Porous beads and method of production thereof
The present invention relates to porous beads and to methods of production thereof, in particular to a method of producing hydrophilic polymeric beads by freeze-drying a droplet containing a polymeric material in a continuous phase of an oil-in-water (O/W) emulsion.
1. A hydrophilic porous polymeric bead comprising a three dimensional open-cell lattice of a water-soluble polymeric material, the lattice having a porous structure providing in the bead an intrusion volume of at least about 3 ml/g.
2. A hydrophilic porous polymeric bead according to claim 1 , wherein the intrusion volume is at least about 3.5 ml/g.
3. A hydrophilic porous polymeric bead according to claim 2 , wherein the intrusion volume is at least about 4 ml/g.
4. A hydrophilic porous polymeric bead according to claim 3 , wherein the intrusion volume is at least about 4.5 ml/g.
5. A hydrophilic porous polymeric bead according to claim 1 formed from an emulsion.
6. A hydrophilic porous polymeric bead according to claim 5 , wherein the emulsion has an internal phase in the range of from about 50% to about 80%.
7. A hydrophilic porous polymeric bead according to claim 1 , wherein the lattice comprises more than one distinct pore type.
8. A hydrophilic porous polymeric bead according to claim 1 , wherein the bead comprises surfactant moieties dispersed throughout the lattice.
9. A hydrophilic porous polymeric bead according to claim 1 , wherein an active ingredient is disposed in the lattice.
10. A population of hydrophilic porous polymeric beads according to claim 1 , the population having a substantially uniform size distribution.
11. A method for producing a population of porous hydrophilic polymeric beads according to claim 10 comprising the steps of:
a) providing an emulsion comprising an aqueous phase, an organic phase and a hydrophilic polymeric material;
b) providing a fluid medium at a temperature effective for freezing the emulsion;
c) injecting the emulsion into the fluid medium to form frozen droplets;
d) isolating the droplets, and
e) freeze-drying the droplets to form beads.
12. A method according to claim 11 , wherein the beads are chemically cross-linked by a cross-linking agent after freeze-drying.
13. A method according to claim 11 , wherein the emulsion comprises an emulsifier.
14. A method according to claim 11 , wherein the emulsion comprises a continuous aqueous phase with the hydrophilic polymeric material dissolved therein and a discontinuous organic phase.
15. A method according to claim 11 wherein the polymeric material is selected from one or more from the following group of polymers; poly(vinyl alcohol), poly(ethylene glycol), poly(ethylene oxide), poly(vinyl pyrrolidone), poly(acrylic acid), poly(acrylic acid)-sodium salt, poly(acrylamide), poly(sodium styrene sulfonate), poly(2-acrylamido-2-methyl-1-propanesulfonic acid) and polysaccharides.
16. A method according to claim 11 , wherein the organic phase comprises a solvent selected from one or more of; heptane, n-hexane, isooctane, dodecane, decane, toluene, xylene, cyclohexane, mineral oil, dichloromethane, dichoroethane and tetrachloroethane.
17. A method according to claim 11 , wherein the aqueous phase comprises an active ingredient for incorporation into the beads.
18. A method according to claim 11 , wherein the organic phase comprises a hydrophobic active ingredient for incorporation into the beads.
19. A method according to claim 11 , wherein the freezing medium comprises an active ingredient for incorporation into the beads.
20. A method according to claim 17 , wherein the active ingredient is selected from one or more from the following group; pharmaceutical actives, pharmaceutical salts, enzymes, dyes, oxidising agents, cleaning agents, fabric softeners, clothes care agents, bleaches, reducing agents, flavours, fragrances, metal nanoparticles, vitamins and nutraceuticals.