RU2729264C1 - Organic-inorganic composition - Google Patents

Abstract

FIELD: materials science.

SUBSTANCE: invention relates to optical material science and can be used as an immersion composition in optical instrument-making for monitoring parameters of materials and optical parts, including large-size articles of complex shape, and can also be used in geology and mineralogy for monitoring and marking samples of natural materials. Also, the optical composition can be used for luminescent marking of articles. Organo-inorganic composition consists of the following components in wt%: polyvinylpyrrolidone – 0.1–3.8; water – 95.00–99.20; potassium iodide – 0.01–0.5; lead nitrate 0.01–0.5.

EFFECT: invention enables to form, at room temperature, on the surface of test materials a uniform transparent coating having a refractive index of 1_51–1_53 and capable of luminescence in the visible part of the spectrum under the action of external light radiation.

1 cl, 2 tbl, 6 dwg

Description

The invention relates to optical materials science and can be used as an immersion composition in optical instrumentation to control the parameters of materials and optical parts, including large-sized items of complex shape, and can also be used in geology and mineralogy to control and mark samples of natural materials. Also, the optical composition can be used for luminescent marking of products.

Immersion media are usually liquids with a specific refractive index. RF patent No. 2051940, published on 10.01.1996 according to IPC indices C09K 3/00, G01M 1/00, G02B 1/06, and RF patent No. 2134708, published on 08.20.1998 according to IPC indices C09K 3/00, G02B 1/06, describe immersion liquids for controlling the optical parameters of inorganic materials containing metal iodides and water. However, the use of liquid immersion media for quality control of large-sized items of complex shape is a laborious process and requires the use of special large-sized cuvettes for immersion of the test items in them and the expense of a large amount of immersion liquids.

This technical problem is solved by using film-forming immersion compositions. The procedure for using the immersion composition, including the formation of a transparent coating on the surface of the test item, is described in RF patent No. 2535065, published on December 10, 2014 by IPC indices C09K 3/00, G02B1 / 04, describes an immersion liquid for optical research containing 97-99 wt. % meta-bis (meta-phenoxyphenoxy) benzene and 1-3 wt. % 2-naphthol. To reduce viscosity and surface tension, said liquid may additionally contain (over 100 wt%) dibutyl sebacate. When applied to the surface of the test product, the immersion liquid described in RF patent No. 2535065 forms a thin transparent film on the surface of the test product, making it possible to control the inner layers of the material without special laborious mechanical polishing of the surface. A significant drawback of the immersion liquid described in this patent is its high refractive index (> 1.6 each), which makes it impossible to use it for quality control of glasses for displays and many widespread optical glasses.

Another transparent organic-inorganic coating containing CdS quantum dots is described in (Chaudhuri T.K., Patel MG High-refractive index Nanocomposite Films of Polyvinyl-pyrolidone and CdS Nanoparticles by In-Sity Thermolysis. - International Conference on Physics of Emerging Functional Materials (PEFM-2010). AIP Conference Proceedings, v. 1313, No. 1, pp. 275-277). In this work, the possibility of obtaining transparent highly refractive composite coatings containing nanocrystals of chalcogenides and polyvinylpyrrolidone was shown, and the process of their preparation on the glass surface was described. Films were obtained by dipping glass in a methanol solution containing a thioorganic complex of cadmium and PVP, followed by heating at 180 ° C for 10 minutes. The resulting films had a thickness of 0.7 μm and exhibited an absorption edge of about 500 nm, which was associated with the presence of CdS particles having a size of 5-10 nm. In the spectral region of transparency, the transmission of the films was 85%. The refractive index of the films was 1.74 (the refractive indices of PVP and CdS are 1.48 and 2.5, respectively). The studies carried out by the authors showed the presence of a strong interaction between the CdS nanoparticles and the PVP matrix, which may indicate the stability of the developed material. A significant disadvantage of these composite coatings is also their high refractive index, which significantly exceeds the refractive index of most commercially produced glasses.

Luminescent marking of various products is widely used in practice. At the same time, various organic dyes are widely used as luminescent components (Bad S.V., Turov Yu.P., Bad V.P., Nekhorosheva A.V., Identification and chemical labeling of substances, materials and products // Journal of Analytical Chemistry , 2010, T. 65, No. 10, S. 1012-1019.). However, a common significant drawback of organic dyes is their low thermal stability and photostability. Therefore, the use of inorganic phosphors in the composition of the composition for marking is preferred.

In terms of technical essence and chemical composition, the closest to the developed immersion composition is the prototype immersion composition described in RF patent No. 2660054, published on July 4, 2018 by IPC indices: C09D 139/06, C09D 7/61, C08L 39/06, C08K 3 / 10, C08K 3/24. The immersion composition described in this patent contains polyvinylpyrrolidone (molecular weight M _w = 1,300,000), propanol-2, water, nitrate of at least one element selected from the group consisting of Zn, Pb, Al, Na, Mg, and, optionally, sulfide nanoparticles of at least one element selected from the group consisting of Zn and Pb. The use of this composition ensures the formation at room temperature on the glass surface of a uniform transparent coating having a refractive index of 1.51-1.70.

A significant drawback of these composite coatings is their narrow field of application, limited by the use of these materials only as immersion media.

The technical problem of the present invention is to develop a multifunctional organic-inorganic composition that ensures the formation at room temperature on the surface of the test materials of a homogeneous transparent coating having a refractive index of 1.51-1.53 and capable of luminescence in the visible part of the spectrum under the influence of external light radiation ...

The composition of the new organic-inorganic composition consists of the following components:

Polyvinylpyrrolidone 0.1-3.8 wt%; Water 95.00-99.20 wt%; Potassium iodide 0.01-0.5 wt% Lead nitrate 0.01-0.5 wt%

As part of the organic-inorganic composition, it is preferable to use high-molecular-weight polyvinylpyrrolidone (molecular weight M _w = 1300000), which provides greater uniformity of coatings than a low-molecular analogue (Evstropyev S.K., Kulagina A.S., Evstropyev K.S., Kolobkova E. V., Nikonorov N.V., Soshnikov I.P., Oreshkina K.V., Khrebtov A.I. Influence of the molecular weight of polyvinylpyrrolidone on the structure, spectral and nonlinear optical properties of composite materials containing CdS / ZnS nanoparticles - Optics and spectroscopy, 2018, vol. 125, issue 5, pp. 608-614).

The introduction of lead nitrate into the composition increases the refractive index of the immersion coating. This compound is highly soluble in water and has a high refractive index (n = 1,782) (Pradyot R. Handbook of Inorganic Chemical Compounds - McGraw-Hill, 2003, p. 475; Richards TW, Schumb WC Refractive index and Solubilities of the Nitrates of Lead Isotopes - Proceedings of the National Academy of Sciences of the United States of America, 1918, V. 4 No. 12, pp. 386-387.).

Lead nitrate is a part of a special immersion liquid for viewing radiation-protective glasses (Arbuzov V.I., Volynkin V.M. Immersion liquid for viewing radiation-protective glasses. - Proceedings of the XI International Conference "Applied Optics - 2014", St. Petersburg, 2014, vol. 3, pp. 11-13.) And the immersion composition described in RF patent No. 2660054.

An increase in the refractive index of the composition is also facilitated by the introduction of potassium iodide into its composition. Iodide anions are characterized by high values of ionic refraction [3] (Batsanov SS Structural refractometry, M .: "High school", 1976, 304 S.). Zinc and cadmium iodides were used as components of immersion liquids in RF patent No. 2051940, published on 08/20/1999 according to IPC indices: C09K 3/00, G01M1 / 00, G02B 1/06, and in RF patent No. 2134708, published on 08/20/1999 according to IPC indices C09K 3/00, G02B 1/06.

Polyvinylpyrrolidone (PVP) is a non-toxic organic polymer that is readily soluble in water and lower alcohols and has the structural formula:

The refractive index of PVP at 20 ° C is n = 1.52 (λ = 0.589 μm) (Sidelkovskaya F.P. "Chemistry of N-vinylpyrrolidone and its polymers." - "Science", M., 1970, 150 S.). The effectiveness of using PVP as a component that stabilizes semiconductor nanocrystals PbS and ZnS was shown in (Tran Minh Thi, Le Van Tinh, Bui Hong Van, Pham Van Ben, Vu Quoc Trung, "The Effect of Polyvinylpyrrolidone on the Optical Properties of the Ni- Doped ZnS Nanocrystalline Thin Films Synthesized by Chemical Method ". - Journal of Nanomaterials, Volume 2012, Article ID 528047, 8 pages, doi: 10.1155 / 2012/528047) and (Bagrov I.V., Danilov BB, Evstropiev S.K. , Kiselev V.M., Kislyakov I.M., Panfutova A.S., Khrebtov A.I. Photo-induced change in the luminescent properties of suspensions of PbS nanoparticles stabilized with polyvinylpyrrolidone. - Letters in ZhTF, 2015, vol. 41, issue 2, pp. 25-31.).

Macroscopic lead iodide PbI ₂ is a yellow-orange powder insoluble in water. Lead iodide has a high refractive index and the introduction of this component into the composition of the material increases its refractive index. In addition, lead iodide crystals exhibit intense luminescence in the visible part of the spectrum when exposed to external radiation. However, the use of lead iodide with crystal sizes of more than 100 nm in immersion compositions is impossible due to their opacity in the visible part of the spectrum.

The introduction of highly refractive lead iodide nanocrystals into the immersion composition increases its refractive index while maintaining the transparency of the material in the visible part of the spectrum. However, to maintain the homogeneity and temporary stability of the composition, the mass content of these components in its composition should not exceed 1 wt%. The formation of crystals of lead iodide in solution can be carried out by chemical interaction of lead nitrate and potassium iodide. When aqueous solutions of lead nitrate and potassium iodide are mixed, the chemical reaction of the formation of lead iodide, which is poorly soluble in water, proceeds rapidly:

As a result of the reaction, numerous beautiful small golden lead iodide crystals are rapidly formed in solution.

However, mixing the same solutions in the presence of PVP leads to the formation of a transparent homogeneous solution with a yellowish tint. Within a few tens of minutes, the color intensity slowly increases, but the high homogeneity of the solution remains.

The potassium nitrate formed during the chemical reaction is readily soluble in aqueous solutions, has no absorption bands in the visible part of the spectrum, is easily mixed with the rest of the components of the composition and is included in its composition. The content of this component in the compositions is low and amounts to 0.01-0.1 wt%.

To obtain a thin layer on the surface of the test material, the composition is applied with a brush or swab. After applying a layer of the composition to the polished or frosted surface of the test specimen, inclusions, bubbles, twists and other defects in the bulk of the material can be determined during transmission.

The proposed immersion composition is designed to control individual optical parameters of inorganic materials (helplessness, bubbling, presence of technological inclusions). Control is carried out under stationary conditions at room temperature.

The thickness and transparency of the immersion coating depends on the viscosity of the liquid composition, the method and conditions for its application to the surface of the test product. In turn, the choice of optimal conditions for applying the composition depends on the surface roughness of the product. With an increase in surface roughness, for example, with coarser grinding of the test product, it becomes necessary to apply a thicker coating and a much more accurate correspondence of the refractive indices of the test material and the immersion coating.

The effectiveness of the proposed technical solution is illustrated by examples (Table 1 and Table 2).

Examples: Liquid compositions were prepared by mixing the components at room temperature in different ratios. The chemical composition and properties of the compositions are shown in Table 1. The appearance of the immersion compositions was determined according to GOST 13739-78 by visual inspection of the compositions poured into a test tube of colorless glass according to GOST 10515-75.

The transmission spectra of the samples were measured on a Shimadzu UV-3600 spectrophotometer.

The morphology of composite coatings based on PVP containing zinc iodide nanoparticles was studied by scanning electron microscopy on a scanning electron microscope (SEM) C. Zeiss SUPRA 25.

A Perkin Elmer LS-50B instrument was used to measure the photoluminescence spectra. Luminescence was excited by radiation with wavelengths λ = 380-410 nm.

Table 1 shows the characteristics of immersion compositions based on PVP and additives of inorganic components.

Compositions 1-5 are transparent homogeneous solutions having a refractive index n _D = 1.33 ÷ 1.35. When these compositions are applied to the glass surface, homogeneous transparent coatings are formed, the refractive index n _{D of} which is 1.52–1.53.

Table 2 shows the size values of lead iodide nanocrystals in compositions 3-6, determined on the basis of the positions of the maxima on the curves shown in Figure 1 and literature data of the work (Vikash Gulia, AS Vedeshwar, Optical properties of PbI ₂ films: quantum confinement and residual stress effect. // Phys. Rew. B 75 (2007) 045409).

Figure 1 shows the absorption spectra of compositions containing lead nitrate, lead iodide, potassium nitrate and polyvinylpyrrolidone (compositions 1-5, Table No. 1). Comparison of these spectra shows that the application of an immersion coating practically does not change the transmission of the sample in the visible part of the spectrum. In the UV region of the spectrum, absorption bands are observed that are characteristic of lead iodide nanocrystals. The intensity of these absorption bands increases with an increase in the content of lead iodide in composite coatings.

Figure 2 shows the absorption spectrum of an immersion coating made from liquid composition 1. From the data presented it can be seen that the resulting immersion coating is characterized by high transparency in the visible part of the spectrum.

Figure 3 shows the photoluminescence spectrum (luminescence excitation wavelength of 400 nm) of an immersion coating made from liquid composition 1. These data indicate that a thin and transparent immersion composite coating luminesces in the visible part of the spectrum under the action of external radiation with a wavelength of 400 nm ... The maximum of the luminescence band is ~ 600 nm. Thus, it can be concluded that the developed coating can be used for luminescent marking of products.

Figure 4 shows a photograph of a glass sample with a composite coating 1 applied to its surface. It can be seen that the coating applied to the glass surface is practically invisible and transparent. It should also be noted that the applied coating does not distort the image of the text located behind the coated glass sample. This confirms the high uniformity of the coating and the possibility of its use for quality control and uniformity of optical elements and materials.

Figure 5 shows an electron microscopic image of a section of an immersion composite coating made from a liquid composition 1. The image shows that the immersion composite coating has a thickness of 10 μm and evenly covers the surface of the glass sample.

Figure 6 shows an electron microscopic image of the surface of an immersion composite coating made from liquid composition 1.

It can be seen that there are no inhomogeneities or aggregates of particles larger than 10 nm in the given images. The absence of large irregularities determines the low level of light scattering by coatings and their high transparency in the visible part of the spectrum.

Composition 6 containing more than 3.0 weight. % PVP, is a transparent but viscous composition that is difficult to use for the manufacture of uniform coatings.

Composition 7, made without using PVP, is a yellow inhomogeneous liquid mixture. When applied to the glass surface of this composition, a non-uniform opaque yellow coating is formed. Composition 8 contains less than 0.01 wt% lead nitrate and is a clear liquid. When this composition was used to form an immersion coating on a glass surface, the resulting coating did not possess luminescent properties, since it contained virtually no lead iodide nanocrystals.

Composition 9 contains less than 0.01 wt% potassium iodide and is a clear liquid. When this composition was used to form an immersion coating on a glass surface, the resulting coating did not possess luminescent properties, since it contained virtually no lead iodide nanocrystals.

Composition 10 contains more than 99.2 wt% water and 0.39 wt% polyvinylpyrrolidone. The content of the stabilizer is insufficient for the formation of a homogeneous composition and it is a heterogeneous yellow liquid with suspended particles.

Composition 11 contains 94.90 wt% water and 4.10 wt% polyvinylpyrrolidone. The composition is an inhomogeneous viscous yellow-orange liquid with suspended particles.

Composition 12 contains more than 0.5 wt.% Potassium iodide and is a non-uniform yellow liquid with suspended particles.

Composition 13 contains more than 0.5 wt% lead nitrate and is a non-uniform yellow liquid with suspended particles.

Composition 14 contains more than 3.80% by weight of polyvinylpyrrolidone and is a viscous transparent liquid. The coatings on glasses formed with this viscous liquid are not uniform.

Claims (2)

An organic-inorganic composition containing polyvinylpyrrolidone and lead nitrate in an aqueous solution, characterized in that it additionally includes potassium iodide at the following ratio of components in wt%: Polyvinylpyrrolidone 0.1-3.8 Water 95-99.2 Lead nitrate 0.1-0.5 Potassium iodide 0.1-0.5

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