Multiple emulsions and techniques for the formation of multiple emulsions

Abstract

Multiple emulsions and techniques for the formation of multiple emulsions are generally described. A multiple emulsion, as used herein, describes larger droplets that contain one or more smaller droplets therein. In some embodiments, the larger droplet or droplets may be suspended in a carrying fluid containing the larger droplets that, in turn, contain the smaller droplets. As described below, multiple emulsions can be formed in one step in certain embodiments, with generally precise repeatability, and can be tailored in some embodiments to include a relatively thin layer of fluid separating two other fluids.

What is claimed is: 
     
         1 . A method of forming droplets, the method comprising:
 flowing a first fluid in a first conduit;   expelling the first fluid from an exit opening of the first conduit into a second fluid in a second conduit such that droplets of the first fluid are not formed at the exit opening of the first conduit; and   expelling the first fluid and the second fluid from an exit opening of the second conduit into a third fluid to form a multiple emulsion droplets comprising the second fluid surrounding droplets of the first fluid.   
     
     
         2 . A method of forming droplets, the method comprising:
 expelling a first fluid from an exit opening of a first conduit into a second fluid in a second conduit; and   expelling the first fluid and the second fluid from an exit opening of the second conduit into a third fluid to form a multiple emulsion droplets comprising a shell of the second fluid surrounding droplets of the first fluid, wherein:   the shell has an average thickness of less than about 0.05 times the average cross-sectional diameter of the multiple emulsion and/or the shell has an average thickness of less than about 1 micrometer.   
     
     
         3 - 6 . (canceled) 
     
     
         7 . The method of  claim 1 , wherein the flow rate of the first fluid and the flow rate of the second fluid are selected such that jetting flow of the first fluid within the second fluid occurs within the second conduit. 
     
     
         8 . The method of  claim 1 , further comprising collecting the multiple emulsion droplets in a third conduit. 
     
     
         9 . The method of  claim 8 , wherein the multiple emulsion droplets are formed within the third conduit. 
     
     
         10 . The method of  claim 8 , wherein the first fluid and the second fluid ejected from the second conduit form multiple emulsion droplets prior to entering the third conduit. 
     
     
         11 . The method of  claim 1 , wherein substantially all of the multiple emulsion droplets produced are double emulsion droplets. 
     
     
         12 . The method of  claim 1 , wherein the first conduit has a capillary number such that no droplets are produced at the exit opening of the first conduit. 
     
     
         13 . The method of  claim 1 , wherein the first fluid and the second fluid are selected to have viscosities such that no droplets are produced at the exit opening of the first conduit. 
     
     
         14 . The method of  claim 1 , wherein the first fluid and the second fluid are expelled from the exit opening of the second conduit into a third conduit. 
     
     
         15 . The method of  claim 1 , wherein the second fluid comprises a polymer suspended in the fluid. 
     
     
         16 - 33 . (canceled) 
     
     
         34 . An article, comprising:
 a particle having a shell comprising a polymer, the particle having an average diameter of less than about 1 mm, the shell at least partially containing a fluid, wherein:   the shell has an average thickness of less than about 0.05 times the average cross-sectional diameter of the particle and/or the shell has an average thickness of less than about 1 micrometer; and   substantially all of the polymer within the shell has a glass transition temperature of at least about 85° C. and/or substantially all of the polymer within the shell is at least partially soluble in octane.   
     
     
         35 . The article of  claim 34 , wherein the shell has an average thickness of less than about 1 micrometer. 
     
     
         36 . The article of  claim 34 , wherein the shell has an average thickness of less than about 0.05 times the average cross-sectional diameter of the particle. 
     
     
         37 - 42 . (canceled) 
     
     
         43 . The article of  claim 34 , wherein substantially all of the polymer within the shell has a glass transition temperature of at least about 85° C. 
     
     
         44 - 47 . (canceled) 
     
     
         48 . A collection of particles as defined in  claim 34 , wherein the collection has an overall average diameter and a distribution of diameters such that the coefficient of variation of the cross-sectional diameters of the particles is less than about 10%. 
     
     
         49 - 61 . (canceled) 
     
     
         62 . The method of  claim 2 , wherein the flow rate of the first fluid and the flow rate of the second fluid are selected such that jetting flow of the first fluid within the second fluid occurs within the second conduit. 
     
     
         63 . The method of  claim 2 , wherein the first conduit has a capillary number such that no droplets are produced at the exit opening of the first conduit. 
     
     
         64 . The method of  claim 2 , wherein the first fluid and the second fluid are selected to have viscosities such that no droplets are produced at the exit opening of the first conduit. 
     
     
         65 . The method of  claim 2 , wherein the first fluid and the second fluid are expelled from the exit opening of the second conduit into a third conduit.