Articles prepared using curable compositions based on polymerizable ionic species
Curable compositions contain at least one polymerizable ionic species and, when cured (for example, by photocuring), provide cured compositions which are thermoplastic and yet fragmentable by a protic liquid medium such as water. The polymerizable ionic species corresponds to Formula (I) A+B− wherein A+ is a cationic species having a cationic functional group and a first polymerizable, ethylenically unsaturated functional group; and B″ is an anionic species having an anionic functional group and a second polymerizable, ethylenically unsaturated functional group which is the same as or different from the first polymerizable, ethylenically unsaturated functional group. The curable compositions are useful for forming sacrificial or temporary articles, for example by three-dimensional printing methods.
1. A method of making a three-dimensional article, comprising printing the three-dimensional article using a curable composition comprised of at least one polymerizable ionic species corresponding to Formula (I):
A + B − (I)
wherein A + is a cationic species comprising a cationic functional group and a first polymerizable, ethylenically unsaturated functional group; and B − is an anionic species comprising an anionic functional group and a second polymerizable, ethylenically unsaturated functional group which is the same as or different from the first polymerizable, ethylenically unsaturated functional group; wherein the curable composition comprises less than 10,000 ppm of each of (meth)acrylic anhydride and water and wherein the curable composition when cured provides a cured composition which is thermoplastic in the absence of a protic liquid medium, is fragmentable in a protic liquid medium and comprises ionic crosslinks as a result of incorporation of the ionic species into a polymeric matrix.
2. The method of claim 1 , wherein the curable composition when cured provides a cured composition having a hardness greater than 20 on a Durometer OO scale or greater than 0 on an A and D scale.
3. The method of claim 1 , wherein the curable composition when cured provides a cured composition which has a glass transition temperature of at least 35° C.
4. The method of claim 1 , wherein the anionic species is a (meth)acrylamide comprising an anionic functional group.
5. The method of claim 1 , wherein the cationic species is a protonated (meth)acrylamide.
6. The method of claim 1 , wherein the anionic functional group is selected from the group consisting of a sulfonate functional group, a sulfinate functional group, a phosphonate functional group, and a carboxylate functional group.
7. The method of claim 1 , wherein the cationic functional group is selected from the group consisting of ammonium functional groups and N-protonated amide functional groups.
8. The method of claim 1 , wherein the anionic species is selected from the group consisting of 2-acrylamido-2-methylpropane sulfonate, 2-methylacrylamido-2-methylpropanesulfonate, 2-acrylamidobutanesulfonate, 2-acrylamido-2,4,4-trimethylpentanesulfonic acid, vinylsulfonate, allylsulfonate, acrylate, methacrylate, crotonate, itaconate, maleate, fumarate, vinylphosphonate, allylphosphonate, N-(meth)acrylamidoalkylphosphonate, and (meth)acryloyloxyalkylphosphonate.
9. The method of claim 1 , wherein the cationic species is selected from the group consisting of protonated (meth)acrylamide, protonated N,N-dimethyl(meth)acrylamide, protonated N-substituted-(N′-dialkylaminoalkyl) (meth)acrylamides, protonated aminoalkyl(meth)acrylates, protonated dialkylaminoalkyl(meth)acrylates, protonated diacetone (meth)acrylamides and protonated tert-butylaminoethyl (meth)acrylates.
10. The method of claim 1 , wherein the anionic species is 2-acrylamido-2-methylpropane sulfonate and the cationic species is protonated N, N-dimethyl acrylamide.
11. The method of claim 1 , wherein the curable composition additionally comprises at least one carrier polymer which is a water-soluble thermoplastic.
12. The method of claim 1 , wherein the curable composition additionally comprises at least one additive selected from the group consisting of photoinitiators, antioxidants, and light blockers.
13. The method of claim 1 , wherein the curable composition does not contain more than 5000 ppm in total of any compound containing two or more polymerizable ethylenically unsaturated functional groups and capable of forming covalent crosslinks in the cured composition.
14. The method of claim 1 , wherein the curable composition additionally comprises at least one polymerizable mono-ethylenically unsaturated co-monomer which is not a polymerizable ionic species corresponding to Formula (I).
15. The method of claim 1 , comprising curing the curable composition by initiating free radical polymerization of the curable composition.
16. The method of claim 1 , comprising photocuring the curable composition.
17. The method of claim 1 , wherein printing of the three-dimensional article is carried out in a layer-by-layer or continuous manner.
18. The method of claim 1 , wherein printing of the three-dimensional article comprises at least the following steps:
a) coating a first layer of the curable composition onto a surface;
b) curing the first layer, at least partially, to provide a cured first layer;
c) coating a second layer of the curable composition onto the cured first layer;
d) curing the second layer, at least partially, to provide a cured second layer adhered to the cured first layer; and
e) repeating steps c) and d) a desired number of times to build up the three-dimensional article.
19. The method of claim 1 , wherein printing of the three-dimensional article comprises at least the following steps:
a) coating a first layer of the curable composition in liquid form onto a surface;
b) exposing the first layer imagewise to actinic radiation to form a first exposed imaged cross-section, wherein the radiation is of sufficient intensity and duration to cause at least partial curing of the first layer in the exposed area(s);
c) coating an additional layer of the curable composition in liquid form onto the previously exposed imaged cross-section;
d) exposing the additional layer imagewise to actinic radiation to form an additional imaged cross-section, wherein the radiation is of sufficient intensity and duration to cause at least partial curing of the additional layer in the exposed area(s) and to cause adhesion of the additional layer to the previously exposed imaged cross-section;
e) repeating steps c) and d) a desired number of times to build up the three-dimensional article.
20. The method of claim 1 , wherein printing of the three-dimensional article comprises at least the following steps:
a) providing a carrier and an optically transparent member having a build surface, the carrier and build surface defining a build region there between;
b) filling the build region with the curable composition;
c) continuously or intermittently irradiating the build region with actinic radiation to form a cured composition from the curable composition; and
d) continuously or intermittently advancing the carrier away from the build surface to form the three-dimensional article from the cured composition.
21. A three-dimensional article obtained by the method of claim 1 .