Method for forming hydrogels and materials therefor
The present invention provides a dry powder that is suitable for use in forming a hydrogel and characterized by a stable composition at ambient conditions. The dry powder includes a prepolymer including a straight chain polyethylene glycol, and a thermally activated free radical initiator selected from the group consisting of sodium persulfate, potassium persulfate, and ammonium persulfate. The present invention also provides a method of forming the dry powder, and a method of preparing a hydrogel where a reaction mixture is formed including the dry powder and a buffered aqueous solution.
1. A method of preparing a hydrogel comprising:
providing separate amounts of:
a dry powder mixture comprising a first prepolymer and a free radical initiator;
a buffered aqueous solution;
an aqueous solution comprising a second prepolymer; and
an initiator catalyst solution;
wherein the dry powder mixture is stable at ambient conditions and characterized by a particle size of about 500 microns or less,
wherein the first prepolymer comprises a straight chain polyethylene glycol, and
wherein the second prepolymer comprises a branched polyethylene glycol;
combining the dry powder mixture with the buffered aqueous solution, to form a first mixture;
combining the second prepolymer solution with the initiator catalyst solution to form a second mixture;
combining the first and second mixture under suitable conditions to form the hydrogel.
2. The method of claim 1 , wherein the straight chain polyethylene glycol is terminally derivatized with acrylate, methacrylate, vinyl, or substituted vinyl end groups.
3. The method of claim 2 , wherein the straight chain polyethylene glycol is terminally derivatized with two acrylate groups.
4. The method of claim 2 , wherein the branched chain polyethylene glycol is terminally derivatized with three acrylate groups.
5. The method of claim 1 , wherein the free radical initiator is selected from the group consisting of amines, persulfates or ferrous compounds.
6. A method of preparing a hydrogel comprising:
providing separate amounts of:
a dry powder mixture comprising a first prepolymer and a free radical initiator;
a buffered aqueous solution; and
an aqueous solution comprising a second prepolymer, and an initiator catalyst;
wherein the dry powder mixture is stable at ambient conditions and characterized by a particle size of about 500 microns or less,
wherein the first prepolymer comprises a straight chain polyethylene glycol, and
wherein the second prepolymer comprises a branched polyethylene glycol;
combining the dry powder mixture with the buffered aqueous solution, to form a first mixture;
combining the first mixture with the aqueous solution comprising the second prepolymer and initiator catalyst under suitable conditions to form the hydrogel.
7. The method of claim 6 , wherein the straight chain polyethylene glycol is terminally derivatized with acrylate, methacrylate, vinyl, or substituted vinyl end groups.
8. The method of claim 7 , wherein the straight chain polyethylene glycol is terminally derivatized with two acrylate groups.
9. The method of claim 7 , wherein the branched chain polyethylene glycol is terminally derivatized with three acrylate groups.
10. The method of claim 6 , wherein the free radical initiator is selected from the group consisting of amines, persulfates or ferrous compounds.
11. A method of preparing a hydrogel comprising:
providing a dry powder mixture comprising:
a non-crosslinked prepolymer comprising a straight chain polyethylene glycol and a free radical initiator;
wherein the dry powder mixture is stable at ambient conditions and characterized by a particle size of about 500 microns or less;
providing an aqueous solution comprising a branched polyethylene glycol and an initiator catalyst;
combining the dry powder mixture with the aqueous solution under suitable conditions to form the hydrogel.
12. A method of preparing a dry powder mixture comprising:
preparing a solution comprising:
a prepolymer comprising a straight chain polyethylene glycol; and
a thermally activated free radical initiator selected from the group consisting of sodium persulfate, potassium persulfate, and ammonium persulfate; and
dehydrating the solution, to form a dry powder that is stable at ambient conditions and has particle size of about 500 microns or less.
13. A powder mixture formed according to the method of claim 12 .
14. The method of claim 10 , wherein dehydrating the solution comprises lyophilizing or spray drying the solution.