阅读说明：本技术 使用反应性单体方法通过冷烧结方法获得的陶瓷-聚合物复合材料 (Ceramic-polymer composite obtained by cold sintering process using reactive monomer process ) 是由 埃里克·施瓦茨 托马斯·L·埃文斯 特奥多鲁斯·霍克斯 罗伯特·迪尔克·范·德·格兰佩尔 基 于 2017-08-25 设计创作，主要内容包括：本文描述了冷烧结陶瓷聚合物复合材料以及由陶瓷前体材料和单体和/或低聚物制备它们的方法。冷烧结方法和各种单体允许将各种聚合物材料结合至陶瓷中。(Described herein are cold-sintered ceramic-polymer composites and methods of making them from ceramic precursor materials and monomers and/or oligomers. The cold sintering process and various monomers allow the incorporation of various polymeric materials into the ceramic.)

1. A method for preparing a cold-sintered ceramic-polymer composite, comprising:

a. combining at least one inorganic compound in the form of particles having a number average particle size of less than about 30 μm with at least one monomer, reactive oligomer, or combination thereof and a solvent in which the inorganic compound is at least partially soluble to obtain a mixture;

b. subjecting the mixture to polymerization conditions to obtain a pre-ceramic polymer mixture comprising the polymer of the at least one monomer, reactive oligomer, or combination thereof, the inorganic compound in particulate form, and the solvent; and

c. exposing the pre-ceramic polymer mixture to a pressure of no greater than about 5000MPa and a temperature of less than about 200 ℃ above the boiling point of the solvent to obtain the cold-sintered ceramic-polymer composite.

2. A method for preparing a cold-sintered ceramic-polymer composite, comprising:

a. combining at least one inorganic compound in the form of particles having a number average particle size of less than about 30 μm with a solvent in which the inorganic compound is at least partially soluble to obtain a mixture;

b. subjecting the mixture to a pressure of no more than about 5000MPa and a temperature less than 200 ℃ above the boiling point of the solvent to obtain a cold-sintered ceramic;

c. injecting at least one monomer, reactive oligomer, or combination thereof into the cold-sintered ceramic to obtain a cold-sintered ceramic pre-polymer mixture comprising the cold-sintered ceramic and the at least one monomer, reactive oligomer, or combination thereof to be polymerized into a polymer; and

d. subjecting the cold-sintered ceramic pre-polymer mixture to polymerization conditions to obtain the cold-sintered ceramic polymer composite.

3. A method for preparing a cold-sintered ceramic-polymer composite, comprising:

a. combining at least one inorganic compound in the form of particles having a number average particle size of less than about 30 μm with at least one monomer, reactive oligomer, or combination thereof and a solvent in which the inorganic compound is at least partially soluble to obtain a mixture;

b. subjecting the mixture to a pressure of no more than about 5000MPa and a temperature less than 200 ℃ above the boiling point of the solvent to obtain a cold-sintered ceramic prepolymer mixture comprising cold-sintered ceramic and at least one monomer, reactive oligomer, or combination thereof to be polymerized into a polymer; and

c. subjecting the cold-sintered ceramic pre-polymer mixture to polymerization conditions and forming the cold-sintered ceramic polymer composite.

4. A method for preparing a cold-sintered ceramic-polymer composite, comprising:

a. combining at least one inorganic compound in the form of particles having a number average particle size of less than about 30 μm with at least one monomer, reactive oligomer, or combination thereof and a solvent in which the inorganic compound is at least partially soluble to obtain a mixture; and

b. subjecting the mixture to a pressure of no more than about 5000MPa and a temperature less than 200 ℃ above the boiling point of the solvent, whereby the at least one monomer, reactive oligomer, or combination polymerizes into a polymer to obtain the cold-sintered ceramic-polymer composite.

5. The method of any one of claims 1 to 4, wherein the weight percentage of the inorganic compound in the mixture is about 50 to about 99.5% (w/w) based on the total weight of the mixture.

6. The method of any one of claims 1 to 5, wherein the weight percentage of the at least one monomer, reactive oligomer, or combination thereof in the mixture is individually about 0.5 to about 25% (w/w) based on the total weight of the mixture.

7. The method of any one of claims 1 to 6, wherein the solvent comprises water, an alcohol, an ester, a ketone, a dipolar aprotic solvent, or a combination thereof.

8. The method of claim 7, wherein the solvent further comprises an inorganic acid, an organic acid, an inorganic base, a water-soluble metal salt, or an organic base.

9. The method of any one of claims 1 to 8, wherein the method further comprises subjecting the cold-sintered ceramic-polymer composite to a post-curing or finishing step.

10. The method of any one of claims 1 to 9, wherein the polymerization is polycondensation, ring opening polymerization, free radical polymerization, or thermal polymerization.

11. The method according to any one of claims 1 to 10, wherein the polymer is at least one selected from the group consisting of polyimide, polyamide, polyester, polyurethane, polysulfone, polyketone, polyoxymethylene, polycarbonate, polyether.

12. The method of any one of claims 1 to 11, wherein the monomer or reactive oligomer is at least one selected from the group consisting of an epoxide, a cyclic phosphazene, a cyclic phosphite, a cyclic phosphonate, a cyclic organosiloxane, a lactam, a lactone, a cyclic carbonate oligomer, and a cyclic ester oligomer.

13. The method according to any one of claims 1 to 11, wherein the monomer or reactive oligomer is at least one selected from the group consisting of styrene, styrene derivatives, 4-vinylpyridine, N-vinylpyrrolidone, acrylonitrile, vinyl acetate, alkyl olefins, vinyl ethers, vinyl acetate, cycloolefins, maleimides, alicyclics, olefins, and alkynes.

14. The method of any one of claims 1 to 13, wherein the polymer is at least one selected from the group consisting of branched polymers, polymer blends, copolymers, random copolymers, block copolymers, crosslinked polymers, blends of crosslinked polymers with non-crosslinked polymers, macrocycles, supramolecular structures, polymeric ionomers, dynamically crosslinked polymers, and sol-gels.

15. The method of any one of claims 1 to 14, wherein the mixture further comprises one or more of a polymerization catalyst promoter, a polymerization catalyst inhibitor, a polymerization co-catalyst, a photoinitiator in combination with a light source, a phase transfer catalyst, and a chain transfer agent.

16. The method of claim 15, wherein a polymerization catalyst, a polymerization catalyst promoter, a polymerization catalyst inhibitor, a photoinitiator, or a polymerization co-catalyst is dissolved or suspended in the solvent.

17. The method of any one of claims 15 or 16, wherein a polymerization catalyst is coated on at least a portion of the inorganic compound particles.

18. The method of any one of claims 1 to 4, wherein the inorganic compound or cold-sintered ceramic is a polymerization catalyst.

19. The method of any one of claims 15 to 18, wherein the polymerization catalyst is an encapsulated catalyst.

20. The method of any one of claims 1 to 19, wherein the method further comprises one or more steps selected from injection molding, high pressure processing, and calendering.

21. The method of claim 2, wherein the injecting is injecting the at least one monomer, reactive oligomer, or combination thereof in a liquid state into the cold-sintered ceramic.

22. The method of claim 2, wherein the injecting is injecting a solution or suspension comprising the at least one monomer, reactive oligomer, or combination thereof and an injection solvent into the cold-sintered ceramic.

23. The method of any one of claims 1 to 22, wherein the cold-sintered ceramic-polymer composite has a relative density of at least 90%.

24. The method of any one of claims 1 to 23, wherein the cold-sintered ceramic-polymer composite has a relative density of at least 95%.

Background

Many ceramics and composites are sintered to reduce porosity and enhance material properties such as strength, electrical conductivity, translucency and thermal conductivity. The sintering process involves the application of high temperatures (typically above 1,000 ℃) to densify and improve the properties of the material. However, the use of high sintering temperatures precludes the manufacture of certain types of materials and increases the cost of manufacturing the materials.

Certain low temperature methods for sintering ceramics may address some of the challenges associated with high temperature sintering. For example, ultra-low temperature co-fired ceramics (ULTCC) can be fired between 450 ℃ and 750 ℃. See, e.g., He et al, "Low-temperature sintering Li₂MoO₄/Ni_0.5Zn_0.5Fe₂O₄Magneto-Dielectric Composites for High-Frequency Application, "J.am.Ceram.Soc.2014: 97 (8: 1-5). Furthermore, by wetting water-soluble Li₂MoO₄The powder, compacting it and post-treating the resulting sample at 120 ℃ can improve Li₂MoO₄The dielectric characteristics of (1). See Kahari et al, J.am.Ceram.Soc.2015:98(3): 687-689. Even so, when Li₂MoO₄When the particle size of the powder is less than 180 microns, Kahari teaches that a smaller particle size complicates uniform wetting of the powder, thereby creating clayey clusters, density non-uniformities, warping, and cracking, and ultimately concludes that a large particle size is advantageous.

Disclosure of Invention

These and other challenges are addressed by the present invention as follows: a Cold Sintering Process (CSP) is provided in combination with the polymerization of monomers and oligomers to produce a cold sintered ceramic polymer composite. The method enables the production of a wide variety of ceramic polymer composites by a sintering step that occurs at low temperature and moderate pressure.

Accordingly, in one embodiment, the present invention provides a method of making a cold-sintered ceramic-polymer composite comprising:

a. combining at least one inorganic compound in the form of particles having a number average particle size of less than about 30 μm with at least one monomer, reactive oligomer, reactive polymer, or combination thereof and a solvent in which the inorganic compound is at least partially soluble to obtain a mixture;

b. subjecting the mixture to polymerization conditions to obtain a pre-ceramic polymer mixture comprising the polymer of the at least one monomer, reactive oligomer, reactive polymer, or combination thereof, the particulate inorganic compound, and the solvent; and

c. exposing the pre-ceramic polymer mixture to a pressure of no greater than about 5000MPa and a temperature less than about 200 ℃ above the boiling point of the solvent to obtain the cold-sintered ceramic-polymer composite.

Another embodiment is a method of making a cold-sintered ceramic-polymer composite comprising:

a. combining at least one inorganic compound in the form of particles having a number average particle diameter of less than about 30 μm with a solvent in which the inorganic compound is at least partially soluble to obtain a mixture;

b. subjecting the mixture to a pressure of no more than about 5000MPa and a temperature below 200 ℃ above the boiling point of the solvent to obtain a cold-sintered ceramic;

c. injecting at least one monomer, reactive oligomer, reactive polymer, or combination thereof into the cold-sintered ceramic to obtain a cold-sintered ceramic pre-polymer mixture comprising the cold-sintered ceramic and the at least one monomer, reactive oligomer, reactive polymer, or combination thereof to be polymerized into a polymer; and

d. subjecting the cold-sintered ceramic pre-polymer mixture to polymerization conditions to obtain the cold-sintered ceramic polymer composite.

In another embodiment, the present invention provides a method of making a cold-sintered ceramic-polymer composite comprising:

a. combining at least one inorganic compound in the form of particles having a number average particle size of less than about 30 μm with at least one monomer, reactive oligomer, reactive polymer, or combination thereof and a solvent in which the inorganic compound is at least partially soluble to obtain a mixture;

b. subjecting the mixture to a pressure of no more than about 5000MPa and a temperature less than 200 ℃ above the boiling point of the solvent to obtain a cold-sintered ceramic prepolymer mixture comprising a cold-sintered ceramic and at least one monomer, reactive oligomer, reactive polymer, or combination thereof to be polymerized into a polymer; and

c. subjecting the cold-sintered ceramic prepolymer mixture to polymerization conditions and forming a cold-sintered ceramic polymer composite.

A further embodiment of the invention is a method of making a cold-sintered ceramic-polymer composite comprising:

a. combining at least one inorganic compound in the form of particles having a number average particle size of less than about 30 μm with at least one monomer, reactive oligomer, reactive polymer, or combination thereof and a solvent in which the inorganic compound is at least partially soluble to obtain a mixture; and

b. subjecting the mixture to a pressure of no more than about 5000MPa and a temperature less than 200 ℃ above the boiling point of the solvent, whereby the at least one monomer, reactive oligomer, reactive polymer or combination polymerizes into a polymer to obtain a cold-sintered ceramic-polymer composite.

Detailed Description

Throughout this document, values that are expressed as ranges are to be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the ranges, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of "about 0.1% to about 5%" or "about 0.1% to 5%" should be interpreted to include not only about 0.1% to about 5%, but also include individual values (e.g., 1%, 2%, 3%, and 4%) and sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. Unless otherwise indicated, the statement "about X to Y" has the same meaning as "about X to about Y". Likewise, unless otherwise specified, the statement "about X, Y or about Z" has the same meaning as "about X, about Y, or about Z".

In this document, the terms "a", "an" or "the" are used to include one or more than one unless the context clearly dictates otherwise. The term "or" is used to mean a non-exclusive "or" unless otherwise stated. The statement "at least one of a and B" has the same meaning as "A, B or a and B". Also, it is to be understood that the phraseology or terminology employed herein (and not otherwise defined) is for the purpose of description only and not of limitation. Any use of section headings is intended to aid in reading documents and should not be construed as limiting; information related to the chapter title may appear inside or outside of that particular chapter.

In the methods described herein, acts may be performed in any order, unless otherwise indicated herein, without departing from the principles of the invention. Further, unless explicitly recited in a claim language, unless specified actions are performed separately, they may be performed concurrently. For example, the claimed act of doing X and the claimed act of doing Y may be performed simultaneously in a single operation, and the resulting process would fall within the literal scope of the claimed method.

The term "about" as used herein may allow for a degree of variability in a value or range, for example, within 10%, 5%, or 1% of a stated value or a stated range limit, and including an exact stated value or range. The term "substantially" as used herein refers to a majority or majority, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%.

The present invention generally provides a Cold Sintering Process (CSP) to obtain a Cold sintered ceramic polymer composite. The low temperature achieved by CSP allows the incorporation of organic molecules into the ceramic through the polymerization of monomers and/or oligomers, which are generally unable to withstand the high temperatures required in conventional sintering processes.

One advantage of the present invention is the use of small organic molecules, such as monomers, oligomers, and reactive polymers, because they are well dispersed in the ceramic matrix to produce a polymer that is highly dispersed within the sintered ceramic structure after polymerization. Another advantage of the present invention is that monomers and oligomers are utilized to better "wet out" the ceramic material relative to larger polymers, thereby creating strong interfacial interactions between the sintered ceramic and the polymer formed therein. Thus, a well-dispersed polymer within a ceramic with improved interaction between the ceramic and the polymer results in enhanced fracture toughness, improved tribological properties, better scratch performance, better thermal conductivity, and better electrical properties.

The cold sintering process of the present invention summarized above combines the sintering of inorganic compounds and the in situ polymerization of monomers and/or oligomers in various steps and sequences to produce cold sintered ceramic polymer composites. Sintering is the process by which a material forms a dense solid, typically by applying a combination of heat and pressure to the material. The sintering process described herein also achieves densification of the inorganic compounds, as with high temperature sintering, but by partially dissolving the compounds in a solvent and applying only modest amounts of heat, e.g., about 200 ℃ above the boiling point of the solvent.

Inorganic compound

Various embodiments of the methods described herein use at least one inorganic compound in particulate form. Useful inorganic compounds include, but are not limited to, metal oxides, metal carbonates, metal sulfates, metal sulfides, metal selenides, metal tellurides, metal arsenides, metal alkoxides, metal carbides, metal nitrides, metal halides (e.g., fluorides, bromides, chlorides, and iodides), clays, ceramic glasses, metals, and combinations thereof. Specific examples of the inorganic compound include MoO₃、WO₃、V₂O₃、V₂O₅、ZnO、Bi₂O₃、CsBr、Li₂CO₃、CsSO₄、Li₂MoO₄、Na₂Mo₂O₇、K₂Mo₂O₇、ZnMoO₄、Gd₂(MoO₄)₃、Li₂WO₄、Na₂WO₄、LiVO₃、BiVO₄、AgVO₃、Na₂ZrO₃、LiFePO₄And KH₂PO₄. In other embodiments, the precursor metal salt may be used in solution to assist or otherwise facilitate the cold sintering process. For example, water soluble zinc (II) salts such as zinc chloride and zinc acetate deposit water insoluble ZnO on existing inorganic surfaces. In this way, the precipitation of ZnO from the precursor solution thermodynamically favors the progress of the cold sintering process.

In some embodiments, the present methods use mixtures of inorganic compounds that react with each other upon sintering to provide sintered ceramic materials (solid state reaction sintering). One advantage of this approach is thatRelying on relatively inexpensive inorganic compound starting materials. Other advantages of the Solid State Reaction Sintering (SSRS) method include: the proton conducting ceramic (proton conducting ceramics) manufacturing process is simplified by integrating phase formation, densification and grain growth into one sintering step. See S.Nikodemski et al, Solid State Ionics 253(2013) 201-210. An example of a reactive inorganic compound relates to Cu₂S and In₂S₃To produce stoichiometric CuInS₂. See T.Miyauchi et al, Japanese Journal of Applied Physics, vol.27, Part 2, No.7, L1178. Another example is the addition of NiO to Y₂O₃、ZrO₂And BaCO₃To produce BaY after sintering₂NiO₅. See J.Tong, J.Mater.chem.20(2010) 6333-6341.

The inorganic compound is present in particulate form, for example as a fine powder. Any conventional method for preparing an inorganic compound in particulate form is suitable. For example, the particles may be produced by various grinding methods, such as ball milling, grinding milling (attrition milling), vibratory milling, and jet milling.

The particle size (i.e., diameter) of the resulting inorganic compound is about 100 μm or less based on the particle number average. In various embodiments, the number average particle size is less than about 90 μm, less than about 80 μm, less than about 70 μm, less than about 60 μm, less than about 50 μm, less than about 40 μm, less than about 30 μm, less than about 20 μm, or less than about 10 μm. Any suitable method may be used to measure particle size and distribution, such as laser light scattering. In illustrative embodiments, at least 80%, at least 85%, at least 90%, or at least 95% by number of the particles have a size less than the number average particle size.

According to some embodiments of the invention, the inorganic compound is combined with a solvent to obtain a mixture. In other embodiments, the inorganic compound is combined with a solvent and at least one monomer, reactive oligomer, reactive polymer, or combination thereof to obtain a mixture. In these embodiments, the inorganic compound is present in an amount of about 50 to about 99.5 wt%, based on the total weight of the mixture. Exemplary weight percentages of the inorganic compound in the mixture are about 50% to about 99.5%, about 50% to about 95%, and about 80% to about 99%. Other examples of weight percentages are at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, and at least 90%.

Solvent(s)

The process of the invention employs at least one solvent in which the inorganic compound has at least partial solubility. Useful solvents include water, alcohols such as C_1-6Alkyl alcohols, esters, ketones, dipolar aprotic solvents (e.g. dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP) and Dimethylformamide (DMF)) and combinations thereof. In some embodiments, only a single solvent is used. In other embodiments, a mixture of two or more solvents is used.

In still other embodiments, an aqueous solvent system is provided to which one or more additional components are added to adjust the pH. The components include inorganic and organic acids and organic and inorganic bases.

Examples of inorganic acids include sulfurous acid, sulfuric acid, hyposulfurous acid (hyposulfurous acid), persulfuric acid, pyrosulfuric acid, disulfuric acid (disulfurous acid), dithionic acid (dithionous acid), tetrathionic acid (tetrathionic acid), thiosulfurous acid, hydrosulfuric acid, peroxodisulfuric acid, perchloric acid, hydrochloric acid, hypochlorous acid, chlorous acid, hyponitric acid (hyponitrous acid), nitrous acid, nitric acid, peroxynitric acid, nitrous acid, carbonic acid, hypochlorous acid, peroxycarbonic acid, oxalic acid, acetic acid, phosphoric acid, phosphorous acid, hypophosphorous acid, perphosphoric acid, hypophosphorous acid (hypophosphoric acid), pyrophosphoric acid, hydrogenphosphoric acid (hydrobromic acid), hydrobromic acid, bromic acid, hypobromic acid, hypoiodic acid, iodic acid, periodic acid, hydroiodic acid, hypofluoric acid, chromic acid, and sulfuric acid, Selenious acid, hydrocyanic acid, boric acid, molybdic acid, xenon acid (perxenic acid), silicofluoric acid, telluric acid, tellurite acid, tungstic acid, xenon acid (xenic acid), citric acid, formic acid, pyroantimonic acid, permanganic acid, manganic acid, antimonic acid, antimonous acid, silicic acid, titanic acid, arsenic acid, pertechnetic acid, hydrogen arsenic acid, dichromic acid, tetraboric acid, metastannic acid, hypoxonic acid (hypooxalous acid), ferricyanic acid, cyanic acid, metasilicic acid, hydrocyanic acid, thiocyanic acid, uranic acid, and diurenic acid.

Examples of organic acids include malic acid, citric acid, tartaric acid, glutamic acid, phthalic acid, azelaic acid, barbituric acid, benzilic acid (benzilic acid), cinnamic acid, fumaric acid, glutaric acid, gluconic acid, caproic acid, lactic acid, maleic acid, oleic acid, folic acid, propiolic acid, propionic acid, rhodizonic acid, stearic acid, tannic acid, trifluoroacetic acid, uric acid, ascorbic acid, gallic acid, acetylsalicylic acid, acetic acid, and sulfonic acids such as p-toluenesulfonic acid.

Examples of the inorganic base include aluminum hydroxide, ammonium hydroxide, arsenic hydroxide, barium hydroxide, beryllium hydroxide, bismuth (iii) hydroxide, boron hydroxide, cadmium hydroxide, calcium hydroxide, cerium (iii) hydroxide, cesium hydroxide, chromium (ii) hydroxide, chromium (iii) hydroxide, chromium (v) hydroxide, chromium (vi) hydroxide, cobalt (ii) hydroxide, cobalt (iii) hydroxide, copper (i) hydroxide, copper (ii) hydroxide, gallium (iii) hydroxide, gold (i) hydroxide, gold (iii) hydroxide, indium (i) hydroxide, indium (ii) hydroxide, indium (iii) hydroxide, iridium (iii) hydroxide, iron (ii) hydroxide, iron (iii) hydroxide, lanthanum hydroxide, lead (ii) hydroxide, lead (iv) hydroxide, lithium hydroxide, magnesium hydroxide, manganese (ii) hydroxide, manganese (vii) hydroxide, Mercury (i) hydroxide, mercury (ii) hydroxide, molybdenum (ii) hydroxide, neodymium (ii) hydroxide, nickel oxyhydroxide, nickel (ii) hydroxide, nickel (iii) hydroxide, niobium (hi) hydroxide, osmium (iv) hydroxide, palladium (ii) hydroxide, palladium (iv) hydroxide, platinum (ii) hydroxide, platinum (iv) hydroxide, plutonium (iv) hydroxide, potassium hydroxide, radium hydroxide, rubidium hydroxide, ruthenium (iii) hydroxide, scandium hydroxide, silicon hydroxide, silver hydroxide, sodium hydroxide, strontium hydroxide, tantalum (v) hydroxide, technetium (ii) hydroxide, tetramethylammonium hydroxide, thallium (i) hydroxide, thallium (iii) hydroxide, thorium hydroxide, tin (ii) hydroxide, tin (iv) hydroxide, titanium (ii) hydroxide, titanium (iii) hydroxide, titanium (iv) hydroxide, tungsten (ii) hydroxide, uranium (ii) hydroxide, vanadium (iii) hydroxide, Vanadium (v) hydroxide, ytterbium hydroxide, yttrium hydroxide, zinc hydroxide, and zirconium hydroxide.

Organic bases are generally nitrogen-containing because they can accept protons in aqueous media. Exemplary organic bases include primary, secondary and tertiary (C)_1-10) Alkylamines, such as methylamine, trimethylamine, etc. Other examples are (C)_6-10) Aryl amines and (C)_1-10) -alkyl- (C)_6-10) -aryl-amines. Other organic bases incorporate nitrogen into cyclic structures, such as in monocyclic and bicyclic heterocyclic and heteroaryl compounds. These include, for example, pyridine, imidazole, benzimidazole, histidine and phosphazenes.

In some of the methods described herein, an inorganic compound is combined with a solvent to obtain a mixture. According to various embodiments, the solvent is present in an amount of about 40 wt% or less, based on the total weight of the mixture. Alternatively, the weight percent of solvent in the mixture is 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, 5% or less, 3% or less, or 1% or less.

Monomers, oligomers, polymerization processes and polymers

The various steps of the methods described herein incorporate at least one monomer, reactive oligomer, or combination thereof for polymerization, ultimately resulting in a cold-sintered ceramic-polymer composite. The inorganic compound may be cold sintered alone or co-sintered with one or more monomers and/or reactive oligomers, as described herein.

According to some embodiments of the method of the present invention, the monomer, reactive oligomer, or combination thereof is injected into the cold-sintered ceramic in a liquid state. The injection (infusing) may occur passively, for example by immersion. If the monomer or cold-sintered ceramic oligomer is not a liquid at room temperature, heat may be applied to create a melt of the monomer or oligomer, which may then be injected.

Alternatively, the injection may comprise a more positive means, for example by injecting a monomer or oligomer in liquid form into the cold-sintered ceramic. In other embodiments, optionally in combination with any of the embodiments described herein, the monomer, reactive oligomer, reactive polymer, or combination thereof is combined with an injection solvent, which is any suitable solvent described herein. The resulting solution (fully dissolved) or suspension (partially dissolved) can then be poured into the cold-sintered ceramic.

According to various embodiments, the monomer, reactive oligomer, or combination thereof is present in the mixture or cold-sintered ceramic prepolymer mixture in an amount of from about 1% to about 70% (w/w), based on the total weight of the mixture or cold-sintered ceramic prepolymer mixture. Illustrative weight percentages also include about 0.2% to about 40%, about 0.5% to about 25%, about 3% to about 65%, about 5% to about 60%, about 5% to about 50%, about 10% to about 55%, about 15% to about 50%, and about 20% to about 45% based on the total weight of the mixture or cold-sintered ceramic prepolymer mixture.

The methods described herein are not limited to a particular class of monomers. Indeed, various monomers are well known to those skilled in the art of polymers. In general, the monomers can be selected based on a variety of factors, such as compatible polymerization methods, reactivity, properties of the resulting polymers, copolymers, polymer blends, and the like, as can the corresponding reactive oligomers prepared therefrom. Described below for illustrative guidance are various monomers and suitable methods for polymerizing them for use in the process of the invention.

Ring opening polymerization

Ring-opening polymerization processes are advantageous because they can produce polymers that typically have low melt viscosities. The polymer is also readily soluble in organic solvents, combinations of organic solvents and water, and sometimes even water alone. Exemplary cyclic monomers for use in the ring-opening polymerization according to the methods described herein include cyclic ethers, cyclic amines, lactones, lactams, cyclic thioethers, cyclic siloxanes, cyclic phosphites and phosphonites, cyclic imino ethers, cyclic olefins, cyclic carbonates, and cyclic esters. Other examples of cyclic monomers and oligomers include epoxides, cyclic phosphazenes, cyclic phosphonates, cyclic organosiloxanes, cyclic carbonate oligomers, and cyclic ester oligomers. Additional illustrative monomers are cyclic monomers bearing functional groups such as formaldehyde (formals), thioaldehyde (thioformals), sulfides, disulfides, anhydrides, thiolactones, ureas, imides, and bicyclic monomers. Further examples of suitable cyclic monomers for forming polymers in the presence of ceramic materials can be found in Encyclopedia of Polymer science and Engineering, second edition, Vol.14, pp.622-647, John Wiley and Sons (1988).

Further examples of ring systems which can be used in the process of the present invention are aromatic macrocyclic aromatic carbonate oligomers and macrocyclic polyalkylene carboxylate oligomers. When polymerized, these oligomers produce aromatic polycarbonates and polyesters. Representative cyclic compositions, methods of forming these cyclic systems, and polymerization conditions for producing high molecular weight polycarbonates and polyesters therefrom can be found, for example, in U.S. Pat. Nos. 4,644,053 and 5,466,744.

Many cyclic monomers and oligomers are liquids at standard temperature and pressure, while others are low temperature melting solids, producing low viscosity liquids under the same conditions. In these cases, according to various embodiments, such cyclic monomers and oligomers may be used in the processes described herein in a pure form, i.e., without dilution with a solvent. The molecular weight of the polymer produced from these monomers can vary widely depending on the polymerization conditions (e.g., catalyst loading and the presence and concentration of any chain terminating agent).

The polymerizability and polymerization rate of the cyclic monomer can be influenced by the ring size and the substituents on the ring. Generally, smaller ring sizes of three to five ring members or other strained rings typically have high heat of polymerization due to ring strain and other factors. By entropy contribution, larger rings can generally be polymerized even with low heat of polymerization.

Free radical polymerization

In various embodiments, the present invention provides a free radical polymerization process that can be used in conjunction with the cold sintering processes described herein. Many monomers suitable for this purpose contain unsaturated homonuclear or heteronuclear double bonds, dienes, trienes and/or strained cycloaliphatics. Examples of monomers for free radical polymerization include acrylic acid, acrylamide, acrylic esters, esters of acrylic and methacrylic acids (e.g., n-butyl acrylate, 2-hydroxyethyl methacrylate), amides of acrylic and methacrylic acids (e.g., n-isopropylacrylamide), acrylonitrile, methyl methacrylate, (meth) acrylic esters of polyhydric alcohols (e.g., ethylene glycol, trimethylolpropane), styrene derivatives (e.g., 1, 4-divinylbenzene, p-vinylbenzyl chloride, and p-acetoxystyrene), 4-vinylpyridine, n-vinylpyrrolidone, vinyl acetate, vinyl chloride, vinyl fluoride, vinylidene fluoride, ethylene, propylene, butadiene, chloroprene, and vinyl ethers.

Illustrative initiators for this purpose include azo initiators (e.g., dialkyldiazenes, AIBN), peroxides (e.g., dicumyl peroxide, persulfate, and ethyl methyl ketone peroxide), diphenyl compounds, photoinitiators (e.g., α -hydroxy ketones, α -amino ketones, acyl phosphine oxides, oxime esters, benzophenones, and thioxanthones), and silylated benzopinacols₂) Can be photo-induced and thereby generate free radicals for in situ polymerization.

Thermal polymerization

Thermal polymerization processes may be used in the process of the present invention. Monomers which can be polymerized on heating are those which generally have one or more triple carbon-carbon bonds (e.g. ethynyl and propargyl) and/or heteroatom unsaturation, such as isocyanates, cyanates and nitriles. In some embodiments, the rate of polymerization and thus the ultimate formation of the polymer composite may be controlled by the addition of polymerization accelerators containing di-, tri-or polyfunctional reactive groups (e.g., alkynyl groups).

Alternatively, the ring may be opened by exposing a cyclic strained aliphatic monomer (e.g., a hydrocarbon) to sufficient external and capillary pressure. In addition or alternatively, the polymerization of the monomers may be catalyzed by the particulate inorganic compound or by cold sintering the ceramic. In some embodiments, the polymerization initiation temperature is higher than the temperature used in the cold sintering step; in these embodiments, applying greater external pressure can substantially reduce the desired polymerization initiation temperature.

Examples of monomers used for thermal polymerization include cyanates, benzocyclobutenes, alkynes, phthalonitriles, nitriles, maleimides, diphenylenes, benzoxazines, norbornenes, cyclic aliphatic, bridged cyclic hydrocarbons, and cyclooctadienes.

Reactive oligomer

Many of the monomers described herein can be oligomerized to oligomers for use in the process of the present invention, optionally in combination with (co) polymerization with other monomers and/or oligomers. Therefore, the oligomer must be reactive.

The term "reactive oligomer" as used herein is an oligomer carrying one or more chemical moieties capable of participating in a polymerization reaction by which it is incorporated into the final polymer. According to a generally accepted definition in the art, an oligomer is not a polymer, but rather a molecule of intermediate relative molecular mass whose structure essentially comprises a small number of units derived, actually or conceptually, from monomer molecules of lower relative molecular mass. In this case, an oligomer is a molecule of moderate relative molecular mass if it exhibits properties that vary significantly with the removal of one or more monomeric units, as compared to a polymer. See IUPAC, Complex of Chemical terminologies, 2 nd edition ("GoldWood"), written by A.D. McNaught and A.Wilkinson, Blackwell Scientific Publications, Oxford (1997).

Reactive polymer

Many of the monomers described herein can be polymerized to low molecular weight polymers, which are then used in the process of the present invention, optionally in combination with (co) polymerization with other monomers and/or oligomers. Thus, the polymers used in this context are reactive.

The term "reactive polymer" as used herein is a polymer carrying one or more chemical moieties capable of participating in a further polymerization reaction by which a first molecular weight of said reactive polymer is incorporated into a second and higher molecular weight final polymer. In other words, the reactive polymer is a molecule having a lower relative molecular mass than the polymer that produces the cold-sintered ceramic polymer composite of the present invention. According to one embodiment, an example of a reactive polymer is polybutyl acrylate (see experimental example 1). Other non-limiting examples include polyacrylonitrile, poly (vinyl cinnamate), and poly (maleic anhydride).

Polymer and method of making same

A variety of polymers can be produced from the polymerization of monomers, prepolymers, and combinations thereof as described herein. Examples of polymeric structures contemplated for use in the manufacture and use in the methods of the present invention include linear and branched polymers, copolymers such as random and block copolymers, and crosslinked polymers. Polymer blends, blends of copolymers, blends of crosslinked polymers (i.e., interpenetrating networks), and blends of crosslinked polymers with non-crosslinked polymers are also contemplated.

Exemplary polymer classes include polyimides, polyamides, polyesters, polyurethanes, polysulfones, polyketones, polyoxymethylenes, polycarbonates, and polyethers. Other classes and specific polymers include Acrylonitrile Butadiene Styrene (ABS) polymers, acrylic polymers, celluloid polymers, cellulose acetate polymers, Cyclic Olefin Copolymers (COC), ethylene-vinyl acetate (EVA) polymers, ethylene-vinyl alcohol (EVOH) polymers, fluoroplastics, acrylic/PVC alloys, Liquid Crystal Polymers (LCP), polyacetal polymers (POM or acetal), polyacrylate polymers, polymethyl methacrylate Polymers (PMMA), polyacrylonitrile polymers (PAN or acrylonitrile), polyamide polymers (PA, such as nylon), polyamide-imide Polymers (PAI), polyaryletherketone Polymers (PAEK), polybutadiene Polymers (PBD), polybutylene Polymers (PB), polybutylene terephthalate Polymers (PBT), polycaprolactone Polymers (PCL), poly (vinyl acetate) copolymers, poly (vinyl alcohol) (COC), poly (vinyl acetate) copolymers, poly (vinyl alcohol) (EVA), poly (vinyl alcohol) (PAE) copolymers, poly (meth) copolymers, poly, Polychlorotrifluoroethylene Polymer (PCTFE), polytetrafluoroethylene Polymer (PTFE), polyethylene terephthalate Polymer (PET), polycyclohexylenedimethylene terephthalate Polymer (PCT), polycarbonate Polymer (PC), poly (1, 4-cyclohexylidene cyclohexane-1, 4-dicarboxylate) (PCCD), polyhydroxyalkanoate Polymer (PHA), polyketone Polymer (PK), polyester polymer, polyethylene Polymer (PE), polyetheretherketone Polymer (PEEK), polyetherketoneketone Polymer (PEKK), polyetherketoneketone Polymer (PEK), polyetherimide Polymer (PEI), polyethersulfone Polymer (PEs), polyvinyl chloride Polymer (PEC), polyimide Polymer (PI), polylactic acid Polymer (PLA), polymethylpentene polymer (PMP), polyphenylene oxide polymer (PPO), polyphenylene sulfide polymer (PPS), Polyphthalamide Polymer (PPA), polypropylene polymer, polystyrene Polymer (PS), polysulfone Polymer (PSU), polytrimethylene terephthalate Polymer (PTT), polyurethane Polymer (PU), polyvinyl acetate Polymer (PVA), polyvinyl chloride Polymer (PVC), polyvinylidene chloride Polymer (PVDC), polyamideimide Polymer (PAI), polyarylate polymer, polyoxymethylene Polymer (POM), styrene-acrylonitrile polymer (SAN), Polycarbonate (PC), Acrylonitrile Butadiene Styrene (ABS), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), Polyetherimide (PEI), poly (p-phenylene oxide) (PPO), Polyamide (PA), polyphenylene sulfide (PPS), Polyethylene (PE) (e.g., Ultra High Molecular Weight Polyethylene (UHMWPE), Ultra Low Molecular Weight Polyethylene (ULMWPE), High Molecular Weight Polyethylene (HMWPE), High Density Polyethylene (HDPE), high density crosslinked polyethylene (HDXLPE), crosslinked polyethylene (PEX or XLPE), Medium Density Polyethylene (MDPE), Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE) and Very Low Density Polyethylene (VLDPE)), polypropylene (PP) and combinations thereof.

Other useful polymers are ionic polymers or oligomers ("ionomers"). The key feature of ionomers is the relatively modest concentration of acid or ionic groups bound to the oligomer/polymer backbone, which results in substantial changes in the physical, mechanical, optical, dielectric, and dynamic properties of the polymer, and thus the cold-sintered ceramic-polymer composite. For example, polymers with acid functionality can undergo interchain and physical crosslinking through hydrogen bonding between acid groups. Illustrative oligomers include sulfonated oligomers. Furthermore, fatty acids or tetraalkylammonium salts can be introduced by the method of the invention to facilitate additional ionic interactions.

Additional Components

Various embodiments of the method of the present invention contemplate the introduction of one or more additional materials into the mixture for cold sintering or into the cold sintered ceramic. Any combination of these materials may make the cold-sintered ceramic polymer composite easy to manufacture and/or easy to tailor the composition and properties of the cold-sintered ceramic polymer composite.

Supramolecular structures

For example, some embodiments provide for the addition of supramolecular structures, which are generally characterized by the assembly of substructures held together by weak interactions (e.g., non-covalent bonds may be used). At the temperatures used for cold sintering, the interaction may be attenuated, thereby releasing substructure molecules that may flow through or into newly created pores of the particulate inorganic compound or cold sintered ceramic. After cooling, the sub-structural molecules can re-assemble into supramolecular structures, which are embedded in cold-sintered ceramics or cold-sintered ceramic prepolymer mixtures. Typical compounds suitable for this purpose are hydrogen bonding molecules, which may have, for example, single, double, triple or quadruple hydrogen bonds. Other structures take advantage of host-guest interactions and in this way create supramolecular (polymer) structures.

Examples of supramolecular structures include macrocycles such as cyclodextrins, calixarenes, cucurbiturils and crown ethers (host-guest interactions based on weak interactions); amide or carboxylic acid dimers, trimers or tetramers such as 2-ureido-4 [1H ] -pyrimidinone (via hydrogen bonds), bipyridine or tripyridine (via complexation with metals) and various aromatic molecules (via pi-pi interactions).

Sol-gel

Other embodiments provide for the introduction of sol-gel into the mixture of cold-sintered ceramics. The sol-gel process consists of a series of hydrolysis and condensation reactions of metal alkoxides, and in some cases also alkoxysilanes. Hydrolysis is initiated by adding water to the alkoxide or silane solution under acidic, neutral or basic conditions. Thus, by adding a small amount of water to the metal alkoxide, a polymer nanocomposite can be obtained. Examples of compounds that can be used to prepare the sol-gel include silicon alkoxides such as tetraalkyl orthosilicates (e.g., tetraethyl orthosilicate), silsesquioxanes, and phenyltriethoxysilane.

Polymerization assistant

In various embodiments, optionally in combination with any other embodiments, the polymerization step in the process of the present invention may include one or more components for promoting or regulating the polymerization reaction. For example, non-limiting examples well known to those skilled in the polymer art include polymerization catalysts and catalyst promoters, polymerization catalyst inhibitors, polymerization co-catalysts, combinations of photoinitiators and light sources, phase transfer catalysts, chain transfer agents, and polymerization accelerators. In some embodiments, these components are incorporated into the mixture without dilution or dissolution. In other embodiments, the components are partially or completely dissolved in the solvent used in the method of the present invention. Alternatively, the components may be coated onto the inorganic compound particles, for example by first dissolving the components in a suitable solvent, contacting the resulting solution with the particles, and allowing (or allowing) the solvent to evaporate, thereby obtaining coated particles. According to other embodiments, the inorganic compound particles are first cold sintered, and the resulting cold sintered ceramic may be coated with one or more of the components.

According to some embodiments, the methods described herein do not include a polymerization catalyst. For example, inorganic compounds or the resulting cold-sintered ceramics are used as polymerization catalysts, obviating the need for the use of added catalysts. In other embodiments, the acid or base mixed with the solvent promotes polymerization, for example by initiation, without the addition of a polymerization catalyst.

In some embodiments, one or more of the above components are encapsulated. For example, the polymerization catalyst may be an encapsulated catalyst. The use of an encapsulated catalyst allows for the use of higher molecular reactants and the use of heat during cold sintering without the need to pre-cure the reactants. For example, encapsulated catalysts prevent premature reaction of the various reactants during storage and processing, yet produce rapid curing when the capsules are ruptured by a predetermined event (e.g., application of heat, pressure, or solvation). The use of encapsulated catalysts is useful in some embodiments of the invention in which cold sintering and polymerization are performed substantially simultaneously.

Encapsulated catalysts are typically produced by depositing a shell around the catalyst. The catalyst may be contained in a single chamber or reservoir within the capsule, or may be contained in multiple chambers within the capsule. The thickness of the shell can vary significantly depending on the material used, the loading level of the catalyst, the method of forming the capsules, and the intended end use. The loading level of the catalyst is from about 5 to about 90%, from about 10-90%, or from about 30-90%. Some encapsulation processes have a higher core volume loading than others. More than one shell may be required to ensure premature rupture or leakage. Encapsulated catalysts can be prepared by any of a variety of microencapsulation techniques including, but not limited to, coacervation, interfacial addition and condensation, emulsion polymerization, microfluidic polymerization, reverse micelle polymerization, air suspension, centrifugal extrusion, spray drying, pelletizing (casting), and pan coating (coating) (see, e.g., US 2007/017362).

Filler material

According to some embodiments, the cold-sintered ceramic polymer composite may include one or more fillers. The filler is present in an amount of about 0.001 wt% to about 50 wt%, or about 0.01 wt% to about 30 wt%, or about 0.001 wt% or less, or about 0.01 wt%, 0.1, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45 wt%, or about 50 wt% or more of the composite. The filler may be uniformly distributed in the composite material. The filler may be fibrous or particulate. The filler can be aluminum silicate (mullite), synthetic calcium silicate, zirconium silicate, fused silica, crystalline silica graphite, natural silica sand and the like; boron powders such as boron nitride powder, borosilicate powder, and the like; oxides such as TiO₂Alumina, magnesia, and the like; calcium sulfate (as its anhydride, anhydrate or trihydrate); calcium carbonates such as chalk, limestone, marble, synthetic precipitated calcium carbonates, and the like; talc, including fibrous, modular, acicular, lamellar talc and the like; wollastonite; surface treated wollastonite; glass spheres, e.g. hollow and solid glass spheres, silicate spheres, cenospheres (cenospheres), aluminiumSilicates (armosphere), and the like; kaolin, including hard kaolin, soft kaolin, calcined kaolin, kaolin comprising various coatings known in the art to promote compatibility with the polymeric matrix resin, and the like; single crystal fibers or "whiskers" such as silicon carbide, alumina, boron carbide, iron, nickel, copper, and the like; fibers (including continuous and chopped fibers) such as asbestos, carbon fibers, glass fibers; sulfides such as molybdenum sulfide, zinc sulfide, and the like; barium compounds such as barium titanate, barium ferrite, barium sulfate, barite, etc.; metals and metal oxides such as particulate or fibrous aluminum, bronze, zinc, copper and nickel, and the like; flaked fillers such as glass flakes, flaked silicon carbide, aluminum diboride, aluminum flakes, steel flakes, and the like; fibrous fillers, for example short inorganic fibers such as those derived from blends comprising at least one of aluminum silicates, aluminum oxides, magnesium oxides, and calcium sulfate hemihydrate or the like; natural fillers and reinforcements, such as wood flour obtained by pulverizing wood, fibrous products such as kenaf, cellulose, cotton, sisal, jute, flax, starch, corn flour, lignin, ramie, rattan, agave, bamboo, hemp, peanut shells, corn, coconut (coir), rice grain shells, and the like; organic fillers such as polytetrafluoroethylene, reinforcing organic fibrous fillers formed from organic polymers capable of forming fibers such as poly (ether ketone), polyimide, polybenzoxazole, poly (phenylene sulfide), polyesters, polyethylene, aromatic polyamides, aromatic polyimides, polyetherimides, polytetrafluoroethylene, acrylic resins, poly (vinyl alcohol), and the like; and fillers such as mica, clay, feldspar, smoke, fililite, quartz, quartzite, perlite, diatomaceous earth, carbon black, or the like, or a combination comprising at least one of the foregoing fillers. The filler may be talc, kenaf or a combination thereof. The filler may be coated with a layer of metallic material to promote electrical conductivity, or surface treated with silanes, siloxanes, or a combination of silanes and siloxanes to improve adhesion and dispersion within the composite. The filler may be selected from carbon fibers, mineral fillers, and combinations thereof. The filler is selected from mica, talc, clay, wollastonite, zinc sulfide, zinc oxide, carbon fiber, and mixtures thereof,Glass fibers, ceramic coated graphite, titanium dioxide, or combinations thereof.

Cold-sintered ceramic polymer composites

Also contemplated in various embodiments is a cold-sintered ceramic-polymer composite produced by any of the methods described herein. The cold sintering step of the process may result in densification of the inorganic compound. Thus, according to some embodiments, the cold-sintered ceramic-polymer composite or cold-sintered ceramic exhibits a relative density of at least 70%, as determined by mass/geometry ratio, archimedes' method, or equivalent method. The relative density may be at least 75%, 80%, 85%, 90% or 95%.

Briefly, the density of the samples was determined using the Archimedes method using a KERN ABS-N/ABJ-NM balance equipped with an ACS-A03 densitometer. First weigh the dried sample (e.g., pellets) (W)_{Dry matter}) And boiled in 2-propanol for 1 hour. The samples were then suspended in 2-propanol at a known temperature to determine the apparent mass (W) in the liquid_{Suspended in water}) Excess liquid was removed and wiped from the sample surface using a paper towel (tissue) wetted with 2-propanol. The saturated sample (W) was then immediately weighed in air_{Saturation of}). The density was then determined by the following formula:

density of W_{Dry matter}/(W_{Saturation of}-W_{Suspended in water}) Density of solvent

Wherein the density of 2-propanol is 0.786g/cm at 20 deg.C³0.785g/cm at 21 DEG C³And 0.784g/cm at 22 DEG C³。

The geometric method for determining the density, also known as "geometric (volume) method", involves measuring the diameter (D) and thickness (t) of a cylindrical sample using, for example, a digital caliper. Can be represented by the formula V ═ pi (D/2)²x t the volume of the cylinder is calculated. The mass of the cylindrical sample was measured with an analytical balance. The relative density is determined by dividing the mass by the volume.

For simple geometries, such as cubes, cuboids and cylinders, where it is relatively easy to measure the volume, the volume method is comparable to the archimedes method. For samples with highly irregular geometries, accurate measurement of volume may be difficult, in which case archimedes' method may be more suitable for measuring density.

In some embodiments, any of the inventive methods described herein further comprise processing steps that can affect the physical form or geometry of the cold-sintered ceramic-polymer composite, for example. For example, the additional steps may include one or more of injection molding, compression molding, autoclaving, and calendering.

Alternatively or additionally, embodiments provide a post-treatment or post-curing step. For example, the cold-sintered ceramic polymer composite may be subjected to an optionally pre-programmed temperature and/or pressure ramp (ramp), hold, or cycle, wherein the temperature or pressure, or both, is increased or decreased (optionally multiple times) to facilitate completion of the polymerization or crosslinking.