LT7057B - A method for production of a photo-curable inorganic-organic hybrid resin and a method for production of hard sioxcy ceramic microstructures using the photo-curable inorganic-organic hybrid resin - Google Patents

Abstract

The object of the present invention is a method for production of a photo-curable inorganicorganic hybrid resin produced by the sol–gel method from trimethoxymethylsilane (responsible for the hardness) and 3-(trimethoxysilyl)propyl methacrylate, which has an acrylate functional group and therefore can participate in laser photopolymerization. Extremely hard 3D ceramic structures are obtained by applying high-temperature pyrolysis in an inert atmosphere to soft organometallic derivatives. The main advantages of this method is that there are no shrinkage defects after sintering, except for a uniform repetitive decrease in volume (the shrinkage after annealing is 75% in all directions compared to the starting polymeric derivative). The starting material is a homogeneous monolithic molecular compound, therefore, the surface smoothness and resolution of the structures are not limited by the initial material undesirable factors such as ceramic particles size. method from trimethoxymethylsilane (responsible for hardness) and 3-(trimethoxysilyl)propyl methacrylate, which has an acrylate functional group and can therefore participate in laser photopolymerization. Ultra-hard 3D ceramic structures are obtained by high-temperature pyrolysis of soft organometallic compounds in an inert atmosphere. The main advantage of this method is that there are no shrinkage defects after annealing, except for a uniform repeated volume reduction (the shrinkage after annealing is 75% in all directions compared to the initial polymer formation). The starting material is a homogeneous monolithic molecular compound, so the surface smoothness and resolution of the structures are not limited by undesirable factors of the starting material, such as the size of the ceramic particles.

Description

TECHNICAL FIELD

This invention relates to a method of producing a photo-curable inorganic-organic hybrid resin and a method of producing solid ceramic microstructures using the hybrid resin. In particular, the present invention relates to a method for producing photocurable inorganic-organic hybrid resin, hybrid resin, and solid SiOxCy ceramic microstructures using the hybrid resin.

STATE OF THE ART

Ceramics are one of the most attractive engineering materials due to their unique mechanical, chemical and thermal properties. Nowadays, there is an increasing interest in new manufacturing processes and materials for the realization of 3D printed microstructures due to their great significance in various technological fields, which otherwise cannot be realized using traditional manufacturing technologies [Malinauskas, Mangirdas & Žukauskas, Albertas & Hasegawa, Satoshi & Hayasaki, Yoshio & Mizeikis, Vygantas & Buividas, Ričardas & Juodkazis, Saulius. (2016). Ultrafast laser processing of materials: from science to industry. Light Sci Appl., 5 (8), 16133. 10.1038/lsa.2016.133.], [Malinauskas, Mangirdas & Žukauskas, Albertas & Purlys, Vytautas & Belazaras, Kastytis & Momot, Andrej & Paipulas, Domas & Gadonas, Roaldas & Piskarskas , Algis & Gilbergs, Holger & Gaidukevičiūtė, Arūne. (2010). Femtosecond laser polymerization of hybrid/integrated micro-optical elements and their characterization. Journal of Optics, 12, 124010. 10.1088/20408978/12/12/124010.]. 3D ceramics can be applied to various applications such as aesthetics, decoration, architecture, mechanics, electronics, optics, metallurgy, space and strategic sectors. Because of its unique properties such as extreme hardness/strength, stability and corrosion resistance, ceramics are considered promising materials for manufacturing medical, orthopedic and dental implants, aircraft components and other mechanical parts. [Merkininkaitė, Greta & Aleksandravičius, Edvinas & Malinauskas, Mangirdas & Gailevičius, Darius & Šakirzanovas, Simas. (2022). Laser additive manufacturing of Si/ZrO2 tunable crystalline phase 3D nanostructures. Opto-Electron Adv 5, 210077.

10.29026/oea.2022.210077].

3D printing methods commonly used for the production of advanced mechanical three-dimensional components using ceramic materials or pre-ceramic resins are: photopolymerization [Malinauskas, Mangirdas & Farsari, Maria & Piskarskas, Algis & Juodkazis, Saulius. (2013). Ultrafast laser nanostructuring of photopolymers: A decade of advances. Physics Reports 533 (1), 1-31. 10.1016/j.physrep.2013.07.005] selective laser melting, stereolithography, extrusion-based 3D printing, direct metal laser melting, melt deposition modeling, inkjet printing, robocasting, electron beam freeform fabrication, electron beam melting, selective thermal melting, fabrication of laminated objects, digital light processing, pulsed inkjet printing, cold extrusion fabrication and direct deposition of materials [Anish Mathews, P., Koonisetty, S., Bhardwaj, S., Biswas, P., Johnson, R., Padmanabham, G (2020). Patent Trends in Additive Manufacturing of Ceramic Materials. In: Mahajan, Y.R., Johnson, R. (eds) Handbook of Advanced Ceramics and Composites. Springer, Cham. 10.1007/978-3-030-16347-1_57],

Pre-ceramic materials for 3D printing usually include liquid or semi-liquid systems in which fine ceramic particles are dispersed as raw material or metal-organic resins [Jonusauskas, Linas & Gailevičius, Darius & Mikoliūnaitė, Lina & Sakalauskas, Danas & Šakirzanovas, Simas & Juodkazis, Saulius & Malinauskas, Mangird. (2017). Optically Clear and Resilient Free-Form μ-Optics 3D-Printed via Ultrafast Laser Lithography. Materials (Basel), 10(1):12. 10.3390/ma10010012], either in liquid or paste form. Composites of polymers and ceramic particles are made of metal or semi-metal oxides, carbides, bohdes, glass grains dispersed in organic monomers such as: oxymethylene, olefins, propylene or ethylene, urethanes, amides, ethers, esters, acrylates. [ Chen, Zhangwei & Li, Ziyong & Li, Junjie & Liu, Chengbo & Liu, Changyong & Li, Yang & Wang, Pei & Yi, He & Lao, Changshi & Yuelong, Fu. (2018). 3D printing of ceramics: A review. Journal of the European Ceramic Society. 39. 10.1016/j.jeurceramsoc.2018.11.013], [Anish Mathews, P., Koonisetty, S., Bhardwaj, S., Biswas, P., Johnson, R., Padmanabham, G. (2020). Patent Trends in Additive Manufacturing of Ceramic Materials. In: Mahajan, Y.R., Johnson, R. (eds) Handbook of Advanced Ceramics and Composites. Springer, Cham. 10.1007/978-3-030-163471_57], In the case of organometallic resins, monomeric metal alkoxides and organic monomers such as acrylates are used as precursors in the production of homogeneous photoactive organometallic materials [Malinauskas, Mangirdas & Žukauskas, Albertas & Bičkauskaitė, Gabija & Gadonas, Roaldas & Juodkazis, Saulius. (2010). Mechanisms of three-dimensional structuring of photo-polymers by tightly focused femtosecond laser pulses. Opt. Express 18, 10209-10221. 10.1364/OE.18.010209]. After additive manufacturing, the raw organic parts must be further processed, usually by pyrolysis to remove the organic material, followed by high-temperature sintering to obtain the pure inorganic material [Gailevicius, Darius & Padolskyte, Viktorija & Mikoliunaite, Lina & Sakirzanovas, Simas & Juodkazis, Saulius. (2018). Additive-Manufacturing of 3D Glass-Ceramics down to Nanoscale Resolution. 4. 647-651. 10.1039/C8NH00293B].

A higher percentage of inorganic materials in the precursors for producing high-hardness and high-quality ceramic structures reduces shrinkage during pyrolysis, which results in a stronger 3D printed ceramic structure. The lower the amount of organic matter, the higher the degree of condensation reactions, which makes it more difficult to dissolve the substance in the solvent. This reduces the resolution of structures or makes the manufacturing process impossible. These long-term problems make it difficult to produce structures that are both high-resolution and stiff. The combination of ceramic nano/micro particles and organic resists is another way to obtain 3D ceramics, but it has several drawbacks: the resolution of the structures depends on the size of the particles and it is difficult to obtain a stable and transparent solution, and the structures deform when heated.

There are many patents describing the production of photoactive resists/composites and the production of 3D ceramics, but many problems have yet to be solved to obtain ultra-hard yet precise ceramics.

US Patent No. US8969219B2 discloses a process for preparing an ultraviolet (UV) curable inorganic-organic hybrid resin containing about 4% or less volatile matter and less than 30% organic residue. The UV-curable inorganic-organic hybrid resin obtained by this method can be UV-cured in a very short time, and after curing, a transparent, non-shrinking and crack-free glass-like product with high optical quality, high thermal stability and good adhesion properties is formed. Considering these properties, this hybrid resin can be used in various applications such as electro-optics, microelectronics, stereolithography and biophotonics. However, the final materials obtained have a relatively high content of organic matter, which leads to low resistance to aggressive conditions.

EP Application No. 15190461.2 (Publication No. EP3009416A1) discloses additive manufacturing systems, methods and resins. In one embodiment, the additive manufacturing method of the ceramic structure includes a resin comprising a preceramic polymer and inorganic ceramic filler particles dispersed in the preceramic polymer. The preceramic polymer is suitable for conversion to the ceramic phase. The method includes functionalizing the inorganic ceramic filler particles with a reactive group and applying an energy source to the resin to create at least one layer of the ceramic phase from the resin. The main disadvantage of this invention is that inorganic particles are used to prepare the protective layer, so the resolution of the structures is limited by the size of the particles.

US Patent No. US10737984B2 discloses resin compositions that can be used for 3D printing and pyrolysis to produce a ceramic matrix composite. The resin formulations contain a solid phase filler that provides high thermal stability and mechanical strength (eg, fracture resistance) in the final ceramic material. The invention provides for direct, free-form 3D printing of a preceramic polymer loaded with a solid phase filler, followed by conversion of the preceramic polymer into a 3D printed ceramic matrix composite with potentially complex 3D shapes or large part shapes. Other embodiments provide active solid-phase functional additives as solid-phase fillers to realize or enhance at least one chemical, physical, mechanical, or electrical function in the molded ceramic structure and final structure. Solid-phase functional additives actively improve the final ceramic structure through one or more changes actively induced by the additives during pyrolysis or other heat treatment. Solid phase fillers can be in the form of fibers, filamentous crystals, nanotubes, nanorods, micro/nano particles with an average diameter of 1 nanometer to 100 microns, which limits the clarity of the structure shape.

Chinese Patent No. CN109438631B relates to high precision and high thermal deformation temperature stereolithographic 3D printing photosensitive resin and its manufacturing method. The composite material consists of the following raw materials, expressed in mass percent: 5 - 95% bis[(3-ethyl-3-methoxyoxetane)propyl]diphenylsilane; 3 - 80% acrylate prepolymer; 0 - 40% acrylate thinner; 0.5 - 10% cationic initiator; 0.5 - 10% radical initiator. The light-sensitive resin produced according to the invention has good light sensitivity, high molding accuracy and high thermal deformation temperature, so it can be directly used to produce any complex shaped parts or dies with high precision and high thermal deformation. However, the disclosure does not show resistance to extremely high temperatures and loads, with a distortion temperature of only 75 °C at a load of 1.82 MPa.

Chinese Patent No. CN109128150B discloses 3D printing high strength aluminum alloy metal powder using metal powder 3D printing high strength aluminum alloy printing method and application of 3D printing method. 3D printing high-strength aluminum alloy metal powder including aluminum alloy micron particles, which is characterized by the surface of the aluminum alloy micron particles successively modified with graphene and nano-sized reinforcing particles from the inside to the surface. The amount of graphene additive is 0.3-0.6% of the total weight of metal powder and the total addition level of nano-sized reinforced particles is 1-3% of the total weight of metal powder; The partial micron particle size of aluminum alloy is 10 μm -60 μm; The fractional size of the nano-sized reinforced particle is 30 nm- 60 nm. Metal powder can print high strength aluminum alloy, is widely used in the production of aluminum alloy part. The mechanical properties of the sample are as follows: tensile strength 800-970MPa, yield strength 600-770MPa, elongation percentage 13-16%, while our demonstrated materials exhibited GPa-scale mechanical properties.

The present invention is intended to overcome the above-mentioned disadvantages and to provide additional advantages over the prior art.

BRIEF DESCRIPTION OF THE INVENTION

The invention is a method of producing a photo-curable inorganic-organic hybrid resin and a method of producing SiOxCy ceramic 3D microstructures with hardness and precision properties using the hybrid resin.

The production of photocurable inorganic-organic hybrid resin involves chemical sol-gel synthesis of photocurable inorganic-organic hybrid resin, which includes acid hydrolysis of precursors, laser thermal condensation of sol-gel photopolymerization, and pyrolysis at 1000 °C in an inert atmosphere.

Silica-organic prepolymer is a photo-curable inorganic-organic hybrid resin that can maintain its 3D shape after laser light treatment. The resin contains 20% by weight of the precursor 3-(trimethoxysilyl)propyl methacrylate (MAPTMS), which can participate in photopolymerization, and 80% by weight of the precursor trimethoxymethylsilane (MTMS), which is capable of strengthening. The MTMS precursor allows the ceramic structure to retain its original shape, prevents deformation or cracking, and provides exceptional hardness, such as 12.30 ± 0.17 GPa, after heat treatment. Photo-curable inorganic-organic hybrid resin has a low content of organic matter, but can participate in photopolymerization and can be converted into ceramics after heat treatment.

Thus, 3D solid ceramic structures with complex, highly precise shapes, enormous resolution (micrometer scales) and defect-free can be obtained in this way.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention which are believed to be novel and inventive are specifically set forth in the appended claims. However, the invention itself may be best understood by reference to the following detailed description of the invention, which describes exemplary embodiments of the invention, given by way of non-limiting examples, together with the accompanying drawings, in which:

Fig. 1. shows SEM micrographs of 3D polymer and ceramic structures fabricated using the photocurable inorganic-organic hybrid resin of the present invention: (a-c) high-resolution 3D periodic gyroid; (d, e) 3D fullerene-shaped structure (C60) with smaller fullerene (C60 ) inside. In each case, the left side corresponds to the original structure and the right side to the heat-treated structure.

Fig. 2. shows the FTIR spectrum of a) colloidal solution (sol), b) gel, c) polymer and d) ceramic SiOxCy material used in the method of obtaining 3D-4D precise microstructures of solid ceramics.

Fig. 3. shows the refractive indices of the sol, gel and polymer used in the method of the present invention. Sol, gel and polymer refractive indices at room temperature as a function of wavelength. Each measurement was repeated three times and the calculated standard deviations were negligible.

Fig. 4. shows TGA, DSC and DTG data of the produced polymer and precursors: 3 (trimethoxysilyl)propyl methacrylate (MAPTMS) and trimethoxymethylsilane (MTMS) used in the synthesis of the invention. The analysis was carried out under a nitrogen atmosphere.

Fig. 5. shows the XRD pattern of the SiOxCy ceramic structure annealed at 1000 °C in a nitrogen atmosphere.

Fig. 6. Shows the hardness and Jung's modulus of the as-prepared ceramic plate measured by nanoindentation and compared to fused quartz (PN: 5-0098-2) (a). Optical images after nano-identification of ceramic plate (b) and fused quartz (c).

The best embodiments of the invention will be described below with reference to the drawings. Each figure has the same numbering for the same or equivalent item.

DETAILED DESCRIPTION OF THE INVENTION

It should be understood that many specific details are provided in order to provide a complete and comprehensible description of an embodiment of the invention. However, one skilled in the art will appreciate that the exemplary embodiments are not intended to limit the application of the invention, which may be practiced without these specific instructions. To avoid confusion, well-known methods, procedures and components have not been described in detail in the embodiment. Furthermore, this description should not be construed as limiting the invention to the exemplary embodiments provided, but only as one possible embodiment of the invention.

Abbreviations used in the description and definition of the invention:

3D : three-dimensional

4D : four dimensional

FTIR : Fourier transform infrared spectroscopy

MAPTMS : 3-(trimethoxysilyl)propyl methacrylate

MTMS: trimethoxymethylsilane

PTFE : polytetrafluoroethylene

SEM : scanning electron microscopy

SLM : selective laser melting

TGA: thermogravimetric analysis

UV: Ultraviolet radiation

XRD: X-ray diffraction

According to the present invention, the production of solid SiOxCy ceramic microstructures includes the production of a photo-curable inorganic-organic hybrid resin, creating a 3D structure model with a computer program, irradiating the photo-curable inorganic-organic hybrid resin to initiate localized and controlled polymerization to form an affected 3D shape, to produce processing the structures in a polar organic solvent to produce 3D pre-ceramic resin structures; pyrolytic transformation of a pre-ceramic polymer 3D structure to form a ceramic microstructure.

The preparation of photo-curable inorganic-organic hybrid resin includes the following steps:

In a first step, (a) in the first alkoxysilane monomer, one alkyl group is replaced by a non-polymerizable group, wherein the non-hydrolyzable and non-polymerizable group is C1, and the other three substituents are hydrolyzable C1 alkanol groups; (b) in the second alkoxysilane monomer, one carboxyl group is replaced by a non-hydrolyzable polymerizable C7 acrylate group, and the other three substituents are hydrolyzable C1 alkanol groups.

In a second step, the hydrolysis of the substituted monomers (a) and (b) is carried out in the presence of water and a hydrolysis catalyst in a closed system at room temperature, for example «25 °C, and atmospheric pressure, for example «1013.25 mbar, thereby releasing an alcohol that serves as a common solvent. A solution of hydrolyzed monomer (b) is added dropwise to a solution of hydrolyzed monomer (a) to form a mixture.

In the third step, the polycondensation of the mixture of said hydrolyzed monomers in the second step is carried out by heating in an air atmosphere at a higher temperature, for example 50-100 °C, when this temperature is maintained close to the evaporation temperature of said alcohol solvent, for example 50-70 °C, and below said hydrolyzed monomers boiling point, for example <102 °C. The vapors of the mentioned alcohol solvent and water are removed.

After the second step, an additional photoinitiator is optionally added to the mixture of hydrolyzed monomers (a) and (b) to obtain an even more photosensitive resin. Said photoinitiator can initiate polymerization and its concentration is 0.1-2% by weight based on the weight of the hydrolyzed monomer (b).

In a preferred embodiment, the photocurable inorganic-organic hybrid resin includes trimethoxymethylsilane, which is responsible for the hardness of the printed 3D structure due to the low molar ratio of silicon to carbon (1:1) after pyrolysis. The chemical formula of trimethoxymethylsilane is (I):

CH ₃

H ₃ C---O---Si---O---CH ₃

oh

I ch ₃ (i)

The second monomer of the first step is chosen to ensure photopolymerization. In a preferred embodiment, the second added monomer is 3-(trimethoxysilyl)propyl methacrylate. The chemical formula of 3-(Trimethoxysilyl)propyl methacrylate is (II):

(H)

Precursors of the second stage, i.e. The hydrolysis of monomers (I) and (II) is carried out as follows: 3(trimethoxysilyl)propylmethachlate is hydrolyzed with a 0.01-1 M trifluoroacetic acid (CF3COOH) solution. Trimethoxymethylsilane is hydrolyzed with 0.01-1 M hydrochloric acid (HCI). Hydrolyzed 3-(trimethoxysilyl)propyl methacrylate is then added dropwise to hydrolyzed trimethoxymethylsilane in a molar ratio of 2:3 to 1:9, respectively. Finally, 0.1-2% by weight of 2-benzyl-2-(dimethylamino)-1-[4-(morpholinyl)phenyl)]-1-butanone photoinitiator is added to the mixture of hydrolyzed monomers, compared to the weight of MAPTMS. Such final material is stirred for 3 hours and filtered through a 0.22 pm PTFE syringe filter. During condensation, a droplet of the substance is formed on a transparent substrate and heated at 50 °C for 7 hours. The size of the drop depends on the 3D ceramic structure that will be formed. During heating, condensation occurs, covalent bonds are formed between the components, the hydrolyzed substances MTMS and MAPTMS and the hydrolysis products methanol and water evaporate. The chemical formula of the potential condensation product is (III):

(III)

In order to create a 3D/4D structure, it is necessary to have a digital model of it, which is created by a computer program depending on the photo printing technology.

Condensation is followed by irradiation of the photocurable inorganic-organic hybrid resin (III) to initiate localized and controlled polymerization to form an affected 3D shape, i.e. i.e. 3D printed ceramic object.

3D structuring can be performed by irradiation of the photo-curable inorganic-organic hybrid resin according to the invention using: stereolithography printer, UV lithography, using a mask, interference lithography, electron or ion beam lithography, femtosecond laser source.

3D structuring using a femtosecond laser involves a multiphoton polymerization method: a pulsed laser beam with a duration of 50 - 600 fs, a wavelength of 220 - 1100 nm and a repetition rate of 50 kHz - 80 MHz is focused by a lens with an aperture of 0.2 - 1.4 NA.

3D structuring using stereolithography printer structuring involves focusing an ultraviolet (UV) laser into a reservoir of a photocurable inorganic-organic hybrid resin according to the present invention. A photo-curable inorganic-organic hybrid resin is photochemically cured to form a single layer of the desired 3D object. Then, the production platform moves down one layer and the vane covers the top of the container with material. This process is repeated for each layer of the product until the 3D object is formed.

3D structuring by irradiation of the photocurable inorganic-organic hybrid resin according to the invention using UV lithography with a mask, the photomask is in direct contact with the organic silicon material and light is transmitted through the mask. The patterned areas of the mask are designed to block light, so the negative of the mask pattern is transferred to the material.

3D structuring by irradiation of a photocurable inorganic-organic hybrid resin using interference lithography involves passing a coherent UV laser beam through a spatial filter for cleaning and expansion. The mirror and the substrate coated with a photo-curable inorganic-organic hybrid resin are assembled perpendicular to each other. The expanded laser beam simultaneously hits a mirror and a substrate coated with a photo-curable inorganic-organic hybrid resin. The reflection from the mirror also hits the substrate. Incoming light and reflected light interfere in the substrate to create a standing wave with a 2-D regular pattern of bright and dark spots.

3D structuring of an irradiation photocurable inorganic-organic hybrid resin using electron or ion beam lithography involves focusing an ion or electron beam to impact a patterned pattern across the surface to create very small structures. Ion beam lithography refers to a direct writing process that uses a narrow scanning ion beam source (e.g., 20 nm in diameter), usually made of gallium ions. In the case of electron beam lithography, lower resolution systems can use thermal sources that are usually composed of lanthanum hexaboride. Systems with higher resolution requirements require the use of field electron emission sources such as heated W/ZrO2.

After the photocurable inorganic-organic hybrid resin of the invention, photopolymerization using any of the above-mentioned methods, the structures produced by any of the above-mentioned methods are treated in a polar organic solvent to create 3D pre-ceramic structures. Said polar organic solvent is, as mentioned, acetone, methyl isobutyl ketone or isopropanol.

The final step in the production of a ceramic 3D printed object is pyrolysis in an inert atmosphere. The resulting organic silicon 3D form does not have a high hardness, so it must be pyrolyzed in an inert atmosphere. The 3D structure is placed in a high temperature tube furnace. The furnace is vacuumed, inert gas is introduced and this procedure is repeated three times. In the long run, a continuous flow of inert gas remains. The 3D structures were annealed on the corundum substrate for 5 h at 1000 °C in an inert atmosphere at a temperature rise rate of 2 °C/min, and then the 3D structures were cooled to room temperature. An inert atmosphere is an argon or nitrogen atmosphere.

EXAMPLES OF IMPLEMENTATION OF THE INVENTION

According to a specific example, the selected photo-curable inorganic-organic hybrid resin consists of 1 part by mass of MAPTMS and 4 parts of MTMS. Hydrolysis of the MTMS and MAPTMS precursors is carried out using a 0.1 M acid solution and the amount of photoinitiator is 1 wt% based on MAPTMS. Structures are produced by laser lithography technology; the manufacturing parameters and the subsequent process were as described in the "Detailed Description of the Invention" section.

The structures were subsequently examined with a scanning electron microscope (SEM) to confirm the preservation of fine surface details (Fig. 1). SEM micrographs show a 3D periodic gyroid with precise features (a-c) and a 3D fullerene-shaped structure (C60) with smaller fullerene (C60) inside (d,e) structures fabricated using laser lithography. In each case, the original structure is on the left, and the heat-treated structure on the right.

The resulting structures retain their shape after heat treatment without any distortions and cracks, except for symmetrical shrinkage of the shape.

FTIR analysis was chosen to evaluate changes in chemical structure in prepared sols, gels, polymers and ceramics. Characteristic FTIR absorption peaks provide qualitative information on hydrolysis, condensation, polymerization, and pyrolysis.

The broad band absorption at «3350 cm ^-1 wavelength is characteristic of the axial deformation of Si-OH or C-OH groups, which corresponds to the terminal hydrolyzed silane or methanol groups formed after hydrolysis. It is obvious that methanol is removed from the material during condensation, which is why the band of -OH groups («3330 cm ^-1 ) in the gel spectra decreases.

During condensation and photopolymerization, the absorption of C=O at 1720 cm ^-1 , characteristic of esters, becomes broader, splits into two peaks and shifts to a higher wave number due to the change in the mobility of C=O bonds after polymerization. Furthermore, the Si-OC band almost disappears after condensation, confirming the complete hydrolysis and condensation of the sol. After irradiation (when the polymer is formed), the peaks attributed to the C=C bond around 1640-1620 cm ^-1 decrease, indicating that the polymerization of the acrylate groups in the gel is taking place (see the inset of Fig. 2).

FTIR spectra show the bond rearrangements of the main polymer to ceramic transformation. The material pyrolyzed at 1000 °C has three peaks attributed only to inorganic bonds («800 cm ^-1 Si-C; «440 cm ^-1 and «1010 cm ^-1 Si-O-Si oscillation and stretching, respectively), indicating that no organic material remains and only the inorganic compound SiOxCy is formed.

The refractive indices of the produced sol, gel and polymer indicate the permeability to electromagnetic waves, helping to determine the production factor to avoid inaccuracies due to the path of light through the material. The results of measuring the refractive indices are shown in Fig. 3.

The pyrolytic transformation from pre-ceramic polymer to ceramic was investigated by thermogravimetric analysis under nitrogen atmosphere (Fig. 4). TGA analysis showed that the precursors almost completely decompose/evaporate during exothermic processes at low temperatures (up to 300 °C) (residual mass MAPTMS « 2.2%, MTMS « 0%). Four main decompositions are observed in the thermal gravimetric curve of the photocurable inorganic-organic hybrid resin. The first two non-intense (up to 300 °C) peaks can be attributed to the decomposition of unreacted precursors during hydrolysis, condensation and photopolymerization. The photocurable inorganic-organic hybrid resin undergoes endothermic decomposition most likely at 450 °C, which can be attributed to the decomposition of the organic part. Finally, at 950 °C, amorphous SiOxCy is formed and 76% of the original mass remains. These results indicate that a hydrolysis and condensation procedure is necessary, otherwise, after heating, the precursors decompose at low temperatures without turning into ceramics.

X-ray diffraction (XRD) analysis was performed using a Rigaku MiniFlex II diffractometer operating in Bragg-Brentan (θ/2θ) geometry. Data were collected over a 2Θ angle range from 5° to 80°, measured in 0.01° increments and at 10°/min. at scan rate using a Cu Ka source with a Ni filter. The results of the X-ray diffraction analysis of the SiOxCy ceramic structure fired at 1000 °C in a nitrogen atmosphere are shown in Fig. 5. For the pyrolysis product, the broad peaks at about 10°, 22.5° and about 55° - 80° indicate the characteristics of amorphous/glassy SiOC and β-SiC ceramics, respectively [Shi, Huimin & Yuan, Anboa & Xu, Jiaqiang. Tailored synthesis of monodispersed nano/submicron porous silicon oxycarbide (SiOC) spheres with improved Li-storage performance as an anode material for Li-ion batteries. (2017). Journal of Power Sources. 364, 1, 288-298.

10.1016/j.jpowsour.2017.08.051 ].

Mechanical properties such as hardness and characteristics of the fabricated ceramic plate and fused quartz Jungian modulus (PN: 5-0098-2) were measured using a Hysitron TI Premier nanoindenter with a Berkovich diamond probe with a radius of approximately 87 nm. Nine notches arranged in a square pattern were made in each specimen using the load-controlled partial unloading method with loads ranging from 100 mN to 5 N.

Fig. 6a shows the hardness and Jung's modulus of the fabricated SiOxCy ceramic plate and fused quartz (PN: 5-0098-2). The estimated hardness of the ceramic is 12.30 ± 0.17 GPa, while the fused quartz reference is 10.39 ± 0.34 GPa. Jung's modulus also exceeds that of fused quartz (69.45 ± 1.17 GPa), which is 88.47 ± 4.15 GPa.

Although this description of the invention has listed numerous characteristics and advantages along with constructional details and features, the description is presented as an exemplary embodiment of the invention. Without departing from the principles of the invention, the details, in particular the shape, size and arrangement, may vary according to the most widely understood meanings of the terms and definitions used in the claims.

Claims (14)

DEFINITION OF THE INVENTION 1. A method of producing a photo-curable inorganic-organic hybrid resin for the production of solid SiOxCy ceramic microstructures, when the method includes the synthesis of a photo-curable inorganic-organic hybrid resin, and is characterized in that the method includes steps (i) preparation (I) of the first alkoxysilane monomer, in which one alkyl group is substituted with a non-polymerizable C1 group, and the other three substituents are hydrolyzable C1 alkanol groups; (II) of a second alkoxysilane monomer in which one alkoxyl group is substituted with a polymerizable C7 acrylate group and the other three substituents are hydrolyzable C1 alkanol groups; (ii) carrying out the hydrolysis of said monomers (I) and (II) in the presence of water and a hydrolysis catalyst in a closed system at room temperature and atmospheric pressure, thereby releasing an alcohol that serves as a common solvent; (iii) dropwise addition of the hydrolyzed monomer (II) solution to the hydrolyzed monomer (I) solution to obtain a mixture having a weight ratio of 2:3 to 1:9, respectively; (iv) performing polycondensation of said hydrolyzed monomer mixture by heating in an open system at an elevated temperature, wherein said temperature is maintained above the boiling point of said alcohol solvent and below the boiling point of said hydrolyzed monomers, said alcohol solvent and water vapor are removed. 2. A process according to claim 1, wherein said alkoxysilanes are trimethoxymethylsilane (MTMS) (I) and 3-(trimethoxysilyl)propyl methacrylate (MAPTMS) (II). 3. A process according to claim 2, wherein said hydrolysis catalysts are hydrochloric acid (0.01-1 M) for MTMS and trifluoroacetic acid (0.01-1 M) for MAPTMS. 4. A method according to any one of claims 1-3, wherein an additional photoinitiator is added to the mixture of hydrolyzed monomers (I) and (II) after step (iii). 5. The method according to claim 4, wherein said photoinitiator is 2-benzyl-2(dimethylamino)-1-[4-(morpholinyl)phenyl)]-1-butanone and the concentration of said photoinitiator capable of initiating polymerization is in the range of 0.1- 2% by weight based on the weight of the hydrolyzed monomer (I). 6. A method according to any one of claims 1-5, wherein the polycondensation is carried out at a temperature maintained at 50°C for 7 hours, and the alcohol solvent and water vapors are gradually removed. 7. Photo-curable inorganic-organic hybrid resin for the production of solid SiOxCy ceramic microstructures, which includes an inorganic material in the precursor and an organic material in the precursor, and differs in that the resin includes the mass ratio of the precursor trimethoxymethylsilane and the precursor 3-(trimethoxysilyl)propyl methacrylate in the range of 3:2 - 9 :1. 8. The photocurable inorganic-organic hybrid resin of claim 7, wherein it comprises a weight ratio of said MTMS:MAPTMS monomers of 4:1. 9. A method of producing solid SiOxCy ceramic microstructures, wherein the method comprises providing a photo-curable inorganic-organic hybrid resin, creating a 3D structure model with a computer program, irradiating the photo-curable inorganic-organic hybrid resin to initiate localized and controlled polymerization to form an affected 3D shape, producing processing the structures in a polar organic solvent to produce 3D pre-ceramic resin structures, subjecting the pre-ceramic polymeric 3D structure to pyrolytic transformation to form a ceramic microstructure, characterized in that the photocurable inorganic-organic hybrid resin is a resin according to claim 7 or 8, exposed to a femtosecond laser source, to obtain a polymeric 3D structure. 10. The method according to claim 9, wherein said polymeric 3D structure is placed in a furnace and heated at 1000°C for 5 hours in an inert gas atmosphere at a temperature rise rate of 2°C/min and cooled to room temperature. 11. A compound according to any one of claims 9 or 10, wherein said polar organic solvent is acetone, methyl isobutyl ketone or isopropanol. 12. A method according to claim 10 or 11, wherein the procedure is performed by scanning a Gaussian intensity distribution or any structured beam that produces a sufficient maximum intensity to initiate a localized photopolymerization reaction. 13. A method according to any one of claims 10 - 12, wherein the laser structuring is performed using a multiphoton polymerization method using a pulsed laser beam with a duration of 50 - 600 fs, a wavelength of 220 - 1100 nm and a repetition rate of 50 kHz - 80 MHz pulses focused lens with an aperture of 0.2 - 1.4 NA. 14. A method according to any one of claims 10 to 13, wherein said inert gas atmosphere is an argon or nitrogen atmosphere.