Hydrogel compositions bonded to polymeric substrates

1. A multilayer article comprising:

a polymeric substrate comprising an abstractable atom; and

(ii) a hydrogel coating thereon wherein the hydrogel coating has a water content of at least 10 wt % and is covalently bonded to the polymer substrate, and wherein the hydrogel coating is derived from an aqueous composition having a pH less than 9.5, the aqueous composition comprising:

(a) a hydrophilic monomer selected from at least one of (meth)acrylate or (meth)acrylamide;

(b) at least 0.1 wt % of a water-swellable clay;

(c) a first initiator, wherein the first initiator is water-soluble and is a Type I photoinitiator; and

(d) a second initiator, wherein the second initiator is water-soluble and is a Type II photoinitiator; and

(e) an acid, wherein the polymer substrate is substantially free of a primer.

2. The multilayer article of claim 1 , wherein the polymer substrate is selected from the group consisting of polyurethanes, polyester, polypropylene, and combinations thereof.

3. The multilayer article of claim 1 , wherein the first initiator is 2-hydroxy-4′-(2-hydroxyethoxy)-2-methyl propiophenone.

4. The multilayer article of claim 1 , wherein the aqueous composition is substantially free of an alcohol.

5. The multilayer article of claim 1 , wherein the aqueous composition has a pH less than 8.

6. The multilayer article of claim 1 , wherein the hydrogel coating has a thickness of at least 0.1 mm.

7. The multilayer article of claim 1 , wherein the hydrogel coating further comprises an additive selected from the group consisting of polyethylene glycol, polyethylene glycol-co-polypropylene oxide copolymers, partially hydrolyzed polyvinyl acetate, polyvinyl pyrrolidone, glycerol or glycerol derivative, methylcellulose or other cellulose derivative, polyoxazoline, natural gums, and combinations thereof.

8. The multilayer article of claim 1 , wherein the multilayer article is a wound dressing.

9. The multilayer article of claim 1 , wherein the second initiator is selected from the group consisting of 4-(3-sulfopropyloxy)benzophenone, 2-(3-sulfopropyloxy) thioxanthen-9-one, carboxybenzophenone, salts thereof, and combinations thereof.

10. The multilayer article of claim 1 , wherein the aqueous composition comprises 0.5-20% by weight of the water-swellable clay.

11. The multilayer article of claim 1 , wherein the aqueous composition comprises 0.001 to 5% by weight of the first initiator.

12. The multilayer article of claim 1 , wherein the aqueous composition comprises 0.01 to 5% by weight of the second initiator.

13. The multilayer article of claim 1 , wherein the water-swellable clay is selected from the group consisting of laponite, synthetic hectorite, montmorillonite, and combinations thereof.

14. The multilayer article of claim 1 , wherein the hydrogel coating further comprises an antimicrobial agent.

15. The multilayer article of claim 1 , wherein the polymer substrate comprises a polyurethane.

16. The multilayer article of claim 1 , wherein the polymer substrate is a polyurethane.

17. The multilayer article of claim 1 , further comprising a release liner on the hydrogel coating.

18. A method of making a hydrogel coated article, the method comprising:

(i) providing an aqueous composition having a pH less than 9.5, the aqueous composition comprising:

(a) a hydrophilic monomer selected from at least one of (meth)acrylate or (meth)acrylamide;

(b) at least 0.1 wt % of a water-swellable clay;

(c) a first initiator, wherein the first initiator is water-soluble and is a Type I photoinitiator;

(d) a second initiator, wherein the second initiator is water-soluble and is a Type II photoinitiator; and

(e) an acid;

(ii) contacting the aqueous composition to a polymer substrate comprising an abstractable atom, wherein the polymer substrate is substantially free of a primer; and

(iii) curing the aqueous composition to provide a hydrogel coating on the polymer substrate, wherein the hydrogel coating has a water content of at least 10 wt % and is covalently bonded to the polymer substrate.

19. The method of claim 18 , wherein the curing is by UV radiation.