PROCESS FOR THE PREPARATION OF MONODISPERSE POLYMER PARTICLES

1 . A process for the preparation of monodisperse polymer particles having diameters of 1 μm to 6 μm, the process comprising:

forming an aqueous dispersion comprising monodisperse swellable seed particles and an anionic surfactant;

contacting the aqueous dispersion with a monomer selected from the group consisting of acrylic monomers, methacrylate monomers and vinyl monomers selected from the group consisting of styrene, divinylbenzene (DVB), ethyl vinyl benzene, vinyl pyridine, amino-styrene, methyl-styrene, dimethylstyrene, ethyl styrene, ethyl-methyl-styrene, p-chlorostyrene and 2,4-dichlorostyrene;

allowing the monomer to diffuse into the seed particles to form an aqueous dispersion of swollen seed particles; and

initiating polymerization of the monomer in the aqueous dispersion of swollen seed particles;

wherein the aqueous dispersion of swollen seed particles further comprises a polyvinylpyrrolidone.

2 . The process of claim 1 , wherein the polyvinylpyrrolidone has an average molecular weight of 10 kD to 2000 kD.

3 . The process of claim 1 , wherein the monodisperse swellable seed particles are monodisperse swellable seed oligomer particles.

4 . The process of claim 1 , wherein the monomer comprises at least 30% by weight divinyl benzene.

5 . The process of claim 1 , wherein the anionic surfactant is sodium dodecyl sulfate.

6 . A process for the preparation of monodisperse polymer particles, the process comprising:

forming an aqueous dispersion comprising monodisperse swellable seed particles and an anionic surfactant;

contacting the aqueous dispersion of seed particles with a monomer;

allowing the monomer to diffuse into the seed particles to form an aqueous dispersion of swollen seed particles having a mode diameter of 5 μm to 200 μm; and

initiating polymerization of the monomer in the aqueous dispersion of swollen seed particles;

wherein the aqueous dispersion of swollen seed particles further comprises a water soluble cellulose ether of weight average molecular weight 10 kD to 100 kD.

7 . The process of claim 6 , wherein the water soluble cellulose ether is a hydroxy propylmethyl cellulose.

8 . The process of claim 6 , wherein the monomer comprises at least 30% by weight divinyl benzene.

9 . The process of claim 6 , wherein the anionic surfactant is sodium dodecyl sulfate.

10 . A process for the preparation of monodisperse polymer particles having a diameter of at least 16 μm, the process comprising:

forming an aqueous dispersion comprising monodisperse swellable seed particles and an anionic surfactant;

contacting the aqueous dispersion of seed particles with a monomer;

allowing the monomer to diffuse into the seed particles to form an aqueous dispersion of swollen seed particles; and

initiating polymerization of the monomer in the aqueous dispersion of swollen seed particles to produce a polymer;

wherein the swollen seed particles contain at least two porogens, at least one of which is a solvent for the polymer produced and at least one of which is not a solvent for the polymer produced, and at least one porogen is an aliphatic hydrocarbon having up to 12 carbon atoms.

11 . The process of claim 10 , wherein the porogens comprise toluene and n-heptane.

12 . The process of claim 10 , wherein the aqueous dispersion of swollen seed particles further comprises a water soluble cellulose ether or a polyvinylpyrrolidone.

13 . The process of claim 10 , wherein the aqueous dispersion comprises droplets comprising an organic compound with a molecular weight below 5000 Dalton and a water solubility at 25° C. of less than 10 −2 g/L.

14 . The process of claim 10 , wherein the aqueous dispersion comprises an organic solvent.

15 . The process of claim 10 , wherein the aqueous dispersion comprises dioctanoyl peroxide.

16 . The process of claim 10 , wherein the monomer comprises at least 30% by weight divinyl benzene.

17 . The process of claim 10 , wherein the anionic surfactant is sodium dodecyl sulfate.

18 . A process for the preparation of monodisperse polymer particles, the process comprising:

forming an aqueous dispersion comprising monodisperse swellable seed particles and an anionic surfactant;

contacting the aqueous dispersion of seed particles with at least two monomers;

allowing the monomers to diffuse into the seed particles to form an aqueous dispersion of swollen seed particles that swell as least 3.5 times in diameter; and

initiating polymerization of the monomers in the aqueous dispersion of swollen seed particles to produce polymer particles;

wherein at least two monomers are selected from the group consisting of acrylic, methacrylic acid and ester monomers and combinations of these monomers; and

wherein the aqueous phase of the aqueous dispersion of swollen seed particles during polymerization further contains a steric stabilizer.

19 . The process of claim 18 , wherein at least one of the monomers is glycidyl methacrylate.

20 . The process of claim 18 , wherein the aqueous dispersion comprises droplets comprising an organic compound with a molecular weight below 5000 Dalton and a water solubility at 25° C. of less than 10 −2 g/L and optionally an organic solvent.

21 . The process of claim 18 , wherein the anionic surfactant is sodium dodecyl sulfate.

22 . The process of claim 18 , wherein the monodisperse swellable seed particles are monodisperse swellable seed oligomer particles.