Ultra-low interfacial tension support medium for high-precision polysiloxane 3D printing

Abstract

In one aspect, this disclosure relates to a support material for 3D printing soft materials having a feature size <5 μm over time, a 3D printing method using said support material, and an article comprising a soft material constructed using the disclosed method. In one aspect, the support material may be a blocked reverse emulsion having silicone oil as a continuous phase and a glycerol / water mixture as a dispersed phase. In some aspects, the support material also comprises a surfactant. In any of these aspects, the support material may be optically transparent.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 039,209, filed June 15, 2020, the entire contents of which are incorporated herein by reference. Background Technology

[0003] Additive manufacturing has enabled the fabrication of shapes and structures from plastics, metals, and even ceramics that would otherwise be impossible using conventional manufacturing techniques. Recent advances in this field include advanced tissue engineering, bioprinting, and the fabrication of microfluidic devices. One of the biggest limitations of this approach is that it can only use materials that harden or solidify during extrusion. Additionally, sacrificial supports are often required when the printed structure or part of the printed structure is not supported by the preceding layer. Printing into clogged microgel systems has overcome some of the problems associated with material limitations and the requirement for sacrificial support structures.

[0004] Polysiloxanes are widely used due to their high thermal stability, weather resistance, ozone resistance, moisture resistance, and UV radiation resistance. Their market value is estimated to grow to $19.34 billion by 2025. The fabrication of polysiloxane structures can be performed using conventional techniques such as molding and casting, or more advanced techniques such as soft lithography and 3D printing. However, producing polysiloxane structures using conventional 3D printing techniques often results in low-quality products due to the challenges of printing liquid pre-polymerized silicone elastomers. Traditional methods require the ink to harden or “solidify” once deposited from the nozzle. Recently, a novel 3D manufacturing technique has been developed in which a clogged microgel system is used as a support medium for printing soft materials containing polysiloxane elastomers. The clogged microgels possess unique rheological behavior that allows them to be used as printing support media, fluidizing under large applied stresses and behaving like solids when the applied stress is below the material's yield stress. These properties allow microgels to be generated and flow around the translational printing needles, while capturing “ink” deposited in space, thus eliminating the effects of gravity or buoyancy.

[0005] The fundamental principles of the rheology of blocked microgels are well-studied and fairly well understood. However, the interfacial phenomena between the blocked microgels and the surrounding fluids are less readily understood. These interfacial forces play a major role in 3D printing applications using blocked microgels because the interfacial tension between the ink and the support medium can cause the printed structure to disintegrate over time. To minimize the effects of interfacial tension while balancing the stability provided by the blocked support material, the support material must be chemically similar to the printing ink. Therefore, to overcome the limitations associated with the stability of polysiloxane structures during manufacturing, chemically similar support materials to poly(dimethylsiloxane) (PDMS) should be developed. Furthermore, the inability to overcome unstable interfacial forces will continue to limit the printable resolution of polysiloxane printing, making it impossible to fabricate structures with complex details. Ideally, these fabricated structures will be used in personalized implants, lab-on-a-chip devices, tissue / organ-on-a-chip devices, point-of-care devices, biomachines, and other medical applications.

[0006] Despite advancements in 3D printing of soft materials, there remains a lack of inks and support materials that allow for the fabrication of 3D printed structures with low surface roughness and intricate details, which can then be sustained over long periods. This disclosure addresses these and other needs. Summary of the Invention

[0007] In accordance with the purposes of this disclosure, as embodied and broadly described herein, this disclosure relates, in one aspect, to a support material for 3D printing soft materials having a time-dependent feature size <5 μm, a 3D printing method using the support material, and an article comprising a soft material constructed using the disclosed method. In one aspect, the support material may be a blocked reverse emulsion having silicone oil as a continuous phase and a glycerol / water mixture as a dispersed phase. In some aspects, the support material also comprises a surfactant. In any of these aspects, the support material may be optically transparent.

[0008] Other systems, methods, features, and advantages of this disclosure will be apparent to those skilled in the art after studying the following figures and detailed description. All such additional systems, methods, features, and advantages are intended to be included in this specification, within the scope of this disclosure, and protected by the appended claims. Furthermore, all optional and preferred features and modifications of the embodiments can be used in all aspects of the disclosure taught herein. Moreover, the various features of the dependent claims, as well as all optional and preferred features and modifications of the embodiments, are combinable and interchangeable with each other. Attached Figure Description

[0009] Many aspects of this disclosure can be better understood by referring to the following accompanying drawings. The components in the drawings are not necessarily drawn to scale, but the emphasis is on clearly illustrating the principles of this disclosure. Furthermore, in the drawings, the same reference numerals denote corresponding components in several views.

[0010] Figure 1A The image shows a CAD drawing of the model scaffold to be 3D printed. Figure 1B This demonstrates that conventional 3D printing methods are not effective for printing soft materials or liquid inks because the unsupported structure will sag and the final structure will deviate from the coded structure. Figure 1C This study demonstrates how 3D printing can eliminate sagging by capturing ink in space using a clogging medium; however, the interfacial tension between the support medium and the ink will cause the printed structure to crack over time. Figure 1D The results show that by using a clogging medium similar to ink, cracking associated with interfacial instability of printed features can be avoided, resulting in an infinitely stable structure.

[0011] Figure 2A The phase diagram of a typical polymer blend with the upper critical solution temperature (UCST) is shown. Point (i) on the phase diagram represents the stable phases of the two components. Upon quenching to point (ii), the system spontaneously separates into two phases: a phase (iii) rich in component B and a phase (iii') rich in component A. Figure 2B A schematic diagram is shown illustrating the phase separation of a polymer blend into a continuous phase rich in component A and a droplet phase rich in component B. However, in the case of clogging, the size, shape, and distribution of the droplet phase are controlled by the yield stress of the clogging system. Figure 2C This demonstrates that phase separation within a blockage system can be used as a 3D printing technique for fabricating very fine structures.

[0012] Figure 3 shows the rheological characteristics of the self-assembled microgels. Figure 3A The results of shear modulus measurements obtained by scanning at small amplitude frequencies show that pure triblock and 50:50 blend solutions exhibit solid-like behavior on long time scales, while the pure diblock system behaves like a viscous liquid. Figure 3B The results show the measurement of yield stress in a block copolymer system by performing a uniaxial shear rate scan. Figure 3C The thixotropic time measurements of the 50:50 blend are shown, demonstrating the recovery of solid rheological properties within 1 second after the applied stress is removed. Figure 3DMicroscopic images taken using phase contrast illumination are shown, illustrating the presence of microgels on the order of 2-4 μm in diameter. These results demonstrate that the performance of the microgel system can be evaluated using known techniques; the improved properties of the support of this invention can be observed when these types of measurements are performed on the inverse emulsion-based support of this invention.

[0013] Figure 4 shows 3D-printed polysiloxane structures in self-assembled microorganogels. Figure 4A shows a model tracheal implant printed into a plugged microgel support using RTV polysiloxane. After curing, the printed structure was removed from the support material and processed. Figure 4B shows a cross-sectional view of the model trachea, demonstrating the ability to print structures with a wall thickness of 400 μm. Figures 4C-4D show polysiloxane scaffolds printed with sinusoidal waveform patterns in the xy and xz directions, demonstrating the ability to print structures with a feature size of 250 μm. Figures 4E-4G show macroscopic images of a perfusible tubular network printed into a microorganogel support. In one respect, the plugged inverse emulsion support disclosed herein can be used to print these and other structures while providing improvements in feature size, surface roughness, and feature stability over time.

[0014] Figures 5A-5B The rheological characteristics of inverted emulsions with different volume fractions are shown at a constant droplet size of 2 μm. Figures 5C-5D It shows that in φ aq Rheological characterization of inverse emulsions with different droplet sizes at a constant volume fraction of 0.75. Figure 5A and 5C Shear modulus measurements at small amplitude frequency scans revealed that the inverse emulsion exhibited solid-like behavior over long time scales. Storage modulus measurements showed an increase with increasing emulsion integral number and decreasing droplet size. For Figure 5B and 5D Uniaxial shear rate scanning was performed to measure the yield stress of the inverse emulsion, and it can be seen that the critical yield stress increases with the increase of the emulsion integral number and the decrease of the droplet size.

[0015] Figure 6 This paper displays time-lapse measurements of pure silicone oil printed within a blocked microorganogel. The interfacial tension between the microorganogel and the silicone oil leads to instability-related cracking. The cracking time of the feature depends on the feature size and the viscosity of the printed silicone oil. The cracked feature reduces its total interfacial energy by reforming into a more spherical shape. In one respect, the blocked inverse emulsion support disclosed herein allows for longer stability of the micro-features compared to microorganogel supports.

[0016] Figure 7 The diagram shows that feature size can be predicted from flow rate (Q) and translational velocity (v). The printed feature exhibits ideal behavior under different flow rates and velocities.

[0017] Figure 8 The images show the structures of polydimethylsiloxane (PDMS) (left) and polymethylphenylsiloxane (PMP) (right).

[0018] Figure 9 A schematic diagram of the spinning drop method is shown, in which a capillary filled with a bulk phase of the more concentrated component and a droplet of the lighter component rotates at a constant angular velocity. The droplet radius is related to the interfacial tension between the two liquids via Vonnegut's equation.

[0019] Figure 10 A schematic diagram of spherical segments to be printed with different radii of curvature is shown. Printing accuracy is measured as the deviation of the printed curvature from the encoded curvature. Printing variability is measured as the deviation of the surface roughness of the printed structure relative to the encoded structure.

[0020] Figure 11A-11C The diagram illustrates the effect of interfacial tension between the ink and the supporting matrix. Figure 11A It exhibits high interfacial tension; Figure 11B It exhibits low interfacial tension; and Figure 11C It exhibits ultra-low interfacial tension.

[0021] Figures 12A-12C The polysiloxane 3D printing of a patient's cerebral aneurysm is shown, indicating the accuracy of the disclosed method. Figure 12A It is the original model of an aneurysm based on computed tomography (CT) scans; Figure 12B The model printed using the disclosed technology is shown; and Figure 12C The 3D overlays of the two models are shown.

[0022] Figure 13A yes Figure 12B A photograph of the printing process of a brain aneurysm model. Figure 13B These are photos of the printing process used to create a model of a tricuspid heart valve.

[0023] Other advantages of the invention will be set forth in part in the description which follows, and will be apparent in part from the specification, or may be learned by practice of the invention. The advantages of the invention will be realized and obtained by means of the elements and combinations particularly pointed out in the appended claims. It should be understood that the foregoing general description and the following detailed description are merely exemplary and illustrative, and not intended to limit the claimed invention. Detailed Implementation

[0024] Many modifications and other embodiments of the disclosed compositions and methods will occur to those skilled in the art, taking advantage of the teachings presented in the foregoing description and related drawings. Therefore, it should be understood that this disclosure is not limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Those skilled in the art will recognize many variations and adaptations to the aspects described herein. These variations and adaptations are intended to be included in the teachings of this disclosure and are covered by the claims herein.

[0025] Although specific terms are used here, they are used only in a general and descriptive sense, not for restrictive purposes.

[0026] As will be apparent to those skilled in the art upon reading this disclosure, each individual embodiment described and illustrated herein has discrete components and features that can be readily separated from or combined with features of any of the other several embodiments without departing from the scope or spirit of this disclosure.

[0027] Any enumerated method may be performed in the order of the enumerated events or in any other logically possible order. That is, unless otherwise expressly stated, it is never intended to interpret any method or aspect described herein as requiring its steps to be performed in a particular order. Therefore, unless a method claim in the claims or description specifically states that the steps will be limited to a particular order, no inference is made in any respect of the order. This applies to any possible non-explicit basis of interpretation, including the logical content regarding the arrangement of steps or operational procedures, the simple meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

[0028] All publications mentioned herein are incorporated herein by reference to disclose and describe methods and / or materials relating to the cited publications. The publications discussed herein provide only their disclosure prior to the filing date of this application. This document should not be construed as an admission that the invention is not entitled to rely on prior inventions preceding these publications. Furthermore, the publication dates provided herein may differ from the actual publication dates, which may require independent verification.

[0029] While aspects of this disclosure may be described and claimed in specific statutory categories, such as the systems statutory category, this is merely for convenience, and those skilled in the art will understand that each aspect of this disclosure may be described and claimed in any statutory category.

[0030] It should also be understood that the terminology used herein is for descriptive purposes only and is not intended to be limiting. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed compositions and methods pertain. It should also be understood that terms such as those defined in common dictionaries should be interpreted as having the same meaning as they have in the context of the specification and the relevant field, and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0031] Before describing various aspects of this disclosure, the following definitions are provided and should be used unless otherwise specified. Additional terms may be defined elsewhere in this disclosure.

[0032] definition

[0033] As used herein, “comprising” should be interpreted as specifying the presence of the mentioned feature, whole, step, or component, but does not preclude the presence or addition of one or more features, wholes, steps, or components, or groups thereof. Furthermore, each of the terms “by,” “comprising,” “comprises,” “comprised of,” “including,” “includes,” “included,” “involving,” “involves,” “involved,” and “such as” is used in its open, non-limiting sense and may be used interchangeably. Additionally, the term “comprising” is intended to include instances and aspects covered by the terms “substantially composed of” and “composed of.” Similarly, the term “substantially composed of” is intended to include instances covered by the term “composed of.”

[0034] As used in the specification and appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly indicates otherwise. Thus, for example, references to “silicone oil,” “surfactant,” or “ink” include, but are not limited to, mixtures of two or more such silicone oils, surfactants, or inks.

[0035] As used in this article, "scaffold" refers to a structure that can be used to support ink during 3D printing. Scaffolds are typically three-dimensional and include a solid structure on which ink can be deposited, as well as open spaces. Scaffolds used for 3D printed tissues often incorporate biocompatible materials (…). Figure 1A ).

[0036] "Sagging" refers to the situation where an area of ​​3D printed ink is not supported by a support structure, such as when ink is printed in the open space between solid structures within a support structure. Figure 1B ), the deformation of the region caused by gravity or other forces.

[0037] As used herein, "clogging medium" refers to a medium in which ink can be 3D printed, such as microgels or inverse emulsions. Clogging medium provides support for 3D printed structures without the need for scaffolds. On one hand, a moving injection nozzle can follow any desired 3D path and can locally shear the clogging medium, resulting in temporary fluidization at the injection point. Figure 2C Furthermore, in this respect, ink can be deposited, and then the injection nozzle moves away from the deposition site. As the nozzle leaves, the surrounding clogging medium quickly moves back to its original position, capturing the injected material in the space and eliminating the sagging problem associated with the use of conventional supports. Figure 1C-1D ).

[0038] "Shear stress" is a stress component coplanar with the cross-section of the material and, as used herein, is primarily caused by friction between fluid particles due to the viscosity of the overall fluid. Shear stress tends to cause material deformation by sliding along a plane parallel to the stress. Figure 3B ).

[0039] As used in this article, "shear modulus," usually denoted by G, describes a material's response to shear stress. Materials with a large shear modulus are rigid and require large forces to deform, while materials with a smaller shear modulus deform more easily. Figure 3A ).

[0040] The rate at which this occurs when one layer of material passes through an adjacent layer is called the "shear rate." In one sense, the shear rate is the rate at which a material undergoes progressive shear deformation. Figure 3C ).

[0041] Meanwhile, "yield stress" is a property of a material that can be used to determine the upper limit of the force that can be applied without causing permanent deformation of the material. In one sense, yield stress refers to the point at which a material begins to deform plastically.

[0042] As used in this article, "storage modulus" is a measure of the energy stored in a material, or how much energy must be applied to the material to cause distortion. In one respect, storage modulus represents the elastic response of a material.

[0043] "Microgels" are systems of cross-linked soft particles with a three-dimensional network structure and a liquid phase. Microgels typically swell in a solvent, and their properties can be tuned based on the chemical identity of the cross-linked particles and external stimuli, including but not limited to pH and temperature. In one aspect, this paper discloses microgels that can be used as plugs in support media for 3D printing of soft materials. Meanwhile, "microorganogels" are microgels in which the liquid phase is an organic solvent.

[0044] An emulsion is a mixture of two or more immiscible liquids; one liquid (the "dispersed phase" or "droplet phase") is dispersed as droplets in another liquid (the "continuous phase"). A "normal emulsion" is an emulsion in which water is the continuous phase and oil is the dispersed phase, and a "reverse emulsion" is an emulsion in which oil is the continuous phase and water is the dispersed phase. Figure 2B On the one hand, there are also surfactants or emulsifiers and / or stabilizers.

[0045] As used herein, “volume fraction” is the portion of the total emulsion volume occupied by the phase under discussion. For example, in a normal oil-in-water emulsion, if 20 mL of oil is present in 100 mL of emulsion, the volume fraction is 20%.

[0046] The "highest critical eutectic temperature" or UCST is a temperature above which the components of a mixture can be miscible in all proportions. Figure 2A ).

[0047] Interfacial tension is typically measured in mN / m and refers to the attractive force between molecules at the interface of two fluids (e.g., between a droplet surface and the continuous phase of an emulsion, or between a support material and ink 3D printed on the support material). When the two fluids are immiscible, high interfacial tension leads to a minimization of the contact surface area, thereby promoting the formation of emulsions, micelles, etc.

[0048] As used in this article, "coded structure" refers to the design structure that will be produced if the 3D printer operates perfectly. Meanwhile, "printed structure" refers to the structure actually produced using real-world materials. An ideal printed structure will match the coded structure. "Print accuracy" is a measure or reflection of the overlap between the printed and coded structures.

[0049] As used herein, “surface smoothness” and “surface roughness” refer to variations in the surface topology of 3D printed artifacts. Surface roughness can result from delamination, low process resolution, or material incompatibility in the artifact. In this regard, the 3D printed structures disclosed herein exhibit enhanced surface smoothness.

[0050] As used in this article, "radius of curvature" refers to the radius of the arc that best approximates a given curve. On one hand, the accuracy and variability of a printing method can be evaluated by comparing the radius of curvature of the printed structure with the radius of curvature of its corresponding coded structure. Figure 10 ).

[0051] As used herein, “fine structure” refers to programmed features on the surface of a 3D-printed object, wherein said features have a size as small as approximately 4 μm. In some respects, the methods and compositions disclosed herein are capable of producing 3D-printed objects with a fine structure that does not disintegrate over time. Without wishing to be bound by theory, the fine structure can be preserved in the disclosed methods due to the low interfacial tension between the continuous phase and the ink used in the methods disclosed herein.

[0052] "Flow rate" refers to the rate at which ink is deposited from the print nozzle into the support medium disclosed herein (in μL / h). Meanwhile, "translational velocity" is typically measured in mm / s and refers to the speed at which the print nozzle moves through the support medium disclosed herein.

[0053] The "spin-drop method" can be used to measure interfacial tension. In this method, a rotating horizontal tube contains droplets of both dense and less dense fluids. The rotation of the tube generates a centrifugal force towards the tube wall, causing the droplets to deform into an elongated shape. Elongation stops when the interfacial tension and the centrifugal force are equal.

[0054] As used in this article, "self-assembly" refers to the formation of an ordered structure without external influence due to local interactions between the components of a disordered system.

[0055] "Room temperature vulcanizing polysiloxane" (RTV polysiloxane) is a type of siloxane that cures at room temperature. It can consist of one or two components and offers a variety of hardness levels. RTV polysiloxanes are typically cured with a catalyst.

[0056] "Soft matter" is a substance that is easily deformed by external forces or, in some cases, by thermal fluctuations. Examples of soft matter include, but are not limited to, certain polymers, colloids, surfactants, liquid crystals, microgels, emulsions, etc. In one aspect, this paper discloses a support medium for 3D printing soft matter. Figure 4A-4G The 3D printed structure of soft matter can be seen in the image.

[0057] As used herein, "ink" refers to a material extruded by a 3D printer and may include various plastics (acrylonitrile butadiene styrene or ABS, polylactic acid or PLA, nylon, etc.), conductive materials, carbon fibers, and other materials. In one aspect, this document discloses polysiloxane inks for 3D printing.

[0058] It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed in range format herein. It should also be understood that the endpoints of each range are meaningful relative to and independent of the other endpoint. It should also be understood that many values ​​are disclosed herein, and each value is also disclosed herein as “about” that particular value, in addition to being the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. In this document, a range may be expressed as from “about” one particular value and / or to “about” another particular value. Similarly, when a value is expressed as an approximation using the antecedent “about”, it should be understood that the particular value forms another aspect. For example, if the value “about 10” is disclosed, then “10” is also disclosed.

[0059] When indicating a range, on the other hand, it includes a range from one specific value and / or to another specific value. For example, if the range includes one or two limit values, the range excluding one or two of the included limit values ​​is also included in this disclosure. For example, the phrase "x to y" includes a range from "x" to "y" and a range greater than "x" and less than "y". The range can also be expressed as an upper limit, such as "about x, y, z or less", and should be interpreted as including a specific range of "about x", "about y", and "about z" as well as a range of "less than x", "less than y", and "less than z". Similarly, the phrase "about x, y, z or greater" should be interpreted as including a specific range of "about x", "about y", and "about z" as well as a range of "greater than x", "greater than y", and "greater than z". In addition, the phrase "about 'x' to 'y'" (where 'x' and 'y' are numerical values) includes "about 'x' to about 'y'".

[0060] It should be understood that this range form is used for convenience and brevity, and therefore should be interpreted flexibly as including not only the numerical values ​​explicitly listed as limits of the range, but also all individual numerical values ​​or subranges contained within that range, as if each numerical value and subrange were explicitly listed. For example, the numerical range of “about 0.1% to 5%” should be interpreted as including not only the explicitly stated values ​​of about 0.1% to about 5%, but also individual values ​​(e.g., about 1%, about 2%, about 3%, and about 4%) and subranges within the indicated range (e.g., about 0.5% to about 1.1%; about 5% to about 2.4%; about 0.5% to about 3.2% and about 0.5% to about 4.4%, and other possible subranges).

[0061] As used herein, the terms “about,” “approximately,” “equal to or about,” and “substantially” mean that the quantity or value in question can be an exact value or value that provides an equivalent result or effect as described in the claims or taught herein. That is, it should be understood that quantities, dimensions, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximate and / or larger or smaller as needed, reflecting tolerances, conversion factors, rounding, measurement errors, and other factors known to those skilled in the art, resulting in an equivalent result or effect. In some cases, it is not reasonable to determine a value that provides an equivalent result or effect. In such cases, it is generally understood that, as used herein, “about” and “equal to or about” are indicative values ​​indicating a variation of ±10%, unless otherwise indicated or inferred. Generally, whether explicitly stated or not, quantities, dimensions, formulations, parameters, or other quantities or characteristics are “about,” “approximately,” or “equal to or about.” It should be understood that, unless otherwise specifically stated, when “about,” “approximately,” or “equal to or about” is used before a quantity value, the parameter also includes the specific quantity value itself.

[0062] As used herein, the term "effective amount" refers to an amount sufficient to achieve the desired modification of the physical properties of a composition or material. For example, the "effective amount" of a surfactant refers to an amount sufficient to achieve the desired improvement in properties regulated by the formulation components, such as achieving the formation of a stable reverse emulsion. The specific level, expressed in wt%, required as an effective amount in a composition will depend on a number of factors, including the amount and type of silicone oil in the continuous phase and the ratio of water to glycerol in the dispersed phase.

[0063] As used herein, the terms “optional” or “optionally” mean that the event or situation described below may or may not occur, and the description includes both the possibility that the event or situation may occur and the possibility that it may not occur.

[0064] Unless otherwise stated, the temperatures mentioned in this article are based on atmospheric pressure (i.e., one atmosphere).

[0065] 3D printing support material

[0066] In one aspect, this paper discloses a support material for 3D printing of soft materials. In another aspect, the support material can be an emulsion or a reverse emulsion. In yet another aspect, when the support material is a reverse emulsion, the reverse emulsion comprises a continuous phase and a dispersed phase. In either of these aspects, the support material can be a blocking medium.

[0067] On the other hand, the soft material to be printed can be a polysiloxane. On the other hand, the continuous phase can be a silicone oil, comprising, but not limited to, poly(dimethylsiloxane) (PDMS), poly(methylphenylsiloxane) (PMPS), or combinations thereof. On the other hand, the silicone oil can be about 0.1 to about 0.9% by weight of PDMS, or about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, or about 0.9% by weight of PDMS, or any combination of the foregoing values, or a range including any of the foregoing values. On the other hand, the silicone oil may be about 0.1 to about 0.9% PMPS by weight, or may be about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85 or about 0.9% PMPS by weight, or any combination of the above values, or a range including any of the above values. In any of these aspects, the silicone oil has a viscosity of about 5 cSt to about 1000 cSt, or about 5, 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950 or about 1000 cSt, or any combination of the foregoing values, or a range including any of the foregoing values. In one aspect, the silicone oil has a viscosity of about 10 to about 100 cSt. On the other hand, silicone oils can have a concentration of about 950 g / mol to about 28,000 g / mol, or about 1250 g / mol to about 5970 g / mol, or about 950, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, 10,000 g / mol. Molecular weights of 0, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000, 20,000, 21,000, 22,000, 23,000, 24,000, 25,000, 26,000, 27,000, or about 28,000 g / mol, or any combination of the foregoing values, or a range including any of the foregoing values. In some aspects, when the silicone oil is dissolved in a low-viscosity solvent (e.g., about 1250 g / mol), the molecular weight of the silicone oil can be up to 62,700 g / mol.

[0068] In some respects, the continuous phase may be or contain fluorocarbon oil. In other respects, the fluorocarbon oil may be a C5-C18 perfluorinated compound, such as the compound with CAS number 86508-42-1, named FLUORINERT. TM FC-40 or FLUORINERT TM FC-770 (3M Company) for sale.

[0069] On another front, the dispersed phase of a reverse emulsion may comprise water, glycerol, or a combination thereof, in any ratio from 100% glycerol and 0% water to 0% glycerol and 100% water. On another front, the dispersed phase of a reverse emulsion may comprise a glycerol to water ratio of 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, 10:90, or 0:100, or any combination of the foregoing values, or a range comprising any of the foregoing values. On another front, the dispersed phase of a reverse emulsion comprises 50% glycerol and 50% water. On another front, the dispersed phase of a reverse emulsion comprises 51% glycerol and 49% water. In some aspects, a glycerol to water ratio deviating from 50:50 or 51:49 may result in reduced transparency.

[0070] In any of these aspects, the dispersed phase and the continuous phase have the same refractive index. Furthermore, in this respect, the supporting material can be optically transparent.

[0071] On one hand, the reverse emulsion comprises a dispersed phase having a volume fraction of about 0.64 to about 0.85, or about 0.64, 0.65, 0.675, 0.70, 0.725, 0.75, 0.775, 0.8, 0.825 or about 0.85, or any combination of the foregoing values, or a range including any of the foregoing values.

[0072] In some aspects, the reverse emulsion contains a surfactant. In one aspect, the surfactant comprises cyclopentasiloxane and dimethicone copolyol. In another aspect, the dimethicone copolyol can be PEG / PPG-18 / 18 dimethicone or another dimethicone copolyol (DOW). 5225 Formulation Additives). On the other hand, the surfactant can be lauryl PEG / PPG18 / 18 polymethylsiloxane (DOWN). 5200 Formulation Additives), cyclopentasiloxane and PEG-12 polydimethylsiloxane crosspolymer (DOW) 9011 polysiloxane elastomer blend), cyclopentalylsiloxane and PEG / PPG-19 / 19 polydimethylsiloxane (DOW) BY-11-030), PEG / PPG-19 / 19 polydimethylsiloxane and C13-16 isoalkanes and C10 / 13 isoalkanes (DOW) BY-25-337), PEG-10 polydimethylsiloxane (DOW) ES-5612 formulation additive), diisobutyl PEG / PPG-10 / 7 / polydimethylsiloxane copolymer (DOW) FZ-2233), polydimethylsiloxane and PEG / PPG-18 / 18 polydimethylsiloxane (DOW) ES-5226DM formulation additive), polydimethylsiloxane and PEG / PPG-18 / 18 polydimethylsiloxane (DOW) ES-5227 Formulation Additive), Lauryl PEG-10 Tris(trimethylsiloxy)silylethyl dimethicone (DOW) ES-5300 Formulation Additive), Cetyl diglyceryl tris(trimethylsiloxy)silylethyl dimethicone (DOW) ES-5600 polysiloxane glycerol emulsifier), PEG-12 polydimethylsiloxane ( OFX-5329 fluid or DOW ES-5373 low-odor formulation additive, or similar surfactants.

[0073] In any of the foregoing aspects, the reverse emulsion has a yield stress of about 0.1 to 100 Pa, or about 1 to 20 Pa, or about 5 Pa. In another aspect, the yield stress may be about 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 40, 50, 60, 70, 80, 90 or about 100 Pa, or any combination of the foregoing values, or a range including any of the foregoing values.

[0074] Methods for 3D printing soft materials

[0075] In one aspect, this document discloses a method for 3D printing soft materials. In another aspect, the method involves injecting ink into a support material disclosed herein. In some aspects, the ink may be PDMS or PMPS. In another aspect, the ink may be UV-curable. In another aspect, the ink may be room temperature curable, photocurable, or curable at elevated temperatures. In some aspects, the ink may contain other polymers or resins, such as acetates, vinyl, acrylates, or epoxy polymers or resins. In yet another aspect, room temperature vulcanizing (RTV) polysiloxanes (e.g., SYLGARD of Dow Chemical, Inc.) may be used. TM 184; Polytek Development Company Platinum-cured silicone rubber, SMOOTH-ON tin-cured and platinum-cured silicone rubber (such as those from SMOOTH-ON), and water-curable polysiloxane sealants can be used to formulate inks applicable to this document. On the other hand, polyvinyl alcohol (PVA), polyethylene glycol (PEG) and conjugated PEG, poly(N-isopropylacrylamide) (PNIPAM), 4-(hydroxymethyl)phenoxyacetic acid resin (HMPA), starch and starch derivatives, cellulose and cellulose derivatives, and / or other polysaccharides can be used to formulate inks applicable to this document.

[0076] On one hand, the ink can be injected into the support material at a deposition rate of about 10 to about 10,000 μL / h, or about 100 to 100 μL / h, or about 10, 100, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500 or about 10,000 μL / h, or any combination of the foregoing values, or a range including any of the foregoing values. On the other hand, the ink may be injected into the support material at a translational velocity of about 0.01 to about 20 mm / s, or about 10 to 10 mm / s, or about 0.01, 0.05, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or about 20 mm / s, or any combination of the foregoing values, or a range including any of the foregoing values.

[0077] On the other hand, the interfacial tension between the support material and the ink is between about 0.1 and about 10 mN / m, or about 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or about 10 mN / m, or about 3.4 mN / m.

[0078] Soft materials

[0079] In one aspect, this document discloses articles comprising soft matter produced by the methods disclosed herein. In another aspect, the soft matter has a minimum stable feature size from about 4 to about 80 μm, or about 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or about 80 μm, or any combination of the foregoing values, or a range including any of the foregoing values. In one aspect, the minimum stable feature size is about 4.3 μm. In another aspect, the article has a surface roughness of less than about 150 nm.

[0080] On one hand, the article can be a model organ, tissue on a chip, lab-on-a-chip, medical implant, or similar device. On another hand, the soft material and article are biocompatible. On the other hand, the article can be an immediate care implant, such as an ear accessory for a hearing aid, a nasal accessory for a breathing assist or sleep apnea device, a custom-made vascular implant, a custom-made stoma seal, or similar device.

[0081] Having described aspects of this disclosure, the following embodiments illustrate some additional aspects of this disclosure. While various aspects of this disclosure have been described in conjunction with the following embodiments and corresponding text and drawings, it is not intended to limit the aspects of this disclosure to the description. Rather, it is intended to cover all alternatives, modifications, and equivalents that fall within the spirit and scope of this disclosure.

[0082] References

[0083] 1. Silicone Market Trends | Industry Growth Analysis Report, 2019-2025. https: / / www.grandviewresearch.com / industry-analysis / silicon-market

[0084] 2. Ozbolat V, et al (2018) 3D Printing of PDMS Improves Its Mechanicaland Cell Adhesion Properties. ACS Biomaterials Science and Engineering, 4(2): 682-693.

[0085] 3.Femmer T,et al Print your own membrane:Direct rapid prototyping ofpolydimethylsiloxane.Lab Chip,14:2610-2613.

[0086] 4.O’Bryan CS,et al(2017)Self-assembled micro-organogels for 3Dprinting silicone structures.Science Advances,3(5)https: / / doi.org / 10.1126 / sciadv.1602800

[0087] 5.Bhattacharjee T,et al(2015)Writing in the granular gelmedium.Science Advances,1(8):e1500655-e1500655.

[0088] 6.Bhattacharjee T,et al(2018)Polyelectrolyte scaling laws formicrogel yielding near jamming.Soft Matter,14(9):1559-1570.

[0089] 7.Shen Y,et al(2017)3D printing of large,complex metallic glassstruetures.Materials and Design,117:213-222.

[0090] 8.Shao H,et al(2017)3D gel-printing of zirconia ceramicparts.Ceramics International,43(16):13938-13942.

[0091] 9.Ho CMB,et al(2015)3D printed microfluidics for biologicalapplications.Lab on a Chip,15(18):3627-3637.

[0092] 10.Murphy S V.,et al(2014)3D bioprinting of tissues and organs.NatureBiotechnology,32(8):773-785.

[0093] 11.Kolesky DB,et al(2016)Three-dimensional bioprinting of thickvascularized tissues.Proc.of the National Academy of Sciences of the UnitedStates of America,113(12):3179-3184.

[0094] 12.Bosi S,et al(2015)From 2D to 3D:Novel nanostructured scaffolds toinvestigate signalling in reconstructed neuronal networks.Scientific Reports,5:9562.

[0095] 13.Mata A,et al(2009)A three-dimensional scaffold with precise micro-architecture and surface micro-textures.Biomaterials,30(27):4610-4617.14.HuhD,et al(2012)Microengineered physiological biomimicry:Organs-on-Chips.Lab ona Chip,12(12):2156-2164.

[0096] 15.Grosberg A,et al(2011)Ensembles of engineered cardiac tissues forphysiological and pharmacological study:Heart on a chip.Lab on a Chip,11(24):4165-4173.

[0097] 16.Odom TW,et al(2002)Improved pattern transfer in soft 1ithographyusing composite stamps.Langmuir,18(13):5314-5320.

[0098] 17.Qin D,et al(2010)Soft lithography for micro-and nanoscalepatterning.Nature Protocols,5(3):491-502.

[0099] 18.Xia Y,et al(1998)SOFT LITHOGRAPHY.Annual Rev.of Materials Science,28(1):153-184.

[0100] 19.Tumbleston JR,et al(2015)Continuous liquid interface production of3D objects.Science,347(6228):1349-1352.

[0101] 20.Hinton TJ,et al(2016)3D Printing PDMS Elastomer in a HydrophilicSupport Bath via Freeform Reversible Embedding.ACS Biomaterials Science andEngineering,2(10):1781-1786.

[0102] 21.Luo G,et al(2019)Freeform,Reconfigurable Embedded Printing of All-Aqueous 3D Architectures.Advanced Materials,31(49):1-7.

[0103] 22.O’Hern CS,et a1 Jamming at zero temperature and zero appliedstress:The epitome of disorder.Phys.Rev.E,68:011306.

[0104] 23.Cates ME,et al(1998)Jamming,force chains,and fragilematter.Physical Review Letters,81(9):1841-1844.

[0105] 24.Bi D,et al(2011)Jamming by shear.Nature,480(7377):355-358.

[0106] 25.Corwin EI,et al(2005)Structural signature of jamming in granularmedia.Nature,435(7045):1075-1078.

[0107] 26.Menut P,et a1(2012)Does size matter?Elasticity of compressedsuspensions of colloidal-and granular-scale microgels.Soft Matter,8(1):156-164.

[0108] 27.Schweizer KS,et al Collisions,caging,thermodynamics,and jamming inthe barrier hopping theory of glassy hard sphere fluids.The Journal ofChemical Physics,127(16):164505-164505.

[0109] 28.Liu AJ,et al(1998)Jamming is not just cool any more.Nature,396(6706):21-22.

[0110] 29.Mattsson J,et al(2009)Soft colloids make strong glasses.Nature,462(7269):83-86.

[0111] 30.Kuo CM,et al(1993)The effects of end-groups on the criticalmiscibility temperatures and thermodynamic interactions in poly(dimethylsiloxane)and poly(methylphenylsiloxane)blends.European PolymerJournal,29(5):661-664.

[0112] 31.Kuo CM,et al(1994)Studies of cyclic and linear poly(dimethylsiloxane)s:

[0113] 31.Effect of molecular architecture / topology on blends of poly(methylphenylsiloxane)and poly(dimethylsiloxane).Polymer,35(21):4623-4626.

[0114] 32.Kuo CM,et al(1992)Investigation of the Interactions and PhaseBehavior in Poly(dimethylsiloxane)and Poly(methylphenylsiloxane)Blends.Macromolecules,25(8):2192-2195.

[0115] 33.Horiuchi H,et al(1991)Molecular weight dependence of the cloud-point curve of po1y(dimethylsiloxane) / poly(methylethylsiloxane)mixtures.Polymer,32(11):1970-1974.

[0116] 34.Dufresne ER,et al(2009)Self-assembly of amorphous biophotonicnanostructures by phase separation.Soft Matter,5(9):1792-1795.

[0117] 35.Wen Q,et al(2011)Polymer physics of the cytoskeleton.CurrentOpinion in Solid State and Materials Science,15(5):177-182.

[0118] 36.Brangwynne CP,et al(2015)Polymer physics of intracellular phasetransitions.Nature Physics,11(11):899-904.

[0119] 37.Style RW,et al(2018)Liquid-Liquid Phase Separation in an ElasticNetwork.Physical Review X,8(1)https: / / doi.org / 10.1103 / PhysRevX.8.011028

[0120] 38.Rosowski KA,et al(2020)Elastic ripening and inhibition of liquid-liquid phase separation.Nature Physics,16(April)https: / / doi.org / 10.1038 / s41567-019-0767-2

[0121] 39.Krause S(1978)Chapter 2-Polymer-Polymer Compatibility.PolymerBlends:15-113.https: / / doi.org / https: / / doi.org / 10.1016 / B978-0-12-546801-5.50008-6

[0122] 40.Krause S(1986)Polymer-polymer miscibility.Pure and AppliedChemistry,58(12)

[0123] 41.Olabisi O,et al(1979)Polymer-Polymer Miscibility.https: / / doi.org / 10.13140 / 2.1.2644.3206

[0124] 42.Conley GM,et al(2017)Jamming and overpacking fuzzy microgels:Deformation,interpenetration,and compression.Science Advances,3(10):e1700969.

[0125] 43.Pairam E,et al Stability of toroidal droplets inside yield stressmaterials.Phys.Rev.E,90:021002.

[0126] 44.Mehrabian H,et al Capillary breakup 0f a liquid torus.J.FluidMech.,717:281-292.

[0127] 45.Vonnegut B(1942)Rotating bubble method for the determination ofsurface and interfacial tensions.Review of Scientific Instruments,13(1):6-9.

[0128] 46.Lo HY,et al(2019)Diffusion-Dominated Pinch-Off of Ultralow SurfaceTension Fluids.Physical Review Letters,123(13)https: / / doi.org / 10.1103 / PhysRevLett.123.134501

[0129] 47. Hinton TJ, et al 3D printing PDMS elastomer in a hydrophilicsupport bath via freeform reversible embedding. ACS Biomater. Sci. Eng., 2: 1781-1786.

[0130] 48. Bhattacharjee T, et al (2016) Liquid-like Solids Support Cells in 3D. ACS Biomater. Sci. Eng., 2(10): 1787-1795.

[0131] aspect

[0132] This disclosure can be described according to the following numbered aspects, which should not be confused with the claims.

[0133] Aspect 1. A support material for 3D printing of soft materials, the support material comprising a reverse emulsion, wherein the reverse emulsion comprises a continuous phase and a dispersed phase.

[0134] Aspect 2. The support material according to aspect 1, wherein the soft material comprises polysiloxane.

[0135] Aspect 3. The support material according to aspect 1 or 2, wherein the continuous phase comprises silicone oil.

[0136] Aspect 4. The support material according to aspect 3, wherein the silicone oil comprises poly(dimethylsiloxane), poly(methylphenylsiloxane), or a combination thereof.

[0137] Aspect 5. The support material according to aspect 4, wherein the silicone oil has a molecular weight of about 9,50 g / mol to about 28,000 g / mol.

[0138] Aspect 6. The support material according to aspect 4, wherein the silicone oil has a molecular weight of about 1250 g / mol to about 5970 g / mol.

[0139] Aspect 7. The support material according to aspect 3, wherein the polysiloxane oil comprises poly(dimethylsiloxane).

[0140] Aspect 8. The support material according to aspect 3, wherein the silicone oil comprises about 0.1 to about 0.9 wt% of poly(dimethylsiloxane) and about 0.1 to about 0.9 wt% of poly(methylphenylsiloxane).

[0141] Aspect 9. The support material according to any one of aspects 3-8, wherein the silicone oil has a viscosity of about 5 cSt to about 1000 cSt.

[0142] Aspect 10. The support material according to any one of aspects 3-8, wherein the silicone oil has a viscosity of about 10 cSt to about 100 cSt.

[0143] Aspect 11. The support material according to any one of aspects 1-9, wherein the dispersed phase comprises water, glycerol, or a combination thereof.

[0144] Aspect 12. The support material according to aspect 11, wherein the dispersed phase comprises glycerol:water in a ratio of about 100:0 to about 0:100.

[0145] Aspect 13. The support material according to aspect 11, wherein the dispersed phase comprises glycerol:water in a ratio of about 50:50 to about 51:49.

[0146] Aspect 14. The support material according to aspect 11, wherein the dispersed phase comprises 51% glycerol and 49% water.

[0147] Aspect 15. The support material according to any one of aspects 1-14, wherein the dispersed phase and the continuous phase comprise matched refractive indices.

[0148] Aspect 16. The support material according to aspect 15, wherein the support material is optically transparent.

[0149] Aspect 17. The support material according to any one of aspects 1-16, wherein the reverse emulsion comprises the dispersed phase having a volume fraction of about 0.64 to about 0.85.

[0150] Aspect 18. The support material according to any one of aspects 1-17 further includes a surfactant.

[0151] Aspect 19. The support material according to aspect 18, wherein the surfactant comprises cyclopentasiloxane and polydimethylsiloxane copolyol, polydimethylsiloxane and polydimethylsiloxane copolyol, lauryl polymethylsiloxane copolyol, polydimethylsiloxane copolyol and at least one C10-C16 isoalkane, cyclopentasiloxane and polydimethylsiloxane copolyol crosspolymer, alkyl polydimethylsiloxane copolyol, siloxane glycerol emulsifier or combinations thereof.

[0152] Aspect 20. The support material according to aspect 19, wherein the polydimethylsiloxane copolyol comprises PEG / PPG-18 / 18 polydimethylsiloxane.

[0153] Aspect 21. The support material according to any one of aspects 1-20, wherein the reverse emulsion comprises a yield stress of about 0.1 Pa to about 100 Pa.

[0154] Aspect 22. The support material according to any one of aspects 1-20, wherein the reverse emulsion comprises a yield stress of about 1 Pa to about 20 Pa.

[0155] Aspect 23. The support material according to any one of aspects 1-20, wherein the reverse emulsion comprises a yield stress of 5 Pa.

[0156] Aspect 24. A method for 3D printing soft materials, the method comprising injecting ink into a support material of any one of Aspects 1-23.

[0157] Aspect 25. The method according to aspect 24, wherein the ink comprises poly(dimethylsiloxane) or poly(methylphenylsiloxane).

[0158] Aspect 26. The method according to aspect 24 or 25, wherein the ink comprises a polymer having a molecular weight of about 1250 g / mol to about 28,000 g / mol.

[0159] Aspect 27. The method according to aspect 24 or 25, wherein the ink is UV curable.

[0160] Aspect 28. The method according to any one of aspects 24-27, wherein the ink is injected into the support material at a deposition rate of about 10 to about 10,000 μL / h.

[0161] Aspect 29. The method according to any one of aspects 24-27, wherein the ink is injected into the support material at a deposition rate of about 100 to about 1000 μL / h.

[0162] Aspect 30. The method according to any one of aspects 24-29, wherein the ink is injected into the support material at a translational speed of about 0.01 to about 20 mm / s.

[0163] Aspect 31. The method according to any one of aspects 24-29, wherein the ink is injected into the support material at a translational speed of about 1 to about 10 mm / s.

[0164] Aspect 32. The method according to any one of aspects 24-31, wherein the interfacial tension between the support material and the ink is about 0.1 mN / m to about 10 mN / m.

[0165] Aspect 33. The method according to any one of aspects 24-31, wherein the interfacial tension between the support material and the ink is about 3.4 mN / m.

[0166] Aspect 34. An article comprising a soft substance produced by the method described in any one of aspects 23-32.

[0167] Aspect 35. The article of manufacture according to aspect 34, wherein the soft matter comprises a minimum stable feature size of about 4 μm to about 80 μm.

[0168] Aspect 36. The article of manufacture according to aspect 34 or 35, wherein the article of manufacture includes a surface roughness of less than 150 nm.

[0169] Aspect 37. The article of any one of aspects 34 to 36, wherein the article of the article comprises a model organ.

[0170] Aspect 38. The article of manufacture according to aspect 37, wherein the article of manufacture includes an ear accessory for a hearing aid, a nasal accessory for breathing assistance, a nasal accessory for a sleep apnea device, a custom vascular implant, or a custom ostomy seal.

[0171] Example

[0172] The following embodiments are provided to provide those skilled in the art with a complete disclosure and description of how to prepare and evaluate the compounds, compositions, articles, apparatus, and / or methods claimed herein, and are intended purely as illustrative examples of this disclosure and not to limit the scope of the disclosure as the inventors believe it to be. Efforts have been made to ensure accuracy regarding figures (e.g., amounts, temperatures, etc.), but some errors and deviations should be taken into account. Unless otherwise stated, parts are parts by weight, temperatures are in °C or at ambient temperature, and pressures are at or near atmospheric pressure.

[0173] Example 1: The effect of clogged emulsion droplets on liquid-liquid phase separation

[0174] The phase behavior of liquid-liquid multiphase systems and the rheological behavior of clogged systems are well-studied topics, but their interdependence has not been previously investigated. Anticipated clogged silicone oil-in-water reverse emulsions of poly(methylphenylsiloxane) (PMPS) and poly(dimethyl)siloxane (PDMS) (see...) Figure 8The phase behavior of the two-phase system, as well as the size and curvature of the discontinuous phase, will be controlled by the yield stress of the blocked emulsion without altering the phase boundaries. Homogeneous mixtures of PDMS and PMP, representing the continuous phase of the blocked inverse emulsion, at different weight fractions, will be used to study phase separation using small-angle light scattering and optical microscopy. The signal from small-angle light scattering is expected to provide insight into the bulk of the sample, and optical microscopy will allow for visual confirmation over time of the size and shape of the discontinuous phase within the blocked system.

[0175] The first step involves obtaining samples of PMP and PDMS and constructing a phase diagram for the system, as phase behavior is known to vary with the molecular weight and polydispersity of the components. Polymer blends of PDMS and PMP were prepared with PDMS weight fractions of 0.1, 0.25, 0.5, 0.75, and 0.9%, and vortexed at 180 °C to produce a single-phase system. The polymer blends were then annealed to 4 °C, and the cloud point was identified using small-angle light scattering and bright-field microscopy. Phase diagrams of the polymer blends were plotted based on the determined cloud point for different weight fractions. For a given quench rate, the kinetics of phase separation will also be better understood. This will provide valuable control for comparison with the behavior of the same system under clogging conditions.

[0176] Phase separation of PDMS and PMP blends, which have known phase diagrams, will be performed in clogged reverse emulsions as follows. Reverse emulsions with a continuous phase consisting of PDMS and PMP blends, wherein the weight fractions of PDMS are 0.1, 0.25, 0.5, 0.75, and 0.9%, will be prepared. The aqueous phase of the reverse emulsion will consist of a mixture of water and glycerol in specific weight fractions to match the refractive index of the continuous phase. The aqueous phase (φ) will be prepared... ａｑ Inverse emulsions with volume fractions of 0.70, 0.75, 0.80, and 0.85 were used to produce plugging emulsions with different yield stresses (see...). Figures 5A-5D Inverted emulsions were prepared by controlling droplet size and monodispersing them using a homogenizer. To characterize whether a given volume fraction of the inverted emulsion behaves like a solid or a liquid, an oscillation frequency scan was performed at a low strain amplitude (1%) to measure the loss modulus (G”) and storage modulus (G’) of different compositions. The yield stress (γ) of the clogged emulsion was also measured. G ), will apply unidirectional shear rate A scan is used to measure the corresponding shear stress (γ). This will be determined at 1 Hz (G). 1Hz Yield stress (γ) measured at ′) c ), emulsion droplet size (D) dropThe scaling relationship between the energy storage modulus and the energy storage modulus. It is expected that phase separation under blockage will lead to the formation of irregular / skewed shapes of discontinuous phases, and the property distribution of discontinuous phases will be strongly controlled by the yield stress of the blockage emulsion.

[0177] The clogging transition of flexible packaging microgels has been used in 3D printing soft structures, living cells, and tissues. The rheological characteristics of these clogging microgels exhibit a critical shear stress above which the bulk phase yields and begins to flow, and below which it remains solid. Similar behavior has been observed in clogging emulsions; to investigate and characterize this behavior, a clogging inverse emulsion of water in silicone oil was prepared. This 3D printing technology requires a transparent support material to allow for imaging and analysis of the structures fabricated within it during and after printing. To make the emulsion clear and transparent, 51% by weight of glycerol was added to the aqueous phase to match the refractive indices of the aqueous and oil phases. The continuous phase consisted of silicone oil (10 cSt) mixed with an emulsifier (DOWSIL 5225c formulation aid), which accounted for 10% by weight of the total emulsion weight. The aqueous phase was then dropped into the continuous phase while homogenizing for 15 minutes. Inverted emulsions with aqueous phase (φaq) volume fractions of 0.65, 0.70, 0.75, 0.80, and 0.85 were prepared and characterized using uniaxial shear rate and oscillatory strain frequency sweep tests. By changing the volume fraction of the inverted emulsion and the droplet size, the yield stress was found to be highly tunable.

[0178] Example 2: The role of interfacial tension in the stability of small print features

[0179] It is known that interfacial tension between printing ink and the clogging system causes interfacial instability, leading to the disintegration of the printed structure. This is a phenomenon believed to be controlled by the yield stress of the clogging microgel, while the disintegration time is thought to be controlled by the ink viscosity. It is necessary to quantify the minimum stable characteristic size from the interfacial tension and yield stress of the clogging material. It is also necessary to develop a scale that relates to the minimum characteristic size corresponding to the interfacial tension and yield stress of the clogging emulsion. It is believed that the decomposition of the polysiloxane structure associated with interfacial instability can be eliminated by generating the clogging emulsion system with a continuous phase, which is a silicone oil with slightly different chemical properties from the ink (PDMS or PMP). Interfacial tension measurements will be performed using the spin-drop method, which is versatile and well-suited for characterizing liquid-liquid systems with ultra-low interfacial tension. Figure 9 The calculated interfacial tension, yield stress, and ink viscosity of the clogged emulsion will enable the development of a scaling rule for quantitatively stable minimum printable properties.

[0180] PDMS and PMP are similar silicone polymers with different side chains. Although the surface tensions of PDMS and PMP are known individually, the interfacial tension between them needs to be determined to quantify the minimum feature size of any resulting printed structure. The interfacial tension between PDMS and PMP can be determined using the spin-drop method. This method uses a glass capillary filled with droplets of a heavier and lighter phase arranged horizontally along its axis. As the capillary rotates along its axis at an angular velocity ω, the droplets of the lighter phase align and elongate along the axis of rotation due to centrifugal force; the radius (R) of the elongated droplets is related to the interfacial tension γ, as shown by the Vonnegut equation:

[0181] γ=[(Δρ·ω 2 ) / 4]·R 3

[0182] Where Δρ is the density difference between the droplet and the surrounding liquid. In this case, since PMP is the heavier component (Δρ = 0.1246 g / cc), the bulk phase of the capillary will be filled with PMP, and the isolated droplet will be made of PDMS. For a fixed angular velocity, the radius of the elongated PDMS droplet perpendicular to the axis of rotation will be determined using a long working distance microscope objective mounted on a high-resolution camera. From the difference in surface tension between each individual fluid, we estimate the interfacial tension between PDMS and PMPS to be approximately 3.4 mN / m. Therefore, the Vonnegut equation predicts that rotating the sample at an angular velocity between 25 and 100 rad / s will drive the PDMS droplet to elongate axially and shrink radially to a diameter between 500 μm and 1.25 mm. To minimize the error caused by the curvature-related force contribution from the ends of the elongated PDMS droplet at the interface, the droplet volume should be fixed such that the length of the elongated droplet is greater than four times the droplet diameter. The minimum droplet volume corresponding to these diameters is between 2 and 7.5 μL, falling within the typical range used in a spinning droplet tensiometer. Based on the differences in surface tension measurements of the components, the ultra-low interfacial tension between PDMS and PMPS measured by the spinning drop method is estimated to be approximately 3.4 mN / m.

[0183] It is believed that the interfacial tension between the two components will be affected when one of the components is the continuous phase of the plugged system. To confirm our hypothesis, the spin-drop method will be repeated to determine the interfacial tension between PDMS and a plugged reverse emulsion with PMP as the continuous phase. In this case, the Vonnegut equation will be modified to relate the interfacial tension to the yield stress (σ) of the plugged emulsion:

[0184] γ=[(Δp·ω) 2 ) / 4]·R ３-κσR

[0185] Where κ is the geometric coefficient. Interfacial tension measurements will be performed at angular velocities between 25 and 100 rad / s to reduce errors associated with droplet size measurements. In these experiments, the centripetal forces on the emulsions cause them to yield and separate from the PMPS droplets trapped within them. Balancing these opposing forces, we estimate the minimum yield stress required to prevent spontaneous emulsion flow to be approximately 10. -4 The stress is Pa, which is many orders of magnitude lower than the yield stress of the sample presented in this paper. Therefore, we expect to improve the spin-drop tensiometer to make it compatible with using blocked emulsions as the continuous phase. In completing this study, we expect to develop a technique based on the Vonnegut equation to measure the interfacial tension of substances in blocked emulsions.

[0186] It is believed that the balance between interfacial tension and yield stress will determine the minimum feature that can be 3D printed using the emulsion-supported technique disclosed herein. To determine the constraints on stability and explore their fundamental sources, PDMS will be printed into a plugged inverse emulsion with PMP as the continuous phase, and vice versa. Plugged inverse emulsions with different yield stresses using PMP as the continuous phase will be generated, and linear features of PDMS oil will be directly 3D printed into these filled emulsions. By varying the nozzle translation speed and PDMS flow rate, features with different cross-sectional areas will be produced. Over time, the stability of the features will be analyzed by time-delay measurements, and the minimum stable feature size for plugged inverse emulsions with different yield stresses will be determined. The same experiment will be repeated, using PDMS as the continuous phase, to measure the minimum stable size of PMPS features in plugged inverse emulsions. Furthermore, a scaling factor will be established that quantifies the minimum stable feature diameter for a given yield stress and interfacial tension in the plugged system.

[0187] Due to the similar chemical properties of PDMS and PMPS oils, ultra-low interfacial tension can be expected between them, and we estimate that this ultra-low interfacial tension is close to the difference in their respective surface tensions, which is 3.4 mN / m. A modified Vonnegut equation is predicted to determine the interfacial tension between one component and another free component within the plugged system. Furthermore, the minimum feature size is expected to be proportional to γ / σ. These results will enable predictive control of the quality and overall performance of this novel 3D printing technology using new material pairs for future applications.

[0188] Samples with different yield stresses were prepared using varying emulsion filling ratios, which may result in different surfactant concentrations in their continuous phases. To illustrate the excess surfactant in the continuous phase and its potential adsorption at the PDMS-PMP interface, the surfactant concentration was measured using UV-Vis spectroscopy. This process allows the determination of new proportional relationships for predicting the minimum printable feature size. In some experiments, phase separation studies were performed within clogged siloxane microgels rather than clogged reverse emulsions because surfactants are typically absent in microgel systems.

[0189] The effect of interfacial tension on the breakdown of printed structures has been briefly investigated previously. Pure silicone oil was printed into a clogged microorganic gel composed of self-assembled block copolymers. The feature size of the printed ink was controlled by adjusting the ink flow rate (Q) and the translational velocity of the print head (v). When analyzing the printed features over time, the interfacial tension between the silicone oil and the clogged microorganic gel led to the instability-related decomposition of the features (see [link to study]). Figure 6 The stability of printed features was found to increase with increasing feature diameter, feature viscosity, and yield stress of the blockage system containing them. The minimum stable feature size is expected to be measurable using a similar method, quantified from interfacial tension measurements and the yield stress of the blockage emulsion (see [link to study]). Figure 7 ).

[0190] Example 3: Quantification of the accuracy and variability of 3D-printed polysiloxane structures fabricated using fine features

[0191] Printing into plugging systems has proven to be an effective technique for fabricating a variety of soft materials and has been applied in polysiloxane manufacturing and tissue engineering. However, previous plugging systems used for 3D printing were already filled microgel systems, so the effectiveness of using plugging emulsion systems should be explored. Emulsions are a very attractive alternative to microgels because the development of plugging emulsion systems is very simple and highly versatile for the materials being printed, and also has tunable rheological properties. Therefore, the effectiveness of using plugging emulsions as support media and PMPS or PDMS as the continuous phase to fabricate polysiloxane structures will be investigated. By utilizing phase separation and using plugging emulsions with very low interfacial tension with the ink, stable features with very high resolution and surface finish can be printed. Spherical portions with different curvatures will be printed with fluorescently labeled inks, and surface curvature will be measured using confocal microscopy, while surface roughness will be studied using scanning white light interferometry (SWLI) and scanning electron microscopy (SEM). The deviation between the measured curvature and the encoded curvature will quantify the accuracy of the printed structure, and the measurement of surface roughness will be quantified as the variability of the printed structure.

[0192] The cross-sectional area (A) of the printed polysiloxane structure is quantified using the continuity equation, Q / v = A, through the printer's translational speed (v) and ink flow rate (Q). This equation needs to be validated in estimating the feature dimensions of this technique used to print polysiloxane structures within a clogged emulsion. In this study, UV-curable liquid silicone rubber (Momentive UV Electro 225) diluted with rhodamine-labeled silicone oil was printed into a clogged inverse emulsion at different printer speeds and ink flow rates. The cross-sectional area of ​​the printed feature was measured using confocal microscopy by collecting z-stacks and sampling the diameter along the vertical and horizontal directions of the print. The linear scaling of the cross-sectional area to the ratio of ink flow rate to translational speed will be analyzed. Similarly, the maximum print speed of the clogged emulsion with different yield stresses will be identified by measuring the deviation between the diameters along the vertical and horizontal directions of the print at a given print speed. The linear scaling between the cross-sectional area of ​​the printed feature and the ratio of flow rate to print speed will then be established. The maximum possible printing speed for a given yield stress of a clogged emulsion will also be determined.

[0193] The quantification of the quality and mechanical strength of the printed structure will serve as benchmark data regarding the effectiveness of using the disclosed technology. Spherical segments with different radii of curvature and constant depth will be printed. Momentive UV Electro225, using diluted fluorescently labeled silicone oil, will be used as the ink. The printed structure will be analyzed using confocal microscopy. The curvature of the printed spherical segments will be measured by collecting z-stacks of the printed features. Intensity projections on the X and Y axes will be fitted to a sector, and the radius of this sector will be compared with the coded curvature to measure the accuracy of the printed structure. To measure variability, the surface roughness of the spherical segments will be measured using scanning white light interferometry and scanning electron microscopy. To test the mechanical strength of the printed structure, “dog bone” structures will be printed in both horizontal and vertical directions, and the cured structure will be subjected to an external stress-strain test to measure mechanical integrity. Upon completion of this study, highly uniform features with surface roughness less than 150 nm and excellent mechanical integrity due to excellent layer-to-layer and side-layer adhesion are expected to be observed.

[0194] Further, it is expected that a linear relationship will be observed between the cross-sectional area of ​​the printed feature and the ratio of the flow rate to the translational speed of the print head. Measurements of the printed feature size are expected to demonstrate the ability to produce uniform feature sizes down to 3 μm in diameter, which are infinitely stable over time. For inverse emulsions with a yield stress of 4–5 Pa, stable and uniform features should be observed even at translational speeds of 20 mm / s.

[0195] In some experiments, the low surface tension between the ink and the clogging emulsion can produce a rough surface on the printed object. In such cases, a combination of Q and v that reduces the roughness along the printed surface will be identified. Modifying the layer height relative to the printed feature size will eliminate this problem. Preliminary results indicate that it takes 2 hours for 100 cSt fluorescently labeled silicone oil to diffuse 500 μm from the ink boundary into the clogging system. By increasing the molecular weight of the labeled silicone oil, the diffusion of fluorescent material from the ink can be significantly reduced. Since the printing time for spherical segments will be between 5 and 15 minutes based on the printing speed, the feature surface and roughness can still be analyzed without difficulty.

[0196] To observe whether the clogged emulsion behaved similarly to the clogged microgel, a structure of Momentive UV Electrode 225 was printed within the clogged emulsion at a yield stress of 5 Pa. Complex features and geometries were printed, exhibiting exceptional robustness upon curing. To observe whether the printed feature size was proportional to the translational velocity and flow rate of the printing needle, part A of a PlastSil formulation diluted with low-viscosity silicone oil (10 cSt) was printed within the clogged emulsion at a yield stress of 5 Pa. Features were printed at translational velocities ranging from 0.1 to 20 mm / s and flow rates ranging from 10 to 5000 μL / hr. The diameter of the printed features was measured using a bright-field microscope, and it showed a linear proportionality to the ratio of flow rate to the translational velocity of the printing needle. The printed features could be predicted from a continuity equation:

[0197] (πD 2 ) / 4=(Q / v)

[0198] Where D is the diameter of the feature to be printed, Q is the ink flow rate, and v is the translational velocity of the printed object. In this case, the PlastSil formulation is miscible in a blockage emulsion with PDMS as the continuous phase, and we expect to observe smaller and more uniform features when printing in a blockage emulsion with PMP as the continuous phase.

[0199] It should be emphasized that the above embodiments of this disclosure are merely possible examples of implementation methods described for the purpose of clearly understanding the principles of this disclosure. Many variations and modifications can be made to the above embodiments without substantially departing from the spirit and principles of this disclosure. All such modifications and variations are intended to be included within the scope of this disclosure and protected by the appended claims.

Claims

1. A support material for 3D printing of soft materials comprising polysiloxane, said support material being composed of a reverse emulsion, The reverse emulsion comprises: a continuous phase of silicone oil; and a dispersed phase of water, glycerol, or a combination thereof. or The reverse emulsion comprises: a continuous phase of silicone oil; a dispersed phase of water, glycerol, or a combination thereof; and a surfactant. The silicone oil is composed of polydimethylsiloxane, or the silicone oil is composed of a blend of polymethylphenylsiloxane and polydimethylsiloxane in a weight fraction of 0.1 to 0.9 wt%, or a blend of polydimethylsiloxane and polymethylphenylsiloxane in a weight fraction of 0.1 to 0.9 wt%.

2. The support material according to claim 1, wherein the silicone oil has a viscosity of 5 cSt to 1000 cSt.

3. The support material according to claim 1, wherein the dispersed phase and the continuous phase comprise matched refractive indices.

4. The support material according to claim 3, wherein the support material is optically transparent.

5. The support material according to claim 1, wherein the reverse emulsion comprises the dispersed phase having a volume fraction of 0.64 to 0.

85.

6. The support material according to claim 1, wherein the surfactant comprises cyclopentasiloxane and polydimethylsiloxane copolyol, polydimethylsiloxane and polydimethylsiloxane copolyol, lauryl polymethylsiloxane copolyol, polydimethylsiloxane copolyol and at least one C10-C16 isoalkane, cyclopentasiloxane and polydimethylsiloxane copolyol crosspolymer, alkyl polydimethylsiloxane copolyol, siloxane glycerol emulsifier or combinations thereof.

7. The support material according to claim 1, wherein the reverse emulsion comprises a yield stress of 0.1 Pa to 100 Pa.

8. The support material according to claim 1, wherein the dispersed phase comprises glycerol:water in a ratio of 50:50 to 51:

49.

9. A method for 3D printing soft materials, the method comprising injecting polysiloxane ink into a support material according to any one of claims 1-8.

10. The method of claim 9, wherein when the ink comprises polydimethylsiloxane, the continuous phase comprises polymethylphenylsiloxane as a principal component, or when the ink comprises polymethylphenylsiloxane, the continuous phase comprises polydimethylsiloxane as a principal component.

11. The method of claim 10, wherein the ink is UV-curable.

12. The method according to any one of claims 9-11, wherein the ink is injected into the support material at a deposition rate of 10 to 10,000 μL / h, and / or wherein the ink is injected into the support material at a translational speed of 0.01 to 20 mm / s, and / or wherein the interfacial tension between the support material and the ink is 0.1 mN / m to 10 mN / m.

13. An application of a support material for 3D printing a soft material comprising polysiloxane onto the support material using the method according to any one of claims 9-12, the support material comprising a reverse emulsion. The reverse emulsion comprises: a continuous phase of silicone oil; and a dispersed phase of water, glycerol, or a combination thereof; or The reverse emulsion comprises: a continuous phase of silicone oil; a dispersed phase of water, glycerol, or a combination thereof; and a surfactant. The support material described herein is the support material according to any one of claims 1-8.

14. An article comprising a soft matter produced by the method according to any one of claims 9-12, wherein the soft matter comprises a minimum stable feature size of 4 μm to 80 μm.

15. The article of claim 14, wherein the article comprises a surface roughness of less than 150 nm.

16. The article of claim 14, wherein the article of claim 14 comprises a model organ.

17. The article of claim 14, wherein the article comprises a trilobed heart valve, an ear accessory for a hearing aid, a nasal accessory for respiratory assistance, a nasal accessory for a sleep apnea device, a custom-made vascular implant, or a custom-made ostomy seal.

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