing the gas flow, ranging between 90...110 sccm, together with SnSe vapours towards the surface to be coated and c. reassembling the vapour phase into a solid phase on the surface, with a deposition time between 10...15 minutes, the specific shape of the deposited layer being determined by the synthesis conditions and the surface used.

Description

STATE OFFICE FOR INVENTIONS AND MARTS

Patent application _No. Λ c2r>^

Denominated date ...l X .'.Îl·.

Surfaces coated with metal nanoparticles with hydrophobic properties and a simple and clean method for obtaining them

Angel-Theodor Buruiana, Florinei Sava, Elena Matei, Irina Zgura, Mihai Burdusel, Claudia Mihai, Alin Velea

Introduction

Metallic nanomaterials with different morphologies have attracted significant attention recently due to their properties, which are different from those of bulk materials [N. Munkhbaatar et al. al. Appl. Sci. Converge TechnoL 24 (2015)]. Sn is notable for having a low melting point, being abundant and environmentally friendly, and Sn nanoparticles can have diverse applications such as the next generation of lithium-ion batteries [Y. Zou et al. al. ACS Nano 5 (2011)] or in solder alloys for metallic interconnections [Y. H. Jo et al. al. Nanotechnology 22 (2011)].

Among the methods of obtaining metal-based nanoparticles, some are very complicated and include either several chemical steps [S. S. Chee et al. al. Thin Solid Films 562 (2014)] followed by thermal treatments, others are simpler but still involve chemical reduction and the use of organometallic precursors, reducing agents, surfactants and organic solvents [S. S. Chee, et al. al. Electron. Mater. Lett. 8 (2012)] that can contaminate the nanoparticles. Moreover, in some chemical methods, nanoparticles are obtained in a colloidal dispersion and additional steps, such as dripping and drying or heat treatment, are required for transfer to a substrate. The physical vapor transport method has the advantages of a fast process and allows obtaining high-quality nanostructures, if the deposition parameters are optimally adjusted. This method also has some limitations such as the difficulty of growing massive crystals of large size as well as difficulties in generating uniform nucleation seeds necessary to produce high quality thin films [X. Xue et al. al. RSC Adv. 5 (2015)].

Director General INCDFM

Dr. Ionul Enculescu

Wettability is an important characteristic for various surface-related technologies. The free energy of the surface, its geometry (which is given by the size of the particles covering it and the roughness of the surface), as well as the chemical composition determine the wettability of the surface. Hydrophobic surfaces have diverse applications such as self-cleaning fabrics, anti-corrosive industrial components, lubrication systems and anti-freeze coatings [L. Cao et al. al. Langmuir. 25 (2009)].

Figure description

FIG. I illustrates a surface coated with metal nanoparticles in accordance with an example. FIG. 2 illustrates a surface coated with metal nanoparticles according to another example. FIG. 3 illustrates the hydrophobic properties of surfaces coated with metal nanoparticles according to the two examples.

FIG. 4 illustrates a simple and clean method of depositing metal nanoparticles on a surface.

Director General INCDFM

Invention description

As discussed herein, this patent application claims surfaces coated with metal nanoparticles with hydrophobic properties and a simple and clean method for obtaining them.

FIG. 1(A) shows the morphology of a hydrophobic surface coated with metal nanoparticles in accordance with at least one example. The substrate on which the nanoparticles are distributed can be a rigid one such as glass, silicon, sapphire, silicon carbide, etc. or it can be a flexible one such as plastic foils resistant to high temperatures. Hemispherical metal nanoparticles can be made of Sn. Their average diameter can be 280 ± 40 nm (FIG. 1(B)) and their height up to 140 nm. The density of nanoparticles on the hydrophobic surface can be 4-5 nanoparticles per pm ² .

FIG. 2(A) shows the morphology of a hydrophobic surface coated with metal nanoparticles in accordance with at least one example. The substrate on which the nanoparticles are distributed can be a rigid one such as glass, silicon, sapphire, silicon carbide, etc. or it can be a flexible one such as plastic foils resistant to high temperatures. Hemispherical metal nanoparticles can be made of Sn. Their average diameter can be 180 ± 20 nm (FIG. 2(B)) and their height up to 90 ± 5 nm. The density of nanoparticles on the hydrophobic surface can be 3-4 nanoparticles per pm ² .

Testing the hydrophobic properties of the metallic nanoparticle-coated surfaces of FIG. 1 and FIG. 2 can be made based on contact angle measurements of a liquid droplet resting on the surface as shown in FIG. 3. The liquid can be water, diiodomethane, etc. If this contact angle is less than 90° then the surface is hydrophilic and the liquid wets the surface, as is the case for the substrate not coated with nanoparticles (FIG. 3(A)). If the contact angle is greater than 90° then the surfaces are hydrophobic (FIG. 3(B) and FIG. 3(C)) and the liquid does not wet the surfaces. The hydrophobicity of the surface thus increases by coating with metal nanoparticles by up to 20%. This increase depends on the size of the nanoparticles, their density on the surface and their chemical composition.

Director General INCDFM Dr. loj^Bhtf^^

For the deposition of metal nanoparticles on the substrate, a modified physical vapor deposition method is used having the experimental configuration in FIG. 4. The submission is made in 3 stages. in the first stage, a quartz tube that can have a diameter of 2.5 cm or 5 cm is inserted into a tubular furnace, which can have one or more heating zones. in the quartz tube is placed a boat that can be made of quartz or alumina in which the powder to be decomposed is located. The boat is left at this stage upstream of the heating zone, a short distance away. The powder can be of high purity SnSe. A substrate that can be rigid or flexible is positioned face down on the quartz boat, a short distance above the powder. Also at this stage, the quartz tube is purged with a large flow of inert gas to reduce the oxygen concentration in the tube. The gas can be Ar, N ₂ or a mixture of Ar and H ₂ . After purging, the flow rate of the gas stream is reduced to a value that may be between 90 and 110 sccm and is kept constant during furnace heating. in the second stage, when the furnace reaches the temperature necessary to decompose the powder, which can be between 650 °C and 700 °C, the preheated powder at a temperature between 400 °C and 500 °C is quickly moved to the center of the heating zone by moving the tube of quartz. Decomposition of the powder occurs and the gas flow carries the vapors to the substrate. Expect a time that can be between 10 and 15 minutes. in the third step, the boat is moved back to its initial position to favor vapor condensation on the substrate and nanoparticle formation, the furnace is turned off, and the gas flow through the quartz tube is increased for rapid cooling. Optimization of the following parameters: tube purge time, gas flow, powder amount, deposition time, oven temperature, powder preheating temperature, powder-substrate distance, leads to the formation of nanoparticles with different diameters and different densities on the surface which determines the hydrophobicity of the surface.

The method is simple and can be used to obtain metal nanoparticles directly on the substrate. Unlike commonly used chemical reduction procedures, this method is cleaner because no organometallic precursors, reducing agents, surfactants, and organic solvents that can contaminate the particles are used.

in one example, the nanoparticle-coated surfaces of FIG. 1 and FIG. 2 with hydrophobic properties, obtained by the method of FIG. 4, can be used as waterproof surfaces.

Director General INCDFM

Dr.

Claims (11)

demand 1. A surface with hydrophobic properties characterized by the fact that it consists of: - a flat substrate; - a coating of metal nanoparticles that is obtained directly from the deposition process and does not require further processing. 2. A surface with hydrophobic properties as described in claim 1 characterized in that the substrate is silicon coated with a thin layer of silicon oxide. 3. A surface with hydrophobic properties as described in claim 1 characterized in that the nanoparticles are of Sn. 4. A surface with hydrophobic properties as described in claim 1 characterized in that the nanoparticles have a size between 180 and 240 nm. 5. A surface with hydrophobic properties as described in claim 1 characterized in that the density of nanoparticles on the surface is 3-4 per pm ² . 6. A method for obtaining surfaces covered with nanoparticles characterized by the fact that it consists of the following stages: - the division of the powder source into a vapor phase by a thermal process in an enclosure through which a gas flow passes (stage 1); - vapor transport to the surface to be covered using a gas flow (stage 2); - the reassembly of the vapor phase into a solid phase on the surface, having a specific shape that depends on the synthesis conditions and the surface used (stage 3). 7. A method as described in claim 6 characterized in that the powder is SnSe. 8. A method as described in claim 6 characterized in that the thermal decomposition process of the powder takes place at a temperature between 650 and 700 °C. 9. A method as described in claim 6 characterized in that the gas flow carrying the vapor is between 90 and 110 sccm. Director General INCDFM 10. A method as described in claim 6 characterized in that the gas stream carrying the vapor is a mixture of H2 and Ar. 11. The method as described in claim 6 characterized in that the deposition is between 10 and 15 min. Director General INCDFM