Polymer hollow particles with controllable holes in their surfaces

Abstract

A hollow polymer particle having a single, substantially circular opening in the particle's surface, methods for making and using the polymer particle.

1 . A hollow, polymer particle, comprising a substantially spherical polymeric particle having a radius of about 200 nm to less than about 500 nm and having a single, substantially circular opening in the particle's surface.  
     
     
         2 . The polymer particle of  claim 1 , wherein the circular opening has a radius smaller than or equal to the radius of the polymer particle.  
     
     
         3 . The polymer particle of  claim 1 , wherein the opening has a radius of from about 50 nm to about 225 nm.  
     
     
         4 . The polymer particle of  claim 1 , wherein the polymer is selected from the group consisting of polystyrene, polymethylmethacrylate, polycaprolactones, and poly(L-lactic acid).  
     
     
         5 . The polymer particle of  claim 1 , further comprising a small molecule, a macromolecule, a nanoparticle, or a colloidal particle.  
     
     
         6 . The polymer particle of  claim 5 , wherein the small molecule, macromolecule, nanoparticle, or colloidal particle is substantially positioned inside the radius of the polymer particle.  
     
     
         7 . A method for making a hollow, polymer particle having a single, substantially circular opening, comprising: 
 (a) suspending solid polymer particles in a first solvent to provide first solvent suspended particles;    (b) swelling the first solvent suspended particles with a second solvent to provide second solvent swollen particles;    (c) cooling the second solvent swollen particles below the freezing temperature of the second solvent, to create a void within each particle, providing second solvent-containing particles having frozen second solvent; and    (d) warming the second solvent-containing particles having frozen solvent, wherein the second solvent escapes from the particle resulting in the formation of a single opening in the surface of the particle to provide a hollow, polymer particle having a single, substantially circular opening.    
     
     
         8 . The method of  claim 7 , wherein the first solvent comprises water.  
     
     
         9 . The method of  claim 7 , wherein the second solvent comprises an organic solvent.  
     
     
         10 . The method of  claim 7 , wherein the second solvent is selected from the group consisting of toluene and styrene.  
     
     
         11 . The method of  claim 7 , wherein the polymeric particle is a polystyrene particle or a polymethylmethacrylate particle.  
     
     
         12 . The method of  claim 7 , wherein cooling of the second solvent swollen particles comprises cooling with liquid nitrogen.  
     
     
         13 . The method of  claim 7 , wherein the second solvent is allowed to escape by evaporation.  
     
     
         14 . The method of  claim 13 , wherein the evaporation occurs below the ambient pressure melting point of the second solvent and under vacuum.  
     
     
         15 . The method of  claim 13 , wherein the evaporation occurs above the melting point of the second solvent and under ambient pressure.  
     
     
         16 . A method for making a hollow, polymer particle having a single, substantially circular opening particle, comprising: 
 (a) dissolving a polymer in a first solvent;    (b) adding the dissolved polymer solution to a second solvent solution containing a surfactant;    (c) agitating the mixture providing an emulsion of the polymer in the second solvent;    (d) cooling the second solvent emulsion below the freezing temperature of the second solvent to create a void within each particle, providing second solvent-containing particles with frozen second solvent; and    (e) warming the second solvent-containing particles having frozen solvent, wherein the second solvent escapes from the particle resulting in the formation of a single opening in the surface of the particle to provide a hollow, polymer particle having a single, substantially circular opening.    
     
     
         17 . A method for encapsulating a material within a polymer particle, comprising: 
 (a) contacting a plurality of hollow, polymer particles, each having a single, substantially circular opening, with a material such that at least some of the material is positioned within the hollow, polymeric particle; and    (b) closing the opening to provide a polymer particle containing the material.    
     
     
         18 . The method of  claim 17 , wherein closing the opening comprises heating at a temperature above the glass transition temperature of the polymeric particle.  
     
     
         19 . The method of  claim 18 , wherein closing the opening comprises solvent treatment.