Microcapsules modified with nanomaterial for controlled release of active agent and process for preparation thereof

1. A microcapsule modified with nanomaterial for controlled release of active agent comprising:

a) a hydrophobic polymer shell comprising a polymer nanocomposite, wherein the polymer nanocomposite is formed by in-situ interfacial polymerization in an aqueous medium;

b) a core comprising a water-insoluble active agent and said polymer shell encompassing said core;

characterized in that said polymer shell is devoid of formaldehyde, and

wherein the incorporation of the nanomaterial into the microcapsule shell results in (i) a reduction in porosity and pore dimension of the polymer nanocomposite, (ii) microcapsules obtained from the polymer nanocomposite having enhanced fracture strength, (iii) reduction in release rate of the water-insoluble active agent, and (iv) rigidification of the polymer nanocomposite.

2. The microcapsule as claimed in claim 1 , said active agent is selected from the group consisting of perfume, pharmaceutical, insect repellent, self-healing agent, flavouring agent, pesticide, enzyme, biocide, and insect pheromone.

3. The microcapsule as claimed in claim 1 , wherein said active agent is selected from the group consisting of dimethyl phthalate, Jasmine oil and O,O-diethyl O-quinoxalin-2-yl phosphorothioate.

4. The microcapsule as claimed in claim 1 , wherein said nanomaterial is selected from the group consisting of graphene oxide, carbon nanofibers, nanoclays, and carbon nanotubes.

5. A process for the preparation of the microcapsules modified with nanomaterial as claimed in claim 1 , the process comprising the steps of:

a) adding nanomaterial to the aqueous medium and sonicating to obtain the dispersed solution followed by addition of surfactant solution to the nanomaterial dispersed solution to afford reaction mixture;

b) adding a mixture of active agent and polyisocyanate to the reaction mixture of step (a) with constant stirring at temperature in the range of 25 to 30° C. to afford reaction mixture;

c) adding a solution of polyamine and catalyst diluted in surfactant solution to the reaction mixture of step (b) followed by stirring the mixture at temperature in the range of 25 to 50° C. for the period in the range of 3 to 24 hrs;

d) isolating the microcapsules by filtration of reaction mixture of step (c) followed by drying to afford microcapsules;

characterized in that said polymer shell is made up of the polymer nanocomposite.

6. The process as claimed in claim 5 , wherein aqueous medium is water.

7. The process as claimed in claim 5 , wherein said polyisocyanate is selected from the group consisting of 2,4-and 2,6-toluene diisocyanate, naphthalene diisocyanate, diphenyl methane diisocyanate, triphenyl methane-p,p′p″-trityl triisocyanate, polymethylene polyphenylene isocyanate, 2,4,4′-diphenylether triisocyanate, 3,3′-dimethyl-4,4′-diphenyl diisocyanate, 3,3′-dimethoxy-4,4′diphenyl diisocyanate, triphenylmethane 4,4′, 4″ triisocyanate, Dicyclohexylmethane 4,4′-diisocyanate, hexamethylenel, 6-diisocyanate, isophorone diisocyanate, trimethyl-hexamethylene diisocyanate, trimethylene diisocyanate, propylene-1,2-diisocyanate, butylene 1,2-diisocyanate and mixtures thereof.

8. The process as claimed in claim 5 , wherein said polyisocyanate is selected from Toluene diisocyanate and Isophorone diisocyanate.

9. The process as claimed in claim 5 , wherein said polyamine is selected from the group consisting of polyaziridine, Diethylenetriamine, Triethylenetetraamine, Tetraethylene Pentamine, 2,4,4′-Triaminodiphenylether, Bis(Hexamethylene) Triamine, Ethylene Diamine, Trimethylenedipiperidine, Guanidine Carbonate, Phenylene Diamine, Toluene Diamine, Pentamethylene Hexamine, 1,6-Hexamethylene Diamine, 2,4-Diamino-6-Methyl-1,3,5-Triazine, 1,2-Diaminocyclohexane, 4,4′-Diaminodiphenylmethane, 1,5-Diaminonaphthalene, Isophorone Diamine, Diamino Propane, Diaminobutane, Piperazine, Aminoethylenepiperazine, Tetraethylenepentamine, poly (propylene glycol) bis (2-aminopropyl ether), and O,O′-bis(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-poly propylene glycol.

10. The process as claimed in claim 5 , wherein said polyamine is ethylene diamine (EDA).

11. The process as claimed in claim 5 , wherein said catalyst is selected from 4-Diazabicyclo (2, 2, 2) octane, N,N′-dimethylaminoethanol, N, N′-dimethylcyclohexylamine, bis-(2-dimethylaminoethyl)ether, N, N′-dimethylacetylamine, diaminobicyclooctane, stannous octoate, dibutyltindilaurate and mixtures thereof.

12. The process as claimed in claim 5 , wherein said catalyst is 1,4-Diazabicyclo (2, 2, 2) octane.

13. The process as claimed in claim 5 , wherein said surfactant is selected from the group consisting of polyvinylpyrrolidone, polyethylene glycol sorbitan monolaurate, polyethylene glycol sorbitan monopalmitate, polyethylene glycol sorbitan monooleate, polyvinyl alcohol, poly(ethoxy)nonyl phenol, ethylene maleic anhydride copolymer, sodium or potassium polyacrylate, sodium or potassium polymethacrylate, sodium lignosulphate and mixtures thereof.

14. The process as claimed in claim 5 , wherein said surfactant is Polyvinylpyrrolidone.

15. The process as claimed in claim 5 , wherein said active agent is selected from perfume, pharmaceutical, insect repellent, self-healing agent, flavouring agent, pesticide, enzyme, biocide, insect pheromone and industrial chemical reagent.

16. The process as claimed in claim 5 , wherein said nanomaterial is selected from graphene oxide, carbon nanofibers, nanoclays, and carbon nanotubes.

17. The microcapsule as claimed in claim 1 , wherein said microcapsule shows reduction in the release rate of active agent as compared to pristine microcapsules of which polymer shell is devoid of nanocomposite structure.

18. The microcapsule as claimed in claim 1 , wherein said polymer is a polyurea.

19. The microcapsule as claimed in claim 4 , wherein the nanomaterial is carbon nanotubes selected from the group consisting of unmodified multi-walled carbon nanotubes and modified multi-walled carbon nanotubes.

20. The microcapsule as claimed in claim 4 , wherein the nanomaterial is nanoclay selected from the group consisting of Montmorillonite (MMT), Laponite, Hectorite, Saponite, Fluorohectorite, Fluoromica Kaolinite, Halloysite, and Cloisite Na + .

21. The microcapsule as claimed in claim 20 , wherein the polymer is a polyurea.

22. A microcapsule modified with nanomaterial for controlled release of active agent comprising:

a) a hydrophobic polymer shell made up of a polymer nanocomposite, wherein the polymer is a polyurea and the nanomaterial is nanoclay and the polymer nanocomposite is formed by in-situ interfacial polymerization in an aqueous medium and exhibits an intercalated structure;

b) a core comprising a water-insoluble active agent and said polymer shell encompassing said core;

characterized in that said polymer shell is devoid of formaldehyde.

23. The microcapsule according to claim 19 , wherein the carbon nanotubes are unmodified multi-walled carbon nanotubes.

24. The microcapsule as claimed in claim 1 , wherein the nanomaterial is clay and the polymer nanocomposite exhibits an intercalated structure.

25. The microcapsule according to claim 22 , wherein wherein the incorporation of the nanomaterial into the microcapsule shell results in (i) a reduction in porosity and pore dimension of the polymer nanocomposite, (ii) microcapsules obtained from the polymer nanocomposite having enhanced fracture strength, (iii) reduction in release rate of the water-insoluble active agent, and (iv) rigidification of the polymer nanocomposite.