Biodegradable polymer particulates and methods for production and use thereof

Abstract

To provide biodegradable polymer particulates and methods for production and use thereof.SOLUTION: A composition comprises: a plurality of polymer particulates comprising a matrix polymer and one or more types of nanoparticles selected from the group consisting of biopolymer nanoparticles, biomineral nanoparticles excluding biomineralized silica alone, and any combination thereof. Illustrative examples of such nanoparticles may include cellulose nanoparticles, hydroxyapatite nanoparticles or any combination thereof, to be associated with the matrix polymer. The polymer particulates can be prepared by melt emulsification. The method includes depositing such polymer particulates on a powder bed, and heating a portion of the powder bed to consolidate a portion of the polymer particulates into a consolidated part having a specified shape. The biodegradable matrix polymer can be biodegradable one and obtained from Pseudomonas cepacian (≥30U / mg).SELECTED DRAWING: None

Description

[Background technology]

[0001] Additive manufacturing, also known as three-dimensional (3-D) printing, is a rapidly growing field of technology. While additive manufacturing has traditionally been used for rapid prototyping, the technique is increasingly being adopted to produce commercial and industrial objects that may have structural and mechanical tolerances entirely different from those of rapid prototypes.

[0002] Additive manufacturing operates by depositing either 1) small droplets or flows of molten or solidifiable material, or 2) powder particles, into a larger object that may have any number of complex shapes, at precise deposition locations for subsequent solidification. The larger object may be referred to herein as a “solidified body” or “part.” Such deposition and solidification processes are typically carried out under computer control, stacking the larger object layer by layer. In certain examples, the solidification of powder particles may be carried out in an additive manufacturing system that uses a laser to facilitate selective laser sintering (SLS). Incomplete interlayer fusion during selective laser sintering can result in structural weaknesses, which can be problematic for printing objects with tight structural and mechanical tolerances.

[0003] Powder particles usable in additive manufacturing include thermoplastic polymers (including thermoplastic elastomers), metals, and other solidifiable materials. While a wide variety of thermoplastic polymers are known, relatively few possess properties suitable for use in current additive manufacturing printing techniques, particularly when using powder bed fusion (PBF) and other additive manufacturing techniques such as selective laser sintering (SLS), electron beam melting (EBM), binder jetting, and multi-jet fusion (MJF) to facilitate particle solidification. In the SLS printing method, powder particles can be solidified together using energy from a high-power laser. Typical thermoplastic polymers suitable for use in three-dimensional printing include those with sharp melting points and recrystallization points approximately 30–50°C lower than their melting points. This temperature difference allows for more effective bonding between adjacent polymer layers, thereby promoting improved structural and mechanical integrity. Among these, thermoplastic polymers that possess these characteristics and have demonstrated success in three-dimensional printing processes include, for example, crystalline polyamides, polyurethanes, and polyether block amides.

[0004] To achieve good printing performance, powder particles must maintain good flow properties in their solid state. Flow properties can be evaluated, for example, by measuring the percentage of powder particles from a sample that can pass through a standard sieve of a specified size, and / or by measuring the angle of repose. A high percentage of sieved powder particles often indicates that the powder particles exist substantially as individual particles rather than clumping together, which may be characterized by easy powder flow and a lower angle of repose. A relatively narrow particle size distribution, regularity of particle shape, and a low Hausner ratio in the sample can also help promote good powder flow performance.

[0005] Commercially available powder particles are often obtained by low-temperature grinding or precipitation processes, which can result in irregular particle shapes and a wide particle size distribution. Irregular particle shapes can lead to insufficient powder flow performance during additive manufacturing printing processes. Furthermore, powder particles with broad morphological irregularities, particularly those obtained from current commercial processes, result in insufficient filling efficiency after deposition during additive manufacturing. This can lead to voids forming within the printed object due to the powder particles not being tightly packed together during deposition and solidification. A wide particle size distribution can also be problematic in this regard. While insufficient powder flow performance can be addressed to some extent by dry blending with fillers and flow aids, these techniques may have limited effectiveness with softer polymer materials such as elastomers due to particle aggregation. Moreover, fillers and flow aids may have little to no improvement in the insufficient filling efficiency of irregularly shaped powder particles.

[0006] Thermoplastic microparticles can also be formed by melt emulsification processes, such as those described in U.S. Patent No. 4,863,646, which is incorporated herein by reference in its entirety. In a melt emulsification process, a thermoplastic polymer is dispersed as liquefied droplets in a carrier fluid, in which the thermoplastic polymer is non-soluble or minimally soluble above its melting or softening temperature. Cooling the liquefied droplets below their melting or softening temperature can form thermoplastic microparticles that are substantially spherical but have a broad microparticle size distribution. Therefore, thermoplastic microparticles produced by conventional melt emulsification processes may still not be ideal for three-dimensional printing processes.

[0007] The size distribution of the thermoplastic microparticles formed during melt emulsification can be significantly narrowed by incorporating a plurality of nanoparticles into the carrier fluid as an emulsifying stabilizer, as described in U.S. Patent Application Publication No. 2021 / 0070093, which is incorporated herein by reference. Various types of silica nanoparticles and other inorganic nanoparticles may be particularly desirable in this regard. The thermoplastic microparticles thus formed can be characterized by at least a partial coating of nanoparticles on the microparticle surface, where the nanoparticles are firmly adhered to and / or embedded in the microparticle surface. The adhered / embedded nanoparticles can promote much better powder flow performance than that obtained when dry blending uncoated thermoplastic microparticles with a flow aid. The narrow microparticle size distribution of the thermoplastic microparticles having a nanoparticle coating thereon can, in many cases, enable the realization of rapid sintering with a manageable amount of void formation. A wide range of printed objects can be fully formed with thermoplastic microparticles coated with silica, but there are certain cases where it may not be desirable to incorporate silica or other inorganic nanoparticles into the printed object. For example, excessive silica or inorganic nanoparticles may, in some cases, impair the mechanical performance of the printed object. Even more significantly, in the case of biodegradable thermoplastic polymers, silica may impair the biodegradation performance.

Summary of the Invention

[0008] The present disclosure generally relates to polymer microparticles and methods of making and using them, including the preparation and use of polymer microparticles that are biodegradable and / or incorporate an emulsifying stabilizer having a biological origin or a commercially available trigger and can be formed by melt emulsification.

[0009] In some embodiments, the compositions of the present disclosure include a matrix polymer and one or more types of nanoparticles selected from the group consisting of biopolymer nanoparticles, biogenic mineral nanoparticles excluding only biogenic mineralized silica, and any combination thereof, and include a plurality of polymer microparticles. The one or more types of nanoparticles may include cellulose nanoparticles, hydroxyapatite nanoparticles, or any combination thereof. The part may be formed by consolidation of the polymer microparticles in a powder bed.

[0010] In other embodiments, the methods of the present disclosure include depositing such polymer microparticles in a powder bed and heating a portion of the powder bed to consolidate a portion of the polymer microparticles into a consolidated part having a specified shape.

[0011] In yet other embodiments, the compositions of the present disclosure include a biodegradable matrix polymer and oxide nanoparticles disposed on the outer surface of the polymer microparticles, and include a plurality of polymer microparticles. The biodegradable matrix polymer is obtained from Pseudomonas cepacia (≧30 U / mg) and loses at least about 40% of its mass after 6 days in a phosphate buffer (0.2 M, pH 7.0) containing 0.2 mg / mL of lipase incubated at 37°C. The part may be formed by consolidation of the polymer microparticles in a powder bed.

[0012] In yet another embodiment, the composition of the present disclosure comprises a plurality of polymer microparticles comprising a biodegradable matrix polymer and one or more types of nanoparticles selected from the group consisting of biopolymer nanoparticles, biomineralized nanoparticles excluding only biomineralized silica, and any combination thereof, wherein the biodegradable matrix polymer is obtained from Pseudomonas cepacia (≧30 U / mg) and loses at least about 40% of its mass after 6 days in phosphate buffer (0.2 M, pH 7.0) containing 0.2 mg / mL of lipase incubated at 37°C. The one or more types of nanoparticles may include cellulose nanoparticles, hydroxyapatite nanoparticles, or any combination thereof. The components may be formed by the aggregation of polymer microparticles in a powder bed.

[0013] In further embodiments, the method of the present disclosure comprises combining a matrix polymer and a plurality of emulsifying stabilizers with a carrier fluid at a heating temperature above the melting or softening temperature of the matrix polymer, wherein the matrix polymer and the carrier fluid are substantially immiscible at the heating temperature, the matrix polymer is biodegradable, and / or the plurality of emulsifying stabilizers include one or more types of nanoparticles selected from the group consisting of biopolymer nanoparticles, biomineralized nanoparticles excluding only biomineralized silica, and any combination thereof; applying a shear force sufficient to disperse the matrix polymer as liquefied droplets in the carrier fluid at the heating temperature in the presence of the emulsifying stabilizers; cooling the carrier fluid to a temperature at which at least a plurality of polymer nanoparticles form liquefied droplets, wherein the plurality of polymer nanoparticles include the matrix polymer and emulsifying stabilizers; and separating the polymer nanoparticles from the carrier fluid. The one or more types of nanoparticles may include cellulose nanoparticles, hydroxyapatite nanoparticles, or any combination thereof. [Brief explanation of the drawing]

[0014] The following figures are included to illustrate specific aspects of the disclosure and should not be viewed as exclusive embodiments. The disclosed subject matter can be reasonably modified, altered, combined, and equivalent in form and function, which would be conceivable to those skilled in the art and in the interest of the disclosure.

[0015] [Figure 1] This is a flowchart illustrating a non-limiting example method for producing polymer nanoparticles according to the present disclosure.

[0016] [Figure 2A] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with silica nanoparticles according to this disclosure. [Figure 2B] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with silica nanoparticles according to this disclosure. [Figure 2C] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with silica nanoparticles according to this disclosure. [Figure 2D] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with silica nanoparticles according to this disclosure.

[0017] [Figure 3A] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with cellulose nanoparticles according to this disclosure. [Figure 3B] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with cellulose nanoparticles according to this disclosure. [Figure 3C] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with cellulose nanoparticles according to this disclosure. [Figure 3D] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with cellulose nanoparticles according to this disclosure.

[0018] [Figure 4A]The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with hydroxyapatite nanoparticles according to this disclosure. [Figure 4B] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with hydroxyapatite nanoparticles according to this disclosure. [Figure 4C] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with hydroxyapatite nanoparticles according to this disclosure. [Figure 4D] The following are scanning electron microscope images of polycaprolactone polymer microparticles prepared with hydroxyapatite nanoparticles according to this disclosure.

[0019] [Figure 5A] The following are scanning electron microscope images of polylactic acid polymer microparticles prepared with silica nanoparticles according to this disclosure. [Figure 5B] The following are scanning electron microscope images of polylactic acid polymer microparticles prepared with silica nanoparticles according to this disclosure. [Figure 5C] The following are scanning electron microscope images of polylactic acid polymer microparticles prepared with silica nanoparticles according to this disclosure. [Figure 5D] The following are scanning electron microscope images of polylactic acid polymer microparticles prepared with silica nanoparticles according to this disclosure.

[0020] [Figure 6A] The following are scanning electron microscope images of polylactic acid polymer microparticles prepared with hydroxyapatite nanoparticles according to this disclosure. [Figure 6B] The following are scanning electron microscope images of polylactic acid polymer microparticles prepared with hydroxyapatite nanoparticles according to this disclosure. [Figure 6C] The following are scanning electron microscope images of polylactic acid polymer microparticles prepared with hydroxyapatite nanoparticles according to this disclosure. [Figure 6D] The following are scanning electron microscope images of polylactic acid polymer microparticles prepared with hydroxyapatite nanoparticles according to this disclosure.

[0021] [Figure 7] The image shows a polarized optical microscope image of polycaprolactone polymer nanoparticles prepared with 2 wt% silica nanoparticles according to this disclosure.

[0022] [Figure 8] The image shows a polarized optical microscope image of polycaprolactone polymer nanoparticles prepared with 2% by weight of cellulose nanoparticles according to this disclosure.

[0023] [Figure 9] The image shows a polarized microscope image of polycaprolactone polymer nanoparticles prepared with 2% by weight of hydroxyapatite nanoparticles according to this disclosure.

[0024] [Figure 10] The image shows a polarized optical microscope image of polylactic acid microparticles prepared with 1% by weight silica nanoparticles according to this disclosure.

[0025] [Figure 11] The image shows a polarized optical microscope image of polylactic acid polymer microparticles prepared with 1% by weight of hydroxyapatite nanoparticles according to this disclosure.

[0026] [Figure 12] This image shows an optical microscope image of a sintered single layer prepared from comparative samples of polymer nanoparticles.

[0027] [Figure 13] This graph shows the mass loss as a function of enzymatic hydrolysis of a number of polymer microparticles prepared according to this disclosure. [Modes for carrying out the invention]

[0028] This disclosure relates, in general, to polymer microparticles, and more specifically to polymer microparticles that are biodegradable and / or have a biological origin or are derived from an emulsifying stabilizer, and that can be formed by dissolution emulsification.

[0029] In many additive manufacturing processes, polymer raw materials often need to meet numerous criteria for acceptable performance, including optimal ranges of particulate size, polydispersity, particulate flow, and, in some cases, controlled morphological and thermal properties. This problem is further complicated by the fact that commercially available powder particles containing thermoplastic polymers suitable for additive manufacturing often exist as mixtures with irregular particulate shapes and broad particulate size distributions, which can result in insufficient powder flow and deposition characteristics. Poor flow performance of powder particles can affect the filling efficiency after deposition, thereby increasing the likelihood of void formation and corresponding structural and mechanical integrity deficiencies in printed objects (parts). While flow performance can be improved by additional processing with various flow aids and / or dry blending, these techniques increase material and time costs.

[0030] Polymer microparticles produced by the melt emulsification techniques disclosed herein may have high sphericity, good microparticle size uniformity, low angle of repose, and good flowability. Increased handling and flowability can enhance the usefulness of polymer microparticles in many applications, including additive manufacturing, thermoforming, and other molding processes. The polymer microparticles of this disclosure can be used in additive manufacturing processes to increase density and reduce the incidence of void formation in printed parts, thereby promoting higher mechanical and structural integrity than currently achievable with commercially available polymer powders. The increased microparticle size uniformity associated with the polymer microparticles disclosed herein can also facilitate solidification in laser sintering processes at lower laser power, primarily by minimizing the occurrence of larger polymer microparticles and their aggregates, which may require higher laser power to facilitate sintering.

[0031] Advantageously, the polymer nanoparticles and related methods disclosed herein may feature biodegradable polymers and / or incorporate emulsifying stabilizers having a biological origin or catalysis during melt emulsification. Such emulsifying stabilizers may help maintain the biodegradation of the biodegradable matrix polymer, but they may also be used in combination with non-biodegradable matrix polymers. Exemplary emulsifying stabilizers having a biological origin or catalysis may include biopolymer nanoparticles, biomineral nanoparticles, or any combination thereof, e.g., cellulose nanoparticles and / or hydroxyapatite nanoparticles. In the presence of conventional emulsifying stabilizers such as silica nanoparticles, biodegradable matrix polymers may be more readily biodegradable than other types of thermoplastic polymers conventionally used in addition manufacturing processes.

[0032] The terms used in this specification and in the claims shall have their obvious and ordinary meanings unless modified by the following paragraphs.

[0033] As used herein, the term “immiscible” refers to a mixture of components that, when combined, form two or more phases with less than 5% by weight solubility of each other at ambient pressure and at room temperature, or, if solid at room temperature, at the melting point of the components. For example, polyethylene oxide with a molecular weight of 10,000 g / mol is solid at room temperature and has a melting point of 65°C. Therefore, if a material that is liquid at room temperature and the polyethylene oxide have less than 5% by weight solubility of each other at 65°C, the polyethylene oxide is immiscible with the material.

[0034] As used herein, the term "nanoparticles" refers to particulate materials having particle sizes ranging from approximately 1 nm to approximately 500 nm.

[0035] As used herein, the terms “associated,” “associated,” and their grammatical variations refer to a mixture or blend of nanoparticles and a matrix polymer. Depending on the type, nanoparticles may be blended homogeneously or heterogeneously with the matrix polymer in the disclosure herein, including localization on the surface of the matrix polymer. At least some nanoparticles may associate with the outer surface of the polymer microparticles by physical adhesion, hydrogen bonding, and / or other mechanisms. However, some degree of chemical bonding may occur.

[0036] As used herein, the terms “embedded” with respect to the surface of nanoparticles and polymer microparticles mean that the nanoparticles extend at least partially into the surface such that the matrix polymer is in contact with the nanoparticles to a greater extent than would occur if the nanoparticles were simply stacked on the surface of the polymer microparticles.

[0037] As used herein, the term “core” refers to any portion of a polymer microparticle located beneath the surface layer of the polymer microparticle.

[0038] As used herein, the term "thermoplastic polymer" refers to a polymer material that softens / melts upon heating and cooling and reversibly hardens / solidifies. Thermoplastic polymers include thermoplastic elastomers.

[0039] As used herein, the term “elastomer” refers to a copolymer comprising a crystalline “rigid” portion and an amorphous “soft” portion. In the case of polyurethane, the crystalline portion may include a portion of polyurethane containing urethane functionality and optional chain-extending groups, and the soft portion may include, for example, a polyol.

[0040] As used herein, the term "polyurethane" refers to the polymer reaction product between a diisocyanate, a polyol, and an optional chain extender.

[0041] As used herein, the term "oxide" refers to both metal oxides and non-metal oxides. For the purposes of this disclosure, silicon is considered to be a metal.

[0042] In this specification, D 10 , D 50 , D 90 , and the diameter span are used to describe the particle size. As used herein, the term "D 10 " refers to the diameter composed of particles having a diameter smaller than the value of that diameter for 10% of the sample (volume basis, unless otherwise specified). As used herein, the term "D 50 " refers to the diameter composed of particles having a diameter smaller than the value of that diameter for 50% of the sample (volume basis, unless otherwise specified). As used herein, the term "D 90 " refers to the diameter composed of particles having a diameter smaller than the value of that diameter for 90% of the sample (volume basis, unless otherwise specified).

[0043] As used herein, the terms "diameter span", "span", and "span size", when referring to the diameter, provide an indication of the width of the particle size distribution and are calculated as (D 90 - D 10 ) / D 50 (in this case too, each D value is volume-based, unless otherwise specified).

[0044] The particle size can be determined by light scattering techniques using Malvern's MASTERSIZER® 3000 or by analysis of optical digital microscope images. Unless otherwise specified, light scattering techniques are used herein to analyze particle size. In light scattering techniques, the control sample was glass beads with a diameter in the range of 15 μm to 150 μm, traded as Quality Audit Standards QAS4002®, obtained from Malvern Analytical Ltd. Unless otherwise specified, the sample was analyzed as a dry powder. The particle size was dispersed in air and analyzed using the MASTERSIZER® 3000 with the AEROS dry powder dispersion module. The particle size was derived using instrument software from a plot of volume density as a function of size.

[0045] Particle size and diameter span can also be determined by optical digital microscopy. Optical images are obtained using a Keyence VHX-2000 digital microscope with version 2.3.5.1 software (system version 1.93) for particle size analysis.

[0046] When used herein, sieving is referred to as pore / screen size as described in USA Standard Sieve (ASTM E11-17).

[0047] As used herein, the terms “roundness” and “sphericity” refer to the degree to which a particle is as close to a perfect sphere as possible. To determine roundness, an optical microscope image of the particle is taken. The perimeter (P) and area (A) of the particle in the plane of the microscope image are calculated (for example, using the SYSMEX FPIA 3000 particle shape and particle size analyzer, available from Malvern Instruments). The roundness of a particle is C EA / P and C EA This is the circumference of a circle having an area equivalent to the area (A) of the actual microparticle.

[0048] As used herein, the term “sintering window” refers to the difference between the melting temperature (Tm) onset and the crystallization temperature (Tc) onset, i.e., the (Tm-Tc) onset. Tm, Tm(onset), Tc, and Tc(onset) are determined by differential scanning calorimetry (DSC) according to ASTM E794-06 (2018) with a heating rate of 10°C / min and a cooling rate of 10°C / min.

[0049] In this disclosure, the melting point may be determined by ASTM E794-06(2018) with a heating rate of 10°C / min and a cooling rate of 10°C / min. Glass transition temperature (T g ) - This can be determined by the heating and cooling rates of 10°C / min according to ASTM E1356-08(2014).

[0050] The softening temperature or softening point of a polymer is determined according to ASTM D6090-17 unless otherwise specified. The softening temperature can be measured using a cup-and-ball apparatus available from Mettler-Toledo, with a heating rate of 1°C / min and a sample of 0.50 grams.

[0051] The angle of repose is a measure of the fluidity of a powder. The angle of repose is determined using Hosokawa Micron's PT-R powder characterization tester, which employs ASTM D6393-14 "Standard Test Method for Bulk Solids," characterized by the Carr index.

[0052] Hausner ratio (H r ) is a measure of the fluidity of powders, H r =ρ tap / ρ bulk It is calculated by, in the formula, ρ bulk This is the bulk density according to ASTM D6393-14, and ρ tap This is the tap density according to ASTM D6393-14.

[0053] When used herein, the viscosity of the carrier fluid is the kinematic viscosity at 25°C, measured according to ASTM D445-19, unless otherwise specified. For commercially sourced carrier fluids (e.g., PDMS oil), the kinematic viscosity data cited herein was provided by the manufacturer, whether measured according to the aforementioned ASTM or according to another standard measurement technique.

[0054] As used herein, the term “shear force” refers to agitation or similar processes that induce mechanical agitation in a fluid.

[0055] As used herein, the term "aspect ratio" refers to the length divided by the width, where the length is greater than the width.

[0056] As used herein, the term “biodegradable polymer” refers to a polymer that can be degraded by biological entities and / or environmental conditions into component oligomers and / or monomers and other by-products, such as those having lower molecular weights than the parent polymer. Biodegradation according to this disclosure can be assayed by preparing a film from a sample of polymer microparticles having dimensions of 0.5 cm x 2.0 cm and a thickness of about 500 μm. The film sample is then placed in 5 mL of phosphate buffer (0.2 M, pH 7.0) containing 0.2 mg / mL of lipase obtained from Pseudomonas cepacia (≧30 U / mg) and incubated at 37°C throughout the measurement. To be classified as biodegradable, the polymer microparticles disclosed herein may lose at least about 40%, or at least about 50%, or at least about 60%, or at least about 80% of their mass after 6 days under the conditions described. Polymer microparticles and articles formed therefrom may also be considered biodegradable according to ISO 20200 (2015), an international standardized test for polymer decomposition in a laboratory composting environment.

[0057] As used herein, the term “biopolymer” refers to a polymer containing multiple repeating monomer units synthesized by a biological organism. Synthetic variants are also included in the term “biopolymer,” provided that the synthetic biopolymer is functionally similar to its corresponding natural biopolymer.

[0058] As used herein, the term “biomineral” refers to an inorganic compound or complex of inorganic compounds that is mineralized by a biological organism. Synthetic variants are also included in the term “biomineral,” provided that the synthetic biopolymer is functionally similar to the corresponding natural biopolymer.

[0059] The polymer nanoparticles disclosed herein may be produced by melt emulsification, in which a matrix polymer is dispersed in a carrier fluid acting as the outer phase, and the matrix polymer nanoparticles are emulsified with the help of an emulsifying stabilizer containing multiple nanoparticles. In addition to promoting the integrity of the emulsification, the emulsifying stabilizer may also be embedded on the surface of the polymer nanoparticles to impart beneficial mechanical properties to the polymer nanoparticles and articles formed therefrom. By adjusting the hydrophobic / hydrophilic association with the matrix polymer, the emulsifying stabilizer may be localized on the surface of the polymer nanoparticles, distributed throughout the core of the polymer nanoparticles, or vary between the two. The adjustment may include pairing of the matrix polymer with the nanoparticles based on polarity and solubility, or by chemical modification of one or more types.

[0060] Polymer microparticles may also have adjustable biodegradability, where one or more of the matrix polymer and nanoparticles are prepared from biodegradable materials and / or materials having a biosource or biotrigger. Disclosed polymer microparticles include and / or can be recycled thermoplastic polymers or nanoparticles of biological origin (including bio-derived materials, biosources) that are environmentally friendly or "green" materials. Incorporation of various types of nanoparticles can also be used to control biodegradability. For example, polymer microparticles may increase various environmentally beneficial aspects of the polymer microparticles by incorporating biosource, biotrigger, and / or biodegradable nanoparticles. Such types of nanoparticles may include, for example, biopolymer nanoparticles (e.g., polysaccharide nanoparticles, e.g., cellulose nanoparticles, starch nanoparticles, chitosan nanoparticles, lignin nanoparticles, cyclodextrin nanoparticles, etc.; protein nanoparticles, etc.) and / or biomineral nanoparticles (e.g., hydroxyapatite, silica, magnetite, ferrite, calcium carbonate, calcium phosphate, etc., and composites of one or more of these biominerals with biopolymers). Optionally, silica nanoparticles or other oxide nanoparticles may also be incorporated onto polymer microparticles to improve cost-effectiveness and / or modify the overall hydrophobicity of the nanoparticle coating on the polymer microparticles.

[0061] The polymer microparticles disclosed herein may be prepared by heating a matrix polymer in the presence of a carrier fluid that acts as a melt emulsifying medium to form individual polymer microparticles. The melt emulsification in the disclosed herein may also be carried out in the presence of an emulsifying stabilizer that associates with (and / or is embedded in) the formed polymer microparticles, which may affect the particle size and shape as solidified polymer microparticles.

[0062] Figure 1 is a flow diagram of a non-limiting example of a melt emulsification method 100 for producing polymer fine particles according to the present disclosure. As shown, a matrix polymer 102, a carrier fluid 104, and an emulsifying stabilizer 106 108 are combined to produce a mixture 110.

[0063] The matrix polymer 102, the carrier fluid 104, and one or more types of emulsifying stabilizers 106 may be combined in any order 108, and the combination process 108 may include mixing and / or heating. In certain examples, the carrier fluid 104 may be heated above the melting point or softening temperature of the matrix polymer 102 before combining the matrix polymer 102 with the emulsifying stabilizer 106 108. The matrix polymer 102 and the carrier fluid 104 may be selected such that their components are immiscible or substantially immiscible (<5% by weight solubility), particularly <1% by weight solubility, at a range of processing temperatures (e.g., from room temperature to a temperature at which liquefied droplets are formed and maintained as two or more phases).

[0064] The loading (concentration) of the matrix polymer 102 in the carrier fluid 104 can vary over a wide range. In non-limiting examples, the loading of the matrix polymer 102 in the carrier fluid 104 may range from about 1% by weight to about 99% by weight relative to the weight of the carrier fluid 104. In more specific examples, the loading of the matrix polymer 104 may range from about 5% by weight to about 75% by weight, or about 10% by weight to about 60% by weight, or about 20% by weight to about 50% by weight, or about 20% by weight to about 30% by weight, or about 30% by weight to about 40% by weight, or about 40% by weight to about 50% by weight, or about 50% by weight to about 60% by weight. The matrix polymer 104 may be present in amounts ranging from about 5% to about 60% by weight, or about 5% to about 25% by weight, or about 10% to about 30% by weight, or about 20% to about 45% by weight, or about 25% to about 50% by weight, or about 40% to about 60% by weight, relative to the combined amount of the matrix polymer 102 and the carrier fluid 104 (solid loading).

[0065] Heating above the melting or softening temperature of the matrix polymer 102 can be any temperature below the decomposition or boiling temperature of any of the components in the mixture 110. In non-limiting examples, heating may be performed at temperatures about 1°C to about 50°C, or about 1°C to about 25°C, or about 5°C to about 30°C, or about 20°C to about 50°C above the melting or softening temperature of the matrix polymer 102. The melting or softening temperature of the matrix polymer 102 may be in the range of about 50°C to about 400°C. The matrix polymer 102 has a glass transition temperature T of about -50°C to about 400°C, or about -50°C to about 0°C, or about -25°C to about 50°C, or about 0°C to about 150°C, or about 100°C to about 250°C, or about 150°C to about 300°C, or about 200°C to about 400°C. g It may have.

[0066] Next, the mixture 110 is treated by applying a shear force sufficient to produce liquefied droplets of the matrix polymer 102 at a temperature higher than the melting or softening temperature of the matrix polymer 102, thereby forming a molten emulsion 114. While not limited to theory, it is conceivable that increasing the shear force may reduce the size of the liquefied matrix polymer droplets in the carrier fluid 104, all other equal. In some respects, and similarly, it should be understood that increasing the shear force and decreasing the droplet size may result in a decrease in benefits and / or a breakdown into the droplet contents that reduces the quality of the fine particles produced therefrom. Examples of mixing apparatus used to produce the molten emulsion 114 include, but are not limited to, extruders (e.g., continuous extruders, batch extruders, etc.), agitated reactors, blenders, reactors with inline homogenizer systems, and apparatus derived therefrom.

[0067] In non-limiting examples, liquefied droplets may have sizes ranging from approximately 1 μm to 1,000 μm, or approximately 1 μm to 500 μm, or approximately 1 μm to 150 μm, or approximately 1 μm to 130 μm, or approximately 1 μm to 100 μm, or approximately 10 μm to 100 μm, or approximately 20 μm to 80 μm, or approximately 20 μm to 50 μm, or approximately 50 μm to 90 μm. Particle size measurement can be performed by analyzing optical images or by using the onboard software of the Malvern MASTERSIZER3000 Aero S instrument, which employs light scattering techniques for particle size measurement.

[0068] A shear force sufficient to form liquefied droplets may be applied by stirring the carrier fluid 104 in certain examples of this disclosure. In non-limiting examples, the stirring speed may range from about 50 revolutions per minute (RPM) to about 1500 RPM, or about 250 RPM to about 1000 RPM, or about 225 RPM to about 500 RPM. The stirring speed while the matrix polymer is melting may be the same as or different from the stirring speed used when liquefied droplets are formed. The liquefied droplets may be stirred for stirring times of about 30 seconds to about 18 hours or more, or about 1 minute to about 180 minutes, or about 1 minute to about 60 minutes, or about 5 minutes to about 6 minutes, or about 5 minutes to about 30 minutes, or about 10 minutes to about 30 minutes, or about 30 minutes to about 60 minutes.

[0069] Next, the molten emulsion 114 is cooled 116 to solidify the liquefied droplets into polymer microparticles. The cooling rate may be in the range of about 100°C / sec to about 10°C / hour or about 10°C / sec to about 10°C / hour, and includes any cooling rate in between. The shear force may be interrupted during cooling or maintained at the same rate or a different rate during cooling. The cooled mixture 118 may then be processed 120 to isolate the polymer microparticles 122 from other components 124 (e.g., carrier fluid 104, excess emulsifying stabilizer 106, etc.). Processing 120 may include washing, filtering, and / or the like. The polymer microparticles 122 comprise a matrix polymer 102 and at least a portion of the emulsifying stabilizer 106 associated therewith.

[0070] The process 120 for separating the polymer particles 122 from the carrier fluid 104 can be carried out by any of the various known separation techniques. The polymer particles 122 can be separated from the carrier fluid 104 using any of the following: gravity sedimentation and filtration, decantation, centrifugation, etc. The polymer particles 122 can be washed with a solvent in which the carrier fluid 104 is soluble and the polymer particles 122 are insoluble during the separation process. In addition, a solvent in which the carrier fluid 104 is soluble and the polymer particles 122 are insoluble can be mixed with the carrier fluid 104 and the polymer particles 122 before separation.

[0071] Suitable solvents for washing polymer fine particles 122 or mixing them with the carrier fluid 104 include, but are not limited to, aromatic hydrocarbons (e.g., toluene and / or xylene), aliphatic hydrocarbons (e.g., heptane, n-hexane, and / or n-octane), cyclic hydrocarbons (e.g., cyclopentane, cyclohexane, and / or cyclooctane), ethers (e.g., diethyl ether, tetrahydrofuran, diisopropyl ether, and / or dioxane), halogenated hydrocarbons (e.g., dichloroethane, trichloroethane, dichloromethane, chloroform, and / or carbon tetrachloride), alcohols (e.g., methanol, ethanol, isopropanol, and / or n-propanol), ketones (e.g., methyl ethyl ketone and / or acetone); esters (e.g., ethyl acetate, etc.), water, and any combination thereof.

[0072] After the polymer microparticles 122 are separated 120, heating, vacuum drying, air drying, or any combination thereof may be performed. In some cases, the polymer microparticles 122 may contain a limited amount of carrier fluid 104. In non-limiting examples, any of the polymer microparticles 122 of this disclosure may contain a non-zero amount of carrier fluid 104, up to about 5% by weight, which remains associated with the polymer microparticles 122. The carrier fluid 104 may associate with the outer surface of the polymer microparticles 122 and / or be trapped in voids or cavities within the polymer microparticles 122. Up to 5% by volume of voids may be present within the polymer microparticles 122, and these voids may be filled or unfilled.

[0073] The emulsifying stabilizer 106, or a portion thereof, may be embedded on the surface and / or distributed throughout the polymer microparticles 122 within their core. In contrast, grinding and dry blending methods for producing polymer microparticles using flow aids such as silica nanoparticles do not result in the aggregation or embedding of nanoparticles on the surface of the polymer microparticles or within the core of the polymer microparticles. The localization of the emulsifying stabilizer 106 on the surface and / or within the polymer microparticles 122 can be tuned by modifying the surface of the emulsifying stabilizer 106 by increasing or decreasing the compatibility of the emulsifying stabilizer 106 and / or the matrix polymer 102, for example, by increasing or decreasing surface hydrophobicity, or by selecting a matrix polymer 102 with higher or lower polarity. For example, emulsifying stabilizers 106 such as hydroxyapatite nanoparticles and / or cellulose nanoparticles, particularly crystalline nanocellulose, may be located both outside and inside (or in the core) of the polymer microparticles 122, while hydrophobic emulsifying stabilizers 106 such as oxide nanoparticles may be located mainly on the outer surface of the polymer microparticles 122. Other biopolymer or biomineral nanoparticles may similarly be located on the outside and / or within the core of the polymer microparticles 122.

[0074] After separating the polymer microparticles 122 from other components 124, the polymer microparticles 122 may be subjected to further processing 126 to obtain modified polymer microparticles 128. For example, the polymer microparticles 122 may be optionally further purified to remove larger and aggregated microparticles that may have flow characteristics insufficient to produce modified polymer microparticles 128. To narrow the microparticle size distribution (or reduce the diameter span), the polymer microparticles 122 may be passed through a sieve having pore sizes of approximately 10 μm to approximately 250 μm, or approximately 10 μm to approximately 100 μm, or approximately 50 μm to approximately 200 μm, or approximately 150 μm to approximately 250 μm.

[0075] In yet another example, polymer microparticles 122 may be blended with additives (and possibly purified) to form modified polymer microparticles 128. Examples of additives include antioxidants, acid scavengers, stabilizers, flow aids, fillers, or other substances intended to modify the properties of the polymer microparticles 128 for their intended use. The mixing of additives may be carried out by dry blending techniques. Suitable examples of flow aids (e.g., carbon black, graphite, silica, etc.) and similar substances are well known to those skilled in the art.

[0076] Accordingly, the melt emulsification process of the present disclosure may include: combining a matrix polymer, a carrier fluid, and an emulsifying stabilizer at a heating temperature above the melting or softening temperature of the matrix polymer; applying a shear force sufficient to disperse the matrix polymer as liquefied droplets in the carrier fluid in the presence of the emulsifying stabilizer at the heating temperature; cooling the carrier fluid to a temperature at which at least solid polymer microparticles form from the liquefied droplets after the liquefied droplets have formed; and separating the polymer microparticles from the carrier fluid. In such a process, the matrix polymer and the carrier fluid are substantially immiscible at the heating temperature. The polymer microparticles comprise the matrix polymer and a plurality of emulsifying stabilizers, the matrix polymer defining the core and outer surface of the polymer microparticles, and the plurality of emulsifying stabilizers located at least on the outer surface and / or optionally within the core. The matrix polymer may be biodegradable as specified herein, and / or the emulsifying stabilizer may comprise one or more types of nanoparticles, such as biopolymer nanoparticles, biomineralized nanoparticles excluding only biomineralized silica, or any combination thereof. In some cases, preferred examples of such nanoparticles may include hydroxyapatite nanoparticles, cellulose nanoparticles, or any combination thereof.

[0077] The matrix polymers suitable for use in this disclosure are not particularly limited. In some examples, suitable matrix polymers may have properties consistent with their use in addition manufacturing. Thermoplastic polymers suitable for other applications may be selected as needed.

[0078] Suitable matrix polymers may include bio-based and partially bio-based polymers, such as polymers prepared with low or zero greenhouse gas emissions. Bio-based matrix polymers may be derived from renewable resources such as natural fats and oils, and may also include biodegradable polymers. Bio-based polymers may include those obtained from the production of biomaterials, and biological and partially bio-derived polymers that are identical or nearly identical to their fossil fuel counterparts, and / or are considered “drop-ins” or substitutes for their fossil fuel counterparts. Synthetic variants that are functionally equivalent to bio-based and partially bio-based matrix polymers are also included in the term “bi-based.” Bio-based matrix polymers, in particular biodegradable matrix polymers, may be used in the production of sustainable biodegradable materials, such as in applications where waste generation is high and rapid biodegradation is desired for environmentally friendly disposal.

[0079] Suitable biodegradable matrix polymers include, but are not limited to, bio-based and biodegradable polymers, such as polyhydroxyalkanoates (PHA), poly(3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), polylactic acid (PLA), and polyglycolic acid (PHA), polyglycolic acid (PLA), polyglycolic acid (PHA), polyhydroxybutyrate (PHB), poly(3-hydroxyvalerate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxyvalerate Examples include acid (PGA), poly(ε-caprolactone) (PCL), starch, and chitosan; partially bio-based and biodegradable polymers, e.g., polybutylene succinate, poly(butylene adipate-co-terephthalate), PLA blends, and starch blends; and chemical fuel-based and biodegradable polymers, e.g., polybutylene succinate, poly(butylene adipate-co-terephthalate), poly(butylene succinate-colactide), poly(butylene succinate-co-terephthalate), poly(ε-caprolactone), polyglycolide, poly(methylene adipate-co-terephthalate), and polyvinyl alcohol. Combinations (blends) of these matrix polymers and / or copolymers thereof may also be used in the disclosure herein.

[0080] Non-biodegradable matrix polymers that can be combined with biodegradable, biosource, and / or bio-catalyzed emulsifying stabilizers include, but are not limited to, bio-based polymers such as polyethylene (LDPE, LLDPE, and HDPE), polyamides (PA11, PA12, etc.), polyethylene terephthalate, and polytrimethylene terephthalate; partially bio-based and non-biodegradable polymers such as polybutylene terephthalate, polyethylene terephthalate, polytrimethylene terephthalate, polyvinyl chloride, styrene-butadiene rubber, acrylonitrile-butadiene-styrene, polyurethane, and epoxy resins; and fossil fuel-based and non-biodegradable polymers such as PE, polyethylene (LDPE, HDPE), polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene, polybutylene terephthalate, polyurethane, PA6, epoxy resins, and synthetic rubbers. Combinations (blends) of these matrix polymers and / or copolymers thereof may also be utilized in the disclosure herein.

[0081] Other non-biodegradable matrix polymers include natural or synthetic thermoplastic elastomers, which may include thermoplastic polyolefin elastomers, thermoplastic vulcanized products (also called elastomer alloys), thermoplastic polyamides, and copolymers containing styrene block copolymers, thermoplastic copolyesters, etc. Examples of other suitable thermoplastic elastomers can be found in Handbook of Thermoplastic Elastomers, 2nd ed., BMWalker and CPRader, eds., Van Nostrand Reinhold, New York, 1988. Other thermoplastic elastomers suitable for use in the disclosure herein include, but are not limited to, elastomer polyamides, polyesteramides, polyether esteramides, polycarbonate esteramides, methyl methacrylate-butadiene-styrene (MBS) type core-shell polymers, polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM) block terpolymers, polybutadiene, polyisoprene, styrene-based block copolymers, polyacrylonitrile, and silicones. Non-biodegradable matrix polymers may include styrene-based block copolymers having at least one block selected from the group consisting of isoprene, isobutylene, butylene, ethylene / butylene, ethylene-propylene, and ethylene-ethylene / propylene. More specific examples of elastomer styrene-based block copolymers include, but are not limited to, poly(styrene-ethylene / butylene), poly(styrene-ethylene / butylene-styrene), poly(styrene-ethylene / propylene), poly(styrene-ethylene / propylene / propylene-styrene), poly(styrene-ethylene / propylene-styrene-ethylene-propylene), poly(styrene-butadiene-styrene), poly(styrene-butylene-butadiene-styrene), and any combination thereof.

[0082] The polymer microparticles disclosed herein may comprise one or more types of emulsifying stabilizers that function to promote emulsion formation during melt emulsification. Nanoparticle emulsifying stabilizers can stabilize and control the size and shape of the polymer microparticles to produce polymer microparticles having high roundness, a narrow particle size distribution, and good particle flow properties. Depending on the type, the emulsifying stabilizers may be localized at least on the surface of the polymer microparticles and / or optionally within the core of the polymer microparticles.

[0083] In preferred examples, polymer nanoparticles may comprise one or more types of biodegradable, biosource, and / or bio-activated emulsifying stabilizers, such as biopolymer nanoparticles, biomineral nanoparticles excluding only biomineralized silica, or any combination thereof. Preferred biopolymer nanoparticles may be hydrophilic and may comprise entities such as cellulose nanoparticles (including cellulose fibers and cellulose nanocrystals), starch nanoparticles, chitosan nanoparticles, lignin nanoparticles, cyclodextrin nanoparticles, and protein nanoparticles. Preferred biomineral nanoparticles may comprise, for example, hydroxyapatite, silica, ferrite, magnetite, calcium carbonate, and calcium phosphate. Biomineral nanoparticles may have a crystalline or amorphous form. Other preferred biomineral nanoparticles may comprise bio-generated biomineral composite nanoparticles in any combination using any of the aforementioned materials. In some examples, the polymer nanoparticles disclosed herein may comprise emulsifying stabilizers such as hydroxyapatite nanoparticles, cellulose nanoparticles (crystalline nanocellulose), and / or starch nanoparticles, which may be combined with biodegradable or non-biodegradable matrix polymers. Preferably, such emulsifying stabilizers may be used in combination with biodegradable matrix polymers, such as those specified above.

[0084] Suitable emulsifying stabilizers for use in the disclosure herein also include synthetic biodegradable polymers, such as poly-DL-glycolides, poly-DL-lactide-co-glycolides, poly-cyanoacrylates, polylactic acid, and poly-e-caprolactone; as well as biodegradable nanoparticles prepared from a variety of materials, including but not limited to proteins, polysaccharides, chitosan, alginates, collagen, gelatin, and hyaluronic acid, and biopolymer nanoparticles.

[0085] The polymer nanoparticles disclosed herein may preferably be produced without silica nanoparticles. Therefore, unless otherwise specified as containing silica, the polymer nanoparticles disclosed herein may be silica-free. Silica-free polymer nanoparticles may also include those produced without using biomineralized silica alone as an emulsifying stabilizer. However, it should be understood that in some cases, it may be advantageous to include silica nanoparticles and / or biomineralized silica in combination with one or more biopolymer nanoparticles and / or biomineralized nanoparticles other than silica.

[0086] However, it should be understood that the polymer nanoparticles disclosed herein may also include biodegradable and / or biologically derived emulsifying stabilizers used in combination with non-biodegradable or less biodegradable oxide nanoparticles. In some cases, the polymer nanoparticles may include non-biodegradable oxide nanoparticles, such as silica nanoparticles, either alone or in combination with a biodegradable matrix polymer. Oxide nanoparticles that may be used in such embodiments may include silica nanoparticles, titania nanoparticles, zirconia nanoparticles, alumina nanoparticles, iron oxide nanoparticles, copper oxide nanoparticles, tin oxide nanoparticles, boron oxide nanoparticles, cerium oxide nanoparticles, thallium oxide nanoparticles, tungsten oxide nanoparticles, or any combination thereof. Mixed oxides such as aluminosilicates, borosilicates, and aluminoborosilicates are also included by the term “oxide.” Oxide nanoparticles may be hydrophilic or hydrophobic, which may be due to the nature of the nanoparticles or may result from surface treatment of the nanoparticles. For example, silica nanoparticles having hydrophobic surface treatments such as dimethylsilyl and trimethylsilyl may be formed by reacting hydrophilic surface hydroxyl groups with hydrophobic functionalizing agents. Hydrophobic functionalized oxide nanoparticles may be particularly desirable in this disclosure. Unfunctionalized oxide nanoparticles may also be suitable for use.

[0087] Certain examples of silica nanoparticles suitable for use in the disclosure herein may be hydrophobically functionalized. Such hydrophobic functionalization may lower the water compatibility of the silica nanoparticles compared to unfunctionalized silica nanoparticles. In addition, hydrophobic functionalization may improve the dispersion of silica nanoparticles in a carrier fluid, which may be highly hydrophobic. Hydrophobic functionalization may be non-covalent or covalently bonded to the surface of the silica nanoparticles. Covalent bonding may be achieved, for example, by functionalizing surface hydroxyl groups on the surface of the silica nanoparticles. In non-limiting examples, silica nanoparticles may be treated with hexamethyldisilazane to result in covalent functionalization of hydrophobic modification. Commercially available hydrophobic functionalized silica nanoparticles include, for example, Aerosil RX50 (Evonik, average particle size = 40 nm) and Aerosil R812S (Evonik, average particle size = 7 nm).

[0088] In non-limiting examples, the loading of silica nanoparticles in the carrier fluid may range from about 0.01% to about 10% by weight, or about 0.05% to about 10% by weight, or about 0.05% to about 5% by weight relative to the weight of the matrix polymer. In more specific examples, the loading of nanoparticles may range from about 0.1% to about 5% by weight, or about 0.1% to about 2% by weight, or about 0.25% to about 1.5% by weight, or about 0.25% to about 1.0% by weight, or about 0.25% to about 1% by weight, or about 0.25% to about 0.5% by weight. Any oxide nanoparticles, such as biopolymer nanoparticles, biomineral nanoparticles, or silica nanoparticles, may be present in the aforementioned concentration ranges. In specific examples, any oxide nanoparticles, such as hydroxyapatite nanoparticles, cellulose nanoparticles, or silica nanoparticles, may be present in these concentration ranges. Biosource or bio-activated nanoparticles, such as hydroxyapatite and / or cellulose nanoparticles, may be present in combination with oxide nanoparticles, such as silica nanoparticles, in any weight ratio ranging from about 99:1 to about 1:99.

[0089] In non-limiting examples, the particle size of emulsifying stabilizers may range from approximately 1 nm to approximately 100 nm. In some cases, the particle size of emulsifying stabilizers may be up to 500 nm. If present, the particle size of silica nanoparticles may range from approximately 5 nm to approximately 75 nm, or approximately 5 nm to approximately 50 nm, or approximately 5 nm to approximately 10 nm, or approximately 10 nm to approximately 20 nm, or approximately 20 nm to approximately 30 nm, or approximately 30 nm to approximately 40 nm, or approximately 40 nm to approximately 50 nm, or approximately 50 nm to approximately 60 nm. Any of the oxide nanoparticles, such as biopolymer nanoparticles, biomineral nanoparticles, and / or silica nanoparticles, may exist within the aforementioned size ranges. In certain examples, any of the oxide nanoparticles, such as hydroxyapatite nanoparticles, cellulose nanoparticles, or silica nanoparticles, may exist across these particle size ranges.

[0090] The emulsifying stabilizers disclosed herein are approximately 10 ml 2 / g~about 500m 2 / g, or approximately 10m 2 / g~about 150m 2 / g, or approximately 25m 2 / g~about 100m 2 / g, or approximately 100m 2 / g ~ approx. 250m 2 / g, or approximately 250m 2 / g~about 500m 2 It may have a BET surface area of ​​g.

[0091] When polymer nanoparticles are formed according to this specification, at least a portion of the emulsifying stabilizer may be disposed as a coating on the outer surface of the polymer nanoparticles, and / or optionally, at least a portion of the emulsifying stabilizer may be present within the core of the polymer nanoparticles. Hydroxyapatite nanoparticles and cellulose nanoparticles, in particular, may tend to localize within the core of the polymer nanoparticles during melt emulsification, given their increased hydrophilicity. Other types of biopolymer or biomineral nanoparticles may exhibit similar behavior. When present as a coating, the coating may be distributed substantially uniformly or non-uniformly on the outer surface of the polymer nanoparticles. When used herein with respect to coatings, the term “substantially uniform” refers to the surface area covered by the emulsifying stabilizer, in particular the horizontal coating thickness over the entire outer surface. The coating coverage of the emulsifying stabilizer on the polymer microparticles may range from about 5% to about 100%, or about 5% to about 25%, or about 20% to about 50%, or about 40% to about 70%, or about 50% to about 80%, or about 60% to about 90%, or about 70% to about 100% of the surface area of ​​the polymer microparticles. The coverage can be determined by image analysis of SEM micrographs. The polymer microparticles of this disclosure may contain about 90% to about 99.5% by weight of a matrix polymer.

[0092] Suitable carrier fluids for use in the disclosure herein include those in which the matrix polymer is substantially immiscible with the carrier fluid, the carrier fluid having a boiling point above the melting or softening temperature of the matrix polymer, and the carrier fluid having a viscosity sufficient to form substantially spherical liquefied droplets when the matrix polymer is melted therein. Suitable carrier fluids may include, for example, silicone oils, fluorinated silicone oils, perfluorinated silicone oils, polyethylene glycols, alkyl-terminated polyethylene glycols (e.g., C1-C4 terminal alkyl groups such as tetraethylene glycol dimethyl ether (TDG)), paraffin, liquid petrolatum, mink oil, turtle oil, soybean oil, perhydrosqualene, sweet almond oil, calophyllum oil, palm oil, pearl reem oil, grapeseed oil, sesame oil, corn oil, rapeseed oil, sunflower oil, cottonseed oil, apricot oil, castor oil, avocado oil, jojoba oil, olive oil, cereal germ oil, lanolinic acid esters, oleic acid esters, lauric acid esters, stearic acid esters, aliphatic esters, higher fatty acids, aliphatic alcohols, fatty acid-modified polysiloxanes, aliphatic alcohol-modified polysiloxanes, polyoxyalkylene-modified polysiloxanes, and any combination thereof.

[0093] A suitable carrier fluid is approximately 0.6 g / cm³. 3 ~Approx. 1.5g / cm 3 The matrix polymer may have a density of approximately 0.7 g / cm³. 3 ~Approx. 1.7g / cm 3 The matrix polymer may have a density lower or higher than that of the carrier fluid, similar to the density of the carrier fluid.

[0094] Particularly preferred silicone oils are polysiloxanes. Examples of silicone oils suitable for use in the disclosure herein include, for example, polydimethylsiloxane (PDMS), methylphenylpolysiloxane, alkyl-modified polydimethylsiloxane, alkyl-modified methylphenylpolysiloxane, amino-modified polydimethylsiloxane, amino-modified methylphenylpolysiloxane, fluorine-modified polydimethylsiloxane, fluorine-modified methylphenylpolysiloxane, polyether-modified polydimethylsiloxane, polyether-modified methylphenylpolysiloxane, and any combination thereof.

[0095] In non-limiting examples, the carrier fluid and matrix polymer may be heated to temperatures above approximately 200°C. A suitable heating temperature may be selected based on the melting or softening temperature of the matrix polymer and the boiling point of the carrier fluid. The cooling rate after the formation of liquefied polymer droplets may vary as desired. In some cases, cooling may occur with natural (uncontrolled) heat dissipation into the ambient environment after heating has been interrupted. In other cases, controlled cooling may be employed (e.g., by gradually decreasing the heating temperature and / or increasing or decreasing the cooling rate by using jacketed temperature control).

[0096] Carrier fluids such as polysiloxanes, including PDMS, may have viscosities of approximately 1,000 cSt to 150,000 cSt, or approximately 1,000 cSt to 60,000 cSt, or approximately 40,000 cSt to 100,000 cSt, or approximately 75,000 cSt to 150,000 cSt at 25°C. The viscosity of the carrier fluid may be obtained from a commercial supplier or, if desired, measured by the art.

[0097] The polymer microparticles disclosed herein have a density of approximately 0.3 g / cm³, as determined according to ASTM D6683-19. 3 ~Approximately 1.4g / cm 3 , or approximately 0.3 g / cm³ 3~Approx. 1.3g / cm 3 , or approximately 0.4 g / cm³ 3 ~Approx. 1.3g / cm 3 , or approximately 0.5 g / cm³ 3 ~Approx. 1.3g / cm 3 , or approximately 0.5 g / cm³ 3 ~Approx. 1.2g / cm 3 It may have a bulk density.

[0098] The methods for preparing polymer nanoparticles disclosed herein may result in the formation of polymer nanoparticles exhibiting an increased crystallization temperature compared to the initial matrix polymer. The crystallization temperature of the polymer nanoparticles, as determined by ASTM E794-06(2018), may exceed a crystallization temperature of at least about 2°C, at least about 5°C, or at least about 10°C.

[0099] The polymer microparticles are approximately 5 μm to 50 μm, or approximately 10 μm to 50 μm, approximately 10 μm to 40 μm, approximately 15 μm to 35 μm, or approximately 15 μm to 25 μm. 10 D 50 , and D 90 It may have, D 10 <D 50 <D 90 Polymer microparticles may also have a diameter span of about 2.0 or less, about 1.7 or less, or about 1.5 or less. Polymer microparticles may also have a diameter span in the range of about 0.7 to about 2.0, or about 0.7 to about 1.8, or about 0.8 to about 1.7, or about 0.9 to about 1.7. Microparticle size measurement may be performed using any suitable test device, including the Malvern MASTERSIZER 3000.

[0100] The above arbitrary range of average particle diameter values ​​(i.e., D 10 , D 50 , D 90) can be combined with any other particle diameter value range mentioned above (i.e., D 50 The range, and / or D 90 D having the range 10 It is intended that polymer microparticles may be combined with a range of (approximately 30 μm to approximately 130 μm) and / or any diameter span range. 50 And it may have a diameter span of approximately 1.7 or less.

[0101] The polymer microparticles disclosed herein may have decomposition temperatures in the range of about 180°C to about 400°C, about 180°C to about 300°C, or about 180°C to about 250°C.

[0102] The polymer fine particles disclosed herein may have a roundness of about 0.7 or more, or about 0.7 to about 0.95, or about 0.90 to about 1.0, or about 0.93 to about 0.99, or about 0.95 to about 0.99, or about 0.97 to about 0.99, or about 0.98 to 1.0.

[0103] The polymer fine particles disclosed herein may have a Hausner ratio of about 1.0 to about 1.5, or about 1.0 to about 1.2, or about 1.1 to about 1.3, or about 1.2 to about 1.35, or about 1.3 to about 1.5.

[0104] The polymer microparticles disclosed herein may have angles of repose determined according to ASTM D6393-14, such as about 25° to about 45°, about 25° to about 35°, or about 30° to about 40°, or about 35° to about 45°.

[0105] At least the majority of the polymer microparticles obtained according to the disclosure herein may be substantially spherical in shape. More typically, about 90% or more, or about 95% or more, or about 99% or more of the polymer microparticles produced by melt emulsification according to the disclosure may be substantially spherical in shape. In other non-limiting examples, the polymer microparticles of the disclosure may have a roundness of about 0.9 or greater, including about 0.90 to about 1.0, or about 0.93 to about 0.99, or about 0.95 to about 0.99, or about 0.97 to about 0.99, or about 0.98 to 1.0.

[0106] The polymer microparticles disclosed herein may be used in additive manufacturing processes, particularly those employing selective laser sintering to facilitate microparticle solidification. Additive manufacturing processes may include powder bed fusion (PBF), selective laser sintering (SLS), selective heat sintering (SHS), selective laser melting (SLM), electron beam melting (EBM), binder jetting, and multi-jet fusion (MJF).

[0107] The additive manufacturing process method of the present disclosure may include depositing polymer microparticles of the present disclosure onto the surface of a specified shape and / or layer, and, once deposited, heating at least a portion of the polymer microparticles to promote their solidification and form a solidified body (object). The solidified body may have a porosity of about 5% or less after solidification (e.g., 0% to about 5%, or about 0.5% to about 2%, or about 1% to about 3%, or about 2% to about 5%).

[0108] In addition to additive manufacturing, the polymer microparticles disclosed herein may be applicable to other manufacturing techniques including extrusion, co-extrusion, extrusion coating, injection molding, injection blow molding, injection stretch blow molding, thermoforming, cast film extrusion, blow film extrusion, foaming, extrusion blow molding, injection stretch blow molding, rotational molding, pulping, calendering, additive manufacturing, lamination, electrospinning, and electrospray.

[0109] The polymer microparticles disclosed herein can be used to prepare articles having enhanced modulus and yield strength compared to alternative thermoplastic materials such as nylon. Examples of objects that can be formed from the polymer microparticles disclosed herein include containers (e.g., for food, beverage, cosmetic, personal care compositions, medical, etc.), shoe soles, toys, furniture parts, decorative household items, plastic gears, screws, nuts, bolts, cable ties, medical supplies, such as scaffolds, sutures, and drug delivery systems in tissue optics, prosthetics, orthopedic implants, generation of artifacts to aid learning in education, 3D anatomical models to assist surgery, robotics, biomedical devices (orthotology), home appliances, dental, automotive and aircraft / aerospace components, electronic equipment, and sporting goods. The polymer microparticles disclosed herein can be used as raw materials for injection molding of disposable articles such as food packaging, bags, and earth retention sheaths. Polymer microparticles may also be used in agricultural applications, for example, to provide biodegradable packaging for plants and / or as biodegradable vehicles for seeds, fertilizers, herbicides, insecticides, etc. Other applications of the polymer microparticles of this disclosure may include, but are not limited to, use as fillers in paints and powder coatings, inkjet materials, and electrophotographic toners.

[0110] Embodiments disclosed herein include the following:

[0111] A. A polymer microparticle composition incorporating a biodegradable, biosource, and / or bio-activated emulsifying stabilizer. The composition comprises a plurality of polymer microparticles, each comprising a matrix polymer and one or more types of nanoparticles selected from the group consisting of biopolymer nanoparticles, biomineralized nanoparticles excluding only biomineralized silica, and any combination thereof.

[0112] A1. The polymer microparticle composition according to A, comprising one or more types of nanoparticles, cellulose nanoparticles, hydroxyapatite nanoparticles, or any combination thereof.

[0113] B. Polymer microparticle composition containing a biodegradable matrix polymer. The composition comprises a plurality of polymer microparticles, each containing a biodegradable matrix polymer and oxide nanoparticles arranged on the outer surface of the polymer microparticles, wherein the biodegradable matrix polymer is obtained from Pseudomonas cepacia (≧30 U / mg) and loses at least about 40% of its mass after 6 days in phosphate buffer (0.2 M, pH 7.0) containing 0.2 mg / mL of lipase incubated at 37°C.

[0114] C. Polymer microparticle composition containing a biodegradable matrix polymer and incorporating a biodegradable and / or biologically derived emulsifying stabilizer. The composition comprises a plurality of polymer microparticles comprising a biodegradable matrix polymer and one or more types of nanoparticles selected from the group consisting of biopolymer nanoparticles, biomineralized nanoparticles excluding only biomineralized silica, and any combination thereof, wherein the biodegradable matrix polymer is obtained from Pseudomonas cepacia (≧30 U / mg) and loses at least about 40% of its mass after 6 days in phosphate buffer (0.2 M, pH 7.0) containing 0.2 mg / mL of lipase incubated at 37°C.

[0115] C1: A polymer microparticle composition according to C, comprising one or more types of nanoparticles, cellulose nanoparticles, hydroxyapatite nanoparticles, or any combination thereof.

[0116] A component made from the polymer microparticle composition described in DA, A1, B, C, or C1.

[0117] E. Method for preparing polymer nanoparticles. The method comprises combining a matrix polymer and a plurality of emulsifying stabilizers with a carrier fluid at a heating temperature above the melting point or softening temperature of the matrix polymer, wherein the matrix polymer and the carrier fluid are substantially immiscible at the heating temperature, the matrix polymer is biodegradable, and / or the plurality of emulsifying stabilizers include one or more types of nanoparticles selected from the group consisting of biopolymer nanoparticles, biomineral nanoparticles, and any combination thereof; applying a shear force sufficient to disperse the matrix polymer as liquefied droplets in the carrier fluid at the heating temperature in the presence of the emulsifying stabilizers; cooling the carrier fluid to a temperature at which at least a plurality of polymer nanoparticles form from liquefied droplets, wherein the plurality of polymer nanoparticles include the matrix polymer and emulsifying stabilizers; and separating the polymer nanoparticles from the carrier fluid.

[0118] E1. The method according to E, wherein one or more types of nanoparticles include cellulose nanoparticles, hydroxyapatite nanoparticles, or any combination thereof.

[0119] Each of embodiments A, A1, B, C, C1, D, E, and E1 may have one or more of the following additional elements in any combination.

[0120] Element 1: Polymer microparticles in the range of approximately 30 μm to approximately 130 μm 50 and has a diameter span of approximately 1.7 or less.

[0121] Element 2: The composition further comprises oxide nanoparticles arranged on the outer surface of polymer microparticles.

[0122] Element 3: Oxide nanoparticles include silica nanoparticles.

[0123] Element 4: At least a portion of one or more types of nanoparticles is present within the core of the polymer microparticle.

[0124] Element 4A: At least a portion of the cellulose nanoparticles or hydroxyapatite nanoparticles is present within the core of the polymer microparticles.

[0125] Element 5: Each of the polymer microparticles has a crystallization temperature at least about 5°C higher than the crystallization temperature of the matrix polymer, as determined by ASTM E794-06(2018).

[0126] Element 6: The method further comprises depositing the composition layer by layer on a powder bed and heating a portion of the powder bed to solidify a portion of the polymer fine particles into solidified parts having a specified shape.

[0127] Element 7: The composition further comprises one or more types of nanoparticles selected from the group consisting of biopolymer nanoparticles, biomineral nanoparticles, and any combination thereof.

[0128] Element 7A: The composition further comprises cellulose nanoparticles, hydroxyapatite nanoparticles, or any combination thereof, which associate with a biodegradable matrix polymer.

[0129] Element 8: At least a portion of one or more types of nanoparticles is present within the core of the polymer microparticle.

[0130] Element 8A: At least a portion of the cellulose nanoparticles or hydroxyapatite nanoparticles is present within the core of the polymer microparticles.

[0131] Element 9: The carrier fluid contains silicone oil.

[0132] Element 10: The biodegradable matrix polymer contains polycaprolactone or polylactic acid.

[0133] As a non-limiting example, exemplary combinations applicable to A, A1, B, C, C1, and D include, but are not limited to, 1 and 2; 1-3, 1 and 4 or 4A; 1 and 5; 1 and 10; 2 and 3; 2 and 4 or 4A; 2 and 10; 4 and 5; 4 and 10; and 5 and 10.

[0134] As a non-limiting example, exemplary combinations applicable to E and E1 include: element 1 and one or more of elements 2-9; element 2 and one or more of elements 1 or 3-9; element 3 and one or more of elements 1-2 or 4-9; element 4 and one or more of elements 1-3 or 5-9; element 5 and one or more of elements 1-4 or 6-9; element 6 and one or more of elements 1-5 or 7-9; element 7 and one or more of elements 1-6 or 9; element 8 and one or more of elements 1-7 or 9; and element 9 and one or more of elements 1-8.

[0135] To facilitate a better understanding of the embodiments of this disclosure, the following examples of preferred or representative embodiments are provided. The following examples should not be interpreted in any way as limiting or defining the scope of this disclosure. [Examples]

[0136] In the following examples, the flow properties of polymer microparticles were evaluated using two techniques: (1) sieving and (2) angle of repose measurement. Sieving yield was determined by measuring the percentage of the mass of polymer microparticles that passed through a USAStandard Sieve ASTM E11 with a 250 μm opening (>95% for polyester samples in all examples). The angle of repose was measured using a Hosokawa Micron powder characterization tester PT-R.

[0137] Comparative Example 1: PCL containing 1% by weight silica nanoparticles. 280 g of PSF-30000 30000 cSt poly(dimethylsiloxane) (PDMS) from Clearco, 1.2 g of Aerosil RX50 silica nanoparticle stabilizer (1% by weight), and 120 g of poly(ε-caprolactone) (PCL) (Mn 80,000) (30% solid load) from Sigma-Aldrich were added to a 500 mL glass kettle equipped with a heating mantle. An overhead stirrer was set to 300 rpm with a single propeller stirrer. Vacuum and repeated argon or nitrogen purging (3 times) were applied to remove dissolved air and maintain an argon flow throughout the process. The temperature was raised to 140°C over 10 minutes. Once the temperature reached 140°C, the stirring speed was increased to 500 rpm. After 30 minutes, the glass kettle was removed from the heating and stirring was stopped. The emulsion was cooled to room temperature. The slurry was dispersed in excess heptane and vacuum filtered. This process was repeated a total of three times to remove the silicone oil. The polymer microparticles were dried overnight at room temperature and then sieved using a USA Standard Sieve ASTM E11 with a 250 μm opening.

[0138] Comparative Example 2: PCL containing 2% by weight of silica nanoparticles. Comparative Example 2 was prepared in the same manner as Comparative Example 1, except that 2.4 g of Aerosil RX50 silica nanoparticle stabilizer (2% by weight) was used, in contrast to 1.2 g (1% by weight).

[0139] Comparative Example 3: PLA containing 1% by weight silica nanoparticles. Comparative Example 3 was prepared in the same manner as Comparative Example 1, except that poly(L-lactide (PLA)) from Ingeo (Biopolymer 3D850) was used instead of PCL. The reaction temperature was also increased from 140°C to 210°C.

[0140] Example 1: PCL containing 2 wt% crystalline nanocellulose (CNC) nanoparticles. Example 1 was prepared in the same manner as Comparative Example 1, except that crystalline nanocellulose nanoparticles from CelluForce were used instead of Aerosil RX50 silica nanoparticles.

[0141] Example 2: PCL containing 2 wt% hydroxyapatite (HA) nanoparticles. Example 2 was prepared in the same manner as Comparative Example 1, except that hydroxyapatite nanoparticles from Sigma-Aldrich were used instead of Aerosil RX50 silica nanoparticles.

[0142] Example 3: PLA containing 2 wt% HA nanoparticles. Example 3 was prepared in the same manner as Comparative Example 1, except that hydroxyapatite nanoparticles from Sigma-Aldrich were used instead of Aerosil RX50 silica nanoparticles, and the polymer was PLA instead of PCL.

[0143] The reaction conditions for Examples 1-3 and Comparative Examples 1-3 are summarized in Table 1. [Table 1]

[0144] The molecular weight of the polymers in Comparative Examples 1-3 and Examples 1-3 was reduced by 10-20% during processing, as shown in Table 2. The change in matrix polymer molecular weight appears to correlate with increasing process temperature and additive amounts. Cellulose nanoparticles and hydroxyapatite nanoparticles appeared to promote molecular weight reduction more than silica nanoparticles. [Table 2]

[0145] The particle size and size distribution of Comparative Examples 1-3 and Examples 1-3 were measured by dynamic light scattering using a MALVERN MASTERSIZER 3000. The results are shown in Table 3. Polymer particles prepared using CNC nanoparticles were compared to polymer particles incorporating an equivalent mass of HA or silica nanoparticles. 50 A reduction in the value was observed. Furthermore, increasing the concentration of silica nanoparticles resulted in the generation of even smaller particles and a corresponding increase in their span. [Table 3]

[0146] The polymer microparticles were also characterized by scanning electron microscopy (SEM). Figures 2A–2D show SEM images of comparative example 2, polycaprolactone polymer microparticles prepared with silica nanoparticles. The PCL microparticles containing silica nanoparticles showed a bimodal distribution with a significant population of small microparticles. Several irregularly shaped microparticles were observed in the SEM images, and the silica nanoparticles were distributed on the surface of the microparticles. In the cross-sectional image of Figure 2D, no silica nanoparticles were observed.

[0147] Figures 3A–3D show SEM micrographs of polycaprolactone polymer microparticles prepared with crystalline nanocellulose nanoparticles in Example 1. The microparticles containing CNCs showed a relatively narrow size distribution with several elongated microparticles present. The SEM showed that the CNC nanoparticles were well dispersed on the surface of the polymer microparticles. As shown in the cross-sectional image of Figure 3D, CNC nanoparticles were also present within the particles.

[0148] Figures 4A-4D show SEM micrographs of polycaprolactone polymer microparticles prepared with hydroxyapatite nanoparticles in Example 2. The microparticles in Example 2 showed an acceptable size distribution in which some irregularly shaped microparticles were observed. The HA nanoparticles were well dispersed on the surface of the polymer microparticles. As shown in the cross-sectional image in Figure 4D, the HA nanoparticles were also present within the microparticles. Figures 5A-5D show SEM micrographs of polylactic acid polymer microparticles prepared with silica nanoparticles in Comparative Example 3. The microparticles in Comparative Example 3 showed a somewhat bimodal size distribution, and the silica nanoparticles were well distributed on the surface of the polymer microparticles. As shown in the cross-sectional image in Figure 5D, the silica nanoparticles were not present internally.

[0149] Figures 6A to 6D show SEM micrographs of polylactic acid polymer microparticles prepared with hydroxyapatite nanoparticles in Example 3. The microparticles of Example 3 showed a somewhat bimodal microparticle size distribution. The surface of the polymer microparticles showed hydroxyapatite nanoparticles that were well distributed on the surface, and the nanoparticles are not visible in the cross-sectional image of Figure 6D.

[0150] Optical microscope images of the sample from the example are shown in Figures 7 to 11, each of which shows good sphericity of the polymer microparticles.

[0151] The average particle size was also calculated as shown in Table 4. The average particle size was somewhat lower than that calculated by dynamic light scattering, which is likely due to measurement errors in aggregates and sample size. [Table 4]

[0152] The polymer nanoparticles were also analyzed by DSC according to ASTM E794-06(2018), as shown in Table 5. The DSC data suggest that the nanoparticles may act as nucleating agents, promoting polymer crystallization and increasing the observed crystallization temperature (Tc1). Additive manufacturing methods can be improved with relatively rapid and controlled crystallization, which can affect many mechanical properties. Example 3 was an unusual case in which the interaction between the CNC nanoparticles and PCL appeared to reduce the flexibility of the polymer chains and slow the crystallization rate. However, the crystallization rate was still relatively fast for additive manufacturing applications and also showed an increase in the sintering temperature window (ΔT). [Table 5]

[0153] The angle of repose measurements are shown in Table 6. Almost all samples showed a value of <30.0°, which corresponds to excellent flow properties. The only exception was the PLA sample containing silica nanoparticles, which had a value of 34.0° and still corresponds to good flow. [Table 6]

[0154] The samples were also performed by selective laser sintering (SLS). During testing, all sample powders showed good flow and formed a uniform coating in the SLS test experiments. The polymer mass and porosity results are shown in Table 7. After heating cycles, no soft aggregates or blocking were present. Also, there was little powder adhering to the back of the printed layer. The fine particles of Example 1 required a lower laser power (20%) to successfully sinter compared to those of Comparative Example 2 or Example 2 (approximately 30%). Some edge curling was observed during cooling (Comparative Example 2 < Example 2 < Example 1). Single-layer porosity was very low (Example 1 < Example 2 < Comparative Example 2). Some surface texture was observed in samples containing silica and HA. Figure 12 shows optical microscope images of sintered single layers prepared from polymer fine particles prepared in Comparative Example 2 and Examples 1 and 2. [Table 7]

[0155] Biodegradability was also tested by exposing the samples to a lipase enzyme buffer solution. Comparative Example 2, as well as Examples 1 and 2, were prepared by pressing approximately 100 mg of each sample in a hydraulic press to a size of 10 × 20 × 0.35 mm. 3 The samples were formed into thin films. Each sample was then placed in 5 mL of phosphate buffer (0.2 M, pH 7.0) containing 0.2 mg / mL lipase obtained from Pseudomonas cepacia (≧30 U / mg) and incubated at 37°C throughout the measurement. Hydrolysis was measured over time. Control samples without lipase were also measured, and only slight weight loss was observed for all control samples over 6 days. All samples exhibited similar crystallinity, as shown in the DSC data in Table 5. The mass loss of the samples during biodegradation is plotted as a function of time in Figure 13.

[0156] The pure PCL control degraded completely in 6 days. Samples containing nanoparticles showed a reduced hydrolysis rate. The hydrophobic silica nanoparticles in Comparative Example 2 appeared to be detrimental to enzymatic hydrolysis. The nanoparticles in Examples 1 and 2 had a much milder effect on hydrolysis, resulting in materials that retained similar biodegradability characteristics to the control samples.

[0157] All documents described herein are incorporated herein by reference for the purposes of all jurisdictions in which such practice is permitted, and include any preferred documents and / or test procedures to the extent that they do not conflict with this text. As is evident from the general description and specific embodiments set forth above, the forms of this disclosure have been illustrated and described, but various modifications can be made without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not intended to be limited thereto. For example, the compositions described herein do not have to include any components or compositions not expressly enumerated or disclosed herein. Any method may lack any steps not enumerated or disclosed herein. Similarly, the terms “comprising” are considered to be synonymous with the terms “including.” Whenever a method, composition, element, or group of elements is preceded by the transitional phrase “comprising,” it is understood that the inventors may also intend the same composition or group of elements to be preceded by the transitional phrases “essentially consisting of,” “consisting of,” “selected from a group consisting of,” or “is,” and vice versa.

[0158] Unless otherwise stated, all numbers used in this specification and related claims, representing quantities such as components, properties such as molecular weight, and reaction conditions, should be understood in all cases as being modified by the term "approximately." Therefore, unless otherwise indicated, the numerical parameters described in the following specification and appended claims are approximations that may vary depending on the desired properties to be obtained by embodiments of the present invention. At the very least, without attempting to limit the application of the doctrine of equivalents to the claims, each numerical parameter should be interpreted by applying the usual rounding method in light of the number of significant figures reported.

[0159] Whenever a numerical range with lower and upper limits is disclosed, any number and any range included within that range are specifically disclosed. In particular, all ranges of values ​​disclosed herein (in the form of "about a to about b," or equivalently "approximately a to b," or equivalently "about a to b") should be understood to describe all numbers and ranges encompassed within a broad range of values. Furthermore, terms in the claims have plain, ordinary meanings unless explicitly and clearly defined by the patent holder. In addition, when used in the claims, the indefinite articles "a" or "an" are defined herein to mean one or more of the elements they introduce.

[0160] One or more exemplary embodiments are presented herein. For clarity, not all features of a physical implementation are described or illustrated in this application. It is understood that in developing a physical embodiment of the disclosure, numerous implementation-specific decisions must be made to achieve the developer's objectives, which vary by implementation and from time to time, including compliance with system-related, business-related, government-related, and other constraints. While this may require considerable time and effort from the developer, such efforts would still be routine work for those skilled in the art who are interested in the disclosure.

[0161] Accordingly, this disclosure is well-adapted to achieve the objectives and benefits mentioned herein, as well as those inherent thereto. The specific embodiments described above are illustrative only, and this disclosure may be modified and implemented in different but equivalent ways, which will be obvious to those skilled in the art who have a teaching interest in this specification. Furthermore, it is not intended to limit this specification to any structural or design details other than those described in the following claims. Accordingly, it is obvious that the specific exemplary embodiments disclosed above may be modified, combined or altered, and all such variations will be considered within the scope and spirit of this disclosure. The embodiments preferably illustrated herein may be implemented in the absence of any elements not specifically disclosed herein, and / or any optional elements disclosed herein.

Claims

1. A composition comprising: a plurality of polymer microparticles comprising a matrix polymer and nanoparticles selected from the group consisting of biopolymer nanoparticles, biogenic mineral nanoparticles excluding only biogenic silica, and any combination thereof, wherein at least a majority of said polymer microparticles are substantially spherical in shape as defined by having a circularity of about 90% or greater, and said polymer microparticles further have a diameter span of about 1.7 or less.

2. The composition of claim 1, wherein said one or more types of nanoparticles comprise cellulose nanoparticles, hydroxyapatite nanoparticles, or any combination thereof.

3. The composition of claim 2, wherein at least a portion of said cellulose nanoparticles or hydroxyapatite nanoparticles are present within the core of said polymer microparticles.

4. The composition of claim 1, wherein said polymer microparticles have a D50 in the range of about 30 μm to about 130 μm.

5. The composition of claim 1, further comprising oxide nanoparticles disposed on the outer surface of said polymer microparticles.

6. The composition of claim 5, wherein said oxide nanoparticles comprise silica nanoparticles.

7. A method comprising: combining a matrix polymer and a plurality of emulsifying stabilizers with a carrier fluid at a heating temperature equal to or above the melting point or softening temperature of said matrix polymer, wherein said matrix polymer and said carrier fluid are substantially immiscible at said heating temperature, said matrix polymer is biodegradable, and / or said plurality of emulsifying stabilizers comprise nanoparticles selected from the group consisting of biopolymer nanoparticles, biogenic mineral nanoparticles excluding only biogenic silica, and any combination thereof, Applying a shear force sufficient to disperse the matrix polymer as liquefied droplets in the carrier fluid in the presence of the emulsifying stabilizer at the heating temperature; Cooling the carrier fluid to a temperature at which at least a plurality of polymer microparticles are formed from the liquefied droplets, wherein the plurality of polymer microparticles comprise the matrix polymer and the emulsifying stabilizer; At least a majority of the polymer microparticles are substantially spherical in shape as defined by having a roundness of about 90% or more, and the polymer microparticles further have a diameter span of about 1.7 or less; Separating the polymer microparticles from the carrier fluid, a method comprising. The method according to claim 7, wherein the nanoparticles comprise cellulose nanoparticles, hydroxyapatite nanoparticles, or any combination thereof. The method according to claim 7, wherein the polymer microparticles have a D50 in the range of about 1 μm to about 130 μm. The matrix polymer comprises a biodegradable matrix polymer, The biodegradable matrix polymer is obtained from Pseudomonas cepacia (≧30 U / mg) and loses at least about 40% of its mass after 6 days in a phosphate buffer (0.2 M, pH 7.0) containing 0.2 mg / mL of lipase incubated at 37° C., the composition according to claim 1. The composition according to claim 10, wherein the biodegradable matrix polymer comprises polycaprolactone or polylactic acid. The composition according to claim 11, wherein the nanoparticles comprise cellulose nanoparticles, hydroxyapatite nanoparticles, or any combination thereof.

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