Microspheres comprising polydisperse polymer nanospheres and porous metal oxide microspheres

Abstract

The present invention relates to a porous microsphere comprising a metal oxide having a continuous solid structure. The porous microsphere exhibits a saturated color and is suitable as a colorant for various end uses.

Description

[0001] This application is a divisional application of international application PCT / US2018 / 050175, filed on September 10, 2018, entitled "Microspheres Containing Polydisperse Polymer Nanospheres and Porous Metal Oxide Microspheres". International application PCT / US2018 / 050175 entered the Chinese national phase on May 8, 2020, with national application number 201880072326.1. Technical Field

[0002] Porous metal oxide microspheres, their preparation methods, and their applications are disclosed. These 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, structural colorants that exhibit distinct visible light colors perceptible to the naked eye when present in batches are needed. 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] Overview

[0007] Accordingly, a method for preparing polymer microspheres comprising polydisperse polymer nanospheres is disclosed, the method comprising forming a liquid solution or dispersion of monodisperse polymer nanoparticles; forming at least one additional liquid solution or dispersion of monodisperse polymer nanoparticles; mixing the solutions or dispersions together; forming microdroplets of the mixture; and drying the microdroplets to provide polymer microspheres comprising polydisperse polymer nanospheres; wherein the average diameter of the monodisperse polymer nanoparticles in the solutions or dispersions is different.

[0008] Polymer microspheres comprising more than one monodisperse polymer nanosphere group are also disclosed, wherein each monodisperse polymer nanosphere group has a different average diameter. Batch samples of polymer microspheres can exhibit colors perceptible to the human eye.

[0009] A method for preparing porous metal oxide microspheres is also disclosed, the method comprising: forming a liquid solution or dispersion of monodisperse polymer nanoparticles; forming at least one additional liquid solution or dispersion of monodisperse polymer nanoparticles; mixing the solutions or dispersions together; wherein a metal oxide is added to one or more of the solutions or suspensions and / or wherein a metal oxide is added to the mixture to form a liquid dispersion of polymer nanoparticles and metal oxide; forming liquid droplets of the liquid dispersion; drying the droplets to provide polymer template microspheres comprising polydisperse polymer nanospheres and metal oxide; and removing the polymer nanospheres from the template microspheres to provide porous metal oxide microspheres; wherein the average diameter of the monodisperse polymer nanoparticles in the solutions or dispersions is different.

[0010] Also disclosed are porous microspheres comprising metal oxides, wherein the microspheres have an average diameter of about 0.5 µm to about 100 µm and an average porosity of about 0.10 to about 0.90 or about 0.10 to about 0.80; wherein the porous microspheres have more than one pore group, each group having an average pore size, wherein each group has a different average pore size; and wherein the average pore size is about 50 nm to about 999 nm; for example, wherein the microspheres have a first pore group with an average pore size of about 50 nm to about 999 nm and a second pore group with an average pore size of about 50 nm to about 999 nm, wherein the first and second average pore sizes are different.

[0011] They also disclosed porous microspheres containing metal oxides, wherein batch samples of the porous microspheres exhibited colors perceptible to the human eye.

[0012] Compositions comprising a matrix and the microspheres are also disclosed; for example, said composition is an aqueous formulation, an oil-based formulation, a coating formulation, an ink, a food, a plastic, a cosmetic formulation, or a material for medical or safety purposes.

[0013] In particular, the present invention relates to the following technical solutions: 1. A method for preparing porous metal oxide microspheres containing metal oxides, the method comprising: Liquid solutions or dispersions that form monodisperse polymer nanoparticles; At least one other liquid solution or dispersion that forms monodisperse polymer nanoparticles; Mix the solutions or dispersions together; wherein a metal oxide is added to one or more solutions or dispersions and / or wherein a metal oxide is added to the mixture to form a liquid dispersion of polymer nanoparticles and metal oxides; Liquid droplets forming the liquid dispersion; Drying the liquid droplets to provide polymer-templated microspheres comprising polydisperse polymer nanospheres and metal oxides; and Remove polymer nanospheres from template microspheres to provide porous metal oxide microspheres; The average diameter of the monodisperse polymer nanoparticles in each solution or dispersion is different.

[0014] 2. The method according to technical solution 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.

[0015] 3. The method according to technical solution 1 includes forming liquid droplets using a vibrating nozzle.

[0016] 4. According to the method of technical solution 1, the liquid droplets are aqueous droplets or oil droplets.

[0017] 5. The method according to technical solution 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.

[0018] 6. The method according to technical solution 5 includes drying the microdroplets to provide polymer template microspheres containing polydisperse polymer nanospheres.

[0019] 7. The method according to technical solution 6, wherein microdroplet drying includes microwave irradiation, oven drying, drying under vacuum, drying in the presence of a desiccant, or a combination thereof.

[0020] 8. The method according to technical solution 5, wherein the microdroplets are formed in a microfluidic device.

[0021] 9. The method according to any one of technical solutions 1 to 8, wherein the total wt / wt ratio of polymer nanoparticles to metal oxide is from about 0.5 / 1 to about 10.0 / 1.

[0022] 10. The method according to any one of claims 1 to 8, wherein the polymer nanoparticles have an average diameter of about 50 nm to about 990 nm.

[0023] 11. The method according to any one of technical solutions 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.

[0024] 12. The method according to any one of technical solutions 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.

[0025] 13. The method according to any one of technical solutions 1 to 8, wherein the microspheres are monodisperse.

[0026] 14. The method according to any one of technical solutions 1 to 8, wherein the porous metal oxide microspheres are batch samples of microspheres.

[0027] 15. The method according to any one of technical solutions 1 to 8, wherein removing the polymer nanospheres from the template microspheres includes calcination, pyrolysis or solvent removal.

[0028] 16. The method according to any one of technical solutions 1 to 8, wherein removing the polymer nanospheres includes calcining the template microspheres at a temperature of about 350°C to about 700°C for about 1 hour to about 8 hours.

[0029] 17. Porous microspheres, which are made according to any one of technical solutions 1 to 8.

[0030] 18. A batch of porous microspheres, wherein the porous microspheres are manufactured according to any one of technical solutions 1 to 8.

[0031] 19. Porous microspheres comprising metal oxides, wherein the microspheres have

[0032] Average diameter from approximately 0.5 µm to approximately 100 µm and

[0033] Average porosity of approximately 0.10 to approximately 0.80; The porous microspheres have more than one pore group, each group having an average pore size, wherein each group has a different average pore size and wherein the average pore size is from about 50 nm to about 999 nm.

[0034] 20. The porous microspheres according to claim 19, wherein the microspheres have an average diameter of about 1 µm to about 75 µm.

[0035] 21. The porous microspheres according to technical solution 19, wherein the average pore size is from about 50 nm to about 800 nm.

[0036] 22. The porous microsphere according to claim 19, wherein the microsphere has an average porosity of about 0.45 to about 0.65.

[0037] 23. The porous microsphere according to technical solution 19, wherein the microsphere has

[0038] 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.

[0039] 24. The porous microspheres according to any one of claims 19 to 23, comprising approximately 60.0% to approximately 99.9% by weight of metal oxide based on the total weight of the microspheres.

[0040] 25. Porous microspheres according to any one of technical solutions 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.

[0041] 26. The porous microspheres according to any one of claims 19 to 23, comprising one or more light absorbers at a weight percentage of about 0.1% to about 40.0% based on the total weight of the microspheres.

[0042] 27. Porous microspheres according to any one of technical solutions 19 to 23, wherein batch samples of the porous microspheres exhibit a color perceptible to the human eye.

[0043] 28. The porous microsphere according to any one of technical solutions 19 to 23, wherein the porous microsphere is monodisperse.

[0044] 29. A composition comprising a matrix and porous microspheres according to any one of claims 19 to 23.

[0045] 30. The composition according to technical claim 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.

[0046] 31. Porous microspheres comprising metal oxides, wherein a batch of samples of the porous microspheres exhibits a color perceptible to the human eye; wherein the porous microspheres have more than one pore group, each group having an average pore size, wherein each group has a different average pore size.

[0047] 32. The porous microspheres according to technical solution 31, wherein batch samples of the porous microspheres exhibit angle-independent color perceptible to the human eye.

[0048] 33. The porous microspheres according to technical solution 31, wherein batch samples of the porous microspheres exhibit angle-dependent colors perceptible to the human eye.

[0049] 34. A composition comprising a matrix and porous microspheres according to any one of claims 31 to 33.

[0050] 35. The composition according to technical claim 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.

[0051] 36. A method for preparing polymer microspheres comprising polydisperse polymer nanospheres, the method comprising:

[0052] Liquid solutions or dispersions that form monodisperse polymer nanoparticles; At least one other liquid solution or dispersion that forms monodisperse polymer nanoparticles; Mix the solutions or dispersions together; The microdroplets that form the mixture; and The microdroplets are dried to provide polymer microspheres containing polydisperse polymer nanospheres; The average diameter of the monodisperse polymer nanoparticles in each solution or dispersion is different.

[0053] 37. The method according to technical solution 36 includes mixing the solution or dispersion together and spray drying the mixture to provide polymer microspheres.

[0054] 38. The method according to technical solution 36 includes forming liquid droplets using a vibrating nozzle.

[0055] 39. The method according to technical solution 36 includes providing a continuous phase and mixing the solution or dispersion with the continuous phase to form an emulsion containing dispersed liquid solution or dispersion droplets and collecting the droplets.

[0056] 40. The method according to claim 39 includes drying the droplets to provide polymer microspheres comprising polydisperse polymer nanospheres.

[0057] 41. The method according to any one of technical solutions 36 to 40, 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.

[0058] 42. Polymer microspheres, which are made according to any one of technical solutions 36 to 40.

[0059] 43. A batch of polymer microspheres, wherein the polymer microspheres are manufactured according to any one of technical solutions 36 to 40.

[0060] 44. Polymer microspheres comprising more than one monodisperse polymer nanosphere group, wherein each monodisperse polymer nanosphere group has a different average diameter.

[0061] 45. The polymer microspheres according to claim 44, wherein the polymer nanospheres have an average diameter of about 100 nm to about 970 nm.

[0062] 46. ​​The polymer microspheres according to technical solution 44, 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.

[0063] 47. The polymer microspheres according to any one of claims 44 to 46, wherein the microspheres have an average diameter of about 0.5 µm to about 100 µm.

[0064] 48. The polymer microspheres according to any one of technical solutions 44 to 46, wherein batch samples of the polymer microspheres exhibit a color perceptible to the human eye.

[0065] 49. The polymer microspheres according to any one of technical solutions 44 to 46, wherein batch samples of the polymer microspheres exhibit angle-independent color perceptible to the human eye.

[0066] 50. The polymer microspheres according to any one of technical solutions 44 to 46, wherein batch samples of the polymer microspheres exhibit angle-dependent colors perceptible to the human eye.

[0067] 51. The polymer microspheres according to any one of technical solutions 44 to 46 are monodisperse.

[0068] 52. The polymer microspheres according to any one of technical solutions 44 to 46, further comprising a metal oxide. Brief description of the attached diagram

[0069] The accompanying drawings are for illustrative purposes only and not as a limitation of the disclosure described herein. For simplicity and clarity of illustration, the elements shown 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 the drawings where deemed appropriate to indicate corresponding or similar elements.

[0070] Figure 1 This provides a general overview of the preparation of these porous microspheres.

[0071] Figure 2This is a scanning electron microscope (SEM) image of polymer template microspheres according to one embodiment of the present invention.

[0072] Figure 3 This is a SEM image of porous silica microspheres according to one embodiment of the present invention.

[0073] Figure 4 This is an illustration of a spray drying method according to some embodiments of the present invention. Detailed Implementation

[0074] Detailed Explanation

[0075] These metal oxide microspheres, or photonic balls, can be prepared using a polymer sacrificial template. In one embodiment, an aqueous colloidal dispersion containing polymer nanoparticles, typically nanoscale, and a metal oxide is prepared. This aqueous colloidal dispersion is mixed with a continuous oil phase, for example, 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 the polymer nanoparticles and the metal oxide. 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. These microspheres may contain varying pore sizes, a result of the polydispersity of the polymer particles.

[0076] Figure 1 This provides a general overview of the preparation of these 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 are polydisperse. The polymer nanospheres define the interstitial spaces. Calcination results in the removal of the polymer, providing the metal oxide microspheres with high porosity or pore volume (inverse structure).

[0077] The porous metal oxide microspheres are advantageously sintered to produce a thermally and mechanically stable continuous solid structure.

[0078] 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 prepared, 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.

[0079] In some implementations, vibrating nozzle technology can be used. In these technologies, a liquid dispersion is prepared; microdroplets are formed; and the microdroplets are introduced into a bath of continuous phase. The microdroplets are then dried and calcined. 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.

[0080] Polymer nanoparticles, for example, have an average diameter of about 50 nm to about 999 nm. Polymer nanospheres are polydisperse. According to the invention, a polydisperse sample of polymer nanospheres contains more than one monodisperse population of polymer nanospheres, that is, at least first and second monodisperse populations of polymer nanospheres, wherein the first and second average particle sizes are different.

[0081] 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, polyesters, polyurethanes, polyethylene, polypropylene, polylactic acid, polyacrylonitrile, polyvinyl ether, their derivatives, their salts, their copolymers, and combinations thereof. For example, the polymer is selected from polymethyl methacrylate, polyethyl methacrylate, poly(n-butyl methacrylate), polystyrene, poly(chlorostyrene), poly(α-methylstyrene), poly(N-hydroxymethylacrylamide), styrene / methyl methacrylate copolymer, polyalkylated acrylates, polyhydroxyacrylates, polyaminoacrylates, polycyanoacrylates, polyfluorinated acrylates, 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.

[0082] In some embodiments, the polymer template includes polystyrenes, including polystyrene and polystyrene copolymers. Polystyrene copolymers include copolymers with water-soluble monomers, such as polystyrene / acrylic acid, polystyrene / poly(ethylene glycol) methacrylate, and polystyrene / styrene sulfonate.

[0083] This metal oxide includes oxides of transition metals, metalloids and rare earth elements, such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, chromium oxide, mixed metal oxides, and combinations thereof.

[0084] 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.

[0085] The continuous oil phase includes, for example, organic solvents, silicone oil, or fluorinated oil. 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.

[0086] 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, by spray drying, or a combination thereof.

[0087] 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.

[0088] 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.

[0089] Alternatively, a liquid dispersion of polymer nanoparticles and metal oxides is prepared and spray-dried to form polymer-templated microspheres without forming a liquid-in-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 to 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 this spray drying method, the liquid feed contains a water or oil phase, polymer particles, and optionally a metal oxide. Polymer microspheres containing polymer nanospheres and optionally 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.

[0090] In this spray drying technology, air can be considered as a continuous phase with a dispersed liquid phase (liquid-in-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.

[0091] Figure 4 This is an illustration of a spray drying method according to some embodiments of the present invention.

[0092] In some embodiments of spray drying technology, a feed solution or dispersion is fed 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 preheated gas in an evaporation chamber, causing the solvent to evaporate to produce solid particles. The dried particles are carried by drying gas through a cyclone separator and deposited in a collection chamber. The gas includes nitrogen and / or air. In this spray drying method, the liquid feed contains water, polymer nanoparticles, and metal oxides.

[0093] 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 and nanoscale, 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 nanoscale.

[0094] The metal oxide of the dispersion can be provided as a metal oxide or can be provided by a metal oxide precursor, for example by sol-gel technology.

[0095] The drying of polymer / metal oxide droplets and the removal of the polymer provide microspheres with voids (pores). Generally, in this method, each droplet 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, a pore size approximately 10% to approximately 40% smaller than the polymer particle size. The pore size changes when the polymer particle size varies (is polydisperse).

[0096] In some implementations, the pore size can be from about 50 nm to about 999 nm.

[0097] The average porosity of these 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".

[0098] In some embodiments, the porous microspheres may have a solid core (center), wherein the porosity generally tends towards the outer surface of the microsphere. In other embodiments, the porous microspheres may have a hollow core, wherein the porosity is mostly tended towards 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.

[0099] 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.

[0100] 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.

[0101] Polymer-templated microspheres containing polydisperse polymer nanospheres can provide metal oxide microspheres with pores that typically have different pore sizes when the polymer is removed.

[0102] 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.

[0103] 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. These microspheres may not exhibit a perceptible color without the addition of a light absorber but exhibit a perceptible color with the addition of a light absorber.

[0104] Porous microspheres can be used as colorants in, for example, aqueous formulations, oil-based formulations, inks, paint formulations, food, plastics, cosmetic formulations, or materials for medical or safety applications. Paint formulations include, for example, automotive coatings, architectural coatings, and varnishes.

[0105] These 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.

[0106] Angle-independent colors can be achieved, for example, using polydisperse polymer nanospheres. Angle-independent colors can also be achieved when the drying of liquid droplets proceeds rapidly to provide polymer template microspheres, thus preventing the polymer nanospheres from becoming ordered. Angle-dependent colors can be achieved when the drying of liquid droplets proceeds slowly.

[0107] 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.

[0108] The subject of this invention also relates to polymer microspheres comprising polydisperse polymer nanospheres, methods for preparing them, and compositions comprising them. The method includes forming an aqueous dispersion of monodisperse polymer nanoparticles; forming at least one further aqueous dispersion of monodisperse polymer nanoparticles; providing a continuous oil phase; mixing the aqueous dispersion and the oil phase together to form a water-in-oil emulsion; forming emulsion droplets; and drying the emulsion droplets to provide polymer microspheres comprising polydisperse polymer nanospheres; wherein the average diameter of the monodisperse polymer nanoparticles in each dispersion is different.

[0109] Advantageously, porous microspheres and polymer microspheres can be monodisperse.

[0110] 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.

[0111] 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 porosimeter 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.

[0112] 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 ≥ 0.5 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.

[0113] The phrase "exhibiting colors perceptible to the human eye" means that the average person would observe the colors. This can refer to any batch of samples distributed over any surface area, such as those distributed over approximately 1 cm². 2 Approximately 2 cm 2 Approximately 3 cm 2 Approximately 4 cm 2 Approximately 5cm 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 11 cm 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.

[0114] The term “of” can mean “containing”, for example, “a liquid dispersion of…” can be interpreted as “a liquid dispersion containing…”.

[0115] The terms “microsphere,” “nanosphere,” “droplet,” etc., used in this article can refer to, for example, multiple of them, their collections, their populations, their samples, or their batches.

[0116] 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.

[0117] The terms "sphere" and "particle" are used interchangeably.

[0118] 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. For example, a population of monodisperse microspheres or nanospheres may have 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% of the particles having a diameter within ±7%, ±6%, ±5%, ±4%, ±3%, ±2%, or ±1% of the average diameter of the population. The term "monodisperse polymer nanoparticles" refers to a population of monodisperse polymer nanoparticles.

[0119] The term "polydisperse" in relation to nanospheres refers to a sample comprising a first monodisperse population having a first average diameter and at least a second monodisperse population having a second average diameter, the first and second diameters being different. A polydisperse microsphere sample contains at least two monodisperse populations, and may contain 3, 4, 5, 6, etc., monodisperse populations, each with a different average particle size. A polydisperse sample containing only the first and second monodisperse polymer nanospheres is a "bimodal" sample with a bimodal particle size distribution.

[0120] The term "substantially free of other components" means, for example, containing ≤ 5%, ≤ 4%, ≤ 3%, ≤ 2%, ≤ 1%, or ≤ 0.5% of other components by weight. Similarly, the term "substantially none" means almost none.

[0121] "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.

[0122] The removal of a monodisperse group of polymer nanospheres yields porous metal oxide microspheres having a corresponding pore group (which has an average pore size). The removal of more than one monodisperse group of polymer nanospheres (polydisperse polymer nanospheres) yields porous metal oxide microspheres having corresponding pore groups (which have different average pore sizes), that is, porous metal oxide microspheres having more than one pore group, each group having an average pore size, wherein each group has a different average pore size and wherein the average pore size is from about 50 nm to about 999 nm.

[0123] The diameter of polymer nanospheres and the pore size of porous microspheres can be, for example, bimodal, trimodal, or quadrmodal.

[0124] The articles “a” and “an” in this document refer to one or more (e.g., at least one) grammatical objects. 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 may 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.

[0125] 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.

[0126] 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.

[0127] The first set of non-limiting embodiments of this disclosure relating to methods for preparing polymer microspheres includes: In a first embodiment, a method for preparing polymer microspheres comprising polydisperse polymer nanospheres is disclosed, the method comprising forming a liquid solution or dispersion of monodisperse polymer nanoparticles; forming at least one additional liquid solution or dispersion of monodisperse polymer nanoparticles; mixing the solutions or dispersions together; forming microdroplets of the mixture; and drying the microdroplets to provide polymer microspheres comprising polydisperse polymer nanospheres; wherein the average diameter of the monodisperse polymer nanoparticles in the solutions or dispersions is different.

[0128] Microdroplet drying may include microwave irradiation, oven drying, drying under vacuum, drying in the presence of a desiccant, or a combination thereof in some embodiments.

[0129] In a second embodiment, the method of embodiment 1 includes mixing a solution or dispersion together and spray-drying the mixture to provide polymer microspheres. In a third embodiment, the method of embodiment 1 includes forming liquid droplets using a vibrating nozzle. In a fourth embodiment, the method of embodiments 1 to 3, wherein the liquid droplets are aqueous droplets. In a fifth embodiment, the method of embodiments 1 to 3, wherein the liquid droplets are oil droplets.

[0130] In a sixth embodiment, the method according to embodiment 1 includes providing a continuous phase and mixing the solution or dispersion with the continuous phase to form an emulsion containing dispersed liquid solution or dispersion droplets.

[0131] In a seventh embodiment, the method of embodiment 6 includes providing a continuous oil phase and mixing an aqueous solution or 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 solution or dispersion with the continuous phase to form an oil-in-water emulsion containing oil droplets. In a ninth embodiment, the methods of embodiments 6 to 8 include collecting the droplets.

[0132] In a tenth embodiment, the method of embodiment 9 includes drying the microdroplets to provide polymer microspheres comprising polydisperse polymer nanospheres. In an eleventh embodiment, the method of embodiments 6 to 10 includes microdroplet drying comprising microwave irradiation, oven drying, drying under vacuum, drying in the presence of a desiccant, or a combination thereof. In a twelfth embodiment, the method of embodiments 7 to 11 includes the oil phase or solution or dispersion comprising hydrocarbons, silicone oils, or fluorinated oils. In a thirteenth embodiment, the method of embodiments 6 to 12 includes microdroplet formation within a microfluidic device.

[0133] In a fourteenth embodiment, according to the method of embodiments 6 to 13, droplet formation is performed in a microfluidic device comprising 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, according to the method of embodiments 13 or 14, the method includes collecting emulsion droplets from the microfluidic device.

[0134] In the sixteenth embodiment, the method according to any of the preceding embodiments includes forming a first liquid solution or dispersion of first monodisperse polymer nanoparticles and a second liquid solution or dispersion of second monodisperse polymer nanoparticles; for example, wherein the wt / wt ratio of the first monodisperse polymer nanoparticles to the second monodisperse polymer nanoparticles is approximately 1 / 20, approximately 1 / 19, approximately 1 / 18, approximately 1 / 17, approximately 1 / 16, approximately 1 / 15, approximately 1 / 14, approximately 1 / 13, approximately 1 / 12, approximately 1 / 11, or approximately 1... Any one of / 10, approximately 1 / 9, approximately 1 / 8, approximately 1 / 7, approximately 1 / 6, approximately 1 / 5, approximately 1 / 4, approximately 1 / 3, approximately 1 / 2 or approximately 1 / 1 to approximately 2 / 1, approximately 3 / 1, approximately 4 / 1, approximately 5 / 1, approximately 6 / 1, approximately 7 / 1, approximately 8 / 1, approximately 9 / 1, approximately 10 / 1, approximately 11 / 1, approximately 12 / 1, approximately 13 / 1, approximately 14 / 1, approximately 15 / 1, approximately 16 / 1, approximately 17 / 1, approximately 18 / 1, approximately 19 / 1 or approximately 20 / 1.

[0135] 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.

[0136] In the eighteenth embodiment, the method according to any of the preceding embodiments, 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. In the 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.

[0137] In a twentieth embodiment, according to the method of any of the preceding embodiments, the microspheres have an average diameter of about 0.5 µm to about 100 µm. In a twenty-first embodiment, according to the method of any of the preceding embodiments, the 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. In the twenty-second embodiment, according to the method of any of the preceding embodiments, the 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.

[0138] In the twenty-third embodiment, the method according to any of the preceding embodiments, wherein the batch sample of polymer microspheres exhibits a color perceptible to the human eye. In the twenty-fourth embodiment, the method according to any of the preceding embodiments, wherein the batch sample of polymer microspheres exhibits an angle-independent color perceptible to the human eye. In the twenty-fifth embodiment, the method according to any of embodiments 1-23, wherein the batch sample of polymer microspheres exhibits an angle-dependent color perceptible to the human eye.

[0139] In a twenty-sixth embodiment, the method according to any of the preceding embodiments, wherein the microspheres are monodisperse. In a twenty-seventh embodiment, the method according to any of the preceding embodiments, wherein the polymer microspheres are batch samples of microspheres.

[0140] In the twenty-eighth embodiment, the method according to any of the foregoing embodiments includes adding a metal oxide to one or more liquid solutions or dispersions; or adding a metal oxide to the mixture.

[0141] In the twenty-ninth embodiment, polymer microspheres are prepared according to any of the foregoing methods. In the thirtieth embodiment, batch samples of polymer microspheres are prepared according to any of the foregoing methods.

[0142] A second set of non-limiting embodiments of the present invention relating to polymer microspheres includes: Polymer microspheres comprising more than one monodisperse polymer nanosphere group, wherein each monodisperse polymer nanosphere group has a different average diameter.

[0143] In the second embodiment, the polymer microspheres according to embodiment 1 comprise a first monodisperse polymer nanoparticle group and a second monodisperse polymer nanoparticle group; for example, the wt / wt ratio of the first polymer nanosphere group to the second polymer nanosphere group is approximately 1 / 20, approximately 1 / 19, approximately 1 / 18, approximately 1 / 17, approximately 1 / 16, approximately 1 / 15, approximately 1 / 14, approximately 1 / 13, approximately 1 / 12, approximately 1 / 11, approximately 1 / 10, approximately 1 / 9, approximately 1 / 8. Any one of approximately 1 / 7, approximately 1 / 6, approximately 1 / 5, approximately 1 / 4, approximately 1 / 3, approximately 1 / 2 or approximately 1 / 1 to approximately 2 / 1, approximately 3 / 1, approximately 4 / 1, approximately 5 / 1, approximately 6 / 1, approximately 7 / 1, approximately 8 / 1, approximately 9 / 1, approximately 10 / 1, approximately 11 / 1, approximately 12 / 1, approximately 13 / 1, approximately 14 / 1, approximately 15 / 1, approximately 16 / 1, approximately 17 / 1, approximately 18 / 1, approximately 19 / 1 or approximately 20 / 1.

[0144] In a third embodiment, the polymer microspheres according to embodiment 1 or 2, wherein the polymer nanospheres have an average diameter of any one of 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 or about 970 nm.

[0145] In the fourth embodiment, the polymer microspheres according to any of the preceding embodiments, 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.

[0146] In the fifth embodiment, the polymer microspheres according to any of the preceding embodiments, wherein the polymer is selected from polystyrene-based polymers, such as polystyrene copolymers, such as polystyrene / acrylic acid, polystyrene / poly(ethylene glycol) methacrylate, or polystyrene / styrene sulfonate.

[0147] In the sixth embodiment, the polymer microspheres according to any of the preceding embodiments are wherein the polymers of each group of polymer nanospheres are the same. In the seventh embodiment, the polymer microspheres according to any of embodiments 1 to 5 are wherein the polymers of each group of polymer nanospheres are different.

[0148] In the eighth embodiment, the polymer microspheres according to any of the foregoing embodiments, wherein the microspheres have an average diameter of about 0.5 µm to about 100 µm. In the ninth embodiment, the polymer microspheres according to any of the preceding embodiments, wherein the 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; 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. In a tenth embodiment, the polymer microspheres according to any of the preceding embodiments, wherein the 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.

[0149] In the twelfth embodiment, the polymer microspheres according to any of the preceding embodiments exhibit a color perceptible to the human eye in batch samples. In the thirteenth embodiment, the polymer microspheres according to any of the preceding embodiments exhibit an angle-independent color perceptible to the human eye in batch samples. In the fourteenth embodiment, the polymer microspheres according to any of embodiments 1-12 exhibit an angle-dependent color perceptible to the human eye in batch samples.

[0150] In the fifteenth embodiment, the polymer microspheres according to any of the foregoing embodiments are monodisperse.

[0151] In the sixteenth embodiment, the polymer microspheres according to any of the foregoing embodiments further comprise a metal oxide.

[0152] A non-limiting third embodiment of the present invention relating to a method for preparing porous metal oxide microspheres includes: In a first embodiment, a method for preparing porous metal oxide microspheres is disclosed, the method comprising: forming a liquid solution or dispersion of monodisperse polymer nanoparticles; forming at least one additional liquid solution or dispersion of monodisperse polymer nanoparticles; mixing the solutions or dispersions together; wherein a metal oxide is added to one or more of the solutions or suspensions and / or wherein a metal oxide is added to the mixture to form a liquid dispersion comprising polymer nanoparticles and a metal oxide; forming liquid droplets of the liquid dispersion; drying the droplets to provide polymer template microspheres comprising polydisperse polymer nanospheres and a metal oxide; and removing the polymer nanospheres from the template microspheres to provide porous metal oxide microspheres; wherein the average diameter of the monodisperse polymer nanoparticles in the solutions or dispersions is different.

[0153] In a second embodiment, the method according to embodiment 1 includes mixing a solution or dispersion together and spray drying the mixture to provide polymer template microspheres and remove polymer nanospheres from the template microspheres.

[0154] In a third embodiment, the method of embodiment 1 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.

[0155] 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.

[0156] 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. In a ninth embodiment, the method of embodiments 6 through 8 includes collecting the droplets. In a tenth embodiment, the method of embodiment 9 includes drying the droplets to provide polymer-templated microspheres comprising polydisperse polymer nanospheres.

[0157] 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.

[0158] In the twelfth embodiment, according to the method of embodiments 7 to 11, the oil phase or solution or dispersion comprises hydrocarbon, silicone oil or fluorinated oil.

[0159] In a thirteenth embodiment, the method according to embodiments 6 to 12 is wherein droplet formation is performed in a microfluidic device. In a fourteenth embodiment, the method according to embodiments 6 to 13 is wherein droplet formation is performed in a microfluidic device comprising 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 according to embodiments 13 or 14 includes collecting emulsion droplets from the microfluidic device.

[0160] In the sixteenth embodiment, the method according to any of the preceding embodiments includes forming a first liquid solution or dispersion of first monodisperse polymer nanoparticles and a second liquid solution or dispersion of second monodisperse polymer nanoparticles; for example, wherein the wt / wt ratio of the first monodisperse polymer nanoparticles to the second monodisperse polymer nanoparticles is approximately 1 / 20, approximately 1 / 19, approximately 1 / 18, approximately 1 / 17, approximately 1 / 16, approximately 1 / 15, approximately 1 / 14, approximately 1 / 13, approximately 1 / 12, approximately 1 / 11, or approximately 1... Any one of / 10, approximately 1 / 9, approximately 1 / 8, approximately 1 / 7, approximately 1 / 6, approximately 1 / 5, approximately 1 / 4, approximately 1 / 3, approximately 1 / 2 or approximately 1 / 1 to approximately 2 / 1, approximately 3 / 1, approximately 4 / 1, approximately 5 / 1, approximately 6 / 1, approximately 7 / 1, approximately 8 / 1, approximately 9 / 1, approximately 10 / 1, approximately 11 / 1, approximately 12 / 1, approximately 13 / 1, approximately 14 / 1, approximately 15 / 1, approximately 16 / 1, approximately 17 / 1, approximately 18 / 1, approximately 19 / 1 or approximately 20 / 1.

[0161] 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.

[0162] In the eighteenth embodiment, the method according to any of the preceding embodiments, 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. In the 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.

[0163] In the 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.

[0164] In the twenty-first embodiment, according to the method of any of the preceding embodiments, the total wt / wt ratio of polymer nanoparticles to 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.

[0165] In the twenty-second embodiment, the method according to any of the preceding embodiments, wherein microdroplet drying includes microwave irradiation, oven drying, drying under vacuum, drying in the presence of a desiccant, or a combination thereof.

[0166] In the twenty-third 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, about 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.

[0167] In the twenty-fourth 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 and an average porosity of about 0.10 to about 0.90 or about 0.10 to about 0.80; the porous microspheres have more than one pore group, each group having an average pore diameter, wherein each group has a different average pore diameter; and wherein the average pore diameter is about 50 nm to about 999 nm; for example, the porous microspheres have a first pore group with an average pore diameter of about 50 nm to about 999 nm and a second pore group with an average pore diameter of about 50 nm to about 999 nm, wherein the first and second average pore diameters are different.

[0168] In the twenty-fifth 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.

[0169] In the twenty-sixth embodiment, according to the method of any of the preceding 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.

[0170] In the twenty-seventh 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, 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.

[0171] 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 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.

[0172] In the twenty-ninth embodiment, according to the method of any of the preceding embodiments, the porous microspheres have an average porosity of any one of about 0.45, about 0.47, about 0.49, about 0.51, about 0.53, about 0.55 or about 0.57 to about 0.59, about 0.61, about 0.63 or about 0.65.

[0173] In the thirtieth 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.

[0174] In the thirty-first 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 any one of 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 any one of 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.

[0175] In the thirty-second 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.

[0176] In the thirty-third 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%. In the thirty-fourth 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.

[0177] In the thirty-fifth 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-sixth embodiment, the method according to any of the preceding embodiments, wherein a batch sample of porous microspheres exhibits an angle-independent color perceptible to the human eye. In the thirty-seventh embodiment, the method according to any of embodiments 1-35, wherein a batch sample of porous microspheres exhibits an angle-dependent color perceptible to the human eye.

[0178] In the thirty-eighth embodiment, the method according to any of the preceding embodiments, wherein the microspheres are monodisperse. In the thirty-ninth embodiment, the method according to any of the preceding embodiments, wherein the porous metal oxide microspheres are batch samples of microspheres.

[0179] In the fortieth embodiment, porous microspheres are prepared according to any of the foregoing methods. In the forty-first embodiment, batch samples of microspheres prepared according to any of the foregoing methods are provided.

[0180] The non-limiting fourth group of embodiments of this disclosure relating to porous metal oxide microspheres includes: In a first embodiment, porous microspheres comprising a metal oxide are disclosed, wherein the microspheres have an average diameter of about 0.5 µm to about 100 µm and an average porosity of about 0.10 to about 0.80; wherein the porous microspheres have more than one pore group, each group having an average pore size, wherein each group has a different average pore size; and wherein the average pore size is about 50 nm to about 999 nm; for example, wherein the microspheres have a first pore group with an average pore size of about 50 nm to about 999 nm and a second pore group with an average pore size of about 50 nm to about 999 nm, wherein the first and second average pore sizes are different.

[0181] In a second embodiment, the porous microspheres according to embodiment 1 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.

[0182] 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.

[0183] In the fourth embodiment, the porous microspheres according to any of the foregoing embodiments have an average pore size 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 up 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. Any one of nm, approximately 780 nm, or approximately 800 nm.

[0184] 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.

[0185] In the sixth embodiment, the porous microspheres according to any of the preceding embodiments have an average porosity of any one of about 0.45, about 0.47, about 0.49, about 0.51, about 0.53, about 0.55 or about 0.57 to any one of about 0.59, about 0.61, about 0.63 or about 0.65.

[0186] In the seventh embodiment, the porous microspheres according to any of the preceding embodiments 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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%.

[0191] 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.

[0192] 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 an angle-independent 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.

[0193] In the seventeenth embodiment, the porous microspheres according to any of the preceding embodiments are monodisperse.

[0194] In the eighteenth embodiment, the composition comprises a matrix and porous microspheres according to any of the preceding embodiments. In the nineteenth embodiment, the composition according to embodiment 18 is an aqueous formulation, an oil-based formulation, a coating formulation, a food, ink, a plastic, a cosmetic formulation, or a material for medical or safety purposes.

[0195] The fifth group of non-limiting embodiments of this disclosure relating to metal oxide microspheres includes: In a first embodiment, porous microspheres comprising metal oxides are provided, wherein batch samples of the porous microspheres exhibit a color perceptible to the human eye; wherein the porous microspheres have more than one pore group, each group having an average pore size, and wherein each group has a different average pore size.

[0196] In a second embodiment, the porous microspheres according to embodiment 1 have an average diameter of about 0.5 µm to about 100 µm and an average porosity of about 0.10 to about 0.90 or about 0.10 to about 0.80; the porous microspheres have more than one pore group, each group having an average pore size, wherein each group has a different average pore size; and wherein the average pore size is about 50 nm to about 999 nm; for example, the microspheres have a first pore group with an average pore size of about 50 nm to about 999 nm and a second pore group with an average pore size of about 50 nm to about 999 nm, wherein the first and second average pore sizes are different.

[0197] 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.

[0198] 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, and approximately 0. Average porosity of approximately 0.44, approximately 0.46, approximately 0.48, 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.

[0199] 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.

[0200] 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.

[0201] In the seventh embodiment, the porous microspheres according to any of the preceding embodiments have an average porosity of any one of about 0.45, about 0.47, about 0.49, about 0.51, about 0.53, about 0.55 or about 0.57 to any one of about 0.59, about 0.61, about 0.63 or about 0.65.

[0202] In the eighth embodiment, the porous microspheres according to any of the foregoing embodiments 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.

[0203] 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.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] In the fifteenth 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.

[0208] In the sixteenth embodiment, the porous microspheres according to any of the foregoing embodiments are monodisperse.

[0209] In the seventeenth embodiment, the porous microspheres according to any of the preceding embodiments exhibit angle-independent color perceptible to the human eye. In the eighteenth embodiment, the porous microspheres according to any of embodiments 1-16 exhibit angle-dependent color perceptible to the human eye.

[0210] In the nineteenth embodiment, the composition comprises a matrix and porous microspheres according to any of the preceding embodiments. In the twentieth embodiment, the composition according to embodiment 19 is an aqueous formulation, an oil-based formulation, a coating formulation, a food, ink, a plastic, a cosmetic formulation, or a material for medical or safety purposes.

[0211] Example

[0212] Example 1 Polymer microspheres

[0213] 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.

[0214] Similarly, styrene / acrylic acid copolymers were prepared to produce polystyrene nanospheres with an average particle size of 350 nm.

[0215] A first aqueous polystyrene colloidal dispersion (250 nm) and a second aqueous polystyrene colloidal dispersion (350 nm) were mixed at a 7 / 3 wt / wt ratio. The mixture was diluted to 1 wt% with deionized water and sonicated to prevent particle agglomeration. The continuous oil phase contained 0.1 wt% polyethylene glycol / perfluoropolyether surfactant in the fluorinated oil. The aqueous colloidal dispersion mixture and the 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.

[0216] The collected droplets were dried in an oven at 45°C for 4 hours to provide monodisperse polymer microspheres. The monodisperse polystyrene microspheres comprise polystyrene nanospheres with a bimodal particle size distribution.

[0217] Example 2 Porous metal oxide microspheres

[0218] Repeating Example 1, 1% by weight of silica nanoparticles were added to an aqueous mixture of the first and second colloidal dispersions before mixing with the oil phase to form a water-in-oil emulsion. Droplets collected from the microfluidic device were dried as in Example 1 to form polymer-templated microspheres. The polymer-templated microspheres were 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. Monodisperse silica microspheres with an average diameter of 15 micrometers and containing two different average pore sizes were provided.

[0219] 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.

[0220] Example 3: Porous silica microspheres containing light absorbers

[0221] The product of Example 2 was physically mixed with various weight percentages of aqueous carbon black dispersions or carbon black powder. 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.

[0222] Example 4 Drying Method

[0223] Repeat Examples 1-3, wherein the drying steps are performed using microwave irradiation, drying under vacuum, and / or drying in the presence of a desiccant.

[0224] Example 5: Preparation of porous silica microspheres by spray drying

[0225] 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.

[0226] Similarly, styrene / acrylic acid copolymers were prepared to produce polystyrene nanospheres with an average particle size of 350 nm.

[0227] A first aqueous polystyrene colloidal dispersion (250 nm) and a second aqueous polystyrene colloidal dispersion (350 nm) were mixed at a 7 / 3 wt / wt ratio. The mixture was diluted to 1 wt% with deionized water, and 1 wt% silica nanoparticles were added to the mixture. The mixture was then acoustically treated to prevent particle agglomeration. The aqueous dispersion was spray-dried to provide polymer-templated microspheres comprising polydisperse 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.

[0228] Example 6: Visible Colors in Batch Samples

[0229] 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.

[0230] A sample of porous silica microspheres was prepared in a manner similar to that of Example 2, wherein the polystyrene nanospheres had average particle sizes of 420 nm and 460 nm with a wt / wt ratio of 7:3. The sample exhibited a red color.

[0231] Samples of porous silica microspheres were prepared according to the method of Example 5, wherein the polystyrene nanospheres have average particle sizes of 360 nm and 420 nm with a wt / wt ratio of 4:1 and a polymer to silica wt / wt ratio of 4:1. Porous microspheres with a porosity of 0.55 and exhibiting a distinct green color were provided. Samples in which a polymer to silica wt / wt ratio of 2:1 was also prepared to provide porous microspheres with a porosity of 0.45 and exhibiting a distinct orange color.

[0232] Example 7: Zinc oxide porous microspheres

[0233] A sample of porous zinc oxide microspheres was prepared according to the method of Example 5, wherein the polystyrene nanospheres have average particle sizes of 250 nm and 320 nm with a wt / wt ratio of 1:1, and wherein the wt / wt ratio of polymer to zinc oxide is 1:2.

[0234] Example 8: Porous microspheres of silica / titanium dioxide

[0235] A sample containing porous microspheres of silica and titanium dioxide was prepared according to the method of Example 2, wherein the polystyrene nanospheres have average particle sizes of 350 nm and 460 nm with a wt / wt ratio of 1:4, and wherein the wt / wt ratio of polymer to total metal oxide is 3:1. The wt / wt ratio of silica to titanium dioxide is 9:1.

Claims

1. A porous microsphere comprising a metal oxide having a continuous solid structure, wherein each of the porous microspheres comprises a pore group distributed throughout the microsphere volume with two different average pore sizes.

2. The porous microspheres according to claim 1, wherein batch samples of the porous microspheres exhibit colors observable by a CIE 1931 2° standard observer and / or a CIE 1964 10° standard observer.

3. The porous microsphere according to claim 1, wherein the porous microsphere has an average diameter of 0.5 µm to 100 µm.

4. The porous microsphere according to claim 1, wherein the porous microsphere has an average porosity of 0.10 to 0.

80.

5. The porous microspheres according to claim 1, wherein the average pore size is independently selected from 50 nm to 800 nm.

6. The porous microsphere according to any one of the preceding claims, wherein the 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.

7. The porous microspheres according to any one of the preceding claims, comprising 60.0% to 99.9% by weight of metal oxide based on the total weight of the microspheres.

8. The porous microspheres according to any one of the preceding claims, 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.

9. The porous microspheres according to any one of the preceding claims, comprising one or more light absorbers at a weight percentage of 0.1% to 40.0% based on the total weight of the microspheres.

10. The porous microspheres according to any one of the preceding claims, wherein batch samples of the porous microspheres exhibit angle-independent color observable by a CIE 1931 2° standard observer and / or a CIE 1964 10° standard observer.

11. The porous microspheres according to any one of the preceding claims, wherein batch samples of the porous microspheres exhibit angle-dependent colors observable by a CIE 1931 2° standard observer and / or a CIE 1964 10° standard observer.

12. The porous microsphere according to any one of the preceding claims, wherein the porous microsphere is monodisperse.

13. A composition comprising a matrix and porous microspheres according to any one of the preceding claims.

14. The composition of claim 13, 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.

15. A batch of porous microspheres comprising two or more pore groups of different average pore sizes distributed throughout the microsphere volume, the batch of samples exhibiting colors observable by a CIE 1931 2° standard observer and / or a CIE 1964 10° standard observer.

16. Porous microspheres comprising metal oxides, wherein the porous microspheres have: Average diameter from 0.5 µm to 100 µm; and Average porosity ranging from 0.10 to 0.80; The porous microspheres have two or more pore groups, each group having an average pore size, wherein each group has a different average pore size, wherein the average pore size of each group is independently selected from 50 nm to 999 nm; and wherein each porous metal oxide microsphere comprises two or more pore groups formed by a continuous solid structure distributed throughout the metal oxide.

17. The porous microsphere of claim 16, wherein the two or more pore groups consist of two pore groups characterized by a bimodal size distribution.

18. The porous microspheres according to claim 16 or 17, wherein the porous microspheres have an average diameter of 0.5 µm to 50 µm.

19. The porous microspheres according to any one of claims 16 to 18, wherein the average pore size of each group is independently selected from 50 nm to 800 nm.

20. The porous microsphere according to any one of claims 16 to 19, wherein the porous microsphere has an average porosity of 0.45 to 0.

65.

21. A cosmetic formulation comprising porous microspheres having an average diameter of 0.5 µm to 50 µm, wherein the porous microspheres have more than one pore group, each group having an average pore size, wherein each average pore size is independently selected from 75 nm to 800 nm, wherein each average pore size is different, and wherein the porous microspheres are formed of a metal oxide.

22. The cosmetic formulation according to claim 21, wherein the pores of each microsphere are distributed throughout the volume of the microsphere.

23. The cosmetic formulation according to claim 21 or 22, wherein the cosmetic formulation exhibits a color perceptible to the human eye.

24. The cosmetic formulation according to any one of claims 21 to 23, wherein the cosmetic formulation exhibits an angle-independent color.

25. The cosmetic formulation according to any one of claims 21 to 24, wherein the average pore size of each group is independently selected from 100 nm to 800 nm.

26. The cosmetic formulation according to any one of claims 21 to 25, wherein the porous microspheres are monodisperse.

27. The cosmetic formulation according to any one of claims 21 to 26, wherein the metal oxide is selected from the group consisting essentially of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, and chromium oxide.

28. The cosmetic formulation according to any one of claims 21 to 27, wherein the metal oxide is silicon dioxide.

29. A batch of porous microspheres exhibiting a color observable to the human eye, wherein the porous microspheres have two or more pore groups, each group having a different average pore size, and wherein the porous microspheres contain one or more light absorbers.

30. The batch sample according to claim 29, wherein the amount of the one or more light absorbers present is from 0.1% to 40.0% by weight based on the total weight of the porous microspheres.

31. The batch sample according to claim 29 or 30, wherein the two or more pore groups consist of two pore groups characterized by a bimodal size distribution.

32. A batch of samples according to any one of claims 29 to 31, wherein the pores of each microsphere are distributed throughout the volume of the microsphere.

33. The batch of samples according to any one of claims 29 to 32, wherein the batch of samples exhibits angle-independent color.

34. The batch of samples according to any one of claims 29 to 33, wherein the average pore size of each group is independently selected from 50 nm to 999 nm.

35. A composition selected from aqueous formulations, oil-based formulations, inks, paint formulations, food, plastics, cosmetic formulations, or materials for medical or safety purposes, said composition comprising porous microspheres having an average diameter of 0.5 µm to 100 µm, said porous microspheres having more than one pore group, each group having an average pore size, wherein each average pore size is independently selected from 75 nm to 999 nm, wherein each average pore size is different, and said porous microspheres are formed from a single metal oxide.

36. The composition of claim 35, wherein the pores of each microsphere are distributed throughout the volume of the microsphere.

37. The composition according to claim 35 or 36, wherein the composition exhibits angle-independent color.

38. The composition according to any one of claims 35 to 37, wherein the average pore size of each group is independently selected from 100 nm to 999 nm.

39. The composition according to any one of claims 35 to 38, wherein the metal oxide is selected from the group consisting essentially of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, cerium dioxide, iron oxide, zinc oxide, indium oxide, tin oxide, and chromium oxide.

40. The composition according to any one of claims 35 to 39, wherein the metal oxide is silicon dioxide.

41. The composition according to any one of claims 35 to 40, wherein the porous microspheres comprise 0.1% to 40.0% by weight of one or more light absorbers based on the total weight of the porous microspheres.

42. The composition according to any one of claims 35 to 41, wherein the average pore size of each pore group is independently selected from 100 nm to 700 nm.

Images