Hydrogel compositions for direct-write printing applications

Patent metadata

Field	Value
Publication number	US-9868870-B2
Application number	US-201615071787-A
Country	US
Kind code	B2
Filing date	Mar 16, 2016
Priority date	Mar 16, 2016
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

A thermo-responsive shear-thinning photo-curable composition comprises water, a linear amphiphilic polyether ABA triblock copolymer comprising at least one pendent ene group (*—CH═CH 2 ) capable of undergoing a thiol-ene reaction, a water-soluble crosslinking agent comprising two or more methylenethiol groups (*—CH 2 SH), and a photoinitiator. Under non-shear conditions and a triblock copolymer concentration suitable for direct-write printing, the composition is a viscoelastic solid (hydrogel) at a temperature of about 15° C. to about 45° C., and is a free-flowing liquid (sol) between 0° C. and about 10° C. The hydrogel form can be shear-thinned at about 15° C. to about 45° C. to form a sol suitable for a direct-write printer using an extruding print-head. The compositions covalently crosslink when flood-exposed to ultraviolet radiation. The compositions have utility in forming three-dimensional scaffolds for growing living cells.

First claim

What is claimed is:

1. A crosslinkable composition, comprising:
water;
an ABA type polyether triblock copolymer comprising a central hydrophilic poly(ethylene oxide) block (block B) linked to two peripheral hydrophobic polyether blocks (blocks A), wherein each of the blocks A comprises a random copolymer of i) a first repeat unit of formula (2):

wherein R′ is a monovalent C 1 -C 10 hydrocarbon group selected from the group consisting of saturated alkyl groups and aromatic groups, and ii) a second repeat unit of formula (3):

wherein L′ is a monovalent C 1 -C 10 hydrocarbon radical comprising an ene group (*—CH═CH 2 ) capable of undergoing a thiol-ene reaction;
a water-soluble crosslinking agent comprising two or more methylenethiol groups (*—CH 2 SH); and
a photoinitiator capable of abstracting hydrogen from a thiol group when exposed to ultraviolet light of wavelength 10 nm to 400 nm;

wherein
the triblock copolymer, the crosslinking agent, and the photoinitiator are in contact with the solvent,
the composition is a liquid at a temperature between 0° C. and about 10° C. and a shear-thinning viscoelastic solid at a temperature of about 15° C. to about 45° C. before crosslinking.

2. The composition of claim 1 , wherein the composition is suitable as an ink for a direct write printing process using an extruding print-head operating at a temperature of about 15° C. to about 45° C.

3. The composition of claim 1 , wherein the composition comprises the triblock copolymer in an amount of about 10-30 wt %, based on total weight of the composition.

4. The composition of claim 1 , wherein R′ is iso-propyl.

5. The composition of claim 4 , wherein L′ is allyl.

6. The composition of claim 1 , wherein the number average molecular weight (Mn) of block B is at least 3 times the Mn of each of blocks A.

7. The composition of claim 1 , wherein the molar ratio of first repeat unit:second repeat of the triblock copolymer is about 100:1 to 3:1.

8. The composition of claim 1 , wherein each of the blocks A has a number average molecular weight (Mn) of about 2400.

9. The composition of claim 1 , wherein the crosslinking agent is selected from the group consisting of 1,2-ethanedithiol, 1,3-propanedithiol, and 1,4-dithiothreitol, and materials of formula (7):

wherein n′ represents average degree of polymerization, and n′ has a value of 1 to 300.

10. The composition of claim 1 , wherein the crosslinking agent is selected from the group consisting of 1,2-ethanedithiol, 1,4-dithiothreitol, and combinations thereof.

11. The composition of claim 1 , wherein the photoinitiator is capable of abstracting hydrogen from a thiol when exposed to ultraviolet light having a wavelength between 300 nm and 400 nm.

12. The composition of claim 1 , wherein the photoinitiator is an alpha-hydroxyalkylphenylketone.

13. The composition of claim 1 , wherein triblock copolymer comprises the first repeat unit and the second repeat unit in a molar ratio of about 10:1 to 8:1.

14. A film layer comprising the composition of claim 1 .

15. A method of printing, comprising:
providing a direct-write printer comprising a printer reservoir containing the composition of claim 1 at a temperature of about 15° C. to about 45° C., the printer equipped with an extruding print-head capable of disposing microdrops and/or strands of the composition pattern-wise onto a surface of a substrate;
extruding the microdrops and/or the strands of the composition from the print-head onto the surface using one or more passes of the print-head over the surface, thereby forming an initial structure comprising a stack of one more patterned layers of the composition disposed on the surface, the layers comprising a self-supporting non-covalently crosslinked hydrogel form of the composition; and
flood-exposing the initial structure with ultraviolet light, thereby forming a photo-cured structure comprising a stack of one more photo-cured patterned layers, the photo-cured patterned layers comprising covalently crosslinked triblock copolymer.

16. The method of claim 15 , wherein the ultraviolet light has a wavelength between 300 nm and 400 nm.

17. The method of claim 15 , comprising separating the photo-cured structure from the substrate.

18. The method of claim 15 , wherein said flood-exposing the initial structure with ultraviolet light initiates a thiol-ene reaction.

19. The method of claim 15 , wherein the photo-cured structure is suitable as a scaffold for growing living cells thereon.

20. The photo-cured structure formed by the method of claim 15 .

Assignees

• IBM

Inventors

• Engler Amanda C
• Han Wei
• Maune Hareem T
• Nelson Alshakim
• Vora Ankit
• Wojtecki Rudy J
• Zhang Mu San

Classifications

• C09D11/101

  Inks specially adapted for printing processes involving curing by wave energy or particle radiation, e.g. with UV-curing following the printing · CPC title

• A61L2420/02

  Methods for coating medical devices · CPC title

• A61L27/18

  obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• C09D11/102 Primary

  containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds · CPC title

• B05B17/0607

  generated by electrical means, e.g. piezoelectric transducers · CPC title