Composite material and method for producing the same

Abstract

To provide a composite material.SOLUTION: A composite material comprises a mixture of a plurality of metal particles and a porous silica particle, where the metal particles are disposed within pores of the porous silica particle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Cross-reference to related patent applications This application claims priority to Singapore Application No. 10201801795R filed on March 5, 2018, the disclosure of which is incorporated herein by reference.

[0002] The present invention relates generally to composite materials, and more particularly to composite materials comprising a mixture of a plurality of metal particles and porous silica particles, the metal particles being disposed within the pores of the porous silica particles. [Background technology]

[0003] The presence of oxygen in packaging is one of the factors that determine the quality of the packaged product. Perishable foods such as fruits and vegetables are sensitive to oxygen and therefore easily deteriorate in its presence. Such deterioration can cause, among other things, loss of vitamin C, rancidity of fats and oils, microbial growth, and discoloration. Therefore, one of the main objectives of food packaging is to protect the packaged food from direct contact with oxygen, thereby preserving the nutritional value of the food and extending the shelf life of the packaged food.

[0004] Efforts have been made to provide packaging with superior barrier properties against the permeation of oxygen molecules. Modified atmosphere and vacuum packaging are widely known methods to reduce the oxygen content in the packaging prior to the sealing process. However, it is noted that the residual oxygen, i.e., oxygen dissolved in the food and / or present in the headspace, cannot be completely removed by the above methods. Moreover, high cost and complicated operations are some of the problems associated with modified atmosphere and vacuum packaging. Therefore, it is highly desirable to develop an effective oxygen scavenger.

[0005] It should be noted that while oxygen scavengers are reported to account for approximately 57% of the world's plastic packaging market, oxygen is one of the main factors contributing to food spoilage. Oxygen scavengers generally function based on an oxidation process. Commonly known oxygen scavengers include iron powder, ascorbic acid, enzymes, unsaturated hydrocarbons, and photosensitive polymers. However, it has been shown that the above-mentioned oxygen scavengers have several limitations. For example, oxygen scavengers of organic and unsaturated hydrocarbons are relatively unstable and tend to release undesirable (unpleasant) odors after the oxidation process. Among the above-mentioned oxygen scavengers, iron-based oxygen scavengers are the most well-known and commercially available due to their high removal efficiency, low cost, and non-toxicity.

[0006] Smaller-sized iron particles tend to exhibit higher removal capabilities compared to their larger-particle counterparts due to the larger amount of reactive surface atoms. Therefore, nano-sized iron particles (or iron nanoparticles) are expected to be applicable as oxygen scavengers. However, such relatively small iron particles are active and tend to be explosive, presenting difficulties in handling such materials, especially during industrial-scale production.

[0007] Accordingly, the present invention provides a composite material used as an oxygen scavenger that overcomes or at least ameliorates one or more of the above-mentioned drawbacks.

Summary of the Invention

[0008] In one aspect, there is provided a composite material comprising a mixture of a plurality of metal particles and porous silica particles, wherein the metal particles are disposed within the pores of the porous silica particles.

[0009] Advantageously, the silica particles can function as a carrier for a plurality of metal particles. The nano-sized channels formed in the porous silica particles function as a carrier and a protective material for the growth of metal particles, thereby increasing the loading of metal particles without aggregation, which is beneficial. Even more advantageously, these formed channels can prevent the explosion of nano-sized metal particles. Therefore, the obtained nanostructured composite material can be easily adopted in industrial production.

[0010] The channels formed within the porous silica particles can advantageously facilitate the diffusion of oxygen into the silica particles, thereby improving the contact between the metal nanoparticles and oxygen molecules. The channels can also control the oxidation rate of the metal particles.

[0011] Even more advantageously, the nanostructured composite material can have a relatively large cavity in the center, and such a relatively large cavity can further improve the contact between oxygen molecules and metal nanoparticles, resulting in a high oxygen removal ability. The nanostructured composite material with a large central cavity can efficiently remove oxygen. The depressions in the nanostructured composite material can further promote the diffusion of oxygen within the particles, strengthen the contact between the metal nanoparticles and oxygen, and exhibit high oxygen removal performance.

[0012] In another aspect, a method for preparing a composite material comprising a mixture of a porous silica particle material for removing oxygen and a plurality of metal particles is provided, the method comprising the following steps: (i) adding porous silica particles to a solution of metal ions while stirring to impregnate the metal ions into the pores of the silica particles; and (ii) reducing the metal ions in the presence of a reducing agent to form metal particles, wherein the metal particles are disposed within the pores of the porous silica particles.

[0013] Advantageously, the composite material can be obtained by a facile method via a one-step emulsion preparation method under mild conditions. Thus, such a process requires a simple production setup and can therefore be considered a low-cost process.

[0014] Even more advantageously, the size and structure of the porous silica particles can be easily adjusted by varying the ratio of the precursors. The size of the channels of the composite material can be substantially uniform along the individual channels of the mesoporous silica particles.

[0015] In another aspect, there is provided a composition comprising a composite material as defined herein and a polymer matrix, wherein the metal particles are disposed within the pores of the porous silica particles.

[0016] In another aspect, there is provided a method for preparing a composition as defined above comprising a composite material and a polymer matrix.

[0017] In another aspect, there is provided an article comprising a composition as defined above comprising a composite material and a polymer matrix.

[0018] In another aspect, there is provided the use of an article as a packaging film for food packaging to improve the oxygen barrier.

[0019] Definitions The following words and terms used in this document have the indicated meanings.

[0020] Unless otherwise specified, the term "mesoporous" as used in this disclosure should be broadly construed to refer to a material containing pores having a diameter between about 2 nm and about 50 nm according to the IUPAC nomenclature.

[0021] The term "microporous" as used herein refers to a material having pores with a diameter less than 2 nm according to the IUPAC nomenclature.

[0022] The term "substantially" does not exclude "completely"; for example, a composition "substantially free of" Y may in some cases be completely free of Y. If desired, "substantially" may be omitted from the definitions of the present invention.

[0023] Unless otherwise specified, the terms "comprising" and "comprise" and their grammatical variations are intended to represent "open" or "inclusive" language that includes the recited elements but also permits the inclusion of additional, unspecified elements.

[0024] As used herein, the term "about" in the context of the concentration of a formulation ingredient typically means + / - 5% of the recited value, more typically + / - 4% of the recited value, more typically + / - 3% of the recited value, more typically + / - 2% of the recited value, even more typically + / - 1% of the recited value, and even more typically + / - 0.5% of the recited value.

[0025] Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the disclosed range. Thus, a range description should be considered to specifically disclose all the possible sub-ranges and the individual numerical values within that range. For example, a description of a range such as from 1 to 6 should be considered to specifically disclose sub-ranges such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., and the individual numerical values within that range, e.g., 1, 2, 3, 4, 5, and 6. This applies regardless of the width of the range.

[0026] Certain embodiments may also be described herein in broad and general terms. Each of the narrower species and sub-groups included in the general disclosure also forms part of the disclosure. This includes general descriptions of embodiments with provisos or negative limitations that exclude any subject matter from the genus, regardless of whether the excised material is specifically recited herein.

[0027] Detailed Disclosure of Embodiments Exemplary, non - limiting embodiments of a composite material comprising a mixture of a plurality of metal particles and porous silica particles are disclosed.

[0028] The present disclosure provides a composite material comprising a mixture of a plurality of metal particles and porous silica particles, wherein the plurality of metal particles are disposed within the pores of the porous silica particles.

[0029] The composite material of the present disclosure can be regarded as a nanostructured composite material. The nanostructured composite material may include cavities. The nanostructured composite material may include cavities in the silica particles. The cavity may be located at the center or core of the silica particle. The cavity can be in contact with the pores of the silica particle such that fluid can be exchanged from the cavity through the pores to the external environment or vice versa.

[0030] The size of the cavity of the silica particle is in the range of about 40 nm to about 80 nm, and can be, for example, about 40 - about 50 nm, about 40 - about 60 nm, about 40 - about 70 nm, about 50 - about 60 nm, about 50 - about 70 nm, about 50 - about 80 nm, about 60 - about 70 nm, about 60 - about 80 nm, or about 70 - about 80 nm. The size of the cavity of the silica particle is preferably about 60 nm. The size of the cavity defined above can refer to the diameter of the cavity when the cross - section of the cavity is substantially circular.

[0031] The metal particles of the composite material defined herein can be metal nanoparticles. The metal element of the metal particles can be a transition metal. Thus, it should be understood that the metal particles of the composite material can be transition metal nanoparticles. The metal element of the metal particles can be selected from Group 8 of the periodic table.

[0032] The metal element of the metal particles can be selected from the group consisting of iron (Fe), ruthenium (Ru), osmium (Os), and hassium (Hs). The metal element of the metal particles is preferably iron (Fe). Thus, the iron particles can be iron nanoparticles. The above metal particles can be derived from a metal precursor, and the metal precursor can be in the form of metal ions of a metal salt. It should be recognized that the Group 8 metal elements in the periodic table can be found in multiple oxidation states. Thus, when iron is the metal element, the precursor of iron can be found in the +2 or +3 oxidation state. In other words, the iron ions can have a charge of Fe 2+ or Fe 3+ . Further, depending on its oxidation state, the iron ions can be reduced or oxidized. The iron ions can be reduced to iron nanoparticles, i.e., the zero oxidation state.

[0033] When iron is the metal element of the metal particles, the salts of iron can be iron chloride, iron bromide, iron fluoride, iron iodide, iron sulfate, iron nitrate, iron oxalate, iron gluconate, iron acetylacetonate, iron fumarate, or iron phosphate. It should be understood that the iron in the above salts of iron can be in the +2 or +3 oxidation state. For example, when the salt of iron is iron chloride, this chloride salt can be iron(II) chloride or iron(III) chloride.

[0034] The metal particles disposed within the pores of the silica particles have a particle size in the range of about 1 nm to about 50 nm, for example, about 1 nm to about 10 nm, about 1 nm to about 20 nm, about 1 nm to about 30 nm, about 1 nm to about 40 nm, about 10 nm to about 20 nm, about 10 nm to about 30 nm, about 10 nm to about 40 nm, about 10 nm to about 50 nm, about 20 nm to about 30 nm, about 20 nm to about 40 nm, about 20 nm to about 50 nm, about 30 nm to about 40 nm, about 30 nm to about 50 nm, or about 40 nm to about 50 nm. The particle size of the metal particles is preferably in the range of about 6 nm to about 10 nm, more preferably in the range of about 1 nm to about 5 nm.

[0035] It should be understood that when the metal particles are spherical, the above particle size refers to the diameter of the metal particles. When the metal particles are substantially spherical, the above particle size refers to the equivalent diameter of the metal particles.

[0036] The porous silica particles in the composite material defined herein can be porous silica nanoparticles. The porous silica nanoparticles can be mesoporous or microporous. The silica nanoparticles can have a high surface area.

[0037] The silica particles are spherical with a size in the range of about 20 nm to about 1000 nm, for example, about 20 nm to about 50 nm, about 20 nm to about 80 nm, about 20 nm to about 300 nm, about 20 nm to about 500 nm, 20 nm to about 700 nm, about 20 nm to about 900 nm, about 50 nm to about 80 nm, about 50 nm to about 300 nm, about 50 nm to about 500 nm, about 50 nm to about 700 nm, about 50 nm to about 900 nm, about 50 nm to about 1000 nm, about 80 nm to about 300 nm, about 80 nm to about 500 nm, about 80 nm to about 700 nm, about 80 nm to about 900 nm, about 80 nm to about 1000 nm, about 300 nm to about 500 nm, about 300 nm to about 700 nm, about 300 nm to about 900 nm, about 300 nm to about 1000 nm, about 500 nm to about 700 nm, about 500 nm to about 900 nm, about 500 nm to about 1000 nm, about 700 nm to about 1000 nm, or about 900 nm to about 1000 nm. The size of the silica particles is preferably within the nanosize range (silica nanoparticles), more preferably about 100 nm.

[0038] The silica particles can be derived from a silicate precursor selected from the group consisting of tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate and tetraisopropyl orthosilicate, and mixtures thereof. It should be understood that the above silicate precursors are not limiting, and thus other suitable silicate precursors can be used.

[0039] The pores of the silica particles can also form channels within the silica particles. The diameter of the pores or channels within the silica particles ranges from about 1 nm to about 20 nm, and can be, for example, from about 1 nm to about 5 nm, from about 1 nm to about 10 nm, from about 1 nm to about 15 nm, from about 5 nm to about 10 nm, from about 5 nm to about 15 nm, from about 5 nm to about 20 nm, from about 10 nm to about 15 nm, from about 10 nm to about 20 nm, or from about 15 nm to about 20 nm. The diameter of the pores or channels is preferably in the range of about 5 to about 10 nm. Therefore, considering the size of the pores or channels within the silica particles, the channels within the silica particles or silica nanoparticles can be referred to as nano-sized channels.

[0040] The pores or channels can extend from one surface of the silica particle to another surface of the silica particle, or, if a cavity is present, from one surface of the silica particle to the cavity. The pores or channels can form a meandering path or can be a relatively straight path. The pores or channels can be short in distance, can be present only within the interior of the silica particle, or can extend from the surface to the interior of the silica particle.

[0041] The nanostructured composite material defined herein can be iron / silica hybrid nanoparticles. When the nanostructured composite material is iron / silica hybrid nanoparticles, iron ions (Fe 2+ and / or Fe 3+ ) can be adsorbed on the surface of the silica nanoparticles and also in the pores / channels of the silica particles. This adsorption can occur due to the electrostatic attraction between the hydroxyl groups on the surface of the silica nanoparticles and the iron ions. The content of iron particles in the Fe / silica hybrid nanoparticles can depend on the ratio of silica particles to iron salt during the initial wet impregnation step.

[0042] The metal content in the hybrid metal / silica nanostructured composite material ranges from about 1 wt% to about 80 wt% based on the dry weight of the silica particles. For example, based on the dry weight of the silica particles, it can be about 1 wt% - about 10 wt%, about 1 wt% - about 20 wt%, about 1 wt% - about 30 wt%, about 1 wt% - about 40 wt%, about 1 wt% - about 50 wt%, about 1 wt% - about 60 wt%, about 1 wt% - about 70 wt%, about 10 wt% - 20 wt%, about 10 wt% - 30 wt%, about 10 wt% - 40 wt%, about 10 wt% - 50 wt%, about 10 wt% - 60 wt%, about 10 wt% - 70 wt%, about 10 wt% - 80 wt%, about 20 wt% - 40 wt%, about 20 wt% - 80 wt%, about 30 wt% - 60 wt%, about 30 wt% - 80 wt%, about 40 wt% - 60 wt%, about 40 wt% - 80 wt%, about 50 wt% - 80 wt%, about 60 wt% - 80 wt%, about 70 wt% - 80 wt%. When the nanostructured composite material is iron / silica hybrid nanoparticles, the iron content in the hybrid Fe / silica nanoparticles is about 40 wt% to about 50 wt% based on the dry weight of the silica particles.

[0043] Advantageously, the above-mentioned silica particles can function as a carrier for zero-valent metal particles. The nano-sized channels of the porous silica particles can advantageously function as a carrier and / or protective material for the growth of metal particles, thereby enhancing the loading without aggregating such metal particles. More advantageously, these channels can also prevent the explosion of nano-sized metal particles, and thus, the production of the nanostructured composite material can be scaled up in a direct way in industrial production. The channels of the porous silica particles can also promote the diffusion of oxygen into the silica particles, thereby improving the contact between the metal nanoparticles and oxygen molecules. Furthermore, the channels can control the oxidation rate of the metal particles.

[0044] A nanostructured composite material having a relatively large cavity in the center can surprisingly further improve the contact between oxygen molecules and metal nanoparticles, resulting in a high deoxygenation ability. The nanostructured composite material having a large cavity in the center can efficiently remove oxygen. The depression of the nanostructured composite material can further promote the diffusion of oxygen in the particles, strengthen the contact between the metal nanoparticles and oxygen, and result in high deoxygenation performance.

[0045] As defined above, the nanostructured composite material having a large cavity in the center has a metal of about 190 cm 3 / g to about 210 cm 3 / g, for example, a metal of about 190 cm 3 / g to about 192 cm 3 / g, about 190 cm 3 / g to about 194 cm 3 / g, about 190 cm 3 / g to about 196 cm 3 / g, about 190 cm 3 / g to about 198 cm 3 / g, about 190 cm 3 / g to about 200 cm 3 / g, about 190 cm 3 / g to about 202 cm 3 / g, about 190 cm 3 / g to about 204 cm 3 / g, about 190 cm 3 / g to about 206 cm 3 / g, about 190 cm 3 / g to about 208 cm 3 / g, about 192 cm 3 / g to about 210 cm 3 / g, about 194 cm 3 / g to about 210 cm 3 / g, about 196 cm 3 / g to about 210 cm 3 / g, about 198 cm 3 / g to about 210 cm 3 / g, about 200 cm 3 / g to about 210 cm 3 / g, about 200 cm 3 / g to about 210 cm 3 / g, about 202 cm 3 / g ~ about 210 cm 3 / g, about 204 cm 3 / g ~ about 210 cm 3 / g, about 206 cm 3 / g ~ about 210 cm 3 / g, about 208 cm 3 / g ~ about 210 cm 3 / g may have oxygen scavenging performance.

[0046] Exemplary, non - limiting embodiments of a method for preparing a composite material comprising a mixture of a plurality of metal particles and porous silica particles as defined herein are disclosed.

[0047] The present disclosure provides a method for preparing a composite material comprising a mixture of a porous silica particle material for removing oxygen and a plurality of metal particles, the method comprising the following steps: (i) adding the porous silica particles to a solution of metal ions while stirring to impregnate the metal ions into the pores of the silica particles; and (ii) reducing the metal ions in the presence of a reducing agent to form the metal particles, wherein the metal particles are disposed within the pores of the porous silica particles.

[0048] Advantageously, the above - described method for preparing the composite material involves a simple setup and, thus, is expected to result in low manufacturing costs when scaled up. Considering the simplicity of the above process, this method can be scaled up in a straightforward manner.

[0049] Steps (i) and / or (ii) in the above - described method for preparing the composite material can be carried out in a temperature range of about 20 °C to about 50 °C, for example, about 20 °C to about 30 °C, about 20 °C to about 40 °C, about 30 °C to about 40 °C, about 30 °C to about 50 °C, or about 40 °C to about 50 °C, etc. Thus, it should be understood that steps (i) and / or (ii) above can be carried out at room temperature.

[0050] In one embodiment, a method for preparing a composite material comprising a mixture of a porous silica particle material for removing oxygen and a plurality of metal particles may include the following steps: (a) Dissolve a surfactant in water under basic pH conditions and stir the resulting solution at room temperature; (b) Add a solution of a silicate precursor to the solution of step (a) while stirring at room temperature, thereby forming a suspension of silica particles; (c) Immerse purified and air-dried silica particles having a porous structure in a solution of metal ions to impregnate the metal ions into the pores of the silica particles, and stir the resulting suspension for a period of time; (d) Add a solution of a reducing agent to the suspension of step (c) to form a solution of impregnated silica particles; and (e) Purify and dry the solution of impregnated silica particles under an inert gas flow, thereby forming the composite material.

[0051] In the case of steps (a) and (b) of the above method, the room temperature is in the range of about 20 °C to about 30 °C, and can be, for example, about 21 °C, about 22 °C, about 23 °C, about 24 °C, about 25 °C, about 26 °C, about 27 °C, about 28 °C, or about 29 °C.

[0052] A method for preparing a composite material comprising a mixture of a porous silica particle material for removing oxygen and a plurality of metal particles may include the following steps: (a) Dissolve a surfactant in water, and subsequently mix the surfactant solution with a base (basic solution) and a reactant, where the resulting solution is stirred at an appropriate temperature; (b) Add a solution of a silicate precursor to the solution of step (a), and stir the resulting mixture at an appropriate temperature, thereby forming a suspension of silica particles; (c) Immerse purified and air-dried silica particles having a porous structure in a solution of metal ions to impregnate the metal ions into the pores of the silica particles, and stir the resulting suspension for a period of time; (d) Add a solution of a reducing agent to the suspension of step (c) to form a solution of impregnated silica particles; and (e) Purify and dry the solution of the impregnated silica particles under an inert gas flow, thereby forming the composite material.

[0053] The above "suitable temperature" can be regarded as the temperature at which the surfactant can be substantially dissolved in the solvent or a mixture of solvents. Therefore, this suitable temperature may vary depending on the surfactant used. The above suitable temperature is in the range of about 20°C to about 85°C, and can be, for example, about 20°C to about 30°C, about 20°C to about 50°C, about 30°C to about 50°C, about 30°C to about 85°C, or about 50°C to about 85°C. Preferably, the suitable temperature is about 30°C.

[0054] Therefore, the composite material defined herein can be advantageously prepared via a one-step emulsion preparation method under mild conditions, and is thus considered an easy method.

[0055] The surfactant used above can be a cationic, anionic, or zwitterionic surfactant. The cationic surfactant can be a quaternary ammonium salt. The quaternary ammonium salt can contain an alkyl group. The alkyl quaternary ammonium salt can be an alkyltrimethylammonium salt selected from any of cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride (CTAC), or a mixture thereof. The above examples are non-limiting, and it should be understood that other suitable surfactants can be used. As described above, the surfactant can be dissolved in water. However, it can also be dissolved in other suitable polar solvents such as short-chain alcohols including ethanol, n-propanol, isopropanol, n-butanol, or a mixture thereof.

[0056] The basic solution mentioned in the above method can be a solution with a pH value of 8 or higher, for example, a solution with a pH of 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, or 14. It should be understood that the basic solution can contain an inorganic base or an organic base. The basic solution can contain an organic base dissolved in an aqueous solution. The aqueous solution can be water or deionized water. Water is preferred for the aqueous solution. The basic solution used in the above method can be an ammonia solution. The concentration of the basic solution is in the range of about 10 wt% to about 50 wt%, for example, about 10 wt% to about 20 wt%, about 10 wt% to about 30 wt%, about 10 wt% to about 40 wt%, about 20 wt% to about 30 wt%, about 20 wt% to about 50 wt%, about 30 wt% to about 50 wt%, or about 40 wt% to about 50 wt%. Preferably, the concentration of the basic solution is about 30 wt%.

[0057] The solution of the silicate precursor can contain a silicate precursor dissolved in an organic solvent. The organic solvent can be a nonpolar solvent or a polar solvent. Non-limiting examples of nonpolar organic solvents can include pentane, hexane, tetrahydrofuran (THF), cyclohexane, benzene, or mixtures thereof. Non-limiting examples of polar organic solvents can include methanol, ethanol, acetonitrile, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), or mixtures thereof. The organic solvent used is preferably a nonpolar solvent, more preferably hexane.

[0058] When the above aqueous solution is mixed with the nonpolar solvent, an emulsion can be formed. The emulsion system can contain immiscible solvents, that is, a system is formed in which at least two phases that are substantially immiscible with each other are formed. The immiscible solvents having the above two separate phases can include a nonpolar solvent and a polar solvent.

[0059] The solution or mixture obtained in step (i), (a) and / or (b) can be stirred for about 10 minutes to about 14 hours, for example, about 10 minutes to about 30 minutes, 10 minutes to about 1 hour, 1 hour to about 5 hours, about 1 hour to about 10 hours, about 5 hours to about 10 hours, about 5 hours to about 14 hours, about 10 hours to about 11 hours, about 10 hours to about 12 hours, about 10 hours to about 13 hours, about 10 hours to about 14 hours, about 11 hours to about 14 hours, about 12 hours to about 14 hours, or about 13 hours to about 14 hours.

[0060] Stirring can be carried out at a constant or variable stirring speed in the range of about 100 rpm to about 10000 rpm, for example, about 200 rpm, about 500 rpm, about 1000 rpm, about 3000 rpm, about 6000 rpm, or about 9000 rpm. A constant stirring speed is preferably 500 rpm in step (a) and 9000 rpm in step (b). Since a suspension will be formed in step (b), it should be understood that the stirring speed used in step (b) is faster than the stirring speed in step (a). Furthermore, the time of the stirring or mixing process in step (a) and / or (b) may depend on the stirring speed used. Preferably, step (a) is stirred at 500 rpm for about 30 minutes and step (b) is stirred at 9000 rpm for about 12 hours.

[0061] Subsequent to step (b), the obtained silica particles can be purified, for example, via centrifugation, followed by washing the purified silica particles. This purification step can be repeated 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times. Such a purification process can include the addition of an acidic solution to the suspension containing the silica particles defined above, washing and / or redispersion of the silica particles in an organic solvent.

[0062] An acidic solution can contain an acid dissolved in a solvent or a mixture of two or more acids. It is understood that the acidic solution has a pH less than 7, for example, 1, 2, 3, 4, 5, or 6. The solvent used can be an organic solvent or an aqueous solvent. The acid can be an inorganic acid or an organic acid, a strong acid or a weak acid. Non-limiting examples of such acids can include hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and acetic acid. The acidic solution is preferably hydrochloric acid in water. The organic solvent used to wash and / or redisperse the silica particles is as defined above.

[0063] When using centrifugation, the rotational speed of the centrifugation can be in the same range as the above stirring step, that is, for a time similar to the time required for the above stirring, that is, about 10 minutes to about 14 hours, and can be about 100 rpm to about 10,000 rpm. The temperature in the purification process is in the range of about 20°C to about 70°C, and can be, for example, about 30°C, about 40°C, about 50°C, or about 60°C. Other suitable temperatures within the above range can be used.

[0064] In an exemplary embodiment, the silica particles added in step (i) or obtained in step (b) can be purified by centrifugation at about 9000 rpm for about 10 minutes and can be washed twice with ethanol. The silica particles can be redispersed in an ethanol solution containing 1M hydrochloric acid. The resulting suspension can be stirred at about 500 rpm and about 60°C for about 5 hours. Finally, the suspension is purified by centrifugation at about 9000 rpm for about 10 minutes to remove excess surfactant molecules in the silica particles. This final step can be repeated before air-drying and vacuum-drying the purified silica particles.

[0065] Advantageously, the purified silica particles can be porous silica nanoparticles. Such porous silica nanoparticles can be easily dispersed in a solution, for example, an aqueous solution.

[0066] In step (i) of the above method or step (c) of a specific embodiment of the method for preparing the composite material, the solution of metal ions can be a solution of iron ions. The iron ions can be derived from the iron salts defined above. The iron salts can be dissolved in an aqueous solution. The aqueous solution can be water or deionized water.

[0067] For the sake of clarity, when iron is the metal element of the metal ions, the iron ions can be derived from iron salts selected from the group consisting of iron chloride, iron bromide, iron fluoride, iron iodide, iron sulfate, iron nitrate, iron oxalate, iron gluconate, iron acetylacetonate, iron fumarate and iron phosphate. It should be understood that the iron in the above iron salts can be in an oxidation state of +2 or +3. For example, when the iron salt is iron chloride, this chloride salt can be iron(II) chloride or iron(III) chloride.

[0068] Regarding step (c) of a specific embodiment of the method for preparing the above composite material, the silica suspension can be stirred for about 10 hours to about 14 hours, for example, about 10 hours to about 11 hours, about 10 hours to about 12 hours, about 10 hours to about 13 hours, about 11 hours to about 14 hours, about 12 hours to about 14 hours, or about 13 hours to about 14 hours. Preferably, the mixture obtained in step (c) is stirred for about 12 hours to allow complete or substantially complete adsorption of the metal ions into the channels of the silica particles.

[0069] In step (ii) of the above method or step (d) of a specific embodiment of the method for preparing the composite material described herein, the solution of the reducing agent can be added slowly or dropwise to the resulting suspension. The reducing agent that can be used in the above method can be selected from the group consisting of sodium borohydride, lithium aluminum hydride, diisobutylaluminum hydride (DIBAL-H), and sodium cyanoborohydride.

[0070] According to the above steps, a resulting composite material having a particle size in the range of about 10 nm to about 300 nm can be produced. For example, a composite material having a particle size of about 10 nm to about 20 nm, about 10 nm to about 50 nm, about 10 nm to about 100 nm, about 10 nm to about 150 nm, about 10 nm to about 200 nm, about 10 nm to about 250 nm, about 20 nm to about 50 nm, about 20 nm to about 100 nm, about 20 nm to about 150 nm, about 20 nm to about 200 nm, about 20 nm to about 250 nm, about 20 nm to about 300 nm, about 50 nm to about 100 nm, about 50 nm to about 150 nm, about 50 nm to about 200 nm, about 50 nm to about 250 nm, about 50 nm to about 300 nm, about 100 nm to about 150 nm, about 100 nm to about 200 nm, about 100 nm to about 250 nm, about 100 nm to about 300 nm, about 150 nm to about 200 nm, about 150 nm to about 250 nm, about 150 nm to about 300 nm, about 200 nm to about 250 nm, about 200 nm to about 300 nm, or about 250 nm to about 300 nm can be produced. Preferably, the resulting composite material has a particle size of about 20 nm to about 200 nm.

[0071] The size of the channels formed within the resulting composite material is in the range of about 1 nm to about 10 nm. For example, it can be about 1 nm to about 2 nm, about 1 nm to about 3 nm, about 1 nm to about 4 nm, about 1 nm to about 5 nm, about 1 nm to about 6 nm, about 1 nm to about 7 nm, about 1 nm to about 8 nm, about 1 nm to about 9 nm, about 2 nm to about 10 nm, about 3 nm to about 10 nm, about 4 nm to about 10 nm, about 5 nm to about 10 nm, about 6 nm to about 10 nm, about 7 nm to about 10 nm, about 8 nm to about 10 nm, or about 9 nm to about 10 nm. Preferably, the size of the channels is about 5 nm.

[0072] For steps (a) and / or (b) of certain embodiments of the method for preparing the composite material, when stirring is carried out at a temperature higher than about 30°C, large cavities can be formed in the silica particles. The size of such large cavities ranges from about 40 nm to about 80 nm, and can be, for example, about 40 nm to about 50 nm, about 40 nm to about 60 nm, about 40 nm to about 70 nm, about 50 nm to about 80 nm, about 60 nm to about 80 nm, or about 70 nm to about 80 nm. Preferably, the size of the large cavity is about 60 nm.

[0073] Therefore, the composite material obtained when stirring is carried out at a temperature higher than about 30°C in steps (a) and / or (b) can have a larger particle size in the range of about 60 nm to about 100 nm, for example, about 60 nm to about 70 nm, about 60 nm to about 80 nm, about 60 nm to about 90 nm, about 70 nm to about 100 nm, about 80 nm to about 100 nm, or about 90 nm to about 100 nm. The particle size of the composite material having large cavities as described above is preferably about 80 nm.

[0074] The reactant in step (a) described above can be a compound that can produce large hollow cavities within the silica particles. Such a reactant can be an alkyl ester. The alkyl ester can contain a C1-C6 alkyl group such as methyl, ethyl, propyl, or isopropyl. The alkyl ester used as the reactant in step (a) is preferably an ethyl ester.

[0075] Advantageously, the size and structure of the porous silica particles can be easily adjusted by varying the ratio of the precursors. The size of the channels in the composite material can be uniform along the individual channels of the mesoporous silica particles.

[0076] Exemplary, non-limiting embodiments of the compositions comprising the composite materials and porous silica particles as defined herein are disclosed herein.

[0077] The present disclosure further provides a composition comprising: a) a composite material comprising a mixture of a plurality of metal particles and a porous silica particle material, wherein the plurality of metal particles are disposed within the pores of the porous silica particles; and b) a polymer matrix.

[0078] The above composite material can essentially be the composite material described in the previous section and the composite material described in the examples. Therefore, it should be understood that some (if not all) of the properties or characteristics of the aforementioned composite materials are equally applicable here, that is, it is possible to describe component a) of the above composition.

[0079] Non-limiting examples of the polymer matrix can include montmorillonite, bentonite, laponite, kaolinite, saponite, vermiculite, or mixtures thereof. It should be understood that other suitable polymer matrices can be used. Further, the polymer matrix can be a clay selected from the group consisting of natural clays, synthetic clays, and silane-modified clays. The polymer matrix, i.e., component b), can be added in a small amount to the composite material to form the above composition.

[0080] Exemplary, non-limiting embodiments of a method for preparing a composition comprising the above composite material and polymer matrix are disclosed herein.

[0081] Furthermore, the present invention also provides a method for preparing a composition comprising: a) a composite material comprising a mixture of a plurality of metal particles and a porous silica particle material; and b) a polymer matrix, wherein the plurality of metal particles are disposed within the pores of the porous silica particles, wherein the method comprises dispersing the composite material in a solution of an alkyl alcohol and adding an amount of the polymer matrix.

[0082] The method of preparing the composition may include the steps of dispersing the composite material in a solution of an alkyl alcohol and adding a small amount of a polymer matrix. The dispersion of the composite material in the solution of the alkyl alcohol can be obtained by stirring at a high speed or by homogenizing for a certain period of time under an inert gas flow.

[0083] The alkyl alcohol may be composed of a C1-C6 alkyl group or a C6-C 12 alkyl group. The solution of the alkyl alcohol can be ethylene vinyl alcohol (EVOH) or polyvinyl alcohol (PVOH). The inert gas in the inert gas flow can be nitrogen or argon gas. The time required for stirring can range from about 1 minute to about 5 minutes, for example, about 1 minute to about 2 minutes, about 1 minute to about 3 minutes, about 1 minute to about 4 minutes, about 2 minutes to about 5 minutes, about 3 minutes to about 5 minutes, or about 4 minutes to about 5 minutes. Preferably, the above time is about 1 minute.

[0084] To obtain a uniform dispersion of the composition, a high stirring speed may be required when the polymer matrix is added to the suspension of the composite material, i.e., component a). Such a high stirring speed can range from about 5000 rpm to about 15000 rpm, for example, about 8000 rpm, about 9000 rpm, about 1000 rpm, about 12000 rpm, or about 14000 rpm.

[0085] The resulting suspension composition can be applied to a polymer substrate. Non-limiting examples of the polymer of the polymer substrate may include polyethylene terephthalate (PET), polypropylene (PP), or polyethylene (PE). It should be understood that the polymer can be in the form of a homopolymer, a copolymer, or a blend thereof.

[0086] Exemplary, non-limiting embodiments of articles comprising a composition comprising a composite material and a polymer matrix are disclosed herein.

[0087] The present disclosure further provides an article comprising a composite material as described above and a composition comprising a polymer matrix. Specifically, the present disclosure provides an article comprising a composite material as described above and a composition comprising a polymer matrix, wherein the composite material comprises a mixture of a plurality of metal particles and a porous silica particle material as described above.

[0088] The composite material can be substantially the same as those described in the previous section and those described by way of example. Therefore, it should be understood that some (if not all) of the properties or characteristics of the aforementioned composite materials are equally applicable here.

[0089] The article comprising the composition can be in the form of a transparent coated film. The article can be paper or a cellulose material.

[0090] Exemplary, non-limiting embodiments of the use of the articles defined herein for packaging films of the articles are disclosed herein.

[0091] The present disclosure further provides the use of the articles defined herein for packaging films in food packaging having an improved oxygen barrier.

[0092] In summary, the composite materials of the present disclosure and the methods for preparing them have many advantages from at least the following aspects, and thus solve the technical problems associated with iron particles as oxygen scavengers: · The silica particles of the composite material can function as a carrier for the plurality of metal particles. · The nano-sized channels formed in the porous silica particles function as a carrier and a protective material for the growth of metal particles, thereby being beneficial because the loading of metal particles can be increased without aggregation. · The formed channels can prevent the explosion of nano-sized metal particles. Therefore, the obtained nanostructured composite material is easy to adopt in industrial production. · The channels formed within the porous silica particles promote the diffusion of oxygen into the silica particles, thereby improving the contact between the metal nanoparticles and oxygen molecules. · The channels control the oxidation rate of the metal particles. · The composite materials described herein can be obtained in an easy manner via a one-step emulsion preparation method under mild conditions. Thus, such a process requires a simple production setup and can therefore be regarded as a low-cost process. · The size and structure of the porous silica particles can be easily adjusted by varying the ratio of the precursors. The size of the channels in the composite material is substantially uniform along the individual channels of the mesoporous silica particles.

Brief Description of the Drawings

[0093] The accompanying drawings show the disclosed embodiments and serve to explain the principles of the disclosed embodiments. However, it should be understood that the drawings are designed for illustrative purposes only and not as a definition of the limitations of the present invention.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0094] Referring to Figure 1, this figure illustrates two methods for preparing the composite material of the present disclosure. Figure 1A shows the method for synthesizing the composite material Fe / S1 as described in Example 1. In Figure 1A, it can be understood that nano-sized channels (101) are found within the mesoporous silica particles (100). After the addition of the iron solution (102), a composite material Fe / S1 (103) having iron nanoparticles (104) adsorbed in the nano-sized channels (101) of the mesoporous silica particles (100) is formed.

[0095] On the other hand, FIG. 1B shows a method for synthesizing the composite material Fe / S2 described in Example 2. In FIG. 1B, it can be observed that nano-sized channels (101) are found within mesoporous silica particles (100) having large cavities (105). After the addition of an iron solution (102) by a wet impregnation process, a composite material Fe / S2 (106) having iron nanoparticles (104) adsorbed in the nano-sized channels (101) of the mesoporous silica particles (100) having large cavities (100) is formed. The iron nanoparticles (104) can also be adsorbed and adhered to the inner walls of the large cavities (105).

Example

[0096] Non-limiting examples of the present invention and comparative examples are described in more detail by reference to specific examples, which should not be construed as in any way limiting the scope of the present invention.

[0097] Example 1: Preparation of Porous Fe / Silica from Mesoporous Silica Nanoparticles (Fe / S1) A schematic diagram of mesoporous silica nanoparticles and the composite material Fe / S1 is shown in FIG. 1A.

[0098] a) Preparation of Mesoporous Silica Nanoparticles 2 g of cetyltrimethylammonium bromide (CTAB) (98%, purchased from Alfa Aesar, Lancashire, UK) was dissolved in water and mixed with 10 mL of ammonia solution (28 - 30%, purchased from Honeywell, New Jersey, USA). The resulting mixture (i.e., the first mixture) was stirred at 500 rpm for about 30 minutes at room temperature. While stirring vigorously, 40 mL of a hexane solution of tetraethyl orthosilicate (TEOS, purchased from Sigma Aldrich, St. Louis, Missouri, USA) was added dropwise to the first mixture over about 30 minutes. When the addition of the TEOS solution was complete, a second mixture was obtained and stirred for a further about 12 hours at room temperature to form mesoporous silica nanoparticles. The resulting mesoporous silica nanoparticles were recovered by centrifugation at 9000 rpm for about 10 minutes and washed twice with ethanol.

[0099] The purified nanoparticles were redispersed in an ethanol solution (purchased from Green Tropic Products Pte Ltd, Singapore) containing 1 M hydrochloric acid (purchased from Sigma Aldrich, St. Louis, Missouri, USA). The resulting suspension was stirred at about 60 °C for about 5 hours at 500 rpm, and then the nanoparticles were purified using centrifugation at 900 rpm for about 10 minutes to remove excess CTAB molecules in the silica particles. This removal step was repeated to ensure that most of the CTAB molecules were removed from the silica nanoparticles. Subsequently, the nanoparticles were air-dried and then vacuum-dried at room temperature. Transmission electron microscope (TEM) images using low magnification and high magnification of the mesoporous silica nanoparticles are shown in Figures 2A and 2B, respectively.

[0100] b) Preparation of Fe / S1 2 g of the mesoporous silica nanoparticles obtained in step a) were dispersed in 50 mL of water to form a first suspension. Subsequently, 5 mL of a ferric chloride solution (0.5 g, purchased from Sigma Aldrich, St. Louis, Missouri, USA) was added dropwise to the first suspension. The resulting suspension was stirred for about 12 hours to ensure the adsorption of Fe 3+ ions into the channels of the mesoporous silica. While stirring vigorously, 4 mL of a sodium borohydride solution (0.35 g, purchased from Honeywell Fluka, New Jersey, USA) was added dropwise to the silica suspension. The final product was purified by centrifugation followed by drying in an oven or furnace with an inert gas flow. TEM images using low magnification and high magnification of the Fe / S1 nanoparticles are shown in Figures 2C and 2D.

[0101] As shown in Figure 2, the transmission electron microscope (TEM) images revealed that the synthesized porous silica nanoparticles obtained by the emulsion reaction method had a particle size in the range of about 20 nm to about 200 nm. The size and structure of the porous silica nanoparticles can be easily adjusted by changing the ratio of the precursors.

[0102] After the surfactant CTAB is removed, the mesoporous silica nanoparticles are embedded in regularly arranged nano-scale empty channels. In the analysis of Figure 2B, the size of such empty channels is estimated to be about 5 nm and appears to be fairly uniform along the individual channels of the mesoporous silica nanoparticles. The TEM image in Figure 2D reveals that Fe nanoparticles with a size of about 5 nm are uniformly distributed in the silica nanoparticles. The actual iron content in Fe / Si was determined to be about 30 wt% by inductively coupled plasma mass spectrometry (IPC-MS).

[0103] Example 2: Preparation of Porous Fe / Silica from Mesoporous Silica Nanoparticles (Fe / S2) with Large Cavities A schematic diagram of the mesoporous silica nanoparticles and the composite material Fe / S2 with large cavities is shown in Figure 1B.

[0104] a) Preparation of Mesoporous Silica Nanoparticles 0.6 g of CTAB (98%, purchased from Alfa Aesar, Lancashire, UK) was dissolved in 70 mL of water and mixed with 0.6 mL of ammonia solution (28 - 30%, purchased from Honeywell, New Jersey, USA) and 20 mL of anhydrous ethyl ester (purchased from TEDIA, Ohio, USA). The resulting solution was stirred at 30 °C for about 30 minutes at 500 rpm. While stirring vigorously, 3.5 mL of TEOS was added dropwise to the solution over about 10 minutes. After the complete addition of TEOS, the mixture was stirred at 30 °C for about 12 hours to produce mesoporous silica nanoparticles. The product was purified by centrifugation at 9000 rpm for 10 minutes and washed twice with ethanol.

[0105] The silica nanoparticles were redispersed in an ethanol solution containing 1 M hydrochloric acid. The resulting suspension was stirred at about 60 °C for 5 hours at 500 rpm and then purified by centrifugation at about 9000 rpm for about 10 minutes to remove excess CTAB molecules in the silica particles. The step of removing CTAB was repeated to ensure that most of the CTAB was removed from the silica nanoparticles. Finally, the particles were air-dried at room temperature and then vacuum-dried.

[0106] TEM images of mesoporous silica nanoparticles with large cavities at low and high magnifications are shown in FIGS. 3A and 3B.

[0107] b) Adjustment of Fe / S2 1 g of mesoporous silica nanoparticles was dispersed in 25 mL of water to form a suspension. A solution of ferric chloride (0.25 g, 2.5 mL) was added dropwise to the suspension to form a second suspension. The resulting suspension was stirred for about 12 hours to ensure the adsorption of Fe ions into the channels of the mesoporous silica.

[0108] While stirring vigorously, 2 mL of sodium borohydride (0.2 g) solution was added dropwise to the suspension. The final product was purified by centrifugation and dried in a furnace under an inert gas stream. TEM images of Fe / silica nanoparticles synthesized from mesoporous silica nanoparticles with large cavities at low and high magnifications are shown in FIGS. 3C and 3D.

[0109] As can be seen from FIG. 3, mesoporous silica nanoparticles with a size of about 80 nm were observed. Each mesoporous silica nanoparticle had a relatively large cavity with a size of about 60 nm formed therein.

[0110] After the growth of the Fe nanoparticles, there was no significant change in the shape of the silica nanoparticles. The Fe nanoparticles with a size of less than 2 nm were uniformly distributed in the silica nanoparticles.

[0111] In the X-ray diffraction (XRD) analysis shown in FIG. 4, it was revealed that most of the iron particles in the mesoporous silica nanoparticles were zero-valent and only a small amount of iron oxide was present. The actual content of Fe in Fe / S2 determined by ICP-MS was found to be about 34.7 wt%.

[0112] Example 3: Deoxygenation tests of Fe / S1 and Fe / S2 To evaluate the deoxidation performance of samples Fe / S1 and Fe / S2, 0.1 g of each sample containing 7.5 wt% NaCl was placed in a 25 mL glass Erlenmeyer flask. A vial containing 1 mL of water was placed inside the flask, and the indoor humidity (RH) was adjusted to 100%. Next, the flask was sealed with a glass-tight rubber septum stopper and placed at room temperature during the deoxidation experiment. As can be seen from Table 1, both Fe / S1 and Fe / S2 were able to remove most of the oxygen from the model package after 3 days. Fe / S2 showed a higher removal capacity (193 cm 3 versus 177 cm 3 ) and a faster removal rate than Fe / S1.

[0113]

Table 1

[0114] As can be seen in Figure 5, the deoxidation performance of Fe / S2 is comparable to that of an Fe / C nanocomposite (containing 40 wt% Fe). It is noteworthy that the preparation of the Fe / Si deoxidizer in the present invention is more cost-effective than the preparation of the Fe / C nanocomposite.

[0115] Example 4: Preparation of a Polymer Composite Film Using Fe / Si Nanoparticles Fe / S2 was dispersed in an EVOH solution by adding a small amount of clay (about 5 wt% based on the weight of Fe / S2). The dispersion of Fe / S2 in the EVOH solution was achieved by flushing with argon gas and homogenizing at 10,000 rpm for 1 minute. Next, the suspension was coated onto a PET film with a coating thickness of about 20 μm. Next, the coated film was dried in a vacuum oven at 60 °C.

[0116] As can be seen from Figure 6, transparent coated films with an Fe / S2 content up to 20 wt% were obtained. These transparent films containing the Fe / silica deoxidizer can be used as deoxidizing packaging films to extend the shelf life of food and can be incorporated with barrier polymer films to further improve the oxygen barrier.

Industrial Applicability

[0117] As can be seen from the detailed description and the examples provided, the composite materials of the present disclosure exhibit promising deoxygenation performance and thus may be used in food, beverage, and pharmaceutical applications. Specifically, the composite materials of the present disclosure can be used for packaging food, beverages, or pharmaceuticals.

[0118] Composite materials of the present disclosure, such as Fe / silica nanoparticles, can be used directly as sachets for removing oxygen. Additionally, Fe / silica nanoparticles can be incorporated into a polymer matrix to form a coated or laminated film. Alternatively, Fe / silica nanoparticles may be incorporated into an extruded / blown polymer film or bottle.

[0119] In addition to the above, the composite materials can also be used as metal-based oxygen scavengers that cannot be detected by industrial metal detectors commonly used in the food and pharmaceutical processing and packaging industries. The composite materials can also be used in biological applications including bioimaging and drug delivery.

[0120] It will be apparent to those skilled in the art that various other modifications and adaptations of the present invention will become obvious after reading the foregoing disclosure without departing from the spirit and scope of the present invention, and all such modifications and adaptations are intended to fall within the scope of the appended claims.

Claims

1. A composite material comprising a mixture of a plurality of metal particles and porous silica particles containing nano-sized channels, which is used as an oxygen scavenger, wherein the plurality of metal particles are disposed within the pores of the porous silica particles and adsorbed within the nano-sized channels, the composite material has cavities within the range of 40 nm to 70 nm, the nano-sized channels extend from the surface of the porous silica particles to the cavities, and the diameters of the pores and the nano-sized channels are in the range of 1 nm to 20 nm, the particle size of the metal particles is in the range of 1 nm to 20 nm, the particle size of the porous silica particles is in the range of 80 nm to 1000 nm, and the metal of the metal particles is selected from Group 8 of the periodic table, and the composite material is a nanostructured composite material (excluding magnetic nanocomposite materials).

2. The composite material according to claim 1, wherein the porous silica particles are porous silica nanoparticles.

3. The nano-structured composite material having a cavity in the center has a deoxidation performance in the range of 190 cm ３ / g to 210 cm ３ / g as measured by the deoxidation test. The composite material according to claim 1.

4. A method for preparing a composite material comprising a mixture of a plurality of metal particles and a porous silica particle material containing nano-sized channels, which is used as an oxygen scavenger, the following steps: a) Dissolve the surfactant in water, and subsequently mix the surfactant solution with a base and a C １ to C ６ alkyl ester, and here, stir the resulting solution at an appropriate temperature; b) adding a solution of a silicate precursor to the solution of step a), wherein the resulting mixture is stirred at an appropriate temperature to thereby form a suspension of silica particles; c) immersing the purified and air-dried silica particles having a porous structure and the nano-sized channels in a solution of metal ions to impregnate the metal ions into the pores and the nano-sized channels of the silica particles, and stirring the resulting suspension for a period of time, wherein the metal of the metal particles is selected from Group 8 of the periodic table; d) adding a solution of a reducing agent to the suspension of step c) to form a solution of the impregnated silica particles; and e) purifying and drying the solution of the impregnated silica particles under an inert gas flow to thereby form the composite material; Here, the composite material is a nanostructured composite material having cavities in the range of 40 nm to 70 nm, the nano-sized channels extend from the surface of the porous silica particles to the cavities, and the diameters of the pores and the nano-sized channels are in the range of 1 nm to 20 nm, the particle size of the metal particles is in the range of 1 nm to 20 nm, the particle size of the porous silica particles is in the range of 80 nm to 1000 nm, provided that magnetic nano-composite materials are excluded, and, the metal content in the composite material is in the range of 10% by mass to 80% by mass based on the dry mass of the silica particles. A method comprising.

5. The method according to claim 4, wherein the metal ions are iron ions derived from an iron salt selected from the group consisting of iron chloride, iron bromide, iron fluoride, iron iodide, iron sulfate, iron nitrate, iron oxalate, iron gluconate, iron acetylacetonate, iron fumarate, and iron phosphate.

6. The method according to claim 4 or 5, wherein the reducing agent is selected from the group consisting of sodium borohydride, lithium aluminum hydride, diisobutylaluminum hydride (DIBAL-H), and sodium cyanoborohydride.

7. The method according to any one of claims 4 to 6, wherein the silicate precursor is selected from the group consisting of tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, and tetraisopropyl orthosilicate.

8. a) The composite material according to claim 1; and b) Clay A composition comprising.

9. The composition according to claim 8, wherein the clay is selected from the group consisting of montmorillonite, bentonite, laponite, kaolinite, saponite, vermiculite, and mixtures thereof.

10. Further comprising an alkyl alcohol, wherein the alkyl alcohol is C １ to C ６ alkyl group or C ６ to C １２ The composition according to claim 8 or 9, which is composed of an alkyl group.

11. A method for preparing a composition comprising: a) A composite material comprising a mixture of a plurality of metal particles used as a deoxidizer and a porous silica particle material containing nano-sized channels, wherein the metal of the metal particles is selected from Group 8 of the periodic table, provided that magnetic nano-composite materials are excluded; and b) Clay, wherein the plurality of metal particles are disposed within the pores of the porous silica particles and adsorbed within the nano-sized channels, wherein the composite material is a nanostructured composite material having cavities in the range of 40 nm to 70 nm, the nano-sized channels extending from the surface of the porous silica particles to the cavities, and the diameters of the pores and the nano-sized channels are in the range of 1 nm to 20 nm, the particle size of the metal particles is in the range of 1 nm to 20 nm, and the particle size of the porous silica particles is in the range of 80 nm to 1000 nm; and wherein the method comprises dispersing the composite material in a solution of alkyl alcohol and adding an amount of clay.

12. 11. An article comprising the composition of claim 10 comprising a composite material, an alkyl alcohol, and a clay.

13. The article of claim 12, wherein the article is a clear coated film.

14. 14. Use of the article of claim 12 or 13 as a packaging film for food packaging with improved oxygen barrier.

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