Polysiloxane-based prepolymer and hydrogel

1. A polysiloxane-based prepolymer of a three-dimensional network structure produced by hydrolysis-condensation of a first mixture, said first mixture comprising:

(a) a tetra-alkoxysilane compound having the following formula (I):

wherein R 11 , R 12 , R 13 , and R 14 are independently a C 1 -C 8 alkyl group;

(b) an ethylenically unsaturated organosiloxane monomer having the following formula (II):

wherein R 21 , R 22 , and R 23 are independently a C 1 -C 6 alkyl group, and R 24 is a C 1 -C 6 alkyl group, a cyano group, or hydrogen, and X is a C 1 -C 4 alkylene, a single bond,

(c) a hydrophilic silicon-containing polyfunctional monomer having the following formula (III):

wherein Y is a C 2 -C 4 alkylene group, Z 1 and Z 2 independently represent a single bond or a C 1 -C 4 alkylene group, R 31 , R 32 , R 33 , R 34 , R 35 , and R 36 independently represent a C 1 -C 6 alkyl group, and d is an integer ranging from 3 to 90.

2. The polysiloxane-based prepolymer of claim 1 , wherein the molar ratio of said hydrophilic silicon-containing polyfunctional monomer to tetra-alkoxysilane to said ethylenically unsaturated organosiloxane monomer in the first mixture is 1:2˜22:2˜40.

3. The polysiloxane-based prepolymer of claim 1 , wherein tetra-alkoxysilane is tetraethoxysilane.

4. The polysiloxane-based prepolymer of claim 1 , wherein said ethylenically unsaturated organosiloxane monomer is vinyl trimethoxysilane.

5. A hydrogel used for preparation of contact lenses and produced by polymerizing a second mixture, said second mixture comprising:

(a) a polysiloxane-based prepolymer of claim 1 ;

(b) an acrylated silicon-containing monomer having the following formula (V):

wherein D represents O, NH, S or CH 2 ; E represents O or a single bond; R 60 represents H, CH 3 , ph, (CH 2 ) i CH 3 , CH(CH 3 ) 2 , C(CH 3 ) 3 or Cph 2 CH 3 ; R 61 , R 62 , and R 63 independently represent H, CH 3 , (CH 2 ) i CH 3 , CH(CH 3 ) 2 , C(CH 3 ) 3 , Cph 2 CH 3 , O[Si(CH 3 ) 2 O] j Si(CH 3 ) 3 or OSiR 66 R 67 R 68 , where R 66 , R 67 , and R 68 independently represent H, CH 3 or (CH 2 ) i CH 3 ; R 64 and R 65 independently represent H, OH, CH 3 , ph, (CH 2 ) i CH 3 , CH(CH 3 ) 2 , C(CH 3 ) 3 or Cph 2 CH 3 ; g is an integer from 0 to 2; e is an integer from 0 to 5; and f is an integer from 0 to 10; ph representing phenyl, i and j being independently integers from 1 to 10; and

(c) an ethylenically unsaturated hydrophilic monomer.

6. The hydrogel of claim 5 , wherein, based on the total weight of said second mixture, said polysiloxane-based prepolymer is present in an amount ranging from 3 to 50 wt %.

7. The hydrogel of claim 5 , wherein said acrylated silicon-containing monomer is selected from the group consisting of: tris(trimethylsiloxy)silylpropyl methacrylate, bis(trimethylsiloxy)methylsilylpropyl methacrylate, pentamethyldisiloxanepropyl methacrylate, pentamethyldisiloxanyl methylmethacrylate, tris(trimethylsiloxy)silylpropyloxyethyl methacrylate, tris(trimethylsiloxy)silylpropyl methylacryloxyethylcarbamate, tris(trimethylsiloxy)silylpropyl glycerol methacrylate, tris(polydimethylsiloxy)silylpropyl methacrylate, and combinations thereof.

8. The hydrogel of claim 5 , wherein said ethylenically unsaturated hydrophilic monomer is selected from the group consisting of: hydroxyethyl methacrylate, methacrylic acid, N-vinyl pyrrolidone, N,N′-dimethylacrylamide, N,N′-diethylacrylamide, N-isopropylacrylamide, 2-hydroxyethyl acrylate, vinyl acetate, N-acryloyl morpholine, 2-dimethylaminoethyl acrylate, and combinations thereof.

9. The hydrogel of claim 5 , wherein said second mixture further includes a linear silicone-containing prepolymer having the following formula (VI):

wherein n a1 /n b =0˜1.5, n a2 /n b =0˜1.5, and n b is an integer ranging from 4 to 50.