1. A method for the preparation of compositions based on poly(2-propenal, 2-propenoic acid) comprising the steps of dissolving the poly(2-propenal, 2-propenoic acid) in aqueous base, adding an organic compound containing one or more hydrophobic groups, and subsequently acidifying the solution, whereby interaction between the hydrophobic groups of the organic compound and the poly(2-propenal, 2-propenoic acid) prevents precipitation of the poly(2-propenal, 2-propenoic acid) occurring at pH >= 5.5 and the solution is consequently stable over a broad pH range. 2. A method according to claim 1 wherein precipitation of the poly(2-propenal, 2-propenoic acid) is prevented at pH >= 3.5. 3. A method according to claim 1 or 2 wherein the organic compound is selected from at least one compound of the group comprising an anionic surfactant, ethylene diamine tetra acetic acid, a lower alkanol, a phenol, isothiazolinones and glutaraldehyde. 4. A method according to claim 3 wherein an anionic surfactant is added as the organic compound. 5. A method according to claim 4 wherein the composition containing poly(2-propenal, 2-propenoic acid) is firstly stored for a time in basic composition prior to addition of surfactant and acidification. 6. A method according to claim 4 wherein the anionic surfactant is selected from either sodium lauryl sulphate or disodium decyl (sulfophoxy) benzene sulfonate and disodium oxybis (decylsulfophenoxy) benzene sulfonate. 7. A method according to claim 3 wherein at least one compound selected from ethylene diamine tetra acetic acid, a lower alkanol, a phenol, isothiazolinones and glutaraldehyde are used as the organic compound. 8. A method according to claim 3 wherein phenol selected from the group comprising o-phenyl-phenol and 4-tert-amylphenol is used as the organic compound. 9. A method according to claim 3 wherein phenol and/or glutaraldehydeare used as the organic compound, whereby the odour intensity of the phenols and/or glutaraldehyde is reduced by the presence of the poly(2-propenal, 2-propenoic acid). 10. A method according to claim 1 wherein the composition (2-propenal, 2-propenoic acid) is prepared in the presence of air and/or oxygen, wherein prepared composition exhibits increased antimicrobial activity. 11. A method according to claim 1 wherein the composition (2-propenal, 2-propenoic acid) is transformed into an alkaline composition directly prior to its use as antimicrobial preparation, wherein prepared composition exhibits increased antimicrobial activity. 12. An aqueous polymeric composition comprising the poly(2-propenal, 2-propenoic acid) and an organic compound containing at least one hydrophobic group, whereby interaction between the hydrophobic groups of the organic compound and the poly(2-propenal, 2-propenoic acid) prevents precipitation of the poly(2-propenal, 2-propenoic acid) occurring at pH >= 5.5. 13. The composition according to claim 12 wherein preventing precipitation of the poly(2-propenal, 2-propenoic acid) occurring at pH >= 3.5. 14. The composition according to claim 12 or 13 wherein the organic compound is selected from at least one compound of the group comprising an anionic surfactant, ethylene diamine tetra acetic acid, a lower alkanol, a phenol, isothiazolinones and glutaraldehyde. 15. The composition according to claim 14 wherein comprises an anionic surfactant as an organic compound. 16. The composition according to claim 15 wherein comprises a surfactant selected from either sodium lauryl sulphate or disodium decyl (sulfophoxy) benzene sulfonate and disodium oxybis (decylsulfophenoxy) benzene sulfonate as an anionic surfactant. 17. The composition according to claim 14 wherein comprises phenol selected from the group comprising o-phenyl-phenol and 4-tert-amylphenol is used as the organic compound. 18. The composition according to claim 14 wherein contains a sunscreen agent. 19. The composition according to claim 18 wherein comprises either or both of octyl methoxy cinnamate and octyl dimethyl p-aminobenzoate as the sunscreen agent. 20. The composition according to any of claims 12 to 19 wherein the composition is an emulsion. 21. A composition use according to any of claims 12 to 20 as an antimicrobial preparation. 22. A composition use according to any of claims 12 to 20 as skin care. 23. A composition use according to any of claims 12 to 20 as an addition to animal feed.