Silicone membranes

1. A method of preparing a membrane, comprising:

(a) providing an emulsion that includes crosslinked polysiloxane and a surfactant;

(b) applying the emulsion to a substrate to form an emulsion soaked substrate;

(c) contacting the emulsion soaked substrate with an aqueous salt bath to thereby form a pre-dried membrane including the substrate and a cured silicone composition; and

(d) drying the pre-dried membrane.

2. The method of claim 1 , wherein the aqueous salt bath comprises a calcium or magnesium salt.

3. The method of claim 1 , wherein the emulsion further comprises a pH-adjuster, a filler, a pigment, or any combination thereof.

4. The method of claim 1 , wherein steps (b) and (c) are repeated to provide a selected membrane thickness.

5. The method of claim 1 , wherein step (c) comprises passing the emulsion soaked substrate through the aqueous salt bath.

6. The method of claim 1 , wherein the emulsion is prepared by combining the following:

(i) 40 to 60 wt % of a hydroxyl-terminated polysiloxane;

(ii) 1 to 3 wt % of a crosslinker;

(iii) 0.1 to 1 wt % of a catalyst;

(iv) 1 to 3 wt % of a surfactant; and

(v) 40 to 60 wt % water,

wherein wt % is based on total weight of the composition.

7. The method of claim 6 , wherein the hydroxyl-terminated polysiloxane has a viscosity of 20,000 to 300,000 cps.

8. The method of claim 6 , wherein the hydroxyl-terminated polysiloxane has formula:

wherein n ranges from 10 to 1,000.

9. The method of claim 6 , wherein the crosslinker is an alkoxy silane, an oxime silane, or an acetoxy silane.

10. The method of claim 6 , wherein the crosslinker is methyltrimethoxysilane or aminopropyltrimethoxysilane.

11. The method of claim 6 , wherein the catalyst is dimethyltin dineodecanoate, dibutyl tin dilaurate, or stannous octoate.

12. The method of claim 6 , wherein the surfactant is 3-(polyoxyethylene)propylheptamethyltrisiloxane.

13. The method of claim 6 , wherein the emulsion further comprises a pH-adjuster, a filler, a pigment, or any combination thereof.

14. The method of claim 6 , where the surfactant is selected from the group consisting of ethoxylated long chain alcohols, ethoxylated 3-hydroxypropylheptamethyltrisiloxane, ethoxylated silicone polyether, polyalkyleneoxide modified heptamethyltrisiloxane, polydimethylsiloxane, polyalkyleneoxide polysiloxane, or any combination thereof.

15. The method of claim 1 , wherein the emulsion is prepared by combining the following:

(i) hydroxyl-terminated polysiloxane;

(ii) crosslinker;

(iii) catalyst;

(iv) surfactant; and

(v) water.

16. The method of claim 15 , wherein the hydroxyl-terminated polysiloxane has formula:

wherein n ranges from 10 to 1,000.

17. The method of claim 1 , where said step of drying the pre-dried membrane forms a dried membrane, and further comprising the step of rolling the dried membrane.