Encapsulation Of Active Agents For On-Demand Release

Abstract

The present disclosure relates to a method of forming microcapsules. The method may include combining an active agent in a first solvent S 1 and forming a dispersed phase of the active agent in the first solvent, wherein the dispersed phase of active agent has a surface. A reactant may be added to the first solvent, wherein the reactant reacts with the surface of the active agent dispersed phase and encapsulates the active agent wherein at least a portion of the active agent remains unreacted.

1 . A method of forming microcapsules, comprising:
 combining an active agent in a first solvent S 1  and forming a dispersed phase of the active agent in said first solvent, said dispersed phase of active agent having a surface; and   adding a reactant to said first solvent and wherein said reactant reacts with said surface of the active agent dispersed phase; and   encapsulating the active agent wherein 50% by weight or more of said active agent remains unreacted.   
   
   
       2 . The method of  claim 1  wherein 60% by weight or more of the active agent remain unreacted. 
   
   
       3 . The method of  claim 1  wherein said dispersed phase of said active agent comprises droplets having a largest linear dimension of 1 micron to 200 microns. 
   
   
       4 . The method of  claim 3  wherein said reactant diffuses up to and including 10% of said droplet dimension from said surface of said droplet. 
   
   
       5 . The method of  claim 1  wherein said reactant is combined in a second solvent S 2  wherein said first solvent and second solvent have a Hildebrand solubility parameter values, and said solubility parameters are within plus or minus 2.0 units of one another as measured in (MPa) 1/2 . 
   
   
       6 . The method of  claim 1  wherein said first solvent has a viscosity in the range of 10-200 cSt at 40° C. 
   
   
       7 . The method of  claim 1  wherein said active agent has a reactive functionality of 2 or more. 
   
   
       8 . The method of  claim 1 , wherein said first solvent is mineral oil. 
   
   
       9 . A method of forming microcapsules, comprising:
 combining an active agent comprising a compound having amine functionality in a first solvent S 1  and forming a dispersed phase of the active agent in said first solvent, said dispersed phase of active agent having a surface; and   adding a reactant having isocyanate functionality to said first solvent and wherein said reactant reacts with said surface of the active agent dispersed phase and forms a polyurea; and   encapsulating the active agent wherein 50% by weight or more of said active agent remains unreacted.   
   
   
       10 . The method of  claim 9  wherein 60% by weight or more of the active agent remain unreacted. 
   
   
       11 . The method of  claim 9  wherein said dispersed phase of said active agent comprises droplets having a largest linear dimension of 1 micron to 200 microns. 
   
   
       12 . The method of  claim 11  wherein said reactant diffuses up to and including 10% of said droplet dimension from said surface of said droplet. 
   
   
       13 . The method of  claim 9  wherein said reactant is combined in a second solvent S 2  wherein said first solvent and second solvent have a Hildebrand solubility parameter values, and said solubility parameters are within plus or minus 2.0 units of one another as measured in (MPa) 112 . 
   
   
       14 . The method of  claim 9  wherein said first solvent has a viscosity in the range of 10-200 cSt at 40° C. 
   
   
       15 . A method of reducing the propagation of stress, comprising:
 supplying microcapsules containing an encapsulated amine compound, said microcapsules having a size of 1 micron to 200 microns including a shell portion that has a thickness of less than or equal to 20 microns;   distributing said microcapsules in a the presence of an epoxy prepolymer in a selected structure;   wherein upon introduction of stress into said structure, said microcapsules release said amine compound which then reacts with said epoxy prepolymer.   
   
   
       16 . The method of  claim 15  wherein said stress comprises crack propagation. 
   
   
       17 . The method of  claim 15  wherein said amine compound reacts with said epoxy prepolymer and forms a crosslinked epoxy polymer wherein said polymer has a tensile strength of at least 12,500 psi and a tensile modulus of 400,000 psi to 4×10 6  psi. 
   
   
       18 . The method of  claim 15  wherein said epoxy prepolymer has the following formula: 
     
       
         
         
             
             
         
       
     
     where n may have a value of 0-1000. 
   
   
       19 . The method of  claim 15  wherein said epoxy prepolymer is present as microcapsules having a size of 1 micron to 200 microns.