Photoprotective compositions and films, and a preparation method

1. A photoprotective cosmetic composition including particles having a polymeric multilayer interference structure, at least two layers of said structure comprising an amphiphilic polymer, wherein the particles include a swelling agent, the swelling agent including at least one optically active material, the at least one optically active material being dissolved in the swelling agent and being included within the amphiphilic polymer, wherein the amphiphilic polymer comprises a diblock copolymer with the form A-B where A is polystyrene and B is poly(2-vinyl pyridine), wherein the blocks of the diblock copolymer have the same number average molecular weight, wherein the diblock copolymer has a periodic structure having two separate blocks of A-B alternated at regular intervals, and wherein each block of the diblock copolymer has a number average molecular weight of from 1,000 g/mol to 500,000 g/mol, and wherein the particles having a polymeric multilayer interference structure include a fixing agent selected from inorganic materials, glycols, and PEGs having a number average molecular weight in a range of from 400 g/mol to 50,000 g/mol.

2. The composition according to claim 1 , wherein the particles having a polymeric multilayer interference structure have a reflection spectrum including a reflection peak in a wavelength range of from 250 nm to 400 nm.

3. A photoprotective cosmetic composition including particles having a polymeric multilayer interference structure, at least two layers of said structure comprising an amphiphilic polymer, the photoprotective cosmetic composition comprising a fatty phase and an aqueous phase, the aqueous phase including the particles having a polymeric multilayer interference structure, wherein the amphiphilic polymer comprises a diblock copolymer with the form A-B where A is polystyrene and B is poly(2-vinyl pyridine), wherein the blocks of the diblock copolymer have the same number average molecular weight, wherein the diblock copolymer has a periodic structure having two separate blocks of A-B alternated at regular intervals, and wherein each block of the diblock copolymer has an average molecular weight of from 1,000 g/mol to 500,000 g/mol, and wherein the particles having a polymeric multilayer interference structure include a fixing agent selected from inorganic materials, glycols, and PEGs having a number average molecular weight in a range of from 400 g/mol to 50,000 g/mol.

4. The composition according to claim 1 , including at least two different types of particles having a polymeric multilayer interference structure, each particle type having a different transmission spectrum in a wavelength range of from 250 nm to 400 nm.

5. The composition according to claim 1 , wherein the particles having a polymeric multilayer interference structure are plate-like.

6. The composition according to claim 1 , wherein the particles having a polymeric multilayer interference structure include another optically active material.

7. The composition according to claim 1 , wherein the swelling agent is selected from:

water and organic or inorganic saline solutions with a concentration in the range 0.01 M to 5 M;

the following compounds alone, as a mixture, or in aqueous solution: (i) glycerol, PEGs having a number average molecular weight in a range of from 400 g/mol to 50,000 g/mol, mono-, di-, and oligo-saccharides that are soluble in water at at least 1% by weight, sorbitol, propylene glycol, dipropylene glycol, butylene glycol, water-soluble polyols, and water-miscible lower alcohols; (ii) neutralized or non-neutralized solutions of UV screens; and (iii) polar oils, undecane, tridecane, and solutions of oil soluble organic UV screens in oils.

8. A method of preparing a cosmetic composition according to claim 1 , comprising:

a) bringing a swelling agent into contact with a polymeric multilayer structure having at least two layers comprising an amphiphilic polymer;

b) fragmenting a film having a polymeric multilayer structure wherein at least two layers comprise an amphiphilic polymer into particles having a polymeric multilayer structure with a largest dimension of less than 100 μm and with a smallest dimension of 100 nm or more;

c) dispersing the particles with the polymeric multilayer interference structure obtained after carrying out steps a) and b) in a solution containing a fixing agent; and

d) mixing the particles obtained after carrying out step c) with a cosmetically acceptable medium; wherein step b) is carried out before or after step a).

9. A method of photoprotecting human keratinous materials against solar UV radiation, the method comprising applying the cosmetic composition according to claim 1 to the human keratinous materials.

10. The composition according to claim 1 , wherein the at least one dissolved optically active material is selected from the group consisting of a UV screen, a fluorescent agent, a coloring agent and mixtures thereof.

11. The composition according to claim 3 , wherein the fatty phase is free of particles having a polymeric multilayer interference structure.