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This application discloses porous self-sealing media comprising a sintered mixture of an absorbent material and a thermoplastic. The self-sealing media block passage of organic solvents or organic solvents in aqueous mixtures, wherein the organic solvents are at concentrations greater than about 40%

This application discloses porous self-sealing media comprising a sintered mixture of an absorbent material and a thermoplastic. The self-sealing media block passage of organic solvents or organic solvents in aqueous mixtures, wherein the organic solvents are at concentrations greater than about 40%. The self-sealing media also block acidic solutions. The self-sealing media are useful in a variety of applications such as a pipette tip filter, in line filter, vent, non-mechanical check valve, safety valve, and suction canister.

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1. A porous self-sealing composition comprising a sintered porous matrix of particles of an absorbent material and particles of a thermoplastic, wherein the absorbent material comprises polyacrylic acid, and the polyacrylic acid is linear polyacrylic acid with a molecular weight greater than 100 KDa

1. A porous self-sealing composition comprising a sintered porous matrix of particles of an absorbent material and particles of a thermoplastic, wherein the absorbent material comprises polyacrylic acid, and the polyacrylic acid is linear polyacrylic acid with a molecular weight greater than 100 KDa or cross-linked polyacrylic acid with a linear backbone molecular weight between adjacent crosslinks (Mc) greater than 10 KDa. 2. The composition of claim 1, wherein the absorbent material in the sintered porous matrix is from about 1% to about 45%, from about 3% to about 40%, from about 5% to about 35%, or from about 10% to about 30%, by weight of the sintered porous matrix. 3. The composition of claim 1, wherein the sintered porous matrix has a porosity of from about 10% to about 70%, from about 20% to about 60%, or from about 30% to about 50%. 4. The composition of claim 1, wherein the sintered porous matrix has an average pore size of from about 1 micron to about 200 microns, from about 5 microns to about 100 microns, or from about 10 microns to about 50 microns. 5. The composition of claim 1, wherein the cross-linked polyacrylic acid has a cross-linking density of less than about 0.5%, less than about 0.2% or less than about 0.1%. 6. The composition of claim 1, wherein the thermoplastic particles are selected from the group consisting of polyethylene, polypropylene and polyvinylidene fluoride (PVDF). 7. The composition of claim 6, wherein the polyethylene is high density polyethylene (HDPE), low density polyethylene (LDPE), very high molecular weight polyethylene (VHMWPE), or ultrahigh molecular weight polyethylene (UHMWPE). 8. The composition of claim 1, further comprising a thermoplastic elastomer or a color change indicator. 9. The composition of claim 1, further comprising an absorbent material, CMC or a superabsorbent material. 10. A device comprising the composition of claim 1. 11. The device of claim 10, wherein the device is a pipette tip, an in line filter, a vent, a valve, a container, a non-mechanical check valve, a safety valve, a syringe cap, or a suction canister. 12. A method of making the composition claim 1 comprising: providing particles of polyacrylic acid, wherein the polyacrylic acid is linear polyacrylic with a molecular weight greater than 100 KDa or cross-linked polyacrylic with a the linear backbone molecular weight between adjacent crosslinks (Mc) greater than 10 KDa;providing particles of a thermoplastic;blending the particles of polyacrylic acid and the particles of thermoplastic to make a mixture;adding the mixture to a mold;sintering the mixture;removing the mixture from the mold. 13. A method of blocking the passage of a solution comprising: contacting the composition of claim 1 with the solution; and,permitting the composition to absorb the solution and seal, whereby passage of the solution is blocked by the composition. 14. The method of claim 13, wherein the solution comprises an organic solvent or an aqueous solution of more than 40% of an organic solvent. 15. The method of claim 13, wherein the solution comprises more than 5% of an inorganic acid or more than 5% of an organic acid. 16. The method of claim 13, wherein the contacting step occurs at about 2 psi. 17. The method of claim 13, wherein the solution further comprises a surfactant.