Compositions for use in 3D printing

Abstract

In one aspect, compositions for use with a 3D printer are described herein. In some embodiments, a composition described herein comprises a first monomeric component comprising a first functional group in a total amount of m molar equivalents and a second monomeric component comprising a second functional group in a total amount of n molar equivalents. In some implementations, the ratio of m to n « is between 3 :2 and 2:1. Further, in some cases, the first functional group is a cyclic carbonate. Additionally, the first functional group and the second functional group can be polymerizable with one another.

Description

COMPOSITIONS FOR USE IN 3D PRINTING CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority pursuant to 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 63 / 695,965, filed September 18, 2024, which is hereby incorporated by reference in its entirety. FIELD

[0002] The present invention relates to compositions for use with three-dimensional (3D) printing systems. BACKGROUND

[0003] Some commercially available 3D printers, such as the ProJetTM3D Printers manufactured by 3D Systems of Rock Hill, South Carolina, use inks, which are also known as build materials, that are jetted through a print head as a liquid to form various 3D objects, articles, or parts. Other 3D printing systems also use an ink that is jetted through a print head or otherwise dispensed onto a substrate. In some instances, the ink is solid at ambient temperatures and converts to liquid at elevated jetting temperatures. In other instances, the ink is liquid at ambient temperatures. Moreover, in some cases, the ink can be cured following dispensing and / or deposition of the ink onto the substrate.

[0004] Other 3D printers form 3D articles from a reservoir, vat, or container of a fluid ink or build material or a powdered ink or build material. In some cases, a binder material or a laser, digital light processing (DLP) source, or other source of energy is used to selectively solidify or consolidate layers of the ink or build material in a stepwise or layer-by-layer fashion to provide the 3D article.

[0005] Inks for 3D printing systems can be used to form a variety of articles for a variety of applications, including in a manner described hereinabove. However, some inks for 3D printing systems include (meth)acrylates as a primary curable material. Such inks may provide high printing resolution but may provide printed 3D articles having limited toughness. Other inks may provide both high resolution and high toughness but may suffer from the presence of one or 1 PCT.798more toxic or non-biocompatible materials. Therefore, there exists a need for improved inks for 3D printing, including inks that can provide a combination of desirable properties. SUMMARY

[0006] In one aspect, compositions for use with a 3D printer are described herein which, in some embodiments, may offer one or more advantages over prior compositions. In some embodiments, for example, a composition described herein can be used as an ink or build material for a 3D printing system, and the resulting printed 3D article can have improved mechanical properties, such as improved toughness. Such an ink might be particularly useful for a 3D printing system, such as a contacting stereolithography (cSLA) printing system or other stereolithography (SLA) printing system, in which the components of the ink (e.g., a first monomeric component described herein and a second monomeric component described herein) are combined under conditions (e.g., time and temperature conditions) that are not sufficient for substantial reaction between the relevant components to occur prior to printing.

[0007] Alternatively, as described further hereinbelow, 3D printing may be carried out using a plurality of inks, wherein a first ink comprises a first monomeric component described herein, and a second ink comprises a second monomeric component described herein. Such a dual ink system may be particularly useful for a 3D printing system, such as a multi-jet modeling (MJM) system, in which it may be desirable not to combine the relevant monomers or curable materials prior to printing.

[0008] In some implementations, a composition described herein comprises (1) a first monomeric component comprising a first functional group in a total amount of m molar equivalents and also (2) a second monomeric component comprising a second functional group in a total amount of n molar equivalents, wherein the first monomeric component and the second monomeric component differ from one another. In some implementations, the ratio of m to n is between 3:2 and 2:1. Additionally, in some cases, the first functional group and the second functional group are polymerizable with one another. Moreover, in some embodiments, the first functional group is a cyclic carbonate. Further, in some such cases, the second functional group is an amine, thiol, or hydroxyl moiety or functional group.

[0009] It is further to be understood that, in some embodiments, the first monomeric component of a composition described herein can comprise a plurality of first functional groups, 2 PCT.798such as a plurality of cyclic carbonate functional groups. For example, in some cases, the first monomeric component can comprise at least two cyclic carbonate moieties per molecule or at least three cyclic carbonate moieties per molecule. Moreover, in some implementations, the second monomeric component can comprise a plurality of second functional groups. For example, the second monomeric component can comprise at least two second functional groups per molecule or at least three second functional groups per molecule (e.g., at least two or at least three amine, thiol, or hydroxyl functional groups).

[0010] In addition, in some instances, a composition (or ink) described herein further comprises one or more curable materials or monomers other than the first monomeric component and the second monomeric component. For example, in some embodiments, a composition (or ink) further comprises an ethylenically unsaturated monomer, such as a (meth)acrylate monomer. In some cases, an ethylenically unsaturated monomer described herein can be polymerized separately from the first monomeric component and the second monomeric component of the composition (or ink). For instance, the first monomeric component and the second monomeric component of the composition (or ink) can react with one another to form a first polymer network, and (meth)acrylate monomers (or other additional curable material) of the composition (or ink) can react with one another to form a second polymer network. In such cases, the first and second polymer networks can be separate or differing polymer networks. Additionally, in some embodiments, the first and second polymer networks can together form an interpenetrating polymer network. Moreover, the first and second polymer networks can be formed through differing polymerization processes.

[0011] As described hereinabove, 3D printing may be carried out according to the present disclosure using a single composition or ink capable of forming a polymer or oligomer from a first monomeric component and a second monomeric component, or using a combination of differing inks that, when combined, are capable of forming a polymer or oligomer from a first monomeric component and a second monomeric component. Thus, in another aspect, kits for use in a 3D printing system are described herein. In some embodiments, such a kit comprises a first ink comprising a first monomeric component and a second ink comprising a second monomeric component. Moreover, in some such instances, the first ink further comprises an ethylenically unsaturated monomer, such as a (meth)acrylate. 3 PCT.798

[0012] It is to be understood that inks described herein, whether “single” inks or inks that are part of a kit, may further comprise one or more additional components in addition to curable materials described hereinabove. For example, in some embodiments, an ink described herein further comprises one or more additives selected from the group consisting of colorants, inhibitors, stabilizing agents, photoinitiators, and photosensitizers.

[0013] In another aspect, uses of a composition for 3D printing are described herein, wherein the composition comprises an ink or kit described hereinabove. For instance, in some cases, a use of a composition for 3D printing is described herein, wherein the composition comprises an ink comprising a first monomeric component and a second monomeric component.

[0014] In still another aspect, 3D printing systems are described herein. Such a 3D printing system can comprise a composition for 3D printing described hereinabove, such as a composition comprising an ink or kit described hereinabove. In some embodiments, a 3D printing system described herein comprises a 3D printer having at least one ink dispenser or ink reservoir, and a composition described herein disposed in the ink dispenser or the ink reservoir. The composition can comprise any ink described herein for use in 3D printing. For example, in some cases, a 3D printing system described herein comprises a 3D printer having at least one of an ink dispenser and an ink reservoir, and an ink disposed in the ink dispenser, the ink reservoir, or both, wherein the ink comprises a first monomeric component as described above. Moreover, in some instances, such a 3D printer further comprises a second ink dispenser or reservoir and a second ink disposed in the second ink dispenser or reservoir, wherein the second ink comprises a second monomeric component as described above.

[0015] In another aspect, methods of printing a 3D article are described herein, wherein the method is carried out using one or more compositions or inks described herein. In some cases, such a method comprises selectively jetting or otherwise depositing layers of an ink in a fluid state onto a substrate, wherein the ink comprises a first monomeric component and a second monomeric component described herein. Additionally, in some cases, the layers of the ink are deposited in a layer-by-layer manner according to an image of the 3D article in a computer readable or digital format. Moreover, in some embodiments, a method described herein further comprises curing, reacting, or polymerizing the first monomeric component and the second monomeric component. Such curing, reacting, or polymerizing may be carried out in a layer-by- layer manner during the printing process, or in a “post-processing” step, such as a curing step 4 PCT.798carried out after completion of printing of all layers of the article. Further, whenever in the process it occurs, such curing, reacting, or polymerizing can comprise reacting the first monomeric component and the second monomeric component to form a first polymer (such as a polyurethane in the case of a cyclic carbonate and an amine). Moreover, in some instances, an ink used in a method described herein comprises one or more (meth)acrylates and the method further comprises curing, reacting, or polymerizing the (meth)acrylates with electromagnetic radiation, such as ultraviolet (UV) light or visible light. Such curing, reacting, or polymerizing can comprise polymerizing the ethylenically unsaturated moieties of the (meth)acrylates to form a poly(meth)acrylate. Additionally, in some cases, as described further herein, the poly(meth)acrylate and the first polymer (e.g., the polyurethane) can together form an interpenetrating polymer network.

[0016] As described above, a method of printing a 3D article described herein can be carried out using a plurality of inks rather than one ink described herein. Such a method, in some cases, comprises selectively depositing layers of a first ink in a fluid state onto a substrate, and selectively depositing layers of a second ink in a fluid state onto the substrate, wherein the first ink and the second ink comprise a first ink and a second ink, respectively, of a kit described herein. In particular, the first ink can comprise a first monomeric component described herein, and the second ink can comprise a second monomeric component described herein. In addition, in some embodiments, the first ink comprises one or more (meth)acrylates and the method further comprises photocuring the one or more (meth)acrylates, such as with UV light. Such curing can comprise polymerizing the ethylenically unsaturated moieties of the (meth)acrylates to form a poly(meth)acrylate. A method described herein may further comprise curing the first monomeric component of the first ink and the second monomeric component of the second ink, such as by thermally curing, reacting, or polymerizing these monomers.

[0017] Further, in still other embodiments, a method of printing a 3D article described herein does not necessarily comprise jetting or otherwise depositing a composition or ink described herein onto a substrate according to digital data representing the 3D article. Instead, in some cases, a method of printing a 3D article described herein comprises retaining a composition or ink in a fluid state in a container, and selectively applying energy to the composition or ink in the container to solidify at least a portion of a first fluid layer of the composition or ink, thereby forming a first solidified layer that defines a first cross-section of the article. The composition or 5 PCT.798ink can comprise any composition or ink described hereinabove. Moreover, such a method can further comprise raising or lowering the first solidified layer to provide a second fluid layer of the composition or ink at a surface of the fluid composition or ink in the container, and selectively applying energy to the composition or ink in the container to solidify at least a portion of the second fluid layer of the composition or ink, thereby forming a second solidified layer that defines a second cross-section of the article. The first cross-section and the second cross-section are bonded to one another (or “stacked” on top of each other) in a z-direction.

[0018] In another aspect, printed 3D articles are described herein. Such articles can be formed from one or more compositions or inks and / or using one or more methods described hereinabove.

[0019] These and other embodiments are described in greater detail in the detailed description which follows. DETAILED DESCRIPTION

[0020] Embodiments described herein can be understood more readily by reference to the following detailed description and examples. Elements, apparatus and methods described herein, however, are not limited to the specific embodiments presented in the detailed description, and examples. It should be recognized that these embodiments are merely illustrative of the principles of the present disclosure. Numerous modifications and adaptations will be readily apparent to those of skill in the art without departing from the spirit and scope of the disclosure.

[0021] In addition, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1.0 to 10.0” should be considered to include any and all subranges beginning with a minimum value of 1.0 or more and ending with a maximum value of 10.0 or less, e.g., 1.0 to 5.3, 1 to 4, 3 to 7, 4.7 to 10.0, 3.6 to 7.9, or 5 to 8.

[0022] All ranges disclosed herein are also to be considered to include the end points of the range, unless expressly stated otherwise. For example, a range of “between 5 and 10,” “from 5 to 10,” or “5-10” should generally be considered to include the end points 5 and 10.

[0023] Further, when the phrase “up to” is used in connection with an amount or quantity, it is to be understood that the amount is at least a detectable amount or quantity (that is, the amount is a non-zero amount). For example, a material present in an amount “up to” a specified amount 6 PCT.798can be present from a detectable (or non-zero) amount and up to and including the specified amount.

[0024] Additionally, in any disclosed embodiment, the terms “substantially,” “approximately,” and “about” may be substituted with “within [a percentage] of” what is specified, where the percentage includes 0.1, 1, 5, and 10 percent.

[0025] It is also to be understood that the article “a” or “an” refers to “at least one,” unless the context of a particular use requires otherwise.

[0026] The terms “three-dimensional printing system,” “three-dimensional printer,” “printing,” and the like generally describe various solid freeform fabrication techniques for making three-dimensional articles or objects by stereolithography, digital light processing, selective deposition, jetting, fused deposition modeling, multi-jet modeling, and other additive manufacturing techniques now known in the art or that may be known in the future that use a build material or ink to fabricate three-dimensional objects. I. Compositions for 3D Printing

[0027] In one aspect, compositions for use with a 3D printer are described herein. In some embodiments, a composition described herein comprises a first monomeric component comprising a first functional group in a total amount of m molar equivalents and a second monomeric component comprising a second functional group in a total amount of n molar equivalents. That is, the first functional group is present in an amount of m molar equivalents, and the second functional group is present in a total amount of n molar equivalents. For example, in some implementations, there are 3 molar equivalents of the first functional group and 2 molar equivalents of the second functional group (that is, m = 3 and n = 2), such as may occur when the first monomeric component comprises exactly 3 of the first functional groups, and the second monomeric component comprises exactly 2 of the second functional group. In some embodiments, the first functional group is a cyclic carbonate. Moreover, in some cases, the first functional group and the second functional group are polymerizable with one another. In some implementations, the ratio of m to n is between 3:2 and 2:1.

[0028] Turning now in detail to specific components of compositions described herein, in some cases, compositions described herein comprise a first monomeric component comprising a first functional group, wherein the first functional group is a cyclic carbonate. For reference 7 PCT.798purposes herein, it is to be understood that a “monomeric component” is a chemical species (e.g., a “monomeric” or “monomer” curable material described further hereinbelow with reference to relatively low molecular weight or relatively low viscosity) having one or more functional groups or moieties that can react with one another or with another functional group or moiety to form one or more covalent bonds, particularly as part of a polymerization reaction. In some embodiments, the first monomeric component can comprise a plurality of the moiety of the first functional group. That is, in some cases, the first monomeric component can comprise a plurality of the cyclic carbonate functional groups. For example, in some embodiments, the first monomeric component can comprise at least two cyclic carbonate moieties per molecule or at least three cyclic carbonate moieties per molecule.

[0029] Any cyclic carbonate species not inconsistent with the technical objectives of the present disclosure may be used. In some cases, the cyclic carbonate-containing monomer has the structure of Formula (A1), Formula (A2), Formula (A3), or Formula (A4): ,8 PCT.7984), ear or branched C1-C36 alkyl or alkylene, alkenyl or alkenylene, aryl or arylene, or heteroaryl or heteroarylene moiety. For example, in some cases, R1is (CH2)4, and R2and R3are each CH2in the structure of Formula (A2).

[0030] Moreover, in some instances, the cyclic carbonate monomer has the structure of Formula (A5): 9 PCT.7985), ate monomer of an ink described herein may also have the structure of Formula (A6): O .monomer has the structure of Formula(A7), Formula (A8), or Formula (A9): ,OC HNR5HN COWherein each m is independently an integer from 1 to 36, and R5is a linear or branched C2-C36 alkyl or alkylene, alkenyl or alkenylene, aryl or arylene, or heteroaryl or heteroarylene moiety. In some embodiments, for instance, R5is (CH2)6.

[0032] In some instances, the cyclic carbonate monomer has the structure of Formula (A10), Formula (A11), Formula (A12), or Formula (A13): 11 PCT.7983), alkenyl or alkenylene, aryl or arylene, or heteroaryl or heteroarylene moiety, and R5is a linear or branched C2-C36 alkyl or alkylene, alkenyl or alkenylene, aryl or arylene, or heteroaryl or heteroarylene moiety. In some embodiments, for instance, R1is (CH2)1-10, such as (CH2)8, R2is (CH2) or (CH2)2, R3is (CH2) or (CH2)2, and R5is (CH2)6or (C6H4)-C(Me)2-(C6H4).

[0033] Cyclic carbonate monomers such as the foregoing may be commercially available (for example, from SPECIFIC POLYMERS, as in the case of monomers having the structure of Formula (A2) or Formula (A6), for instance), or may be obtained by reacting a first chemical species comprising a hydroxyl moiety and a cyclic carbonate moiety with a second chemical 12 PCT.798species comprising one or more isocyanate moieties. In this manner, one or more cyclic carbonate moieties of the first chemical species may be bonded to the second chemical species through the formation of one or more urethane bonds, such as the urethane bonds of the structures of Formula (A7), Formula (A8), and Formula (A9) above. Cyclic carbonate monomers, such as those having the structures of Formula (A10), Formula (A11), and Formula (A12), may also be formed as described in U.S. Patent 3,072,613. For instance, a cyclic carbonate monomer having the structure of Formula (A10) in which R2and R3are both CH2can be formed by the reaction of diglyercol with diethyl carbonate, including using a basic catalyst. Similarly, a cyclic carbonate monomer having the structure of Formula (A12), such as a structure in which R2and R3are both CH2and R1is a bisphenolic alkane residue (e.g., (C6H4)-C(Me)2- (C6H4)), may be formed by an addition reaction of carbon dioxide to diglycidyl compounds.

[0034] Additionally, in some embodiments described herein, a cyclic carbonate-containing monomer can include one or more other curable or polymerizable moieties, in addition to the cyclic carbonate moieties of the monomer. For instance, in some cases, the cyclic carbonate- containing monomer comprises one or more ethylenically unsaturated moieties, such as one or more (meth)acrylate moieties. In some embodiments, the cyclic carbonate monomer of an ink described herein has the structure of Formula (A14):13 PCT.798wherein each m is independently an integer from 1 to 36; R1is a linear or branched C1-C36 alkyl or alkylene, alkenyl or alkenylene, aryl or arylene, or heteroaryl or heteroarylene moiety; and R6is H or CH3. For example, in some cases, each m is 6, R1is CH2CH2, and R6is CH3.

[0035] Other cyclic carbonate-containing monomers may also be used in composition or ink described herein. It is further to be understood that a first monomeric component of a composition or ink described herein can comprise only one chemical species or a plurality of differing chemical species. For example, in some cases, the first monomeric component of a composition or ink described herein comprises a plurality of differing cyclic carbonate- containing species, such as those described above as (A1) through (A14).

[0036] Moreover, the first monomeric component, in total, can be present in a composition or ink in any amount not inconsistent with the objectives of the present disclosure. For example, in some cases, a composition or ink described herein comprises up to 70 wt. %, up to 60 wt. %, up to 50 wt. %, up to 40 wt. %, or up to 30 wt. % first monomeric component, based on the total weight of the composition or ink. In some instances, a composition or ink comprises 10-70 wt. %, 10-60 wt. %, 10-50 wt. %, 10-40 wt. %, 10-30 wt. %, 20-60 wt. %, 20-50 wt. %, 30-70 wt. %, 30-60 wt. %, 30-50 wt. %, 40-70 wt. %, 40-60 wt. % first monomeric component, based on the total weight of the composition or ink.

[0037] Turning now to the second monomeric component of compositions described herein, any second monomeric component not inconsistent with the technical objectives of the present disclosure may be used. In some implementations, the second monomeric component can comprise a plurality of second functional groups. For example, the second monomeric component can comprise at least two second functional groups per molecule or at least three second functional groups per molecule. Moreover, the second functional group may be any species or moiety not inconsistent with the objectives of the present disclosure. For example, in some implementations, the second functional group comprises an amine group. In some cases, the second functional group comprises a thiol group. In some embodiments, the second functional group comprises a hydroxyl group.

[0038] As stated above, in some implementations, the second functional group comprises an amine group. Any amine-containing monomer not inconsistent with the objectives of the present disclosure may be used. For example, in some cases, the amine-containing monomer comprises only one amine moiety or functional group per molecule. In other cases, the amine-containing 14 PCT.798monomer comprises a plurality of amine moieties, such as two amine moieties or more than two amine moieties. In some instances, the amine-containing monomer is an α,ω-diamine such as an amine monomer having the structure of Formula (B1): (B1), alkyl or alkylene, aryl or arylene, or heteroaryl or

[0039] An amine-containing monomer described herein may also comprise at least one secondary or tertiary amine moiety. Cyclic amine-containing monomers are also possible. Other amine monomers may also be used in a composition or ink described herein.

[0040] In some embodiments, as stated above, the second functional group of the second monomeric species of a composition described herein comprises a thiol group. Any thiol- containing monomer not inconsistent with the objectives of the present disclosure may be used. For example, in some cases, the thiol-containing monomer comprises only one thiol group per molecule. Alternatively, in other instances, the thiol-containing monomer comprises a plurality of thiol moieties, such as two thiol moieties or more than two thiol moieties. In some instances, the thiol-containing monomer is an α,ω-dithiol.

[0041] A thiol-containing monomer described herein may also comprise at least one secondary or tertiary thiol moiety. Other thiol-containing monomers may also be used in a composition or ink described herein.

[0042] Additionally, in some embodiments, as stated above, the second functional group of the second monomeric species of a composition described herein comprises a hydroxyl group. Any hydroxyl-containing monomer not inconsistent with the objectives of the present disclosure may be used. For example, in some cases, the hydroxyl-containing monomer comprises only one hydroxyl group per molecule. Alternatively, in other instances, the hydroxyl-containing monomer comprises a plurality of hydroxyl moieties, such as two hydroxyl moieties or more than two hydroxyl moieties. In some instances, the hydroxyl-containing monomer is an α,ω-diol.

[0043] A hydroxyl-containing monomer described herein may also comprise at least one secondary or tertiary hydroxyl moiety. Other hydroxyl-containing monomers may also be used in a composition or ink described herein.

[0044] It is further to be understood that a second monomeric component of a composition or ink described herein can comprise only one chemical species or a plurality of differing chemical 15 PCT.798species. For example, in some cases, the second monomeric component of an ink described herein comprises a plurality of differing amine species, a plurality of differing thiol species, a plurality of differing hydroxyl species, or a combination of amine species and thiol species, a combination of amine species and hydroxyl species, a combination of hydroxyl species and thiol species, or a combination of amine, hydroxyl, and thiol species.

[0045] Moreover, the second monomeric component, in total, can be present in a composition or ink in any amount not inconsistent with the technical objectives of the present disclosure. For example, in some cases, a composition or ink described herein comprises up to 70 wt. %, up to 60 wt. %, up to 50 wt. %, up to 40 wt. %, or up to 30 wt. % second monomeric component, based on the total weight of the composition or ink. In some instances, a composition or ink comprises 10-70 wt. %, 10-60 wt. %, 10-50 wt. %, 10-40 wt. %, 10-30 wt. %, 20-60 wt. %, 20- 50 wt. %, 30-70 wt. %, 30-60 wt. %, 30-50 wt. %, 40-70 wt. %, 40-60 wt. % second monomeric component, based on the total weight of the composition or ink.

[0046] As stated above, the first functional group of a first monomeric component described herein and the second functional group of a second monomeric component described herein can be polymerizable with one another. As understood by one of ordinary skill in the art, a polymerization reaction used to polymerize or cure a polymerizable functional group described herein can comprise a reaction of a plurality of “monomers” or chemical species having one or more functional groups or moieties that can react with one another to form one or more covalent bonds (in this usage in the context of polymerization in general, the “monomers” may be relatively low molecular weight or relatively high molecular weight). Such polymerizing between the polymerizable moieties of the first monomeric component and second monomeric component can be carried out in any manner not inconsistent with the objectives of the present disclosure. In some embodiments, for example, polymerizing comprises irradiating the composition with electromagnetic radiation having sufficient energy to initiate a polymerization or cross-linking reaction. For instance, in some cases, UV radiation can be used. In some embodiments, the first functional group and the second functional group described herein are photo-polymerizable or photo-curable at wavelengths ranging from about 300 nm to about 400 nm or from about 320 nm to about 380 nm. Alternatively, in other instances, the first functional group and the second functional group described herein are photo-polymerizable at visible wavelengths of the electromagnetic spectrum, such as wavelengths ranging from 450 nm to 650 16 PCT.798nm. Moreover, in some cases, the polymerization reaction between the first functional group and the second functional group described herein comprises a free radical polymerization reaction, such as that between points of unsaturation, including points of ethylenic unsaturation.

[0047] Thermal curing or polymerization can also be used. Thus, in some cases, polymerizing comprises heating the composition to initiate polymerization. Other polymerization reactions may also be used.

[0048] As stated above, the first functional group can be present in a total amount of m molar equivalents and the second functional group can be present in a total amount of n molar equivalents. It is to be understood that, in some implementations, the total amount of the first functional group, that is, the m molar equivalents, is present in an amount that is greater than the total amount of the second functional group, that is, the n molar equivalents. In some preferred embodiments, the ratio of m to n is between 3:2 and 2:1. In some instances, the ratio of m to n is between 1.6:1 and 2:1 or 1.8:1 and 2:1. In some implementations, the ratio of m to n is 3:2. In some cases, the ratio of m to n is 2:1. In some cases, the ratio of m to n is between 1:1 and 3:2. However, in some embodiments, the ratio of m to n is not less than 1:1. It is also to be understood that, in some preferred embodiments, upon polymerization, the second functional group reacts with the first functional group completely. That is, no unreacted second functional groups remain. However, in some cases, upon polymerization, some of the moieties of the first functional group (e.g., the cyclic carbonate), remain “free” or unreacted. In some such embodiments, the percentage of “free” or unreacted first functional groups is 40%, 50%, 60%, or 70% of the total amount of the first functional group (that is, the named percentage of the m molar equivalents of the first functional group). Not intending to be bound by theory, it is believed that such ratios of first and second functional groups can provide improved mechanical properties to a 3D article formed from a composition or kit described herein.

[0049] Moreover, compositions described herein may also comprise additional components. In some embodiments, for example, a composition or ink described herein further comprises an additional curable material or monomer, other than the first monomeric component and the second monomeric component described above. Moreover, in some cases, the additional curable monomer can be polymerized separately from the first monomeric component and the second monomeric component of the composition or ink. 17 PCT.798

[0050] One non-limiting example of a curable or polymerizable moiety of an additional curable material or monomer described herein is an ethylenically unsaturated moiety, such as a vinyl moiety, allyl moiety, or (meth)acrylate moiety, where the term “(meth)acrylate” includes acrylate or methacrylate or a mixture or combination thereof. Additionally, in some cases, a (meth)acrylate comprises a (meth)acrylate monomer, a (meth)acrylate oligomer, or a mixture thereof. Thus, in some embodiments, the additional curable monomer of a composition or ink described herein comprises a (meth)acrylate.

[0051] Further, a (meth)acrylate monomer and / or a (meth)acrylate oligomer described herein can comprise a monofunctional, difunctional, trifunctional, tetrafunctional, pentafunctional, or higher functional (meth)acrylate species. A “monofunctional” (meth)acrylate species, for reference purposes herein, comprises a chemical species that includes one (meth)acrylate moiety. Similarly, a “difunctional” (meth)acrylate species comprises a chemical species that includes two (meth)acrylate moieties; a “trifunctional” (meth)acrylate species comprises a chemical species that includes three (meth)acrylate moieties; a “tetrafunctional” (meth)acrylate species comprises a chemical species that includes four (meth)acrylate moieties; and a “pentafunctional” (meth)acrylate species comprises a chemical species that includes five (meth)acrylate moieties. Thus, in some embodiments, a monofunctional (meth)acrylate component of a composition described herein comprises a mono(meth)acrylate, a difunctional (meth)acrylate component of a composition described herein comprises a di(meth)acrylate, a trifunctional (meth)acrylate component of a composition described herein comprises a tri(meth)acrylate, a tetrafunctional (meth)acrylate component of a composition described herein comprises a tetra(meth)acrylate, and a pentafunctional (meth)acrylate component of a composition described herein comprises a penta(meth)acrylate. Other (meth)acrylate species may also be used.

[0052] Moreover, a (meth)acrylate species (such as a monofunctional, difunctional, trifunctional, tetrafunctional, or pentafunctional (meth)acrylate species), in some cases, can comprise or be a relatively low molecular weight species, i.e., a (meth)acrylate “monomer” (such as a species having a molecular weight below 300, below 200, or below 100), or a relatively high molecular weight species, i.e., a (meth)acrylate “oligomer” (such as a species having a molecular weight above 300, above 400, above 500, or above 600, and optionally below 10,000, where it is understood that the molecular weight may be a weight average molecular weight in the case of an oligomeric species having a molecular weight distribution). In some preferred embodiments, a 18 PCT.798“monomer” has a molecular weight below 400, and an “oligomer” has a weight average molecular weight above 600. Additionally, in some embodiments, a (meth)acrylate “monomer” has a viscosity of 500 centipoise (cP) or less at 25°C, when measured according to ASTM D2983, while a (meth)acrylate “oligomer” has a viscosity of 1000 cP or more at 25°C, when measured according to ASTM D2983. It is to be understood that the foregoing use of the terms “monomer” and “oligomer” are intended to distinguish between ‘types’ of curable materials or species—those having relatively high molecular weight / viscosity as one ‘type,’ and those having relatively low molecular weight / viscosity as the other ‘type.’ In this context, the terms “monomer” and “oligomer” may both be used to refer to a curable material, particularly a curable material that can undergo polymerization with itself or another species. That is, in this context, either a “monomer” (relatively low molecular weight / viscosity species) or an “oligomer” (relatively high molecular weight / viscosity species) can be a “monomer” in the generic sense of being a chemical species having one or more functional groups or moieties that can react with one another or with another functional group or moiety to form one or more covalent bonds, particularly as part of a polymerization reaction. It is further to be understood that the preceding descriptions of “monomer” versus “oligomer” may be applied to other curable materials that are not (meth)acrylates. That is, in general, a “monomer” component may be distinguished from an “oligomer” component based on the molecular weight and / or viscosity ‘dividing lines’ or ranges described above. The meaning of the terms “monomer,” “monomeric,” “oligomer,” and “oligomeric” in a specific instance or usage will be readily understood by one of ordinary skill in the art based on the context. However, in the event of any ambiguity in a particular instance, the broader meaning of “monomer” or “monomeric” is to be adopted for purposes of the present disclosure. Additionally, for purposes of disclosure of possible embodiments, it is to be understood that any specific use of “monomer” or “monomeric” described herein can be read to possibly refer to a “monomer” or “monomeric” species in the more limited meaning described above (a species having a relatively low molecular weight and / or viscosity).

[0053] In general, any (meth)acrylate component not inconsistent with the objectives of the present disclosure may be used in a composition described herein. In some embodiments, for instance, a (meth)acrylate component comprises methyl (meth)acrylate, ethyl (meth)acrylate, n- propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2- 19 PCT.798ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 2- methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2- or 3-ethoxypropyl (meth)acrylate, tetrahydrofurfuryl methacrylate, isobornyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, cyclohexyl methacrylate, 2-phenoxyethyl acrylate, glycidyl acrylate, isodecyl acrylate, 2- phenoxyethyl (meth)acrylate, lauryl methacrylate, or a combination thereof. In some embodiments, a (meth)acrylate component comprises one or more of allyl acrylate, allyl methacrylate, triethylene glycol di(meth)acrylate, tricyclodecane dimethanol diacrylate, and cyclohexane dimethanol diacrylate. Additionally, in some cases, a (meth)acrylate component comprises diacrylate and / or dimethacrylate esters of aliphatic, cycloaliphatic or aromatic diols, including 1,3- or 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, 1,4-dihydroxymethylcyclohexane, 2,2-bis(4- hydroxycyclohexyl)propane or bis(4-hydroxycyclohexyl)methane, hydroquinone, 4,4'- dihydroxybiphenyl, bisphenol A, bisphenol F, or bisphenol S. A (meth)acrylate component described herein may also comprise 1,1-trimethylolpropane tri(meth)acrylate, pentaerythritol monohydroxy tri(meth)acrylate, dipentaerythritol monohydroxy penta(meth)acrylate, and / or bis(trimethylolpropane) tetra(meth)acrylate. Further, in some cases, a (meth)acrylate component can comprise an ethoxylated or propoxylated species, such as ethoxylated or propoxylated neopentyl glycol, ethoxylated or propoxylated bisphenol A, ethoxylated or propoxylated bisphenol F, ethoxylated or propoxylated bisphenol S, ethoxylated or propoxylated 1,1,1- trimethylolpropanetri(meth)acrylate, or ethoxylated or propoxylated glycerol tri(meth)acrylate.

[0054] Additional non-limiting examples of commercially available (meth)acrylate components useful in some embodiments described herein include the following: isobornyl acrylate (IBOA), commercially available from SARTOMER under the trade name SR 506; isobornyl methacrylate, commercially available from SARTOMER under the trade name SR 423A; triethylene glycol diacrylate, commercially available from SARTOMER under the trade name SR 272; triethylene glycol dimethacrylate, commercially available from SARTOMER under the trade name SR 205; tricyclodecane dimethanol diacrylate, commercially available from SARTOMER under the trade name SR 833S; tris(2-hydroxy ethyl)isocyanurate triacrylate, commercially available from SARTOMER under the trade name SR 368; 2-phenoxyethyl acrylate, commercially available from SARTOMER under the trade name SR 339; ethyoxylated 20 PCT.798(3 mole) bisphenol A diacrylate, commercially available from SARTOMER under the trade name SR 349; and dipentaerythritol pentaacrylate, commercially available from SARTOMER under the trade name SR 399 LV. Other commercially available (meth)acrylate components may also be used.

[0055] In addition, any (meth)acrylate oligomer not inconsistent with the objectives of the present disclosure may be used in a composition described herein. In some cases, for instance, the (meth)acrylate oligomer comprises a polyester (meth)acrylate oligomer, a urethane (meth)acrylate oligomer, or an epoxy(meth)acrylate oligomer. Further, in some embodiments, a (meth)acrylate oligomer described herein comprises an aliphatic polyester urethane acrylate oligomer and / or an acrylate amine oligomeric resin, such as EBECRYL 7100. In some cases, a (meth)acrylate oligomer material described herein comprises a polypropylene glycol mono(meth)acrylate or polyethylene glycol mono(meth)acrylate. In some embodiments, a (meth)acrylate oligomer comprises a monofunctional aliphatic urethane (meth)acrylate. Moreover, in some cases, a (meth)acrylate oligomer comprises a diacrylate and / or dimethacrylate ester of an aliphatic, cycloaliphatic or aromatic diol, including polyethylene glycol, ethoxylated or propoxylated neopentyl glycol, ethoxylated or propoxylated bisphenol A, ethoxylated or propoxylated bisphenol F, ethoxylated or propoxylated bisphenol S, ethoxylated or propoxylated 1,1,1-trimethylolpropanetri(meth)acrylate, or ethoxylated or propoxylated glycerol tri(meth)acrylate.

[0056] Some non-limiting examples of commercially available (meth)acrylate oligomers useful in some embodiments described herein include the following: alkoxylated tetrahydrofurfuryl acrylate, commercially available from SARTOMER under the trade name SR 611; monofunctional urethane acrylate, commercially available from RAHN USA under the trade name GENOMER 1122; and aliphatic urethane diacrylate, commercially available from ALLNEX under the trade name EBECRYL 8402. Other commercially available (meth)acrylate oligomer may also be used.

[0057] Urethane (meth)acrylates suitable for use in compositions described herein, in some cases, can be prepared in a known manner, typically by reacting a hydroxyl-terminated urethane with acrylic acid or methacrylic acid to give the corresponding urethane (meth)acrylate, or by reacting an isocyanate-terminated prepolymer with hydroxyalkyl acrylates or methacrylates to give the urethane (meth)acrylate. Suitable processes are disclosed, inter alia, in EP 114982 and 21 PCT.798EP 133908. The weight average molecular weight of such (meth)acrylate oligomers, in some cases, can be from about 400 to 10,000 or from about 500 to 7,000. Urethane (meth)acrylates are also commercially available from SARTOMER under the product names CN980, CN981, CN975 and CN2901, or from BOMAR Specialties Co. under the product name BR-741. In some embodiments described herein, a urethane (meth)acrylate oligomer has a viscosity ranging from about 140,000 centipoise (cP) to about 160,000 cP at about 50°C or from about 125,000 cP to about 175,000 cP at about 50°C when measured in a manner consistent with ASTM D2983. In some cases, a urethane (meth)acrylate oligomer has a viscosity ranging from about 100,000 cP to about 200,000 cP at about 50°C or from about 10,000 cP to about 300,000 cP at about 50°C when measured in a manner consistent with ASTM D2983.

[0058] Moreover, a (meth)acrylate component (or other additional curable material component) can be present in a composition or ink described herein in any amount not inconsistent with the objectives of the present disclosure. In some cases, a (meth)acrylate component (or other additional curable material component), in total, is present in an amount up to about 80 wt. %, up to about 70 wt. %, up to about 60 wt. %, or up to about 50 wt. %, up to about 40 wt. %, up to about 30 wt. %, or up to about 20 wt. %, based on the total weight of the composition or ink. In some cases, a composition or ink described herein comprises about 5-70 wt. % (meth)acrylate component (or other additional curable material component), based on the total weight of the composition or ink. In some embodiments, a composition or ink comprises about 10-60 wt. %, 10-50 wt. %, 10-60 wt. %, 10-50 wt. %, 10-40 wt. %, 15-70 wt. %, 15-50 wt. %, 15-30 wt. %, 20-70 wt. %, 20-50 wt. %, 20-40 wt. %, or 30-60 wt. % (meth)acrylate component (or other additionalcomponent), based on the total weight of the composition or ink.

[0059] As described hereinabove, 3D printing may be carried out according to the present disclosure using a single composition or ink capable of forming a polymer or oligomer from a first monomeric component and a second monomeric component, or using a single composition or ink that is also capable of forming an additional polymer or oligomer from an additional curable material, such as a (meth)acrylate monomer. However, it is also possible to carry out 3D printing using a combination of differing compositions or inks that, when combined, are capable of forming a polymer or oligomer from the first monomeric component and the second monomeric component, and optionally also from an additional curable material such as a 22 PCT.798(meth)acrylate. Thus, in another aspect, kits for use in a 3D printing system are described herein. In some embodiments, such a kit comprises a first ink comprising a first monomeric component described herein and a second ink comprising a second monomeric component described herein. Moreover, in some cases, the first ink and / or the second ink further comprises an additional curable material (other than the first and second monomeric components), such as an ethylenically unsaturated monomer. In some instances, the ethylenically unsaturated monomer comprises a (meth)acrylate. Further, as described further hereinbelow, the first ink and / or the second ink may also comprise a photoinitiator.

[0060] It is to be understood that the first monomeric component, second monomeric component, ethylenically unsaturated monomer (or other additional curable material), and photoinitiator of a kit described herein can comprise any first monomeric component, second monomeric component, ethylenically unsaturated monomer (or other additional curable material), and photoinitiator described herein for a “single” ink or composition. Additionally, it is further to be understood that the first or second ink of a kit described herein can include a plurality or mixture of first monomeric component species, a plurality or mixture of second monomeric component species, a plurality or mixture of ethylenically unsaturated species (or other additional curable materials), and / or a plurality or mixture of photoinitiators. In general, any combination or mixture of differing first monomeric component species, second monomeric component species, ethylenically unsaturated species (or other additional curable materials), and / or photoinitiators described herein may be used in a first ink and / or a second ink of a kit described herein. However, in some cases, an ink described herein does not comprise both a primary or secondary amine species and also an ethylenically unsaturated species such as a (meth)acrylate.

[0061] Moreover, the inks of a kit described herein may be used simultaneously or sequentially in a 3D printing process. Additionally, when at least one ink of a kit comprises an additional curable material such as a (meth)acrylate, the inks of the kit can together provide differing curable materials that form differing polymer networks. In some such instances, the differing curable materials and / or polymer networks of the differing inks of a kit can be cured in a temporally separated manner and / or a spatially separated manner within the geometry of the 3D article. For example, in some embodiments, a curable material of the first (and / or second) ink can be cured during printing of the 3D article to provide a printed article having sufficient 23 PCT.798green strength to be handled and / or to exhibit a desired feature resolution, and a different curable material of the second (and / or first) ink can be cured following printing, such as by placing the article in an oven for thermal curing of the second curable material. Similarly, in other cases, a curable material of the first ink cures or polymerizes within a first region of the printed 3D article, and a curable material of the second ink cures or polymerizes within a second region of the printed 3D article.

[0062] In addition, the two inks of a kit described herein can be used in separate ink dispensers or “channels” of a 3D printing system during 3D printing, or may be combined to form a single composition for forming a 3D article, as described further hereinbelow. Further, it is to be understood that a “channel” of a 3D printing system can refer to a mechanism for depositing a single material from an ink dispenser such as a print head. For example, a channel of a print head can refer to a specific material ejection orifice of a print head, alone or in combination with any material conduits, material storage compartments, and / or other hardware or software of a 3D printing system associated with the specific material ejection orifice. A channel can also refer to an entire print head dedicated to printing a single, specific material, alone or in combination with any material conduits, material storage compartments, and / or other hardware or software of a 3D printing system associated with printing the single, specific material from the channel.

[0063] Turning again to specific components of compositions or inks described herein, compositions or inks described herein can further comprise one or more components in addition to the monomers and curable materials described hereinabove. In some cases, compositions or inks described herein may comprise a colorant. Any colorant not inconsistent with the objectives of the present disclosure may be used. The colorant of a composition or ink described herein can be a particulate colorant, such as a particulate pigment, or a molecular colorant, such as a molecular dye. Any such particulate or molecular colorant not inconsistent with the objectives of the present disclosure may be used. In some cases, for instance, the colorant of a composition or ink comprises an inorganic pigment, such as TiO2and / or ZnO. In some embodiments, the colorant of a composition or ink comprises a colorant for use in a RGB, sRGB, CMY, CMYK, L*a*b*, or Pantone® colorization scheme. In some instances, one or more colorants of a composition or ink described herein exhibits a white color. In other cases, a colorant exhibits a black color. Some non-limiting examples of colorants suitable for use in some embodiments 24 PCT.798described herein include SUN UVDJ107, SUN UVDJ150, SUN UVDJ322, SUN UVDJ350, SUN UVDJ354, RJA D3010-FX-Y150, RJA D3410-FX-Y150, RJA D3410-FX-K, PENN COLOR 9B898, and PENN COLOR 9B989. Moreover, in some cases, a particulate colorant described herein has an average particle size of less than about 5 μm, or less than about 1 μm. In some instances, a particulate colorant described herein has an average particle size of less than about 500 nm, such as an average particle size of less than about 400 nm, less than about 300 nm, less than about 250 nm, less than about 200 nm, or less than about 150 nm. In some instances, a particulate colorant has an average particle size of about 50-5000 nm, about 50-1000 nm, or about 50-500 nm.

[0064] A colorant can be present in a composition or ink described herein in any amount not inconsistent with the objectives of the present disclosure. In some cases, colorant is present in a composition in an amount up to about 2 wt. %, or an amount of about 0.005-2 wt. %, 0.01-2 wt. %, 0.01-1.5 wt. %, 0.01-1 wt. %, 0.01-0.5 wt. %, 0.1-2 wt. %, 0.1-1 wt. %, 0.1-0.5 wt. %, or 0.5- 1.5 wt. %, based on the total weight of the composition or ink.

[0065] Moreover, compositions described herein, in some embodiments, further comprise one or more polymerization inhibitors and / or stabilizing agents. A polymerization inhibitor can be added to a composition to provide additional thermal stability to the composition. Any polymerization inhibitor not inconsistent with the objectives of the present disclosure may be used. Moreover, a polymerization inhibitor can retard or decrease the rate of polymerization, and / or prevent polymerization from occurring for some period of time or “induction time” until the polymerization inhibitor is consumed. Further, in some cases, a polymerization inhibitor described herein is an “addition type” inhibitor. An inhibitor described herein can also be a “chain transfer type” inhibitor. In some instances, a suitable polymerization inhibitor comprises methoxyhydroquinone (MEHQ).

[0066] A stabilizing agent, in some embodiments, comprises one or more anti-oxidants. A stabilizing agent can comprise any anti-oxidant not inconsistent with the objectives of the present disclosure. In some cases, suitable anti-oxidants include various aryl compounds, including butylated hydroxytoluene (BHT), which can also be used as a polymerization inhibitor in some embodiments described herein. More generally, a single species may serve as both a stabilizing agent and a polymerization inhibitor. It is also possible, in some cases, to use a plurality of 25 PCT.798inhibitors and / or stabilizing agents, wherein differing inhibitors and / or stabilizers provide differing effects and / or work synergistically.

[0067] A polymerization inhibitor and / or a stabilizing agent can be present in a composition in any amount not inconsistent with the objectives of the present disclosure. In some embodiments, a polymerization inhibitor is present in an amount ranging from about 0.01 wt. % to about 2 wt. % or from about 0.05 wt. % to about 1 wt. %. Similarly, in some cases, a stabilizing agent is present in a composition in an amount ranging from about 0.1 wt. % to about 5 wt. %, from about 0.5 wt. % to about 4 wt. %, or from about 1 wt. % to about 3 wt. %, based on the total weight of the composition.

[0068] A composition described herein may also comprise one or more photoinitiators. Any photoinitiator not inconsistent with the objectives of the present disclosure may be used. In some cases, a photoinitiator comprises an alpha-cleavage type (unimolecular decomposition process) photoinitiator or a hydrogen abstraction photosensitizer-tertiary amine synergist, operable to absorb light between about 250 nm and about 400 nm or between about 300 nm and about 385 nm, to yield free radical(s). Examples of alpha cleavage photoinitiators are Irgacure 184 (CAS 947-19-3), Irgacure 369 (CAS 119313-12-1), and Irgacure 819 (CAS 162881-26-7). An example of a photosensitizer-amine combination is Darocur BP (CAS 119-61-9) with diethylaminoethylmethacrylate.

[0069] In addition, in some instances, photoinitiators comprise benzoins, including benzoin, benzoin ethers, such as benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether, benzoin phenyl ether and benzoin acetate, acetophenones, including acetophenone, 2,2- dimethoxyacetophenone and 1,1-dichloroacetophenone, benzil, benzil ketals, such as benzil dimethyl ketal and benzil diethyl ketal, anthraquinones, including 2-methylanthraquinone, 2- ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone and 2-amylanthraquinone, triphenylphosphine, benzoylphosphine oxides, such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO), benzophenones, such as benzophenone and 4,4'-bis(N,N'- dimethylamino)benzophenone, thioxanthones and xanthones, acridine derivatives, phenazine derivatives, quinoxaline derivatives or 1-phenyl-1,2-propanedione, 2-O-benzoyl oxime, 1- aminophenyl ketones or 1-hydroxyphenyl ketones, such as 1-hydroxycyclohexyl phenyl ketone, phenyl 1-hydroxyisopropyl ketone and 4-isopropylphenyl 1-hydroxyisopropyl ketone. 26 PCT.798

[0070] Photoinitiators can also comprise photoinitiators operable for use with a HeCd laser radiation source, including acetophenones, 2,2-dialkoxybenzophenones and 1-hydroxyphenyl ketones, such as 1-hydroxycyclohexyl phenyl ketone or 2-hydroxyisopropyl phenyl ketone (=2- hydroxy-2,2-dimethylacetophenone). Additionally, in some cases, photoinitiators comprise photoinitiators operable for use with an Ar laser radiation source including benzil ketals, such as benzil dimethyl ketal. In some embodiments, a photoinitiator comprises an α-hydroxyphenyl ketone, benzil dimethyl ketal or 2,4,6-trimethylbenzoyldiphenylphosphine oxide or a mixture thereof.

[0071] Another class of photoinitiator that may be included in a composition described herein comprises ionic dye-counter ion compounds capable of absorbing actinic radiation and generating free radicals for polymerization initiation. Some ionic dye-counter ion compounds and their mode of operation are disclosed in EP-A-0223587 and U.S. Patents 4,751,102; 4,772,530; and 4,772,541.

[0072] A photoinitiator can be present in a composition described herein in any amount not inconsistent with the objectives of the present disclosure. In some embodiments, a photoinitiator is present in a composition in an amount of up to about 5 wt. %, based on the total weight of the composition. In some cases, a photoinitiator is present in an amount ranging from about 0.1 wt. % to about 5 wt. %.

[0073] Additionally, in some embodiments, a composition described herein further comprises one or more photosensitizers. In general, such a sensitizer can be added to a composition to increase the effectiveness of one or more photoinitiators that may also be present. In some cases, a sensitizer comprises isopropylthioxanthone (ITX) or 2-chlorothioxanthone (CTX).

[0074] A sensitizer can be present in a composition in any amount not inconsistent with the objectives of the present disclosure. In some embodiments, a sensitizer is present in an amount ranging from about 0.1 wt. % to about 2 wt. % or from about 0.5 wt. % to about 1 wt. %, based on the total weight of the composition.

[0075] Additionally, in some cases, a composition described herein is further characterized by components that are not included in the composition, or that are included in only small amounts. For instance, in some embodiments, a composition described herein is free or substantially free of non-curable photoinitiators, including non-curable photoinitiators described hereinabove. A composition that is “substantially” free of non-curable photoinitiator, or from which non-curable 27 PCT.798photoinitiator has been “substantially” excluded, as used herein, can comprise less than about 1 wt. %, less than about 0.5 wt. %, less than about 0.1 wt. %, less than about 0.07 wt. %, less than about 0.05 wt. %, or less than about 0.01 wt. % non-curable photoinitiator, based on the total weight of the composition. Thus, in some cases, a composition described herein comprises 0-0.5 wt. %, 0-0.1 wt. %, 0-0.07 wt. %, 0-0.05 wt. %, or 0-0.01 wt. % non-curable photoinitiator, based on the total weight of the composition. Moreover, a “non-curable” photoinitiator, as used herein, can include any photoinitiator that does not include a moiety that can be polymerized or cured with the curable materials of the composition. For instance, in some cases, a non-curable photoinitiator does not comprise a (meth)acrylate moiety.

[0076] Compositions described herein can exhibit a variety of desirable properties. For example, a composition described herein can have any freezing point, melting point, and / or other phase transition temperature not inconsistent with the objectives of the present disclosure. In some cases, a composition has freezing and melting points consistent with temperatures used in some 3D printing systems, including 3D printing systems designed for use with phase changing inks. In some embodiments, the freezing point of a composition is greater than about 40°C. In some instances, for example, a composition has a freezing point centered at a temperature ranging from about 45°C to about 55°C or from about 50°C to about 80°C. In some cases, a composition has a freezing point below about 40°C or below about 30°C.

[0077] Further, in some embodiments described herein, a composition exhibits a sharp freezing point or other phase transition. In some cases, for instance, a composition freezes over a narrow range of temperatures, such as a range of about 1-10°C, about 1-8°C, or about 1-5°C. In some embodiments, a composition having a sharp freezing point freezes over a temperature range of X ± 2.5°C, where X is the temperature at which the freezing point is centered (e.g., X = 65°C).

[0078] In addition, a composition described herein, in some cases, is fluid at jetting temperatures encountered in some 3D printing systems. Moreover, in some embodiments, a composition solidifies once deposited on a surface during the fabrication of a three- dimensionally printed article or object. Alternatively, in other instances, a composition remains substantially fluid upon deposition on a surface. Solidification of a composition, in some embodiments, occurs through a phase change of the composition or a component of the composition. The phase change can comprise a liquid to solid phase change or a liquid to semi- 28 PCT.798solid phase change. Further, in some instances, solidification of a composition comprises an increase in viscosity of the composition, such as an increase in viscosity from a low viscosity state to a high viscosity state. Solidification of a composition can also occur due to curing of the composition.

[0079] Additionally, in some embodiments, a composition described herein, when non-cured, has a viscosity profile consistent with the requirements and parameters of one or more 3D printing systems, such as a multi-jet modeling, stereolithography, or DLP system. In some cases, for example, a composition described herein has a dynamic viscosity ranging from about 8.0 cP to about 14.0 cP or from about 9.0 to about 14.0 cP at a jetting temperature of the system, such as a temperature of about 80°C, when measured according to ASTM standard D2983 (e.g., using a Brookfield Model DV-II+ Viscometer). In some embodiments, a composition has a dynamic viscosity of about 9.5-12.5 cP or about 10.5-12.5 cP at a temperature of about 80°C. In some cases, a composition has a viscosity of about 8.0-10.0 cP at a temperature of about 85-87°C. In some embodiments, a composition described herein has a dynamic viscosity of about 8.0-19.0 cP, about 8.0-13.5 cP, about 11.0-14.0 cP, about 11.5-13.5 cP, or about 12.0-13.0 cP at a temperature of about 65°C, when measured according to ASTM D2983. In other instances, a composition described herein when non-cured exhibits a dynamic viscosity of about 200-2000 cP, about 200-900 cP, about 300-900 cP, about 300-800 cP, about 400-1000 cP, about 400-900 cP, about 400-800 cP, about 400-600 cP, about 450-550 cP, about 500-700 cP, about 500-600 cP, or about 500-550 cP at 30°C, when measured according to ASTM D2983. In some cases, a composition described herein when non-cured exhibits a dynamic viscosity of less than about 100 cP or more than about 1000 cP, when measured according to ASTM D2983.

[0080] Further, compositions described herein, in some embodiments, can exhibit a combination of one or more desirable features. In some cases, for instance, a composition in the non-cured state has one or more of the following properties: 1. Freezing point below about 30°C, below about 25°C, or below about 15°C; 2. Viscosity of about 9-14 cP at 70–95°C or about 400-1000 cP at 25-35°C; and 3. Thermal stability for at least 6 months at room temperature (25°C).

[0081] As described above, viscosity can be measured according to ASTM D2983 (e.g., using a Brookfield Model DV-II+ Viscometer). In addition, for reference purposes herein, a “thermally stable” material exhibits no greater than about a 35 percent change in viscosity over a specified 29 PCT.798time period (e.g., 3 days) when measured at the specified temperature (e.g., room temperature) at the beginning and at the end of the time period. In some embodiments, the viscosity change is no greater than about 30 percent or no greater than about 20 percent, based on the larger viscosity value. In some cases, the viscosity change is between about 10 percent and about 20 percent or between about 25 percent and about 30 percent. Moreover, in some embodiments, the change in viscosity is an increase in viscosity.

[0082] Compositions described herein can also exhibit a variety of desirable properties, in addition to those described hereinabove in a cured state or in a “green” state. A composition in a “cured” state, as used herein, comprises a composition that includes a curable material or polymerizable component that has been at least partially polymerized and / or cross-linked or that has been largely polymerized and / or cross-linked. For instance, in some cases, a cured composition is at least about 51% polymerized or cross-linked or at least about 60% polymerized or cross-linked. In some embodiments, a cured composition is at least about 70%, at least about 80%, at least about 90%, or at least about 95% polymerized or cross-linked. In some instances, a cured composition is between about 50% and about 99% polymerized or cross-linked. A composition in a “green” state can be less than 50%, less than 40%, less than 30%, or less than 20% polymerized or cross-linked. In some cases, a composition in a green state is 5-50%, 5- 40%, 5-30%, 10-50%, 10-40%, 10-30%, 20-50%, 20-40%, 30-50%, or 30-40% polymerized or cross-linked. Moreover, as understood by one of ordinary skill in the art, a “green” state of a composition can be defined as the state of the composition or ink during or after a layer-by-layer 3D printing process described herein but before a post-processing curing step has been performed.

[0083] Moreover, the degree of polymerization or cross-linking can be determined using any protocol or method not inconsistent with the technical objectives of the present disclosure, such as by determining the percentage of monomers incorporated into the polymer network (e.g., based on molecular weight of the polymer compared to the molecular weight of the monomer, or based on the total polymer mass compared to the theoretical maximum of the total polymer mass) or by determining the amount of unincorporated monomers. When more than one method is used to determine a degree of polymerization or cross-linking, the results of the methods can be averaged to obtain a percentage described herein. It is further to be understood that the degree 30 PCT.798of polymerization or cross-linking described herein is different than “degree of polymerization” defined as the number of repeating units in a polymer molecule.

[0084] In some cases, a composition described herein, when cured or in a green state, has an elongation at break of about 10-400%, 10-300%, 10-200%, 10-100%, 10-80%, 10-40%, 10-30%, 10-20%, 15-400%, 15-300%, 15-100%, 15-30%, 50-400%, 50-300%, 50-200%, 50-100%, 100- 400%, 100-300%, 100-200%, 200-400, 200-300%, or 300-400%, when measured according to ASTM D638. Further, a cured or green composition described herein, in some cases, can have a tensile strength of about 3500-7000 psi or about 4000-6000 psi, when measured according to ASTM D638. Additionally, a cured or green composition described herein, in some embodiments, can have a tensile modulus of about 100-400 ksi or about 150-300 ksi, when measured according to ASTM D638.

[0085] A composition described herein can also exhibit high biocompatibility and / or low cytotoxicity, including in a cured state. For instance, in some cases, a composition described herein, when cured, exhibits a cytotoxicity grade below 2 when measured according to ANSI / AAMI / ISO 10993-5:2009. In some embodiments, a composition described herein, when cured, exhibits a cytotoxicity grade of 0 or 1 when measured according to ANSI / AAMI / ISO 10993-5:2009.

[0086] Moreover, in some cases, a composition described herein, when cured, can exhibit a plurality of the foregoing properties. For example, in some embodiments, a composition when cured has a tensile strength of about 4000-6000 psi when measured according to ASTM D638; a tensile modulus of about 150-300 ksi when measured according to ASTM D638; an elongation at break of about 10-400% when measured according to ASTM D638; and a cytotoxicity grade of 0 or 1 when measured according to ANSI / AAMI / ISO 10993-5:2009.

[0087] Compositions described herein can be produced in any manner not inconsistent with the objectives of the present disclosure. In some embodiments, for instance, a method for the preparation of a composition described herein comprises the steps of mixing the components of the composition, melting the mixture, and filtering the molten mixture. Melting the mixture, in some cases, is carried out at a temperature of about 75°C or in a range from about 75°C to about 85°C. In some embodiments, a composition described herein is produced by placing all components of the composition in a reaction vessel and heating the resulting mixture to a temperature ranging from about 75°C to about 85°C with stirring. The heating and stirring are 31 PCT.798continued until the mixture attains a substantially homogenized molten state. In general, the molten mixture can be filtered while in a flowable state to remove any large undesirable particles that may interfere with jetting or extrusion or other printing process. The filtered mixture can then be cooled to ambient temperatures and stored until ready for use in a 3D printing system. In other instances, the components of a composition are mixed at ambient temperature (e.g., 20- 25°C), without heating, or with minimal heating (e.g., to a temperature of 30-45°C). Such a method can still include filtering the resulting liquid mixture. II. Uses of Compositions for 3D Printing

[0088] In another aspect, uses of a composition for 3D printing are described herein, wherein the composition comprises a composition described hereinabove. For instance, in some cases, a use of a composition for 3D printing is described herein, wherein the composition comprises a first monomeric component comprising a first functional group in a total amount of m molar equivalents and a second monomeric component comprising a second functional group in a total amount of n molar equivalents. In some embodiments, the first functional group is a cyclic carbonate. In some cases, the first functional group and the second functional group are polymerizable with one another. In some implementations, the ratio of m to n is between 3:2 and 2:1. However, any composition or plurality of compositions described hereinabove in Section I may be used for 3D printing. III. 3D Printing Systems

[0089] In still another aspect, 3D printing systems are described herein. Such a 3D printing system can use or comprise a composition for 3D printing described hereinabove, such as a composition comprising an ink, plurality of inks, or kit described hereinabove. In some embodiments, a 3D printing system described herein comprises a 3D printer having at least one of an ink dispenser and an ink reservoir, and an ink described herein disposed in the ink dispenser, the ink reservoir, or both. The ink comprises, consists of, or consists essentially of any composition described hereinabove in Section I. Additionally, in some cases, a 3D printing system described herein comprises a 3D printer having a first ink dispenser and a second ink dispenser, a first ink disposed in the first ink dispenser, and a second ink disposed in the second 32 PCT.798ink dispenser. The first ink and the second ink each comprise, consist of, or consist essentially of a first ink and a second ink described hereinabove in Section I.

[0090] In general, any 3D printer not inconsistent with the objectives of the present disclosure may contain or include an ink described herein, including in an ink dispenser and / or reservoir. In some embodiments, for example, the 3D printer comprises an inkjet or so-called multi-jet modeling (MJM) type 3D printer. In other instances, the 3D printer comprises a stereolithography (SLA) type 3D printer, a digital light processing (DLP) type 3D printer, or a contacted SLA (cSLA) type printer. Other 3D printers may also be used. IV. Methods of Printing a 3D Article

[0091] In another aspect, methods of printing a 3D article or object are described herein. Methods of printing a 3D article or object described herein can include forming the 3D article from a plurality of layers of a composition described herein in a layer-by-layer manner. Any composition described hereinabove in Section I may be used. For example, in some cases, the composition comprises a first monomeric component comprising a first functional group in a total amount of m molar equivalents and a second monomeric component comprising a second functional group in a total amount of n molar equivalents. In some embodiments, the first functional group is a cyclic carbonate. In some cases, the first functional group and the second functional group are polymerizable with one another. In some implementations, the ratio of m to n is between 3:2 and 2:1. Other compositions described herein may also be used. Moreover, in some cases, a method described herein comprises selectively depositing layers of the ink in a fluid state onto a substrate.

[0092] Additionally, a method described herein can further comprise curing or polymerizing one or more curable materials of the composition. Moreover, when an ink comprises a plurality of differing curable materials, the differing curable materials can be cured or polymerized in separate curing or polymerization steps carried out at different time periods and / or in different spatial regions of a layer of ink. Further, differing curable materials can be cured in different manners.

[0093] For instance, in some cases, an ink used in a method described herein comprises a composition comprising a first monomeric component comprising a first functional group in a total amount of m molar equivalents and a second monomeric component comprising a second 33 PCT.798functional group in a total amount of n molar equivalents. In some embodiments, the first functional group is a cyclic carbonate. In some cases, the first functional group and the second functional group are polymerizable with one another. In some implementations, the ratio of m to n is between 3:2 and 2:1. In some embodiments, the first monomeric component comprises a (meth)acrylate moiety in addition to comprising a first functional group. In such instances, a method described herein comprises curing or polymerizing the ethylenically unsaturated moieties of the one or more of the (meth)acrylates (and, if present, the (meth)acrylate moiety of the first monomeric component) to form a poly(meth)acrylate. For example, the (meth)acrylates can be cured or polymerized with UV light. Further, in some embodiments, the method further comprises thermally curing or polymerizing the first functional group and the second functional group. Moreover, in some cases, the polymer network of the first functional group and the second function group and that of the poly(meth)acrylate can together form an interpenetrating polymer network.

[0094] Curing one or more curable materials described herein can be carried out in any manner not inconsistent with the objectives of the present disclosure. For example, in some instances, a layer of deposited ink can be cured (by at least one method or curing mechanism) prior to the deposition of another or adjacent layer of ink. In some cases, a method of printing a 3D article described herein further comprises subjecting the ink to electromagnetic radiation of sufficient wavelength and intensity to cure at least one curable material of the ink, where curing can comprise polymerizing one or more polymerizable moieties or functional groups of one or more components of the at least one curable material. Additionally, as described above, curing one or more layers of deposited ink, in some embodiments, is carried out by exposing the one or more layers to electromagnetic radiation, such as UV light or visible light.

[0095] Similarly, curing can also be carried out thermally. In some embodiments, thermal curing is carried out using thermal energy or heat provided by a photocuring step described herein, including thermal energy released by the photoinitiated polymerization of the one or more (meth)acrylates. Thermal curing can also be carried out by heating the ink (or an article formed from the ink) using a source of thermal energy such as an oven.

[0096] Moreover, it is further to be understood that a deposited ink (or a component thereof) can be cured according to a second curing mechanism after curing an ink according to a first curing mechanism, and / or after completing the printing of the 3D article. For instance, in some 34 PCT.798cases, one or more deposited inks can be cured by UV light in a layer-by-layer manner during layer-by-layer printing of the article, and then subsequently cured in some other manner following completion of layer-by-layer printing. In some such embodiments, subsequently curing the one or more deposited inks comprises thermally curing the one or more inks by heating the article. In some cases, the article is heated in a “post-processing” step, such as by placing a previously formed article in an oven or other space at an elevated temperature. In some such instances, the article can be heated at a temperature and for a time period sufficient to cure a previously uncured curable component of an ink from which the article is formed, as opposed to being heated at a lower temperature and / or for a shorter time period, such as may be used to melt a support material off or away from a completed 3D article. However, in some instances, a support material, if present, may be melted off a completed 3D article at the same time as thermal curing of a curable component of the ink. In addition, in some cases, a thermal curing step is not carried out as a post-processing step but is instead carried out during layer-by-layer printing of the article, as described above.

[0097] A method of printing a 3D article described herein can also comprise forming the 3D article from a plurality of layers of a plurality of inks described herein in a layer-by-layer manner. For instance, in some embodiments, a method comprises forming the 3D article from a plurality of layers of a first ink and a plurality of layers of a second ink. In some such cases, a method of printing a 3D article comprises selectively depositing layers of a first ink in a fluid state onto a substrate and selectively depositing layers of a second ink in a fluid state onto the substrate, wherein the first ink and the second ink respectively comprise a first ink and a second ink described hereinabove in Section I. For example, the first ink can comprise a first monomeric component comprising a first functional group in a total amount of m molar equivalents. In some embodiments, the first functional group is a cyclic carbonate. The second ink can comprise a second monomeric component comprising a second functional group in a total amount of n molar equivalents.

[0098] As with “single” inks, methods described herein using a plurality of differing inks can also comprise curing a plurality of curable materials of the inks, including in separate curing steps carried out at different time periods and / or in different spatial regions of a layer of one or more inks. Moreover, as described further herein, different curable materials can be cured in different manners. For example, in some embodiments, the first ink comprises an acrylate 35 PCT.798component in addition to a first monomeric component comprising a first functional group in a total amount of m molar equivalents, and the method further comprises curing the acrylate component of the first ink with UV light and subsequently thermally curing the first functional group and the second functional group of the second monomeric component.

[0099] Further, the layers of an ink can be deposited according to an image of the 3D article in a computer readable format. In some embodiments, an ink is deposited according to preselected computer aided design (CAD) parameters or other digital or computer readable parameters or models. Moreover, in some cases, one or more layers of an ink described herein has a thickness of about 10 μm to about 100 μm, about 10 μm to about 80 μm, about 10 μm to about 50 μm, about 20 μm to about 100 μm, about 20 μm to about 80 μm, or about 20 μm to about 40 μm. Other thicknesses are also possible.

[0100] Additionally, it is to be understood that methods of printing a 3D article described herein can include so-called multi-jet modeling or stereolithography or DLP 3D printing methods. For example, in some instances, a multi-jet method of printing a 3D article comprises selectively depositing layers of one or more inks described herein in a fluid state onto a substrate, such as a build pad of a 3D printing system. In addition, in some embodiments, a method described herein further comprises supporting at least one of the layers of the one or more inks with a support material. Any support material not inconsistent with the objectives of the present disclosure may be used.

[0101] Further, in some embodiments, a preselected amount of ink described herein is heated to the appropriate temperature and jetted through the print head or a plurality of print heads of a suitable inkjet printer to form a layer on a print pad in a print chamber. In some cases, each layer of ink is deposited according to the preselected CAD parameters or other digital or computer readable parameters or models. A suitable print head to deposit the ink, in some embodiments, is a piezoelectric print head. Additional suitable print heads for the deposition of ink and support material described herein are commercially available from a variety of ink jet printing apparatus manufacturers. For example, Xerox, Hewlett Packard, or Ricoh print heads may be used in some instances.

[0102] Additionally, in some embodiments, an ink described herein remains substantially fluid upon deposition. Alternatively, in other instances, the ink exhibits a phase change upon deposition and / or solidifies upon deposition. Moreover, in some cases, the temperature of the 36 PCT.798printing environment can be controlled so that the jetted droplets of ink solidify on contact with the receiving surface. In other embodiments, the jetted droplets of ink do not solidify on contact with the receiving surface, remaining in a substantially fluid state. Additionally, in some instances, after each layer is deposited, the deposited material is planarized and cured with electromagnetic (e.g., UV) radiation prior to the deposition of the next layer. Optionally, several layers can be deposited before planarization and curing, or multiple layers can be deposited and cured followed by one or more layers being deposited and then planarized without curing. Planarization corrects the thickness of one or more layers prior to curing the material by evening the dispensed material to remove excess material and create a uniformly smooth exposed or flat up-facing surface on the support platform of the printer. In some embodiments, planarization is accomplished with a wiper device, such as a roller, which may be counter-rotating in one or more printing directions but not counter-rotating in one or more other printing directions. In some cases, the wiper device comprises a roller and a wiper that removes excess material from the roller. Further, in some instances, the wiper device is heated. It should be noted that the consistency of the jetted ink described herein prior to curing, in some embodiments, should desirably be sufficient to retain its shape and not be subject to excessive viscous drag from the planarizer.

[0103] Moreover, a support material, when used, can be deposited in a manner consistent with that described hereinabove for the ink. The support material, for example, can be deposited according to the preselected CAD parameters (or other digital or computer readable parameters or models) such that the support material is adjacent or continuous with one or more layers of the ink. Jetted droplets of the support material, in some embodiments, solidify or freeze on contact with the receiving surface. In some cases, the deposited support material is also subjected to planarization.

[0104] Layered deposition of the ink and support material can be repeated until the 3D article has been formed. In some embodiments, a method of printing a 3D article further comprises removing the support material from the ink.

[0105] It is also possible to form a 3D article from an ink described herein using stereolithography (SLA), contacted SLA (cSLA), or digital light processing (DLP) 3D printing. For example, in some cases, a method of printing a 3D article comprises retaining one or more inks described herein in a fluid state in a container and selectively applying energy to the one or 37 PCT.798more inks in the container to solidify at least a portion of a fluid layer of the ink, thereby forming a solidified layer that defines a cross-section of the 3D article. Additionally, a method described herein can further comprise raising or lowering the solidified layer of ink to provide a new or second fluid layer of unsolidified ink at the surface of the fluid ink in the container, followed by again selectively applying energy to the ink in the container to solidify at least a portion of the new or second fluid layer of the ink to form a second solidified layer that defines a second cross- section of the 3D article. Further, the first and second cross-sections of the 3D article can be bonded or adhered to one another in the z-direction (or build direction corresponding to the direction of raising or lowering recited above) by the application of the energy for solidifying the ink. Moreover, selectively applying energy to the ink in the container can comprise applying electromagnetic radiation, such as UV radiation or visible radiation, having a sufficient energy to cure the ink. In some instances, the UV light has an average wavelength of 320-380 nm, 340- 370 nm, or 350-360 nm. In some cases, the curing radiation is provided by a computer controlled laser beam or a DLP light source or projector. In addition, in some instances, raising or lowering a solidified layer of ink is carried out using an elevator platform disposed in the container of fluid ink. A method described herein can also comprise planarizing a new layer of fluid ink provided by raising or lowering an elevator platform. Such planarization can be carried out, in some cases, by a wiper or roller.

[0106] It is further to be understood that the foregoing process can be repeated a desired number of times to provide the 3D article. For example, in some cases, this process can be repeated “n” number of times, wherein n can be up to about 100,000, up to about 50,000, up to about 10,000, up to about 5000, up to about 1000, or up to about 500. Thus, in some embodiments, a method of printing a 3D article described herein can comprise selectively applying energy to an ink in a container to solidify at least a portion of an nth fluid layer of the ink, thereby forming an nth solidified layer that defines an nth cross-section of the 3D article, raising or lowering the nth solidified layer of ink to provide an (n+1)th layer of unsolidified ink at the surface of the fluid ink in the container, selectively applying energy to the (n+1)th layer of ink in the container to solidify at least a portion of the (n+1)th layer of the ink to form an (n+1)th solidified layer that defines an (n+1)th cross-section of the 3D article, raising or lowering the (n+1)th solidified layer of ink to provide an (n+2)th layer of unsolidified ink at the surface of the fluid ink in the container, and continuing to repeat the foregoing steps to form the 3D article. 38 PCT.798Further, it is to be understood that one or more steps of a method described herein, such as a step of selectively applying energy to a layer of ink, can be carried out according to an image of the 3D article in a computer-readable format. General methods of 3D printing using stereolithography are further described, inter alia, in U.S. Patents 5,904,889 and 6,558,606.

[0107] Performing a printing process described above can provide a printed 3D article from an ink described herein that has a high feature resolution. The “feature resolution” of an article, for reference purposes herein, can be the smallest controllable physical feature size of the article. The feature resolution of an article can be described in terms of a unit of distance such as microns (μm), or in terms of dots per inch (dpi). As understood by one of ordinary skill in the art, a higher feature resolution corresponds to a higher dpi value but a lower distance value in μm. In some cases, an article formed by depositing or solidifying an ink described herein can have a feature resolution of about 500 μm or less, about 200 μm or less, about 100 μm or less, or about 50 μm or less, including at elevated temperatures. In some embodiments, an article has a feature resolution between about 50 μm and about 500 μm, between about 50 μm and about 200 μm, between about 50 μm and about 100 μm, or between about 100 μm and about 200 μm. Correspondingly, in some instances, an article described herein has a feature resolution of at least about 100 dpi, at least about 200 dpi, at least about 250 dpi, at least about 400 dpi, or at least about 500 dpi. In some cases, the feature resolution of an article is between about 100 dpi and about 600 dpi, between about 100 dpi and about 250 dpi, or between about 200 dpi and about 600 dpi. V. Printed 3D Articles

[0108] In another aspect, printed 3D articles are described herein. In some embodiments, a printed 3D article is formed from one or more compositions described herein. Any composition described hereinabove in Section I may be used. For example, in some cases, the 3D article is formed from a single ink described herein, such as an ink comprising a composition comprising a first monomeric component comprising a first functional group in a total amount of m molar equivalents and a second monomeric component comprising a second functional group in a total amount of n molar equivalents. In some embodiments, the first functional group is a cyclic carbonate. In some cases, the first functional group and the second functional group are 39 PCT.798polymerizable with one another. In some implementations, the ratio of m to n is between 3:2 and 2:1.

[0109] A printed 3D article described herein may also be formed from a plurality of differing inks. For instance, in some embodiments, a printed 3D article is formed from a first composition and a second composition described hereinabove in Section I. In some such cases, the first ink comprises a first monomeric component comprising a first functional group in a total amount of m molar equivalents and the second ink comprises a second monomeric component comprising a second functional group in a total amount of n molar equivalents. The first and / or second ink may also comprise an acrylate component, in addition to the first and / or second monomeric component. Additionally, such a curable material of a first or second ink can form a polymer network (e.g., a poly(meth)acrylate) that differs from the polymer network formed by the first and second monomeric components. Additionally, in some instances, the two polymer networks together form an interpenetrating polymer network.

[0110] Some embodiments described herein are further illustrated in the following non- limiting examples. EXAMPLE 1 Inks for 3D Printing

[0111] Inks according to some embodiments described herein are prepared as follows. Specifically, in the present Example, a first ink and a second ink are prepared. The first ink and second ink could be used in a kit described herein. Alternatively, as described further below, the first ink and the second ink could be combined with one another to form a single ink which may be used in a 3D printing system or 3D printing method with or without the use of one or more other inks.

[0112] In general, the first ink (which may also be referred to as “Part A”) includes a first monomeric component having a plurality of cyclic carbonate moieties, as described above in Section I. The first ink also included an acrylate component. Further, the first ink includes a photoinitiator. The second ink (which may also be referred to as “Part B”) included a second monomeric component comprising a plurality of primary or secondary amine moieties. The specific components of the first and second ink are provided below. 40 PCT.798

[0113] The first ink (“Part A”) includes 14.48 g TMP tricarbonate (CAS No. 147876-32-2, from SPECIFIC POLYMERS) (first monomeric component); 27.93 g triethylene glycol diacrylate (SR272, from SARTOMER) (acrylate component); and 0.84 g 2,4,6- trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO) (photoinitiator).

[0114] The second ink (“Part B”) includes 7.14 g Jeffamine T-403 (triamine, from HUNTSMAN CHEMICAL) (second monomeric component).

[0115] To form each ink, the individual components of each ink are combined and mixed. The mixture is heated to a temperature of about 20-25°C with stirring. The heating and stirring are continued until the mixture attained a substantially homogenized liquid state. The liquid mixture is then filtered.

[0116] For use in MJM 3D printing, Part A and Part B are fed into two separate channels / ink dispensers and then mixed by jetting the two inks onto adjacent or nearby locations on a substrate or into adjacent or nearby voxels. Such a method of mixing inks can be referred to as “digital mixing.” The jetted materials are then exposed to UV radiation for UV curing. In particular, the UV curing step cures the acrylate component of Part A. During this step, some amount of reaction between the first monomeric component of Part A and the second monomeric component of Part B may also occur. However, the degree of reaction may be limited. The 3D article printed in this manner (without substantial reaction of the first monomeric component and the second monomeric component) can have sufficient green strength to permit handling of the article without damaging the article or loss of printing resolution of the article. To complete the reaction between the first monomeric component and the second monomeric component, the printed article can be placed in an oven to cure the first monomeric component and the second monomeric component. Moreover, if a support material (such as a wax support material) is used, this second (or “post”) curing step can also melt the wax support material away from the printed article (though it is to be understood that, in some cases, such melting of a support material may also be carried out a lower temperature that is insufficient for carrying out the second or “post” curing step; that is, as understood by a person of ordinary skill in the art, a step of melting a wax support material or similar support material is not necessarily the same as a thermal post curing step of reactive components of the build material). Post-curing in the oven can occur at a temperature of 80-100°C for a time period of 2-4 hours. In some cases, an article is first heated 41 PCT.798in an oven at 80°C for 2 hours, followed by heating in the oven at 100°C for an additional 2 hours.

[0117] For use in SLA, cSLA, or DLP 3D printing, Part A and Part B are mixed before use. The mixture is then fed into a vat, reservoir, or ink cartridge for 3D printing. It should be noted that the time and temperature of the combined composition (e.g., during storage or “shelf life”) can be controlled by the user to avoid significant reaction of Part A and Part B prior to printing. In some cases, for instance, Part A and Part B are mixed immediately prior to use (e.g., within an hour or within 30 minutes of use). The photocuring that occurs during the SLA, cSLA, or DLP process can polymerize the acrylate component of Part A, again imparting sufficient green strength to the article to permit handling of the article following the printing process without damage or loss of printing resolution. The article can be removed from the vat or reservoir following printing, optionally cleaned, and then placed in an oven for completion of the reaction between the first monomeric component and the second monomeric component, as described above. EXAMPLE 2 Inks for 3D Printing

[0118] Inks according to some embodiments described herein are prepared as follows. Specifically, in the present Example, a first ink and a second ink are prepared. The first ink and second ink could be used in a kit described herein. Alternatively, as described further below, the first ink and the second ink could be combined with one another to form a single ink which may be used in a 3D printing system or 3D printing method with or without the use of one or more other inks.

[0119] The first ink (which may also be referred to as “Part A”) includes a cyclic carbonate monomer having a cyclic carbonate moiety and a (meth)acrylate moiety. Specifically, the first curable material has the structure of Formula (A9) above, where m is 1 in the structure of Formula (A9). The first ink also includes an acrylate component. Further, the first ink includes a photoinitiator. The second ink (which may also be referred to as “Part B”) includes a second monomeric component. The specific components of the first and second ink are provided below. 42 PCT.798

[0120] The first ink (“Part A”) includes 20.5 g Formula (A9) (first monomeric component); 31.2 g triethylene glycol dimethacrylate (SR205, from SARTOMER) (acrylate component); and 0.94 g 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO) (photoinitiator).

[0121] The second ink (“Part B”) includes 8.4 g Jeffamine XTJ 566 (triamine, from HUNTSMAN CHEMICAL) (second monomeric component). The amounts of the first monomeric component are selected based on a desired molar ratio of cyclic carbonate moiety (in Part A) to the second functional group (in Part B). In general, the ratio can be varied from 2:1 (first functional group:second functional group) to 3:2.

[0122] To form each ink, the individual components of each ink are combined and mixed. The mixture is heated to a temperature of about 20-25°C with stirring. The heating and stirring are continued until the mixture attained a substantially homogenized liquid state. The liquid mixture is then filtered.

[0123] For use in MJM 3D printing, Part A and Part B are fed into two separate channels / ink dispensers and then mixed by jetting the two inks onto adjacent or nearby locations on a substrate or into adjacent or nearby voxels (digital mixing). The jetted materials are then exposed to UV radiation for UV curing. In particular, the UV curing step cures the acrylate component and the (meth)acrylate moiety of the first monomeric component of Part A. During this step, some amount of reaction between the cyclic carbonate moieties of the first monomeric component of Part A and the amine moieties of the second monomeric component of Part B may also occur. However, the degree of reaction may be limited (e.g., less than 30%, less than 25%, less than 20%, less than 15%, or less than 10% of the cyclic carbonate moieties and amine moieties may react during this step). The 3D article printed in this manner (without substantial reaction of the cyclic carbonate and amine moieties) can have sufficient green strength to permit handling of the article without damaging the article or loss of printing resolution of the article. To complete the reaction between the cyclic carbonate and amine moiety, the printed article can be placed in an oven to cure the cyclic carbonate and amine moiety. Moreover, if a support material (such as a wax support material) is used, this second (or “post”) curing step can also melt the wax support material away from the printed article (though it is to be understood that, in some cases, such melting of a support material may also be carried out a lower temperature that is insufficient for carrying out the second or “post” curing step; that is, as understood by a person of ordinary skill in the art, a step of melting a wax support material or similar support material is 43 PCT.798not necessarily the same as a thermal post curing step of reactive components of the build material). Post-curing in the oven can occur at a temperature of 80-100°C for a time period of 2- 4 hours. In some cases, an article is first heated in an oven at 80°C for 2 hours, followed by heating in the oven at 100°C for an additional 2 hours.

[0124] For use in SLA, cSLA, or DLP 3D printing, Part A and Part B are mixed before use. The mixture is then fed into a vat, reservoir, or ink cartridge for 3D printing. It should be noted that the time and temperature of the combined composition (e.g., during storage or “shelf life”) can be controlled by the user to avoid significant reaction of Part A and Part B prior to printing. In some cases, for instance, Part A and Part B are mixed immediately prior to use (e.g., within an hour or within 30 minutes of use). The photocuring that occurs during the SLA, cSLA, or DLP process can polymerize the acrylate component and (meth)acrylate moiety of Formula (A9) of Part A, again imparting sufficient green strength to the article to permit handling of the article following the printing process without damage or loss of printing resolution. The article can be removed from the vat or reservoir following printing, optionally cleaned, and then placed in an oven for completion of the reaction between the cyclic carbonate of the first monomeric component and the amine moiety of the second monomeric component, as described above.

[0125] Some additional non-limiting example Embodiments are below:

[0126] Embodiment 1. A composition comprising: a first monomeric component comprising a first functional group in a total amount of m molar equivalents; and a second monomeric component comprising a second functional group in a total amount of n molar equivalents, wherein the first functional group and the second functional group are polymerizable with one another; wherein the ratio of m to n is between 3:2 and 2:1; and wherein the first functional group is a cyclic carbonate.

[0127] Embodiment 2. The composition of Embodiment 1, wherein the first monomeric component comprises at least two cyclic carbonate functional groups per molecule.

[0128] Embodiment 3. The composition of Embodiment 2, wherein the first monomeric component comprises at least three cyclic carbonate functional groups per molecule. 44 PCT.798

[0129] Embodiment 4. The composition of any of Embodiments 1-3, wherein the second functional group comprises an amine group, a thiol group, or a hydroxyl group.

[0130] Embodiment 5. The composition of any of the preceding Embodiments, wherein the second monomeric component comprises at least two second functional groups per molecule.

[0131] Embodiment 6. The composition of any of the preceding Embodiments, further comprising a (meth)acrylate.

[0132] Embodiment 7. A method of printing a three-dimensional article comprising: selectively depositing layers of an ink in a fluid state onto a substrate, wherein the ink comprises the composition of any of Embodiments 1-6.

[0133] Embodiment 8. A printed three-dimensional article formed from the composition of any of Embodiments 1-6.

[0134] All patent documents referred to herein are incorporated by reference in their entireties. Various embodiments of the invention have been described in fulfillment of the various objectives of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptations thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of the invention. 45 PCT.798

Claims

CLAIMS 1. A composition comprising: a first monomeric component comprising a first functional group in a total amount of m molar equivalents; and a second monomeric component comprising a second functional group in a total amount of n molar equivalents, wherein the first functional group and the second functional group are polymerizable with one another; wherein the ratio of m to n is between 3:2 and 2:1; and wherein the first functional group is a cyclic carbonate.

2. The composition of claim 1, wherein the first monomeric component comprises at least two cyclic carbonate functional groups per molecule.

3. The composition of claim 2, wherein the first monomeric component comprises at least three cyclic carbonate functional groups per molecule.

4. The composition of claim 1, wherein the second functional group comprises an amine group, a thiol group, or a hydroxyl group.

5. The composition of claim 1, wherein the second monomeric component comprises at least two second functional groups per molecule.

6. The composition of claim 1 further comprising a (meth)acrylate.

7. A method of printing a three-dimensional article comprising: selectively depositing layers of an ink in a fluid state onto a substrate, wherein the ink comprises the composition of claim 1.

8. A printed three-dimensional article formed from the composition of claim 1. 46 PCT.798

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