Method of preparing water extractable silicon-containing biomedical devices

1. A method of preparing a water extractable silicon-containing biomedical device comprising; curing a monomer mixture in a mold, the monomer mixture comprising one or more silicon-containing biomedical device-forming monomers in the presence of a diluent to produce a silicon-containing biomedical device; wherein the diluent comprises a boric acid ester of a C 1 to C 8 monohydric alcohol; and dry releasing the silicon-containing biomedical device from the mold.

2. The method of claim 1 , wherein the silicon-containing biomedical device-forming monomer is a silicon-containing monomer containing one or more Si—O units.

3. The method of claim 1 , wherein the monomer mixture further comprises a hydrophilic monomer, hydrophobic monomer or both.

4. The method of claim 3 , wherein the hydrophilic monomer is selected from the group consisting of an unsaturated carboxylic acid, vinyl lactam, acrylamide, polymerizable amine, vinyl carbonate, vinyl carbamate, oxazolone monomer and mixtures thereof.

5. The method of claim 3 , wherein the hydrophilic monomer is selected from the group consisting of methacrylic and acrylic acids, 2-hydroxyethylmethacrylate, N-vinylpyrrolidone, methacrylamide, N,N-dimethylacrylamide and mixtures thereof.

6. The method of claim 3 , wherein the hydrophobic monomer is selected from the groups consisting of an ethylenically unsaturated polymerizable fluorine-containing monomer, ethylenically unsaturated polymerizable fatty acid ester-containing monomer, ethylenically unsaturated polymerizable polysiloxanylalkyl-containing monomer, ethylenically unsaturated polymerizable monomer having ring-opening reactive functionalities, and mixtures thereof.

7. The method of claim 3 , wherein the hydrophobic monomer is selected from the groups consisting of an ethylenically unsaturated polymerizable fluorine-containing monomer, ethylenically unsaturated polymerizable fatty acid ester-containing monomer, ethylenically unsaturated polymerizable ethylenically unsaturated polymerizable monomer having ring-opening reactive functionalities, and mixtures thereof.

8. The method of claim 1 , wherein the monomeric mixture comprises two or more silicon-containing biomedical device-forming monomer which are silicon-containing monomer containing one or more Si—O units, and one or more hydrophilic units.

9. The method of claim 1 , wherein the C 1 to C 8 monohydric alcohol of the boric acid ester is selected from the group consisting of C 1 to C 8 straight or branched chain monohydric alcohols, C 5 to C 8 cycloalkyl monohydric alcohols, C 5 to C 8 aromatic monohydric alcohols and mixtures thereof.

10. The method of claim 9 , wherein the C 1 to C 8 monohydric alcohol of the boric acid ester is selected from the group consisting of methanol, ethanol, propanol, n-propanol, iso-propanol, n-butanol, t-butanol, isobutanol, 2-ethylhexanol, 2-methylcyclohexanol, 2- methyl-1-propanol, n-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-2-butanol, 3,7-dimethyl-3-octanol, 2,2-dimethyl-1-propanol, 1-hexanol, 1-octanol, 2-octanol, cyclohexanol, cyclopentanol, benzyl alcohol, and mixtures thereof.

11. The method of claim 1 , wherein the boric acid ester of a C 1 to C 8 monohydric alcohol is trimethyl borate, triethyl borate, tri-n-propyl borate, triisopropyl borate, tri-n-butyl borate, or tri-tert-butyl borate.

12. The method of claim 1 , wherein the monomer mixture comprises about 5 to about 50 percent by weight of the boric acid ester of a C 1 to C 8 monohydric alcohol, based on the total weight of the monomer mixture.

13. The method of claim 1 , wherein the monomer mixture comprises about 15 to about 30 percent by weight of the boric acid ester of a C 1 to C 8 monohydric alcohol, based on the total weight of the monomer mixture.

14. The method of claim 1 , further comprising the step of replacing the diluent with water.

15. The method of claim 14 , wherein the silicon-containing biomedical device is a silicon hydrogel.

16. The method of claim 1 , further comprising lathing the silicon-containing biomedical device.

17. The method of claim 1 , wherein the mold is a one-piece mold having a concave bottom surface.

18. The method of claim 1 , wherein the mold comprises a first mold section having a molding surface shaped to provide a posterior biomedical device surface and a second mold section having a molding surface shaped to provide an anterior biomedical device surface.

19. The method of claim 18 , further comprising de-capping the first mold section from the second mold section and dry releasing the silicon-containing biomedical device from either the first mold section or the second mold section.

20. The method of claim 1 , further comprising contacting the silicon-containing biomedical device with a solvent.

21. The method of claim 20 , wherein the solvent is a polar solvent.

22. The method of claim 21 , wherein the polar solvent is water.

23. The method of claim 21 , wherein the polar solvent is an alcohol.

24. The method of claim 1 , wherein the silicon-containing biomedical device is an ophthalmic lens.

25. The method of claim 24 , wherein the ophthalmic lens is a contact lens.

26. A method for dry releasing a silicon-containing biomedical device from a mold, the method comprising the steps of:

(a) curing a monomer mixture in a mold under conditions sufficient to polymerize the monomer mixture to produce a water extractable silicon-containing biomedical device, wherein the monomer mixture comprises one or more silicon-containing biomedical device-forming monomers and a diluent; wherein the diluent comprises a boric acid ester of a C 1 to C 8 monohydric alcohol; and

(b) dry releasing the silicon-containing biomedical device from the mold.