Porous metal oxide microspheres

Abstract

The present invention relates to a porous microsphere comprising a metal oxide, a composition comprising the porous microsphere, and a method of making a porous metal oxide microsphere, the method comprising forming a liquid dispersion of polymer nanoparticles and a metal oxide; forming liquid droplets of the dispersion; drying the droplets to provide polymer template microspheres comprising polymer nanospheres; and removing the polymer nanospheres from the template microspheres to provide porous metal oxide microspheres. The porous microspheres exhibit saturated colors and are suitable as colorants for various end uses.

Description

[0001] This application is a divisional application of the invention patent application with application number 201880072327.6, the original application being filed on September 10, 2018, and entitled "Porous Metal Oxide Microspheres". Technical Field

[0002] Porous metal oxide microspheres, their preparation methods, and their applications are disclosed. The microspheres are suitable, for example, for use as structural colorants. Background Technology

[0003] Traditional pigments and dyes exhibit color through light absorption and reflection via chemical structure. Structural colorants, on the other hand, exhibit color through light interference effects via physical structure rather than chemical structure. Structural colorants exist in nature, for example, in bird feathers, butterfly wings, and certain gemstones. Structural colorants are materials containing microstructured surfaces small enough to interfere with visible light and produce color. These materials can be based on photonic materials, including but not limited to opal, inverse opal, photonic particles, photonic spheres, or composite photonic crystals. The term "photonic material" refers to a material with a degree of periodic variation in its structure.

[0004] Structural colorants can exhibit high stability. Therefore, there is a need for structural colorants that, when present in batches, exhibit distinct visible light colors perceptible to the naked eye. Such structural colorants can replace less stable and / or less environmentally friendly pigments or dyes in the formulation of consumer products.

[0005] It has been found that certain porous metal oxide microspheres exhibit high-quality color in batches. The microspheres provide visible color in batches. Summary of the Invention

[0006] Accordingly, a method for preparing porous metal oxide microspheres comprising metal oxides is disclosed, the method comprising forming a liquid dispersion of polymer nanoparticles and metal oxides; forming liquid droplets of the dispersion; drying the liquid droplets to provide polymer template microspheres comprising polymer nanospheres and metal oxides; and removing the polymer nanospheres from the template microspheres to provide porous metal oxide microspheres.

[0007] Also disclosed are porous microspheres comprising metal oxides, wherein the microspheres have an average diameter of about 0.5 µm to about 100 µm, an average porosity of about 0.10 to about 0.90 or about 0.10 to about 0.80, and an average pore size of about 50 nm to about 999 nm.

[0008] They also disclosed porous microspheres containing metal oxides, wherein batch samples of the porous microspheres exhibited colors perceptible to the human eye.

[0009] Compositions comprising a matrix and porous microspheres are also disclosed; for example, said composition is an aqueous formulation, an oily formulation, a coating formulation, a food, an ink, a plastic, a cosmetic formulation, or a material for medical or safety purposes. Attached Figure Description

[0010] The accompanying drawings are for illustrative purposes only and not as a limitation of the disclosure described herein. For simplicity and clarity, the elements shown in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements may be enlarged relative to others for clarity. Furthermore, reference numerals are repeated between drawings where deemed appropriate to indicate corresponding or similar elements.

[0011] Figure 1 This provides a general overview of a method for preparing porous microspheres according to one embodiment of the present invention.

[0012] Figure 2 This is a scanning electron microscope (SEM) image of polymer template microspheres according to one embodiment of the present invention.

[0013] Figure 3 This is a SEM image of porous silica microspheres according to one embodiment of the present invention.

[0014] Figure 4 This is an illustration of a spray drying method according to some embodiments of the present invention. Detailed Implementation

[0015] Metal oxide microspheres, or photonic balls, can be prepared using a polymer sacrificial template. In one embodiment, an aqueous colloidal dispersion containing polymer particles, typically nanoscale, is prepared. For example, the aqueous colloidal dispersion is mixed with a continuous oil phase within a microfluidic device to produce a water-in-oil emulsion. The emulsion is then prepared as aqueous microdroplets, collected, and dried to form microspheres containing polymer nanoparticles and metal oxides. The polymer nanoparticles (nanospheres) are then removed, for example, by calcination, to provide spherical micron-sized metal oxide particles (microspheres) with high porosity and nanoscale pores. The microspheres may contain uniform pore size, a result of the spherical and monodisperse nature of the polymer particles.

[0016] Figure 1This provides a general overview of the preparation of porous microspheres. Emulsion droplets containing polymer nanospheres and metal oxides are dried to remove the solvent, providing assembled microspheres (templated microspheres or "direct structures") containing polymer nanospheres and metal oxides in the interstitial spaces between the polymer nanospheres. The polymer nanospheres define the interstitial spaces. Calcination results in the removal of the polymer, providing metal oxide microspheres with high porosity or pore volume (inverse structures).

[0017] Advantageously, porous metal oxide microspheres are sintered to produce thermally and mechanically stable continuous solid structures.

[0018] In some embodiments, droplet formation and collection occur within a microfluidic device. A microfluidic device is, for example, a narrow-channel device having a micrometer-scale droplet junction connected to a collection reservoir, suitable for generating droplets of uniform size. The microfluidic device, for example, contains a droplet junction having a channel width of approximately 10 µm to approximately 100 µm. The device is made, for example, of polydimethylsiloxane (PDMS) and can be fabricated, for example, by soft lithography. An emulsion can be prepared within the device by pumping an aqueous dispersed phase and an oil continuous phase into the device at a specified rate and mixing therein to provide emulsion droplets. Alternatively, an oil-in-water emulsion can be used.

[0019] In some implementations, vibrating nozzle technology can be used. In these technologies, a liquid dispersion is prepared, forming microdroplets and introduced into a bath of continuous phase. The microdroplets are then dried, followed by the removal of the polymer. Vibrating nozzle devices are available from Büchi and include, for example, a syringe pump and a pulsation unit. Vibrating nozzle devices may also include a pressure regulating valve.

[0020] Polymer nanoparticles, for example, have an average diameter of about 50 nm to about 999 nm and are monodisperse.

[0021] Suitable template polymers include thermoplastic polymers. For example, template polymers are selected from poly(meth)acrylic acid, poly(meth)acrylates, polystyrene, polyacrylamide, polyvinyl alcohol, polyvinyl acetate, polyester, polyurethane, polyethylene, polypropylene, polylactic acid, polyacrylonitrile, polyvinyl ether, their derivatives, their salts, their copolymers, and combinations thereof. For example, polymers are selected from polymethyl methacrylate, polyethyl methacrylate, poly(n-butyl methacrylate), polystyrene, poly(chlorostyrene), poly(α-methylstyrene), poly(N-hydroxymethylacrylamide), styrene / methyl methacrylate copolymer, polyalkylated acrylate, polyhydroxyacrylate, polyamino acrylate, polycyanoacrylate, polyfluorinated acrylate, poly(N-hydroxymethylacrylamide), polyacrylic acid, polymethacrylic acid, methyl methacrylate / ethyl acrylate / acrylic acid copolymer, styrene / methyl methacrylate / acrylic acid copolymer, polyvinyl acetate, polyvinylpyrrolidone, polyvinylcaprolactone, polyvinylcaprolactam, their derivatives, their salts, and combinations thereof.

[0022] In some embodiments, the polymer template includes polystyrene-based materials, including polystyrene and polystyrene copolymers. Polystyrene copolymers include copolymers having water-soluble monomers, such as polystyrene / acrylic acid, polystyrene / poly(ethylene glycol) methacrylate, and polystyrene / styrene sulfonate.

[0023] Metal oxides include oxides of transition metals, metalloids, and rare earth elements, such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxides, zinc oxide, indium oxide, tin oxide, chromium oxide, mixed metal oxides, and combinations thereof.

[0024] The wt / wt ratio of polymer nanoparticles to metal oxide is, for example, from about 0.1 / 1 to about 10.0 / 1 or from about 0.5 / 1 to about 10.0 / 1.

[0025] The continuous oil phase includes, for example, organic solvents, silicone oils, or fluorinated oils. According to the present invention, "oil" refers to an organic phase that is immiscible with water. Organic solvents include hydrocarbons, such as heptane, hexane, toluene, xylene, etc., and alkanols, such as methanol, ethanol, propanol, etc.

[0026] The emulsion droplets are collected, dried, and the polymer is removed. Drying can be carried out, for example, by microwave radiation, in a hot oven, under vacuum, in the presence of a desiccant, or a combination thereof.

[0027] Polymer removal can be performed, for example, by calcination, pyrolysis, or with a solvent (solvent removal). In some embodiments, calcination is carried out at temperatures of at least about 200°C, at least about 500°C, at least about 1000°C, about 200°C to about 1200°C, or about 200°C to about 700°C. Calcination can last for a suitable time, for example, from about 0.1 hours to about 12 hours or from about 1 hour to about 8.0 hours. In other embodiments, calcination can last for at least about 0.1 hours, at least about 1 hour, at least about 5 hours, or at least about 10 hours.

[0028] Alternatively, an oil-in-oil emulsion can be formed by combining an oil dispersion phase with a continuous aqueous phase to create a liquid dispersion containing polymer nanoparticles and metal oxides. The oil droplets can then be collected and dried like aqueous droplets.

[0029] Alternatively, a liquid dispersion of polymer nanoparticles and metal oxides is prepared and spray-dried to form polymer-templated microspheres without forming a liquid-liquid emulsion. In some embodiments of the spray drying technique, the liquid solution or dispersion is fed (e.g., pumped) into an atomizing nozzle associated with a compressed gas inlet. The feed is pumped through the atomizing nozzle to form liquid droplets. The droplets are surrounded by a preheated gas in an evaporation chamber, causing the solvent to evaporate and produce solid particles. The dried particles are carried by the drying gas through a cyclone separator and deposited in a collection chamber. The gas includes nitrogen and / or air. In one embodiment of the spray drying method, the liquid feed contains a water or oil phase, polymer particles, and metal oxides. In another embodiment of the spray drying method, the liquid feed contains a water or oil phase, polymer particles, and optionally metal oxides. Polymer-templated microspheres containing polymer nanospheres and metal oxides in the interstitial spaces between the polymer nanospheres are provided. The polymer nanospheres define the interstitial spaces. Spray drying techniques include inkjet spray drying methods and apparatus.

[0030] In spray drying technology, air can be considered as a continuous phase with a dispersed liquid phase (liquid-gas emulsion). In some embodiments, spray drying includes an inlet temperature of any one of about 100°C, about 105°C, about 110°C, about 115°C, about 120°C, about 130°C, about 140°C, about 150°C, about 160°C, or about 170°C, up to about 180°C, about 190°C, about 200°C, about 210°C, about 215°C, or about 220°C. In some embodiments, pump rates (feed flow rates) of any one to any one of approximately 1 mL / min, approximately 2 mL / min, approximately 5 mL / min, approximately 6 mL / min, approximately 8 mL / min, approximately 10 mL / min, approximately 12 mL / min, approximately 14 mL / min, or approximately 16 mL / min are used, up to approximately 18 mL / min, approximately 20 mL / min, approximately 22 mL / min, approximately 24 mL / min, approximately 26 mL / min, approximately 28 mL / min, or approximately 30 mL / min. Spray drying technology is disclosed, for example, in US2016 / 0170091.

[0031] Figure 4 This is an illustration of a spray drying method according to some embodiments of the present invention.

[0032] The microspheres are spherical or near-spherical and are on the micrometer scale, for example, having an average diameter of about 0.5 micrometers (µm) to about 100 µm. The polymer nanoparticles used as templates are also spherical, nanometer-scale, and monodisperse, having an average diameter of, for example, about 50 nm to about 999 nm. The metal oxides used may also be in particle form, and these particles may be nanometer-scale.

[0033] The metal oxide of the dispersion can be provided as a metal oxide or can be provided by a metal oxide precursor, for example, via sol-gel technology.

[0034] The drying of polymer / metal oxide microdroplets followed by polymer removal yields microspheres with uniform porosity (pores). Generally, in this method, each microdroplet provides a single microsphere. The pore size depends on the particle size of the polymer particles. A certain degree of "shrinkage" or compaction may occur during polymer removal to provide a pore size slightly smaller than the original polymer particle size, for example, approximately 10% to approximately 40% smaller. As with the polymer particle shape and size, the pore size is uniform.

[0035] In some implementations, the pore size can be from about 50 nm to about 999 nm.

[0036] The average porosity of metal oxide microspheres can be relatively high, for example, from about 0.10 or about 0.30 to about 0.80 or about 0.90. The average porosity of a microsphere refers to the total pore volume as a fraction of the total volume of the entire microsphere. Average porosity may be referred to as the "volume fraction".

[0037] In some embodiments, the porous microspheres may have a solid core (center), wherein the porosity is typically near the outer surface of the microsphere. In other embodiments, the porous microspheres may have a hollow core, wherein the porosity is mostly near the interior of the microsphere. In still other embodiments, the porosity may be distributed throughout the microsphere volume. In yet another embodiment, the porosity may exist as a gradient, with higher porosity tending towards the outer surface of the microsphere and lower porosity or no porosity (solid) tending towards the center; or lower porosity tending towards the outer surface and higher or completely porosity (hollow) tending towards the center.

[0038] For any porous microsphere, the average microsphere diameter is greater than the average pore size, for example, the average microsphere diameter is at least about 25 times, at least about 30 times, at least about 35 times, or at least about 40 times the average pore size.

[0039] In some embodiments, the ratio of the average microsphere diameter to the average pore size is, for example, any one of approximately 40 / 1, approximately 50 / 1, approximately 60 / 1, approximately 70 / 1, approximately 80 / 1, approximately 90 / 1, approximately 100 / 1, approximately 110 / 1, approximately 120 / 1, approximately 130 / 1, approximately 140 / 1, approximately 150 / 1, approximately 160 / 1, approximately 170 / 1, approximately 180 / 1, or approximately 190 / 1 to approximately 200 / 1, approximately 210 / 1, approximately 220 / 1, approximately 230 / 1, approximately 240 / 1, approximately 250 / 1, approximately 260 / 1, approximately 270 / 1, approximately 280 / 1, approximately 290 / 1, approximately 300 / 1, approximately 310 / 1, approximately 320 / 1, approximately 330 / 1, approximately 340 / 1, or approximately 350 / 1.

[0040] Polymer-templated microspheres containing monodisperse polymer nanospheres can provide metal oxide microspheres with pores that are typically similar in size when the polymer is removed.

[0041] While not wishing to be bound by theory, it is believed that when the porosity and / or microsphere diameter and / or pore size are within a certain range, batch samples of microspheres exhibit saturated colors with reduced unwanted light scattering. The color properties of batch samples are important because colorants are used in batches, for example in paints, inks, coatings, cosmetics, or materials used for medical or safety purposes. In some embodiments, white microspheres are desirable, for example, as a white colorant.

[0042] Porous microspheres primarily comprise metal oxides; that is, they may consist essentially of or be composed of metal oxides. Advantageously, batch samples of porous microspheres exhibit colors perceptible to the human eye. Light absorbers may also be present in the microspheres, providing a more saturated, perceptible color. Absorbers include inorganic and organic pigments, such as broadband absorbers like carbon black. Absorbers can be added, for example, by physically mixing the microspheres and absorbers together or by including the absorber in the microdroplets to be dried. For carbon black, it can be produced in situ from polymer decomposition using controlled calcination. Microspheres may not exhibit a perceptible color without the addition of a light absorber and may exhibit a perceptible color with the addition of a light absorber.

[0043] Porous microspheres can be used as colorants in applications such as aqueous formulations, oil-based formulations, inks, coatings, food, plastics, cosmetics, or materials for medical or safety purposes. Coatings include, for example, architectural coatings, automotive coatings, and varnishes.

[0044] Porous metal oxide microspheres can exhibit angle-dependent or angle-independent colors. "Angle-dependent" color refers to the observed color being dependent on the angle of incident light on the sample or on the angle between the observer and the sample. "Angle-independent" color refers to the observed color being essentially undependent on the angle of incident light on the sample or on the angle between the observer and the sample.

[0045] Angle-dependent colors can be achieved, for example, using monodisperse polymer nanospheres. Angle-dependent colors can also be achieved when the drying of liquid droplets to provide polymer template microspheres proceeds slowly, allowing the polymer nanospheres to become ordered. Non-angle-dependent colors can be achieved when the drying of liquid droplets proceeds rapidly, thus preventing the polymer nanospheres from becoming ordered.

[0046] For example, porous microspheres may contain from about 60.0% to about 99.9% by weight of metal oxide and from about 0.1% to about 40.0% by weight of one or more light absorbers based on the total weight of the microspheres.

[0047] Advantageously, porous microspheres can also be monodisperse.

[0048] According to the present invention, particle size is synonymous with particle diameter and is determined, for example, by scanning electron microscopy (SEM) or transmission electron microscopy (TEM). Average particle size is synonymous with D50, which refers to the number of particles that are above and below a certain point. Particle size refers to primary particles. Particle size can be measured using laser scattering techniques with dispersions or dry powders.

[0049] The porosity of microspheres is characterized using mercury porosimetry. In mercury porosimetry, a controlled pressure is applied to a sample immersed in mercury. This external pressure causes mercury to penetrate the pores / pores of the material. The amount of pressure required to penetrate the pores / pores is inversely proportional to the size of the pores / pores. The pressure vs. penetration data generated by the mercury porosimetry instrument are used to generate the volume and pore size distribution using the Washburn equation. For example, porous silica microspheres containing pores / pores with an average size of 165 nm have an average porosity of 0.8.

[0050] The term "batch sample" refers to a group of microspheres. For example, a batch sample of microspheres is simply a batch of microspheres, such as ≥ 0.1 mg, ≥ 0.2 mg, ≥ 0.3 mg, ≥ 0.4 mg, ≥ 0.5 mg, ≥ 0.7 mg, ≥ 1.0 mg, ≥ 2.5 mg, ≥ 5.0 mg, ≥ 10.0 mg, or ≥ 25.0 mg. A batch sample of microspheres may be substantially free of other components. The term "porous microspheres" can also refer to a batch sample.

[0051] The phrase "exhibiting colors perceptible to the human eye" refers to colors as observed by the average person. This can apply to any batch of samples distributed over any surface area, for example, distributed over approximately 1 cm². 2 Approximately 2 cm 2 Approximately 3 cm 2 Approximately 4 cm 2 Approximately 5 cm 2 or about 6 cm 2 Any one up to approximately 7 cm 2 Approximately 8 cm 2 Approximately 9 cm 2 Approximately 10 cm 2 Approximately 11cm 2 Approximately 12 cm 2 Approximately 13 cm 2 Approximately 14 cm 2 Or about 15 cm 2 A batch of samples on any of the surface areas. It can also refer to samples observable by a CIE 1931 2° standard observer and / or a CIE 1964 10° standard observer. The background used for color observation can be any background, such as a white background, a black background, or a dark background between white and black.

[0052] The term “...of…” can mean “containing…”, for example, “...of liquid dispersion” can be interpreted as “containing…of liquid dispersion”.

[0053] The terms “microspheres,” “nanospheres,” “microdroplets,” etc., mentioned in this article can refer to, for example, multiple of them, their collections, their groups, their samples, or their batches of samples.

[0054] The term "micrometer" or "micrometer-scale" refers to a size from approximately 0.5 µm to approximately 999 µm. The term "nanometer" or "nanometer-scale" refers to a size from approximately 1 nm to approximately 999 nm.

[0055] The terms "sphere" and "particle" are used interchangeably.

[0056] The term "monodisperse" in relation to a population of microspheres or nanospheres refers to particles having a substantially uniform shape and a substantially uniform diameter. A monodisperse population of microspheres or nanospheres may, for example, have 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% of its particles having a diameter within ±7%, ±6%, ±5%, ±4%, ±3%, ±2%, or ±1% of the average diameter of the population.

[0057] "Matrix" can refer to an aqueous or oil-based matrix or "medium," and the matrix can be a minor or major part of the final composition. Matrix can also refer to solids, semi-solids, gels, liquids, pastes, ointments, etc.

[0058] The removal of monodisperse groups of polymer nanospheres provides porous metal oxide microspheres with corresponding pore groups, the pores having an average pore size.

[0059] The term "substantially free of other components" means, for example, containing ≤ 5%, ≤ 4%, ≤ 3%, ≤ 2%, ≤ 1%, or ≤ 0.5% of other components by weight.

[0060] The articles “a” and “an” refer to one or more (e.g., at least one) grammatical objects in this document. Any ranges referenced herein include the endpoints. The term “approximately” is used throughout to describe and account for small fluctuations. For example, “approximately” can mean that a numerical value can be modified by ±5%, ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.4%, ±0.3%, ±0.2%, ±0.1%, or ±0.05%. All numerical values ​​are modified by the term “approximately”, whether explicitly stated or not. Numerical values ​​modified by the term “approximately” include the specifically specified value. For example, “approximately 5.0” includes 5.0.

[0061] U.S. patents, U.S. patent applications, and published U.S. patent applications discussed in this document are hereby cited and incorporated herein by reference.

[0062] Unless otherwise specified, all parts and percentages are by weight. Unless otherwise specified, weight % (wt%) is based on the whole composition without any volatiles, i.e., based on dry solids content.

[0063] A non-limiting first embodiment of the present invention relates to a method for preparing porous metal oxide microspheres, comprising: In a first embodiment, a method for preparing porous metal oxide microspheres comprising a metal oxide is disclosed, the method comprising forming a liquid dispersion of polymer nanoparticles and a metal oxide; forming liquid droplets of the dispersion; drying the liquid droplets to provide polymer template microspheres comprising polymer nanospheres and a metal oxide; and removing the polymer nanospheres from the template microspheres to provide porous metal oxide microspheres.

[0064] In a second embodiment, the method according to the first embodiment includes forming a liquid dispersion of polymer nanoparticles and metal oxides, spray drying the liquid dispersion to provide polymer template microspheres, and removing the polymer nanospheres from the template microspheres.

[0065] In a third embodiment, the method of the first embodiment includes forming liquid droplets using a vibrating nozzle. In a fourth embodiment, the method of embodiments 1 to 3 is used, wherein the liquid droplets are aqueous droplets. In a fifth embodiment, the method of embodiments 1 to 3 is used, wherein the liquid droplets are oil droplets.

[0066] In a sixth embodiment, the method of embodiment 1 includes providing a continuous phase and mixing the liquid dispersion with the continuous phase to form an emulsion containing dispersed liquid dispersion droplets. In a seventh embodiment, the method of embodiment 6 includes providing a continuous oil phase and mixing an aqueous dispersion with the continuous oil phase to form a water-in-oil emulsion containing aqueous droplets. In an eighth embodiment, the method of embodiment 6 includes providing a continuous aqueous phase and mixing an oil dispersion with the continuous phase to form an oil-in-water emulsion containing oil droplets.

[0067] In a ninth embodiment, the method according to embodiments 6 to 8 includes collecting the microdroplets. In a tenth embodiment, the method according to embodiment 9 includes drying the microdroplets to provide polymer template microspheres comprising polymer nanospheres and metal oxides, and removing the polymer nanospheres from the template microspheres.

[0068] In the eleventh embodiment, according to the methods of embodiments 6 to 10, the microdroplet drying includes microwave irradiation, oven drying, drying under vacuum, drying in the presence of a desiccant, or a combination thereof.

[0069] In a twelfth embodiment, the method of embodiments 7 to 11, wherein the oil phase or dispersion comprises a hydrocarbon, silicone oil, or fluorinated oil. In a thirteenth embodiment, the method of embodiments 6 to 12, wherein droplet formation is performed in a microfluidic device. In a fourteenth embodiment, the method of embodiments 6 to 13, wherein droplet formation is performed in a microfluidic device containing a droplet connector having a channel width of any one to approximately 50 µm, approximately 55 µm, approximately 60 µm, approximately 65 µm, approximately 70 µm, approximately 75 µm, approximately 80 µm, approximately 85 µm, approximately 90 µm, approximately 95 µm, or approximately 100 µm. In a fifteenth embodiment, the method of embodiments 13 or 14, which includes collecting the droplets from the microfluidic device.

[0070] In the sixteenth embodiment, the method according to any of the preceding embodiments, wherein the wt / wt ratio of the polymer nanoparticles to the metal oxide is any one to approximately 3.5 / 1, approximately 4.0 / 1, approximately 5.0 / 1, approximately 5.5 / 1, approximately 6.0 / 1, approximately 6.5 / 1, approximately 7.0 / 1, approximately 8.0 / 1, approximately 9.0 / 1, or approximately 10.0 / 1.

[0071] In the seventeenth embodiment, according to the method of any of the preceding embodiments, the polymer nanoparticles have an average diameter of any one of about 50 nm, about 75 nm, about 100 nm, about 130 nm, about 160 nm, about 190 nm, about 210 nm, about 240 nm, about 270 nm, about 300 nm, about 330 nm, about 360 nm, about 390 nm, about 410 nm, about 440 nm, about 470 nm, about 500 nm, about 530 nm, about 560 nm, about 590 nm, or about 620 nm to about 650 nm, about 680 nm, about 710 nm, about 740 nm, about 770 nm, about 800 nm, about 830 nm, about 860 nm, about 890 nm, about 910 nm, about 940 nm, about 970 nm, or about 990 nm.

[0072] In the eighteenth embodiment, the polymer is selected from poly(meth)acrylic acid, poly(meth)acrylate, polystyrene, polyacrylamide, polyethylene, polypropylene, polylactic acid, polyacrylonitrile, derivatives thereof, salts thereof, copolymers thereof, and combinations thereof, according to any of the preceding embodiments.

[0073] In a nineteenth embodiment, the method according to any of the preceding embodiments, wherein the polymer is selected from polystyrene, such as polystyrene copolymers, such as polystyrene / acrylic acid, polystyrene / poly(ethylene glycol) methacrylate, or polystyrene / styrene sulfonate. In a twentieth embodiment, the method according to any of the preceding embodiments, wherein the metal oxide is one or more of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, or chromium oxide.

[0074] In the twenty-first embodiment, according to the method of any of the preceding embodiments, the porous microspheres have an average diameter of about 0.5 µm to about 100 µm, an average porosity of about 0.10 to about 0.90 or about 0.10 to about 0.80, and an average pore size of about 50 nm to about 999 nm.

[0075] In the twenty-second embodiment, according to the method of any of the preceding embodiments, the porous microspheres have an average diameter of about 1 µm to about 75 µm, about 2 µm to about 70 µm, about 3 µm to about 65 µm, about 4 µm to about 60 µm, about 5 µm to about 55 µm, or about 5 µm to about 50 µm; for example, any one of about 5 µm, about 6 µm, about 7 µm, about 8 µm, about 9 µm, about 10 µm, about 11 µm, about 12 µm, about 13 µm, about 14 µm, or about 15 µm to about 16 µm, about 17 µm, about 18 µm, about 19 µm, about 20 µm, about 21 µm, about 22 µm, about 23 µm, about 24 µm, or about 25 µm.

[0076] In the twenty-third embodiment, according to the method of any of the foregoing embodiments, the porous microspheres have a molecular weight of approximately 0.10, approximately 0.12, approximately 0.14, approximately 0.16, approximately 0.18, approximately 0.20, approximately 0.22, approximately 0.24, approximately 0.26, approximately 0.28, approximately 0.30, approximately 0.32, approximately 0.34, approximately 0.36, approximately 0.38, approximately 0.40, approximately 0.42, approximately 0.44, approximately 0.46, or approximately 0.48. Average porosity of approximately 0.50, approximately 0.52, approximately 0.54, approximately 0.56, approximately 0.58, or approximately 0.60 to approximately 0.62, approximately 0.64, approximately 0.66, approximately 0.68, approximately 0.70, approximately 0.72, approximately 0.74, approximately 0.76, approximately 0.78, approximately 0.80, or approximately 0.90.

[0077] In the twenty-fourth embodiment, according to the method of any of the preceding embodiments, the porous microspheres have a range from approximately 50 nm, approximately 60 nm, approximately 70 nm, 80 nm, approximately 100 nm, approximately 120 nm, approximately 140 nm, approximately 160 nm, approximately 180 nm, approximately 200 nm, approximately 220 nm, approximately 240 nm, approximately 260 nm, approximately 280 nm, approximately 300 nm, approximately 320 nm, approximately 340 nm, approximately 360 nm, approximately 380 nm, approximately 400 nm, approximately 420 nm, or approximately 440 nm to approximately 460 nm, approximately 480 nm, approximately 500 nm, approximately 520 nm, approximately 540 nm, approximately 560 nm, approximately 580 nm, approximately 600 nm, approximately 620 nm, approximately 640 nm, approximately 660 nm, approximately 680 nm, approximately 700 nm, approximately 720 nm, approximately 740 nm, or approximately 760 nm. The average pore size is either nm, approximately 780 nm, or approximately 800 nm.

[0078] In the twenty-fifth embodiment, according to the method of any of the preceding embodiments, the porous microspheres have an average diameter of any one of about 4.5 µm, about 4.8 µm, about 5.1 µm, about 5.4 µm, about 5.7 µm, about 6.0 µm, about 6.3 µm, about 6.6 µm, about 6.9 µm, about 7.2 µm or about 7.5 µm to about 7.8 µm, about 8.1 µm, about 8.4 µm, about 8.7 µm, about 9.0 µm, about 9.3 µm, about 9.6 µm or about 9.9 µm.

[0079] In the twenty-sixth embodiment, according to the method of any of the preceding embodiments, the porous microspheres have an average porosity of any one to any one of about 0.59, about 0.61, about 0.63, or about 0.65, from about 0.45, about 0.47, about 0.49, about 0.51, about 0.53, about 0.55, or about 0.57.

[0080] In the twenty-seventh embodiment, according to the method of any of the preceding embodiments, the porous microspheres have an average pore size of any one of about 220 nm, about 225 nm, about 230 nm, about 235 nm, about 240 nm, about 245 nm or about 250 nm to about 255 nm, about 260 nm, about 265 nm, about 270 nm, about 275 nm, about 280 nm, about 285 nm, about 290 nm, about 295 nm or about 300 nm.

[0081] In the twenty-eighth embodiment, according to the method of any of the preceding embodiments, the porous microspheres have an average diameter of any one of approximately 4.5 µm, approximately 4.8 µm, approximately 5.1 µm, approximately 5.4 µm, approximately 5.7 µm, approximately 6.0 µm, approximately 6.3 µm, approximately 6.6 µm, approximately 6.9 µm, approximately 7.2 µm, or approximately 7.5 µm to approximately 7.8 µm, approximately 8.1 µm, approximately 8.4 µm, approximately 8.7 µm, approximately 9.0 µm, approximately 9.3 µm, approximately 9.6 µm, or approximately 9.9 µm; an average porosity of approximately 0.45, approximately 0.47, approximately 0.49, approximately 0.51, approximately 0.53, approximately 0.55, or approximately 0.57 to approximately 0.59, approximately 0.61, approximately 0.63, or approximately 0.65; and an average porosity of approximately 220 nm, approximately 225 nm. The average pore size is any one of approximately 250 nm, approximately 230 nm, approximately 235 nm, approximately 240 nm, approximately 245 nm or approximately 250 nm to any one of approximately 255 nm, approximately 260 nm, approximately 265 nm, approximately 270 nm, approximately 275 nm, approximately 280 nm, approximately 285 nm, approximately 290 nm, approximately 295 nm or approximately 300 nm.

[0082] In the twenty-ninth embodiment, according to the method of any of the preceding embodiments, the porous microspheres comprise from about 60.0 wt% to about 99.9 wt% of metal oxide based on the total weight of the microspheres, for example, from any one of about 60.0 wt%, about 64.0 wt%, about 67.0 wt%, about 70.0 wt%, about 73.0 wt%, about 76.0 wt%, about 79.0 wt%, about 82.0 wt%, or about 85.0 wt% to about 88.0 wt%, about 91.0 wt%, about 94.0 wt%, about 97.0 wt%, about 98.0 wt%, about 99.0 wt%, or about 99.9 wt% of metal oxide.

[0083] In the thirtieth embodiment, according to the method of any of the preceding embodiments, the porous microspheres comprise one or more light absorbers in an amount of about 0.1 wt% to about 40.0 wt% based on the total weight of the microspheres, for example, comprising one or more light absorbers in any one of the following amounts: about 0.1 wt%, about 0.3 wt%, about 0.5 wt%, about 0.7 wt%, about 0.9 wt%, about 1.0 wt%, about 1.5 wt%, about 2.0 wt%, about 2.5 wt%, about 5.0 wt%, about 7.5 wt%, about 10.0 wt%, about 13.0 wt%, about 17.0 wt%, about 20.0 wt%, or about 22.0 wt% to about 24.0 wt%, about 27.0 wt%, about 29.0 wt%, about 31.0 wt%, about 33.0 wt%, about 35.0 wt%, about 37.0 wt%, about 39.0 wt%, or about 40.0 wt%.

[0084] In the thirty-first embodiment, the method according to any of the foregoing embodiments, wherein the porous microspheres comprise one or more light absorbers selected from inorganic and organic pigments, such as carbon black.

[0085] In the thirty-second embodiment, the method according to any of the preceding embodiments, wherein a batch sample of porous microspheres exhibits a color perceptible to the human eye. In the thirty-third embodiment, the method according to any of the preceding embodiments, wherein a batch sample of porous microspheres exhibits a non-angle-dependent color perceptible to the human eye. In the thirty-fourth embodiment, the method according to any of embodiments 1-32, wherein a batch sample of porous microspheres exhibits an angle-dependent color perceptible to the human eye.

[0086] In the thirty-fifth embodiment, the porous microspheres are monodisperse according to the method of any of the preceding embodiments. In the thirty-sixth embodiment, the porous metal oxide microspheres are batch samples of microspheres according to the method of any of the preceding embodiments.

[0087] In the thirty-seventh embodiment, the method according to any of the preceding embodiments, wherein removing the polymer nanospheres from the template microspheres includes calcination, pyrolysis, or solvent removal.

[0088] In the thirty-eighth embodiment, the method according to any of the preceding embodiments, wherein removing the polymer nanospheres includes calcining the template microspheres at a temperature of about 200°C, about 350°C, about 400°C, 450°C, about 500°C, or about 550°C, up to about 600°C, about 650°C, about 700°C, or about 1200°C for about 0.1 h, 1 h, about 1.5 h, about 2.0 h, about 2.5 h, about 3.0 h, about 3.5 h, or about 4.0 h, up to about 4.5 h, about 5.0 h, about 5.5 h, about 6.0 h, about 6.5 h, about 7.0 h, about 7.5 h, about 8.0 h, or about 12 h. Alternatively, the calcination may be sustained at a temperature of at least about 200°C, at least about 500°C, or at least about 1000°C for a suitable time, for example, at least about 0.1 hours, at least about 1 hour, at least about 5 hours, or at least about 10 hours.

[0089] In the thirty-ninth embodiment, porous microspheres prepared according to any of the foregoing methods are disclosed. In the fortieth embodiment, batch samples of porous microspheres prepared according to any of the foregoing methods are disclosed.

[0090] A non-limiting second embodiment of the present invention relates to porous metal oxide microspheres, comprising: In a first embodiment, porous microspheres comprising metal oxides are provided, wherein the microspheres have an average diameter of about 0.5 µm to about 100 µm, an average porosity of about 0.10 to about 0.90 or about 0.10 to about 0.80, and an average pore size of about 50 nm to about 999 nm.

[0091] In a second embodiment, porous microspheres according to embodiment 1 are disclosed having an average diameter of about 1 µm to about 75 µm, about 2 µm to about 70 µm, about 3 µm to about 65 µm, about 4 µm to about 60 µm, about 5 µm to about 55 µm or about 5 µm; for example, any one of about 5 µm, about 6 µm, about 7 µm, about 8 µm, about 9 µm, about 10 µm, about 11 µm, about 12 µm, about 13 µm, about 14 µm or about 15 µm to about 16 µm, about 17 µm, about 18 µm, about 19 µm, about 20 µm, about 21 µm, about 22 µm, about 23 µm, about 24 µm or about 25 µm.

[0092] In the third embodiment, the porous microspheres according to embodiment 1 or 2 have a molecular weight of approximately 0.10, approximately 0.12, approximately 0.14, approximately 0.16, approximately 0.18, approximately 0.20, approximately 0.22, approximately 0.24, approximately 0.26, approximately 0.28, approximately 0.30, approximately 0.32, approximately 0.34, approximately 0.36, approximately 0.38, approximately 0.40, approximately 0.42, approximately 0.44, approximately 0.46, and approximately 0.48. Average porosity of approximately 0.50, approximately 0.52, approximately 0.54, approximately 0.56, approximately 0.58, or approximately 0.60 to approximately 0.62, approximately 0.64, approximately 0.66, approximately 0.68, approximately 0.70, approximately 0.72, approximately 0.74, approximately 0.76, approximately 0.78, approximately 0.80, or approximately 0.90.

[0093] In the fourth embodiment, the porous microspheres according to any of the foregoing embodiments have a wavelength of approximately 50 nm, approximately 60 nm, approximately 70 nm, approximately 80 nm, approximately 100 nm, approximately 120 nm, approximately 140 nm, approximately 160 nm, approximately 180 nm, approximately 200 nm, approximately 220 nm, approximately 240 nm, approximately 260 nm, approximately 280 nm, approximately 300 nm, approximately 320 nm, approximately 340 nm, approximately 360 nm, approximately 380 nm, approximately 400 nm, approximately 420 nm, or approximately 440 nm to approximately 460 nm, approximately 480 nm, approximately 500 nm, approximately 520 nm, approximately 540 nm, approximately 560 nm, approximately 580 nm, approximately 600 nm, approximately 620 nm, approximately 640 nm, approximately 660 nm, approximately 680 nm, approximately 700 nm, approximately 720 nm, approximately 740 nm, or approximately 760 nm. The average pore size is either nm, approximately 780 nm, or approximately 800 nm.

[0094] In the fifth embodiment, the porous microspheres according to any of the foregoing embodiments have an average diameter of any one of about 4.5 µm, about 4.8 µm, about 5.1 µm, about 5.4 µm, about 5.7 µm, about 6.0 µm, about 6.3 µm, about 6.6 µm, about 6.9 µm, about 7.2 µm or about 7.5 µm to about 7.8 µm, about 8.1 µm, about 8.4 µm, about 8.7 µm, about 9.0 µm, about 9.3 µm, about 9.6 µm or about 9.9 µm. In a sixth embodiment, the porous microspheres according to any of the preceding embodiments have an average porosity of approximately 0.45, approximately 0.47, approximately 0.49, approximately 0.51, approximately 0.53, approximately 0.55, or approximately 0.57 to approximately 0.59, approximately 0.61, approximately 0.63, or approximately 0.65. In a seventh embodiment, the porous microspheres according to any of the preceding embodiments have an average pore size of approximately 220 nm, approximately 225 nm, approximately 230 nm, approximately 235 nm, approximately 240 nm, approximately 245 nm, or approximately 250 nm to approximately 255 nm, approximately 260 nm, approximately 265 nm, approximately 270 nm, approximately 275 nm, approximately 280 nm, approximately 285 nm, approximately 290 nm, approximately 295 nm, or approximately 300 nm.

[0095] In the eighth embodiment, the porous microspheres according to any of the foregoing embodiments have a diameter of any one of approximately 4.5 µm, approximately 4.8 µm, approximately 5.1 µm, approximately 5.4 µm, approximately 5.7 µm, approximately 6.0 µm, approximately 6.3 µm, approximately 6.6 µm, approximately 6.9 µm, approximately 7.2 µm, or approximately 7.5 µm up to approximately 7.8 µm, approximately 8.1 µm, approximately 8.4 µm, approximately 8.7 µm, approximately 9.0 µm, approximately 9.3 µm, approximately 9.6 µm, or approximately 9.9 µm. The average diameter is any one of µm; and it has an average porosity of any one to any one of about 0.59, about 0.61, about 0.63 or about 0.65 from about 0.45, about 0.47, about 0.49, about 0.51, about 0.53, about 0.55 or about 0.57; and it has an average pore size of any one to any one of about 220 nm, about 225 nm, about 230 nm, about 235 nm, about 240 nm, about 245 nm or about 250 nm, up to about 255 nm, about 260 nm, about 265 nm, about 270 nm, about 275 nm, about 280 nm, about 285 nm, about 290 nm, about 295 nm or about 300 nm.

[0096] In the ninth embodiment, the porous microspheres according to any of the preceding embodiments comprise from about 60.0% to about 99.9% by weight of metal oxide based on the total weight of the microspheres, for example, from any one of about 60.0% by weight, about 64.0% by weight, about 67.0% by weight, about 70.0% by weight, about 73.0% by weight, about 76.0% by weight, about 79.0% by weight, about 82.0% by weight, or about 85.0% by weight to about 88.0% by weight, about 91.0% by weight, about 94.0% by weight, about 97.0% by weight, about 98.0% by weight, about 99.0% by weight, or about 99.9% by weight of metal oxide.

[0097] In a tenth embodiment, the porous microspheres according to any of the preceding embodiments, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof. In an eleventh embodiment, the porous microspheres according to any of the preceding embodiments, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, and combinations thereof.

[0098] In the twelfth embodiment, the porous microspheres according to any of the foregoing embodiments comprise one or more light absorbers in an amount of about 0.1 wt% to about 40.0 wt% based on the total weight of the microspheres, for example, comprising one or more light absorbers in any one of the following amounts: about 0.1 wt%, about 0.3 wt%, about 0.5 wt%, about 0.7 wt%, about 0.9 wt%, about 1.0 wt%, about 1.5 wt%, about 2.0 wt%, about 2.5 wt%, about 5.0 wt%, about 7.5 wt%, about 10.0 wt%, about 13.0 wt%, about 17.0 wt%, about 20.0 wt%, or about 22.0 wt% to about 24.0 wt%, about 27.0 wt%, about 29.0 wt%, about 31.0 wt%, about 33.0 wt%, about 35.0 wt%, about 37.0 wt%, about 39.0 wt%, or about 40.0 wt%. In the thirteenth embodiment, the porous microspheres according to any of the foregoing embodiments comprise one or more light absorbers selected from inorganic and organic pigments, such as carbon black.

[0099] In the fourteenth embodiment, the porous microspheres according to any of the preceding embodiments exhibit a color perceptible to the human eye. In the fifteenth embodiment, the porous microspheres according to any of the preceding embodiments exhibit a non-angle-dependent color perceptible to the human eye. In the sixteenth embodiment, the porous microspheres according to any of embodiments 1-14 exhibit an angle-dependent color perceptible to the human eye.

[0100] In the seventeenth embodiment, the porous microspheres according to any of the preceding embodiments are monodisperse. In the eighteenth embodiment, a composition comprising a matrix and porous microspheres according to any of the preceding embodiments is provided. In the nineteenth embodiment, the composition according to embodiment 18 is an aqueous formulation, an oil-based formulation, an ink, a paint formulation, a food product, a plastic product, a cosmetic formulation, or a material for medical or safety purposes.

[0101] The non-limiting third group of embodiments of this disclosure relates to porous metal oxide microspheres, including: In the first embodiment, porous microspheres comprising metal oxides are disclosed, wherein batch samples of the porous microspheres exhibit a color perceptible to the human eye.

[0102] In a second embodiment, the porous microspheres according to embodiment 1 have an average diameter of about 0.5 µm to about 100 µm, an average porosity of about 0.10 to about 0.90 or about 0.10 to about 0.80, and an average pore size of about 50 nm to about 999 nm.

[0103] In a third embodiment, the porous microspheres according to embodiment 1 or 2 have an average diameter of about 1 µm to about 75 µm, about 2 µm to about 70 µm, about 3 µm to about 65 µm, about 4 µm to about 60 µm, about 5 µm to about 55 µm or about 5 µm; for example, any one of about 5 µm, about 6 µm, about 7 µm, about 8 µm, about 9 µm, about 10 µm, about 11 µm, about 12 µm, about 13 µm, about 14 µm or about 15 µm to about 16 µm, about 17 µm, about 18 µm, about 19 µm, about 20 µm, about 21 µm, about 22 µm, about 23 µm, about 24 µm or about 25 µm.

[0104] In the fourth embodiment, the porous microspheres according to any of the foregoing embodiments have a molecular weight of approximately 0.10, approximately 0.12, approximately 0.14, approximately 0.16, approximately 0.18, approximately 0.20, approximately 0.22, approximately 0.24, approximately 0.26, approximately 0.28, approximately 0.30, approximately 0.32, approximately 0.34, approximately 0.36, approximately 0.38, approximately 0.40, approximately 0.42, approximately 0.44, approximately 0.46, and approximately 0.48. Average porosity of approximately 0.50, approximately 0.52, approximately 0.54, approximately 0.56, approximately 0.58, or approximately 0.60 to approximately 0.62, approximately 0.64, approximately 0.66, approximately 0.68, approximately 0.70, approximately 0.72, approximately 0.74, approximately 0.76, approximately 0.78, approximately 0.80, or approximately 0.90.

[0105] In the fifth embodiment, the porous microspheres according to any of the foregoing embodiments have a wavelength of approximately 50 nm, approximately 60 nm, approximately 70 nm, approximately 80 nm, approximately 100 nm, approximately 120 nm, approximately 140 nm, approximately 160 nm, approximately 180 nm, approximately 200 nm, approximately 220 nm, approximately 240 nm, approximately 260 nm, approximately 280 nm, approximately 300 nm, approximately 320 nm, approximately 340 nm, approximately 360 nm, approximately 380 nm, approximately 400 nm, approximately 420 nm, or approximately 440 nm to approximately 460 nm, approximately 480 nm, approximately 500 nm, approximately 520 nm, approximately 540 nm, approximately 560 nm, approximately 580 nm, approximately 600 nm, approximately 620 nm, approximately 640 nm, approximately 660 nm, approximately 680 nm, approximately 700 nm, approximately 720 nm, approximately 740 nm, or approximately 760 nm. The average pore size is either nm, approximately 780 nm, or approximately 800 nm.

[0106] In the sixth embodiment, the porous microspheres according to any of the foregoing embodiments have an average diameter of any one of about 4.5 µm, about 4.8 µm, about 5.1 µm, about 5.4 µm, about 5.7 µm, about 6.0 µm, about 6.3 µm, about 6.6 µm, about 6.9 µm, about 7.2 µm or about 7.5 µm to about 7.8 µm, about 8.1 µm, about 8.4 µm, about 8.7 µm, about 9.0 µm, about 9.3 µm, about 9.6 µm or about 9.9 µm. In a seventh embodiment, the porous microspheres according to any of the preceding embodiments have an average porosity of approximately 0.45, approximately 0.47, approximately 0.49, approximately 0.51, approximately 0.53, approximately 0.55, or approximately 0.57 to approximately 0.59, approximately 0.61, approximately 0.63, or approximately 0.65. In an eighth embodiment, the porous microspheres according to any of the preceding embodiments have an average pore size of approximately 220 nm, approximately 225 nm, approximately 230 nm, approximately 235 nm, approximately 240 nm, approximately 245 nm, or approximately 250 nm to approximately 255 nm, approximately 260 nm, approximately 265 nm, approximately 270 nm, approximately 275 nm, approximately 280 nm, approximately 285 nm, approximately 290 nm, approximately 295 nm, or approximately 300 nm.

[0107] In the ninth embodiment, the porous microspheres according to any of the foregoing embodiments have a diameter of any one of approximately 4.5 µm, approximately 4.8 µm, approximately 5.1 µm, approximately 5.4 µm, approximately 5.7 µm, approximately 6.0 µm, approximately 6.3 µm, approximately 6.6 µm, approximately 6.9 µm, approximately 7.2 µm, or approximately 7.5 µm up to approximately 7.8 µm, approximately 8.1 µm, approximately 8.4 µm, approximately 8.7 µm, approximately 9.0 µm, approximately 9.3 µm, approximately 9.6 µm, or approximately 9.9 µm. The average diameter is any one of µm; and it has an average porosity of any one to any one of about 0.59, about 0.61, about 0.63 or about 0.65 from about 0.45, about 0.47, about 0.49, about 0.51, about 0.53, about 0.55 or about 0.57; and it has an average pore size of any one to any one of about 220 nm, about 225 nm, about 230 nm, about 235 nm, about 240 nm, about 245 nm or about 250 nm, up to about 255 nm, about 260 nm, about 265 nm, about 270 nm, about 275 nm, about 280 nm, about 285 nm, about 290 nm, about 295 nm or about 300 nm.

[0108] In the tenth embodiment, the porous microspheres according to any of the foregoing embodiments comprise from about 60.0% to about 99.9% by weight of metal oxide based on the total weight of the microspheres, for example, from about 60.0% to about 88.0% to about 91.0% to about 94.0% to about 97.0% by weight of any one of about 82.0% or about 85.0% of metal oxide.

[0109] In the eleventh embodiment, the porous microspheres according to any of the preceding embodiments, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof. In the twelfth embodiment, the porous microspheres according to any of the preceding embodiments, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, and combinations thereof.

[0110] In the thirteenth embodiment, the porous microspheres according to any of the preceding embodiments comprise one or more light absorbers in an amount of about 0.1 wt% to about 40.0 wt% based on the total weight of the microspheres, for example, comprising one or more light absorbers in any one of the following amounts: about 0.1 wt%, about 0.3 wt%, about 0.5 wt%, about 0.7 wt%, about 0.9 wt%, about 1.0 wt%, about 1.5 wt%, about 2.0 wt%, about 2.5 wt%, about 5.0 wt%, about 7.5 wt%, about 10.0 wt%, about 13.0 wt%, about 17.0 wt%, about 20.0 wt%, or about 22.0 wt% to about 24.0 wt%, about 27.0 wt%, about 29.0 wt%, about 31.0 wt%, about 33.0 wt%, about 35.0 wt%, about 37.0 wt%, about 39.0 wt%, or about 40.0 wt%. In the fourteenth embodiment, the porous microspheres according to any of the foregoing embodiments comprise one or more light absorbers selected from inorganic and organic pigments, such as carbon black.

[0111] In the sixteenth embodiment, the porous microspheres according to any of the preceding embodiments exhibit a color perceptible to the human eye in batch samples of the porous microspheres.

[0112] In the seventeenth embodiment, the porous microspheres according to any of the foregoing embodiments are monodisperse.

[0113] In the eighteenth embodiment, the porous microspheres according to any of the preceding embodiments exhibit angle-dependent color perceptible to the human eye. In the nineteenth embodiment, the porous microspheres according to any of embodiments 1-17 exhibit angle-dependent color perceptible to the human eye.

[0114] In the twentieth embodiment, the composition comprises a matrix and porous microspheres according to any of the preceding embodiments. In the twenty-first embodiment, the composition according to embodiment 20 is an aqueous formulation, an oil-based formulation, a coating formulation, a food product, an ink, a plastic, a cosmetic formulation, or a material for medical or safety purposes.

[0115] The fourth set of non-restrictive implementations of this disclosure includes: Implementation Scheme 1. A method for preparing porous metal oxide microspheres containing metal oxides, the method comprising: Forming a liquid dispersion of polymer nanoparticles and metal oxides; Liquid droplets forming the dispersion; Drying the liquid droplets to provide polymer-templated microspheres comprising polymer nanospheres and metal oxides; and Polymer nanospheres are removed from template microspheres to provide porous metal oxide microspheres. The microspheres have The average diameter ranges from approximately 0.5 µm to approximately 100 µm. Average porosity of approximately 0.10 to approximately 0.80, and Average pore size: approximately 50 nm to approximately 999 nm.

[0116] Implementation Scheme 2. The method according to Implementation Scheme 1 includes forming a liquid dispersion of polymer nanoparticles and metal oxides, spray drying the liquid dispersion to provide polymer template microspheres, and removing polymer nanospheres from the template microspheres.

[0117] Implementation Scheme 3. The method according to Implementation Scheme 1 includes forming liquid droplets using a vibrating nozzle.

[0118] Implementation Scheme 4. The method according to Implementation Scheme 1, wherein the liquid droplets are aqueous droplets or oil droplets.

[0119] Implementation Scheme 5. The method according to Implementation Scheme 1 includes providing a continuous phase and mixing the liquid dispersion with the continuous phase to form an emulsion containing dispersed liquid dispersion droplets and collecting the droplets.

[0120] Implementation Scheme 6. The method according to Implementation Scheme 5 includes drying the droplets to provide polymer template microspheres comprising polymer nanospheres and metal oxides and removing the polymer nanospheres from the template microspheres.

[0121] Implementation Scheme 7. The method according to Implementation Scheme 6, wherein microdroplet drying includes microwave irradiation, oven drying, drying under vacuum, drying in the presence of a desiccant, or a combination thereof.

[0122] Implementation Scheme 8. The method according to Implementation Scheme 5, wherein the microdroplets are formed in a microfluidic device.

[0123] Implementation Scheme 9. The method according to any one of Implementation Schemes 1 to 8, wherein the wt / wt ratio of polymer nanoparticles to metal oxide is from about 0.5 / 1 to about 10.0 / 1.

[0124] Implementation Scheme 10. The method according to any one of Implementation Schemes 1 to 8, wherein the polymer nanoparticles have an average diameter of about 50 nm to about 990 nm.

[0125] Implementation Scheme 11. The method according to any one of Implementation Schemes 1 to 8, wherein the polymer is selected from poly(meth)acrylic acid, poly(meth)acrylate, polystyrene, polyacrylamide, polyethylene, polypropylene, polylactic acid, polyacrylonitrile, derivatives thereof, salts thereof, copolymers thereof, and combinations thereof.

[0126] Implementation Scheme 12. The method according to any one of Implementation Schemes 1 to 8, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof.

[0127] Implementation Scheme 13. The method according to any one of Implementation Schemes 1 to 8, wherein the porous microspheres are monodisperse.

[0128] Implementation Scheme 14. The method according to any one of Implementation Schemes 1 to 8, wherein the porous metal oxide microspheres are batch samples of microspheres.

[0129] Implementation Scheme 15. The method according to any one of Implementation Schemes 1 to 8, wherein removing the polymer nanospheres from the template microspheres includes calcination, pyrolysis or solvent removal.

[0130] Implementation Scheme 16. The method according to any one of Implementation Schemes 1 to 8, wherein removing the polymer nanospheres comprises calcining the template microspheres at a temperature of about 350°C to about 700°C for about 1 hour to about 8 hours.

[0131] Implementation Scheme 17. Porous microspheres prepared according to any one of Implementation Schemes 1 to 8.

[0132] Implementation Scheme 18. Batch samples of porous microspheres prepared according to any one of Implementation Schemes 1 to 8.

[0133] Implementation Scheme 19. Porous microspheres comprising metal oxides, wherein the microspheres have

[0134] The average diameter is approximately 1 µm to approximately 75 µm. Average porosity of approximately 0.45 to approximately 0.65 and Average pore size: approximately 50 nm to approximately 800 nm.

[0135] Implementation Scheme 20. Porous microspheres according to Implementation Scheme 1, wherein the microspheres have an average diameter of about 1 µm to about 75 µm.

[0136] Implementation Scheme 21. The porous microspheres according to Implementation Scheme 1, wherein the microspheres have an average pore size of about 50 nm to about 800 nm.

[0137] Implementation Scheme 22. The porous microspheres according to Implementation Scheme 1, wherein the microspheres have an average porosity of about 0.45 to about 0.65.

[0138] Implementation Scheme 23. Porous microspheres according to Implementation Scheme 19, wherein the microspheres have

[0139] The average diameter is approximately 4.5 µm to approximately 9.9 µm; Average porosity of approximately 0.45 to approximately 0.65; and Average pore size: approximately 220 nm to approximately 300 nm.

[0140] Implementation Scheme 24. Porous microspheres according to any one of Implementation Schemes 19 to 23, comprising approximately 60.0% to approximately 99.9% by weight of metal oxide based on the total weight of the microspheres.

[0141] Implementation Scheme 25. Porous microspheres according to any one of Implementation Schemes 19 to 23, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof.

[0142] Implementation Scheme 26. The porous microspheres according to any one of Implementation Schemes 19 to 23, comprising about 0.1% to about 40.0% by weight of one or more light absorbers based on the total weight of the microspheres.

[0143] Implementation Scheme 27. Porous microspheres according to any one of Implementation Schemes 19 to 23, wherein batch samples of the porous microspheres exhibit a color perceptible to the human eye.

[0144] Implementation Scheme 28. Porous microspheres according to any one of Implementation Schemes 19 to 23, wherein the porous microspheres are monodisperse.

[0145] Implementation Scheme 29. A composition comprising a matrix and porous microspheres according to any one of Implementation Schemes 19 to 23.

[0146] Implementation Scheme 30. The composition according to Implementation Scheme 29, wherein the composition is an aqueous formulation, an oil-based formulation, an ink, a paint formulation, a food, a plastic, a cosmetic formulation, or a material for medical or safety purposes.

[0147] Implementation Scheme 31. Porous microspheres containing metal oxides, wherein batch samples of the porous microspheres exhibit a color perceptible to the human eye.

[0148] Implementation Scheme 32. Porous microspheres according to Implementation Scheme 31, wherein batch samples of the porous microspheres exhibit angle-independent color perceptible to the human eye.

[0149] Implementation Scheme 33. Porous microspheres according to Implementation Scheme 31, wherein batch samples of the porous microspheres exhibit angle-dependent color perceptible to the human eye.

[0150] Implementation Scheme 34. A composition comprising a matrix and porous microspheres according to any one of Implementation Schemes 31 to 33.

[0151] Implementation Scheme 35. The composition according to Implementation Scheme 34, wherein the composition is an aqueous formulation, an oil-based formulation, a coating formulation, a food, an ink, a plastic, a cosmetic formulation, or a material for medical or safety purposes.

[0152] Example

[0153] Example 1: Porous silica microspheres

[0154] The styrene / acrylic acid copolymer was prepared as follows: 230 mL of deionized (DI) water was added to a three-necked reaction flask equipped with a thermometer, condenser, magnetic stirrer, and nitrogen atmosphere. The water was heated to 80 °C, and 10 g of styrene was added with stirring, followed by the addition of 100 mg of acrylic acid dissolved in 10 mL of DI water via syringe. 100 mg of ammonium persulfate was dissolved in 10 mL of DI water and added to the stirred mixture via syringe. The reaction mixture was stirred at 80 °C for 24 hours. The polymer colloidal dispersion was cooled to room temperature and purified by centrifugation to produce polystyrene nanospheres with an average particle size of 250 nm.

[0155] A polystyrene colloidal aqueous dispersion was diluted to 1 wt% with deionized water and 1 wt% silica nanoparticles were added. The mixture was then sonicated to prevent particle agglomeration. The continuous oil phase contained 0.1 wt% polyethylene glycol / perfluoropolyether surfactant in the fluorinated oil. The colloidal aqueous dispersion and oil were each injected via a syringe associated with a pump into a microfluidic device with a 50 µm droplet connector. The system was allowed to equilibrate until monodisperse droplets were produced. The monodisperse droplets were collected in a reservoir.

[0156] The collected droplets were dried in an oven at 45°C for 4 hours to provide monodisperse polymer-templated microspheres. The polymer-templated microspheres were then calcined as follows: placed on a silicon wafer, heated from room temperature to 500°C for 3 hours, held at 500°C for 2 hours, and cooled back to room temperature for 3 hours. This yielded monodisperse silica microspheres with an average diameter of 15 micrometers.

[0157] Figure 2 and Figure 3 These are scanning electron microscope (SEM) images of polymer template microspheres and porous silica microspheres prepared in a similar manner.

[0158] Example 2: Porous silica microspheres containing light absorbers

[0159] The product of Example 1 was physically mixed with carbon black aqueous dispersions or carbon black powders in various weight percentages. Monodisperse porous silica microspheres containing 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt% carbon black based on the total weight of the microspheres were provided.

[0160] Example 3 Drying Method

[0161] Repeat Examples 1 and 2, wherein the drying steps are performed using microwave irradiation, drying under vacuum, and / or drying in the presence of a desiccant.

[0162] Example 4: Preparation of porous silica microspheres by spray drying

[0163] The styrene / acrylic acid copolymer was prepared as follows: 230 mL of deionized (DI) water was added to a three-necked reaction flask equipped with a thermometer, condenser, magnetic stirrer, and nitrogen atmosphere. The water was heated to 80 °C, and 10 g of styrene was added with stirring, followed by the addition of 100 mg of acrylic acid dissolved in 10 mL of DI water via syringe. 100 mg of ammonium persulfate was dissolved in 10 mL of DI water and added to the stirred mixture via syringe. The reaction mixture was stirred at 80 °C for 24 hours. The polymer colloidal dispersion was cooled to room temperature and purified by centrifugation to produce polystyrene nanospheres with an average particle size of 250 nm.

[0164] A polystyrene colloidal aqueous dispersion was diluted with deionized water to 1% by weight and 1% by weight of silica nanoparticles was added. The mixture was then sonicated to prevent particle agglomeration. The aqueous dispersion was spray-dried to provide polymer-templated microspheres comprising polymer nanospheres and silica. The microspheres were calcined as follows: heated from room temperature to 500°C for 3 hours, held at 500°C for 2 hours, and cooled back to room temperature for 3 hours. Porous silica microspheres were thus provided.

[0165] Example 5: Visible Colors in Batch Samples

[0166] In these batch color examples, 0.5 mg porous microspheres were uniformly arranged on a substrate with a diameter of 6 cm. 2 The color is observed by the human eye in a 10mL transparent glass vial at the bottom.

[0167] Two samples of porous silica microspheres were prepared in a manner similar to that in Example 1, wherein the polymer to silica wt / wt ratios were 1:1 and 3:1, respectively. The 1:1 wt / wt sample was white, while the 3:1 wt / wt sample exhibited a distinct blue color.

[0168] A sample of porous silica microspheres was prepared according to Example 1, wherein the polystyrene nanospheres had an average particle size of 360 nm and a polymer to silica wt / wt ratio of 3:1. The sample exhibited a distinct green color.

[0169] Porous silica microspheres were prepared in a manner similar to that in Example 4, wherein the polystyrene nanospheres had an average particle size of 360 nm. At a polymer-to-silica wt / wt ratio of 4:1, the porous microspheres exhibited a porosity of 0.55 and a distinct green color. At a polymer-to-silica wt / wt ratio of 2:1, the porous microspheres exhibited a porosity of 0.45 and a distinct orange color.

[0170] Example 6: Zinc oxide porous microspheres

[0171] Porous zinc oxide microspheres were prepared according to the procedure in Example 4, using zinc oxide instead of silica, wherein the polystyrene nanospheres had an average particle size of 230 nm and a polymer-to-zinc oxide wt / wt ratio of 1:2. 0.5 mg of the porous microsphere sample was uniformly arranged on a substrate with a diameter of 6 cm². 2 The sample is in a 10 mL transparent glass vial at the bottom. It exhibits a distinct blue color to the human eye.

[0172] Example 7: Porous microspheres of silica / titanium dioxide

[0173] A sample containing porous microspheres of silica and titanium dioxide was prepared according to the method of Example 1, wherein the wt / wt ratio of polymer to total metal oxide was 3:1, and the wt / wt ratio of silica to titanium dioxide was 9:1.

Claims

1. Porous microspheres comprising metal oxides, wherein the porous microspheres have Average diameter from 1 µm to 75 µm Average porosity of 0.45 to 0.80, and Average pore size from 50 nm to 800 nm.

2. The porous microsphere according to claim 1, wherein the porous microsphere has an average diameter of 1 µm to 50 µm.

3. The porous microsphere according to claim 1, wherein the porous microsphere has an average pore size of 50 nm to 500 nm.

4. The porous microsphere according to claim 1, wherein the porous microsphere has an average porosity of 0.45 to 0.

65.

5. The porous microsphere according to claim 1, wherein the porous microsphere has Average diameter ranging from 4.5 µm to 9.9 µm; Average porosity of 0.45 to 0.65; and Average pore size from 220 nm to 300 nm.

6. The porous microspheres according to claim 1, comprising 60.0% to 99.9% by weight of metal oxide based on the total weight of the porous microspheres.

7. The porous microspheres according to claim 1, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof.

8. The porous microspheres according to claim 1, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, cerium dioxide, iron oxide, zinc oxide, and combinations thereof.

9. The porous microsphere according to claim 1, wherein the porous microsphere is monodisperse.

10. A composition comprising: matrix; and Porous microspheres comprising metal oxides, wherein the porous microspheres have: Average diameter from 1 µm to 75 µm Average porosity of 0.45 to 0.80, and Average pore size from 50 nm to 800 nm.

11. The composition of claim 10, wherein the composition is an aqueous formulation, an oil-based formulation, an ink, a coating formulation, a food, a plastic, a cosmetic formulation, or a material for medical or safety purposes.

12. The composition according to claim 10, further comprising one or more light absorbers.

13. The composition of claim 12, wherein the one or more light absorbers are present in an amount of 0.1% to 40.0% by weight based on the total weight of the porous microspheres.

14. The composition of claim 10, wherein batch samples of the composition exhibit angle-dependent color observable by a CIE 1931 2° standard observer and / or a CIE 1964 10° standard observer.

15. The composition of claim 10, wherein batch samples of the composition exhibit angle-independent color observable by a CIE 1931 2° standard observer and / or a CIE 1964 10° standard observer.

16. The composition of claim 10, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, cerium dioxide, iron oxide, zinc oxide, and combinations thereof.

17. The composition of claim 10, wherein the porous microspheres are monodisperse.

18. The composition of claim 10, wherein the porous microspheres have an average diameter of 1 µm to 50 µm.

19. The composition of claim 10, wherein the porous microspheres have an average pore size of 50 nm to 500 nm.

20. The composition of claim 10, wherein the porous microspheres have an average porosity of 0.45 to 0.

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21. The composition of claim 10, wherein the composition is a cosmetic formulation, and wherein the matrix is ​​in the form of a solid, semi-solid, gel, liquid, paste, or ointment.

22. The composition of claim 21, wherein each of the porous microspheres comprises an inorganic array of metal oxides, and wherein the porosity of each porous microsphere is distributed throughout the volume of the porous microsphere.

23. The composition according to claim 21, wherein the porous microspheres have: Average diameter ranging from 4.5 µm to 9.9 µm; Average porosity of 0.45 to 0.65; and Average pore size from 220 nm to 300 nm.

24. The composition of claim 21, further comprising an array of metal oxides selected from silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof.

25. The composition of claim 21, wherein the metal oxide is present in an amount of 60.0% to 99.9% by weight based on the total weight of the porous microspheres.

26. The composition of claim 21, wherein the porous metal oxide microspheres comprise one or more light absorbers.

27. A cosmetic formulation comprising porous microspheres dispersed in a matrix having the form of a solid, semi-solid, gel, liquid, paste, or ointment, the porous microspheres having an average diameter of 0.5 µm to 50 µm, wherein each porous microsphere comprises an inorganic array of metal oxides, and wherein the porosity of each porous microsphere is distributed throughout the volume of the porous microsphere.

28. The cosmetic formulation of claim 27, wherein the porous microspheres have an average diameter of 1 µm to 50 µm.

29. The cosmetic formulation according to claim 27, wherein the porous microspheres have an average pore size of 50 nm to 500 nm.

30. The cosmetic formulation of claim 27, wherein the porous microspheres have an average porosity of 0.45 to 0.

65.

31. The cosmetic formulation according to claim 27, wherein the porous microspheres have: Average diameter ranging from 4.5 µm to 9.9 µm; Average porosity of 0.45 to 0.65; and Average pore size from 220 nm to 300 nm.

32. The cosmetic formulation of claim 27, further comprising an array of metal oxides selected from silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof.

33. The cosmetic formulation of claim 27, wherein the metal oxide is present in an amount of 60.0% to 99.9% by weight based on the total weight of the porous microspheres.

34. The cosmetic formulation of claim 27, wherein the porous microspheres exhibit a color perceptible to the human eye.

35. The cosmetic formulation of claim 27, wherein the porous microspheres exhibit angle-independent color.

36. A cosmetic formulation comprising porous metal oxide microspheres dispersed in a matrix having the form of a solid, semi-solid, gel, liquid, paste, or ointment, wherein the cosmetic formulation exhibits a color perceptible to the human eye, the porous metal oxide microspheres comprising an inorganic array and having an average diameter of 1 µm to 75 µm, and wherein the porous metal oxide microspheres comprise one or more light absorbers.

37. The cosmetic formulation of claim 36, wherein the light absorber is present in an amount of 0.1% to 40.0% by weight based on the total weight of the porous metal oxide microspheres.

38. The cosmetic formulation according to claim 36, wherein the porosity of each porous metal oxide microsphere is distributed throughout the volume of the porous metal oxide microsphere.

39. The cosmetic formulation according to claim 36, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof.

40. The cosmetic formulation according to claim 36, wherein the porous metal oxide microspheres have an average pore size of 50 nm to 999 nm.

41. The cosmetic formulation of claim 36, wherein the metal oxide is present in an amount of 60.0% to 99.9% by weight based on the total weight of the porous metal oxide microspheres.

42. A method for preparing porous metal oxide microspheres containing metal oxides, the method comprising: A liquid dispersion of polymer nanoparticles and metal oxides is formed, wherein the wt / wt ratio of polymer nanoparticles to metal oxides is from about 0.5 / 1 to about 10.0 / 1. Liquid droplets forming the dispersion; Drying the liquid droplets to provide polymer-templated microspheres comprising polymer nanospheres and metal oxides; and Polymer nanospheres are removed from template microspheres to provide porous metal oxide microspheres, each containing a continuous solid structure of metal oxide. The microspheres described herein have an average diameter of about 1 µm to about 100 µm, an average porosity of about 0.10 to about 0.80, and an average pore size of about 50 nm to about 999 nm.

43. The method of claim 42, further comprising forming a liquid dispersion of polymer nanoparticles and metal oxides, spray drying the liquid dispersion to provide polymer template microspheres, and removing the polymer nanospheres from the template microspheres.

44. The method of claim 42, further comprising forming liquid droplets using a vibrating nozzle.

45. The method of claim 42, wherein the liquid droplets are aqueous droplets or oil droplets.

46. ​​The method of claim 42, further comprising providing a continuous phase and mixing the liquid dispersion with the continuous phase to form an emulsion containing dispersed liquid dispersion droplets and collecting the droplets.

47. The method of claim 46, further comprising drying the droplets to provide polymer template microspheres comprising polymer nanospheres and metal oxides, and removing the polymer nanospheres from the template microspheres.

48. The method of claim 47, wherein microdroplet drying comprises microwave irradiation, oven drying, drying under vacuum, drying in the presence of a desiccant, or a combination thereof.

49. The method of claim 46, wherein the microdroplets are formed in a microfluidic device.

50. The method according to any one of claims 42 to 49, wherein the polymer nanoparticles have an average diameter of about 50 nm to about 990 nm.

51. The method according to any one of claims 42 to 49, wherein the polymer is selected from poly(meth)acrylic acid, poly(meth)acrylate, polystyrene, polyacrylamide, polyethylene, polypropylene, polylactic acid, polyacrylonitrile, derivatives thereof, salts thereof, copolymers thereof, and combinations thereof.

52. The method according to any one of claims 42 to 49, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof.

53. The method according to any one of claims 42 to 49, wherein the porous microspheres are monodisperse.

54. The method according to any one of claims 42 to 49, wherein the porous metal oxide microspheres are batch samples of microspheres.

55. The method according to any one of claims 42 to 49, wherein removing the polymer nanospheres from the template microspheres comprises calcination, pyrolysis, or solvent removal.

56. The method according to any one of claims 42 to 49, wherein removing the polymer nanospheres comprises calcining the template microspheres at a temperature of about 350°C to about 700°C for about 1 hour to about 8 hours.

57. Porous microspheres made according to any one of claims 42 to 56.

58. A batch sample of porous microspheres prepared according to any one of claims 42 to 56.

59. Porous microspheres comprising metal oxides, wherein each porous metal oxide microsphere comprises a continuous solid structure of metal oxide, and said microspheres have The average diameter is approximately 1 µm to approximately 75 µm. Average porosity of approximately 0.45 to approximately 0.65 and Average pore size: approximately 50 nm to approximately 800 nm.

60. The method of claim 42, wherein the microspheres have an average diameter of about 1 µm to about 75 µm.

61. The method of claim 42, wherein the microspheres have an average pore size of about 50 nm to about 800 nm.

62. The method of claim 42, wherein the microspheres have an average porosity of about 0.45 to about 0.

65.

63. The porous microsphere according to claim 59, wherein the microsphere has The average diameter is approximately 4.5 µm to approximately 9.9 µm; Average porosity of approximately 0.45 to approximately 0.65; and Average pore size: approximately 220 nm to approximately 300 nm.

64. The porous microspheres according to any one of claims 59 to 63, comprising approximately 60.0% to approximately 99.9% by weight of metal oxide based on the total weight of the microspheres.

65. The porous microspheres according to any one of claims 59 to 63, wherein the metal oxide is selected from silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, and combinations thereof.

66. The porous microspheres according to any one of claims 59 to 63, comprising about 0.1% to about 40.0% by weight of one or more light absorbers based on the total weight of the microspheres.

67. The porous microspheres according to any one of claims 59 to 63, wherein batch samples of the porous microspheres exhibit a color perceptible to the human eye.

68. The porous microspheres according to any one of claims 59 to 63, wherein the porous microspheres are monodisperse.

69. A composition comprising a matrix and porous microspheres according to any one of claims 59 to 68.

70. The composition of claim 69, wherein the composition is an aqueous formulation, an oil-based formulation, an ink, a coating formulation, a food, a plastic, a cosmetic formulation, or a material for medical or safety purposes.

71. Porous microspheres comprising metal oxides, wherein each porous metal oxide microsphere comprises a continuous solid structure of metal oxide, and wherein batch samples of said porous microspheres exhibit a color perceptible to the human eye.

72. The porous microspheres of claim 71, wherein batch samples of the porous microspheres exhibit angle-independent color perceptible to the human eye.

73. The porous microspheres of claim 71, wherein batch samples of the porous microspheres exhibit angle-dependent color perceptible to the human eye.

74. A composition comprising a matrix and porous microspheres according to any one of claims 71 to 73.

75. The composition according to claim 74, wherein the composition is an aqueous formulation, an oil-based formulation, a coating formulation, a food product, an ink, a plastic, a cosmetic formulation, or a material for medical or safety purposes.

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