Imbibing process for contact lens surface modification

1. A process for modifying the surface of a silicon-containing hydrogel, the process comprising the steps of:

imbibing a zwitterionic monomer into the silicon-containing hydrogel in an imbibing mixture comprising the silicon-containing hydrogel, the zwitterionic monomer and a solvent system; wherein the imbibing absorbs the monomer into the hydrogel; and polymerizing the zwitterionic monomer to modify the surface of the silicon-containing polymer with a zwitterionic polymer in a polymerization reaction mixture, the polymerization reaction mixture comprising the imbibed silicon-containing hydrogel, a solvent system, the zwitterionic monomer and a free radical initiator, the polymerization reaction mixture having a composition that differs from the composition of the imbibing mixture.

2. The process of claim 1 wherein the imbibing mixture further comprises a hydrophilic free radical initiator.

3. The process of claim 1 wherein the imbibing mixture comprises the hydrophilic free radical initiator and the zwitterionic monomer, and the imbibing mixture and polymerization reaction comprise different solvent systems.

4. The process of claim 1 wherein the silicon-containing hydrogel contains at least 1 wt. % silicon.

5. The process of claim 1 wherein the silicon-containing hydrogel contains at least 20 wt. % silicon.

6. The process of claim 1 wherein the zwitterionic polymer comprises a carboxyammonium polymer or a sulfoammonium polymer.

7. The process of claim 1 wherein the zwitterionic polymer comprises a carboxybetaine polymer or a sulfobetaine polymer.

8. The process of claim 1 wherein the zwitterionic polymer comprises at least one repeat unit corresponding to Formula 2:

wherein

X 3 is hydrogen, alkyl or substituted alkyl, and

X 4 is a pendant group comprising an oxylated alkylene moiety, a zwitterionic moiety, an anionic moiety, or a cationic moiety.

9. The process of claim 8 wherein X 3 is hydrogen or alkyl.

10. The process of claim 8 wherein the repeat unit of Formula 2 is a zwitterionic repeat unit comprising a zwitterionic moiety corresponding to Formula ZI-1, ZI-2, ZI-3, ZI-4, ZI-5, ZI-6A, ZI-6B, or ZI-7;

wherein

T 1 and T 2 are independently oxygen, sulfur, NH or a bond,

T 3 is hydrocarbylene, substituted hydrocarbylene, ether, or oxylated alkylene,

Z 1 is a moiety comprising a quaternary nitrogen, phosphonium or sulfonium cationic group, and

* designates the point of covalent attachment, direct or indirect, of the zwitterion of Formula ZI-1 to the polymer backbone;

wherein * designates the point of covalent attachment of the zwitterion of Formula ZI-2 to the polymer backbone, T 3 is hydrocarbylene, substituted hydrocarbylene, or oxylated alkylene, and T 4 , T 5 and T 6 are independently hydrogen, hydrocarbyl, substituted hydrocarbyl or heterocyclo;

wherein

T 8 is a bond, hydrocarbylene, substituted hydrocarbylene, heterocyclo, or in combination with T 9 and T 10 and the nitrogen atom to which they are attached form a nitrogen-containing heteroaromatic ring,

T 9 and T 10 are independently hydrogen, hydrocarbyl, substituted hydrocarbyl or heterocyclo, or, T 9 and T 10 , in combination with T 8 and the nitrogen atom to which they are attached form a nitrogen-containing heteroaromatic ring,

T 11 is hydrocarbylene, substituted hydrocarbylene, ether, or oxylated alkylene,

Z 3 is carboxylate, phosphate, phosphonic, phosphonate, sulfate, sulfinic, or sulfonate, and

* designates the point of covalent attachment, direct or indirect, of the zwitterion of Formula ZI-3 to the polymer backbone;

wherein * designates the point of covalent attachment, direct or indirect, of the zwitterion of Formula ZI-4 to the polymer backbone; T 12 is a bond or —(CH 2 ) m —with m being 1 to 3;

T 13 and T 14 are independently hydrogen, alkyl, or substituted alkyl; T 15 is optionally substituted alkylene, phenylene, ether, or oxylated alkylene; and Z 4 is carboxylate or sulfate;

wherein * designates the point of covalent attachment, direct or indirect, of the zwitterion of Formula ZI-5 to the polymer backbone; HET is a heterocycle containing a quaternary nitrogen atom, T 15 is optionally substituted alkylene, phenylene, ether, or oxylated alkylene; and Z 4 is carboxylate or sulfate;

wherein * designates the point of covalent attachment, direct or indirect, of the zwitterion of Formulae ZI-6A and ZI-6B to the polymer backbone; T 15 is optionally substituted alkylene, phenylene, ether, or oxylated alkylene; and Z 4 is carboxylate or sulfate;

wherein T 4 , T 5 and T 6 are independently hydrogen, hydrocarbyl, substituted hydrocarbyl or heterocyclo; T 12 is a bond, hydrocarbylene, substituted hydrocarbylene, or heterocyclo, and * designates the point of covalent attachment, direct or indirect, of the zwitterion of Formula ZI-7 to the polymer backbone.

11. The process of claim 1 wherein the zwitterionic polymer comprises repeat units corresponding to Formula 3:

wherein X 44 comprises an oxylated alkylene moiety, a zwitterionic moiety, an anionic moiety, or a cationic moiety.

12. The process of claim 11 wherein X 44 is —OX 45 , —NHX 45 , or —SX 45 , and X 45 is a substituted hydrocarbyl or heterocyclo moiety comprising an oxylated alkylene moiety, a zwitterionic moiety, an anionic moiety, or a cationic moiety.

13. The process of claim 11 wherein X 44 is —O(CH 2 ) 2 N + (CH 3 ) 2 (CH 2 ) n SO 3 − , —O(CH 2 ) 2 N + (CH 3 ) 2 (CH 2 ) n CO 2 − , —NH(CH 2 ) 3 N + (CH 3 ) 2 (CH 2 ) n CO 2 − , or —NH(CH 2 ) 3 N + (CH 3 ) 2 (CH 2 ) n SO 3 − , and n is 1-8.

14. The process of claim 11 wherein X 44 is —NH(CH 2 ) m N(CH 2 ) n CH 3 (CH 2 ) p SO 3 , —NH(CH 2 ) m N(CH 2 ) n CH 3 (CH 2 ) p CO 2 , —NH(CH 2 ) m N + [(CH 2 ) n CH 3 ] 2 (CH 2 ) p SO 3 , —NH(CH 2 ) N + [(CH 2 ) n CH 3 ] 2 (CH 2 ) p CO 2 , —NH(CH 2 ) m Ncyclo-(CH 2 ) p CO 2 , or —NH(CH 2 ) m Ncyclo-(CH 2 ) p SO 3 , Ncyclo- is a heterocyclic structure or a heterocyclic derivative containing at least one nitrogen atom, m is 1-8; n is 0-5; and p is 1-8.

15. The process of claim 11 wherein X 44 is —O(CH 2 ) m N(CH 2 ) n CH 3 (CH 2 ) p SO 3 , —O(CH 2 ) m N(CH 2 ) n CH 3 (CH 2 ) p CO 2 , —O(CH 2 ) m N + [(CH 2 ) n CH 3 ] 2 (CH 2 ) p SO 3 , —O(CH 2 )N + [(CH 2 ) n CH 3 ] 2 (CH 2 ) p CO 2 , —O(CH 2 ) m Ncyclo-(CH 2 ) p CO 2 , or —O(CH 2 ) m Ncyclo-(CH 2 ) p SO 3 , Ncyclo- is a heterocyclic structure or a heterocyclic derivative containing at least one nitrogen atom, m is 1-8; n is 0-5; and p is 1-8.

16. The process of claim 11 wherein X 44 is —O(CH 2 ) 2 N + (CH 3 ) 2 (CH 2 ) 3 SO 3 , —O(CH 2 ) 2 N + (CH 3 ) 2 (CH 2 ) 2 CO 2 , —NH(CH 2 ) 2 N + (CH 3 ) 2 (CH 2 ) 3 SO 3 , —NH(CH 2 ) 2 N + (CH 3 ) 2 (CH 2 ) 2 CO 2 , —NH(CH 2 ) 3 N + (CH 3 ) 2 (CH 2 ) 3 SO 3 , —NH(CH 2 ) 3 N + (CH 3 ) 2 (CH 2 ) 2 CO 2 , —O(CH 2 ) 2 N + (CH 2 CH 3 ) 2 (CH 2 ) 3 SO 3 , —O(CH 2 ) 2 N + (CH 2 CH 3 ) 2 (CH 2 ) 2 CO 2 , —O(CH 2 ) 2 N + (CH 2 CH 2 CH 2 CH 3 ) 2 (CH 2 ) 3 SO 3 , —O(CH 2 ) 2 N + (CH 2 CH 2 CH 2 CH 3 ) 2 (CH 2 ) 2 CO 2 or —NH(CH 2 ) 3 Ncyclo-(CH 2 ) 3 SO 3 and Ncyclo- is a heterocyclic structure or a heterocyclic derivative containing at least one nitrogen atom.

17. An article formed by the process of claim 1 .

18. The article of claim 17 wherein the article is a contact lens.