Method for end-capping a polysiloxane prepolymer

1. A method comprising the steps of:

(a) reacting a polysiloxane prepolymer having reactive functional end groups with a non-free radical polymerizable reactive end-capping agent, wherein the non-free radical polymerizable reactive end-capping agent is one of a carbonyl-containing non-free radical polymerizable reactive end-capping agent of the general formula:

wherein R 8 is a non-reactive moiety and C(O)X is a non-free radical polymerizable reactive group, or a chloroformate of the general formula:

wherein R 8 has the aforestated meaning; and

(b) reacting the reaction product of step (a) with a free-radical polymerizable reactive end-capping agent.

2. The method of claim 1 , wherein the polysiloxane prepolymer is of formula I:

wherein each R is an independently reactive functional end group, R 1 to R 6 are independently straight or branched, substituted or unsubstituted C 1 -C 30 alkyl group, a substituted or unsubstituted C 3 -C 30 cycloalkyl group, a substituted or unsubstituted C 4 -C 30 cycloalkylalkyl group, a substituted or unsubstituted C 3 -C 30 cycloalkenyl group, a substituted or unsubstituted C 6 -C 30 aryl group, and a substituted or unsubstituted C 7 -C 30 arylalkyl group, and L is independently a linking group.

3. The method of claim 2 , wherein the reactive functional end group includes the same or different reactive functional end group selected from the group consisting of a hydroxyl-containing reactive functional end group and an amine-containing reactive functional end group.

4. The method of claim 1 , wherein the reactive functional end group is —OH.

5. The method of claim 1 , wherein the reactive functional end group is an amine-containing reactive functional end group of the general formula —NHR 7 wherein R 7 is independently hydrogen, an alkyl group, an aryl group, and a cycloalkyl group.

6. The method of claim 1 , wherein the L linking group is independently a straight or branched alkyl group, cycloalkyl group, an aryl group, an ether or polyether group, and an ester group.

7. The method of Claim 1 , wherein R 8 is selected from the group consisting of C 1 to C 18 alkyl groups, C 3 to C 18 cycloalkyl groups and C 6 to C 18 aryl groups and X is selected from the group consisting of —OH, halogen and —OR 9 wherein R 9 is a substituted or unsubstituted heteroaryl or —C(O)R 8 wherein le has the aforestated meanings.

8. The method of claim 1 , wherein the non-free radical polymerizable reactive end-capping agent is reacted with the polysiloxane prepolymer in an amount ranging from about 3 to about 15 mole % of non-free radical polymerizable reactive end-capping agent per mole of end groups in the polymer.

9. The method of claim 1 , wherein the non-free radical polymerizable reactive end-capping agent is reacted with the polysiloxane prepolymer in an amount ranging from about 1 to about 30 mole % of non-free radical polymerizable reactive end-capping agent per mole of end groups in the polymer.

10. The method of claim 1 , wherein the non-free radical polymerizable reactive end-capping agent is reacted with the polysiloxane prepolymer at a temperature ranging from about 0° C. to about 40° C.

11. The method of claim 1 , wherein the free radical polymerizable reactive end-capping agent is a free radical polymerizable reactive end-capping agent having at least one ethylenically unsaturated reactive end group.

12. The method of claim 1 , wherein the free radical polymerizable reactive end-capping agent is selected from the group consisting of a (meth)acrylate-containing free radical polymerizable reactive end-capping agent, a vinyl-containing free radical polymerizable reactive end-capping agent, an unsaturated acidic-containing free radical polymerizable reactive end-capping agent and a styryl-containing free radical polymerizable reactive end-capping agent.

13. The method of claim 12 , wherein the free radical polymerizable reactive end-capping agent is a (meth)acrylate-containing free radical polymerizable reactive end-capping agent selected from the group consisting of a symmetrical (meth)acrylate-containing acid anhydride free radical polymerizable reactive end-capping agent, a (meth)acrylate-containing acid chloride free radical polymerizable reactive end-capping agent, a (meth)acrylate-containing carboxylic acid free radical polymerizable reactive end-capping agent, a (meth)acrylate-containing carbonyl-containing free radical polymerizable reactive end-capping agent, and a (meth)acrylate-containing isocyanate- containing free radical polymerizable reactive end-capping agent.

14. The method of claim 12 , wherein the free radical polymerizable reactive end-capping agent is a vinyl-containing free radical polymerizable reactive end-capping agent selected from the group consisting of a vinyl isocyanate free radical polymerizable reactive end-capping agent, and a vinyl chloroformate free radical polymerizable reactive end-capping agent.

15. The method of claim 12 , wherein the free radical polymerizable reactive end-capping agent is an unsaturated acidic-containing free radical polymerizable reactive end-capping agent which is maleic anhydride.

16. The method of claim 1 , wherein the free radical polymerizable reactive end-capping agent is reacted with the product of step (a) in an excess amount.

17. The method of claim 1 , wherein the free radical polymerizable reactive end- capping agent is reacted with the product of step (a) at a temperature ranging from about 0° C. to about 40° C.

18. The method of claim 1 , wherein the product of step (b) is further reacted with one or more biomedical-device forming monomers to obtain a biomedical device.

19. The method of claim 18 , wherein the biomedical device is an ophthalmic lens.

20. The method of claim 18 , wherein the biomedical device is a contact lens.

21. The method of claim 18 , wherein the biomedical device is an intraocular lens.

22. The method of claim 1 , wherein the carbonyl-containing non-free radical polymerizable reactive end-capping agent is represented by a structure of the general formula:

wherein R 8 has the aforestated meaning.

23. The method of claim 1 , wherein the reaction of the non-free radical polymerizable reactive end-capping agent with the polysiloxane prepolymer is carried out in the presence of a solvent.