Method for preparing biodegradable microcapsules and microcapsules thus obtained
A method for manufacturing microcapsules containing an active substance, the method including: providing an aqueous solution of a surfactant, an oily phase comprising the active substance and a first monomer, and a polar phase comprising a second monomer; preparing an oil-in-water emulsion by adding the oily phase to the aqueous solution of the surfactant; adding the polar phase to the oil-in-water emulsion, in order to obtain a polymer in a reaction mixture, by polymerization of the first monomer and the second monomer; isolating the microcapsules, including a wall formed by the polymer and containing the active substance, from the reaction mixture; wherein the polymer is a poly(beta-amino ester). Microcapsules obtained by the method.
1. A method for manufacturing microcapsules containing an active substance, the method comprising:
providing an aqueous solution of a surfactant, an oily phase comprising said active substance and a first monomer, and a polar phase comprising a second monomer;
preparing an oil-in-water emulsion by adding said oily phase to said aqueous solution of the surfactant;
adding said polar phase to said oil-in-water emulsion to obtain a polymer by polymerization of said first monomer and said second monomer in a reaction mixture; and
isolating said microcapsules, including a wall formed by said polymer and containing said active substance, from the reaction mixture;
wherein said polymer is a poly(beta-amino ester).
2. The method according to claim 1 , wherein said first monomer is a (multi)acrylate.
3. The method according to claim 2 , wherein said first monomer is selected from the group consisting of:
diacrylates;
triacrylates;
polymers carrying acrylic pendant functions;
functional PBAE oligos; and
mixtures thereof.
4. The method according to claim 1 , wherein said second monomer is an amine.
5. The method according to claim 4 , wherein said second monomer is selected from the group consisting of:
primary amines of the type R—NH 2 ;
primary diamines of the type NH 2 (CH 2 ) n NH 2 , where n is between 1 and 20;
primary diamines comprising an aromatic center;
primary (multi)amines;
secondary diamines; and
polymers having primary and/or secondary amine functions.
6. The method according to claim 1 , wherein said polymerization comprises stirring at a temperature of from 20° C. to 100° C.
7. The method according to claim 1 , wherein said surfactant is a macromolecular surfactant.
8. The method according to claim 1 , wherein said active substance is selected from the group consisting of:
essential oils and fragrances;
inks, paints, thermochromic and/or photochromic substances, dyes, and glues, biocidal effect products, fungicidal effect products, antiviral effect products, phytosanitary effect products, cosmetic effect products, pharmaceutical active ingredients; and
natural and edible oils, vegetable and edible oils, liquid alkanes, esters and fatty acids.
9. The method according to claim 1 , wherein a shell of said microcapsules is modified by adding a polymeric coating deposited onto a surface of said microcapsules, or by adding a radical initiator to at least one of the aqueous and the oily phase, or by adding to the aqueous phase a water soluble acrylate capable of modifying a surface state of said microcapsules.
10. The method according to claim 2 , wherein the (multi)acrylate is a (multi)acrylate of formula X′—(—O(C═O)—CH═CH 2 ) n , n≥4, and where X′ represents a molecule whereon n acrylate units are grafted.
11. The method according to claim 3 , wherein the triacrylates are selected from the group consisting of trimethylol propane triacrylate, tetraacrylates, pentaacrylates, hexaacrylates, and mixtures between these different acrylates of the type O[CH 2 C(CH 2 OR) 3 ] 2 where R is H or COCH═CH 2 .
12. The method according to claim 3 , wherein the functional PBAE oligos are prepared by reaction of diacrylate compounds with a functional primary amine and/or a functional secondary diamine.
13. The method according to claim 4 , wherein the second monomer is selected from the group consisting of meta-xylylene diamine, tris(2-aminoethyl)amine, tetraethylene pentamine, piperazine, and polyethyleneimine.
14. The method according to claim 7 , wherein the macromolecular surfactant is selected from the group consisting of polyacrylates, methylcelluloses, carboxymethylcelluloses, polyvinyl alcohol, partially etherified polyvinyl alcohol, partially esterified polyvinyl alcohol, polyacrylamide, synthetic polymers having anhydride functions or carboxylic acid, and ethylene/maleic anhydride copolymers.