FRAGRANCE-CONTAINING CROSSLINKED GELS

1 . A spill-resistant gel comprising a fragrance immobilized within a covalently cross-linked matrix and diffusively releasable from the matrix.

2 . The spill-resistant gel of claim 1 , wherein the covalently cross-linked matrix comprises a cross-linked polymer network or a cross-linked inorganic sol-gel.

3 . The spill-resistant gel of claim 1 , in which the immobilized fragrance comprises an essential oil.

4 . The spill-resistant gel of claim 1 , in which the fragrance comprises at least 60% by weight of the spill-resistant gel.

5 . The spill-resistant gel of claim 1 , wherein a mass concentration of the matrix is about 1% to about 40%, about 2% to about 20%, or about 5% to about 10% on a weight-to-weight basis.

6 . The spill-resistant gel of claim 1 , wherein segments of the matrix comprise reacted monomers of acrylamide, methacrylamide, vinylpyrrolidone, acrylate, methacrylate, resorcinol, bis-acrylamide, N,N′-diallyltartramide, glyoxal, formaldehyde, 2-acrylamido-2-methyl-1-propanesulfonic acid, metal alkoxide, or derivatives of any of the foregoing.

7 . The spill-resistant gel of claim 1 , wherein the gel further comprises an additive.

8 . The spill-resistant gel of claim 7 , wherein the additive comprises a fiber, salt, colloid, soluble or insoluble powder, particulate, soluble polymer not integrated into the matrix, or combination thereof.

9 . A composite, comprising:

a spill-resistant gel comprising a fragrance immobilized within a covalently cross-linked matrix and diffusively releasable from the matrix; and

a freestanding porous substrate with the spill-resistant gel formed at least partially on a surface of the substrate, at least partially within pores of the substrate, or both.

10 . The composite of claim 9 , wherein the substrate comprises a foam, a mat, a sheet, a film, a web, a membrane, or combination thereof.

11 . The composite of claim 9 , wherein the substrate comprises a polymer film, a glass mat, or combinations thereof.

12 . The composite of claim 9 , further comprising free fragrance in at least some of the pores of the substrate not filled with the spill-resistant gel.

13 . The composite of claim 9 , wherein the covalently cross-linked matrix comprises a cross-linked polymer network or cross-linked inorganic sol-gel.

14 . An air freshener comprising the spill-resistant gel of claim 1 .

15 . The air freshener of claim 14 , in which the air freshener has a size and shape compatible with use in a cabin of an automobile.

16 . The air freshener of claim 14 , in which the covalently cross-linked matrix comprises a cross-linked polymer network or cross-linked inorganic sol-gel.

17 . A method of forming a spill-resistant gel, the method comprising:

mixing a monomer, oligomer, cross-linker, polymer, polymer precursor, or combination thereof, with a liquid phase comprising a fragrance; and

reacting the monomer, oligomer, cross-linker, polymer, polymer precursors, or combination thereof, to form a covalently cross-linked matrix that immobilizes the liquid phase, thereby forming the spill-resistant gel.

18 . The method of claim 17 , wherein the polymers prior to the reacting step comprise linear polyacrylamide, polymethacrylamide, polyacrylate, polymethacrylate, polyvinylpyrrolidone, or derivatives of any of the foregoing, or copolymers of any of the foregoing.

19 . The method of claim 17 , wherein the monomer, oligomer, or polymer precursor prior to the reacting step comprises acrylamide, methacrylamide, acrylic acid, acrylate, methacrylate, resorcinol, N-vinylpyrrolidone, 2-acrylamido-2-methyl-1-propanesulfonic acid, metal alkoxide, or derivatives of any of the foregoing.

20 . The method of claim 17 , further comprising reacting the monomer, oligomer, cross-linker, polymer, polymer precursors, or combination thereof, in the presence of a freestanding porous substrate, whereby the spill-resistant gel is formed at least partially on a surface of the substrate, at least partially within pores of the substrate, or both.

21 - 24 . (canceled)