Monodisperse submicron polymer particles
First Claim
1. A process for the preparation of monodisperse particles for use as Ugelstad seed particles, the process comprising an emulsion polymerization process comprising:
- forming an aqueous dispersion comprising a vinylic monomer and a water soluble polymerization initiator; and
agitating until the dispersion becomes visibly cloudy,wherein the aqueous dispersion comprises a surfactant and a chain transfer agent is added after the dispersion becomes visibly cloudy, such that the polymerization forms monodisperse seed particles having a z-average diameter of from 50 nm to 200 nm and, when measured by gel permeation chromatography, the polymer has a mean weight average molecular weight of more than 1,000 and less than 70,000.
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Abstract
This invention relates to monodisperse cross-linked polymer particles, comprising particles with a substantially smooth outer surface and an average diameter of less than 1 μm, wherein the particles are solid or porous, and wherein the coefficient of variation (CV) % of the particles, when measured by CPS disk centrifugation analysis, is less than 15%. These monodisperse cross-linked polymer particles may comprise magnetic material and are useful in various application. This invention also relates to monodisperse polymer particles for use as seed particles in the Ugelstad process.
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Citations
17 Claims
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1. A process for the preparation of monodisperse particles for use as Ugelstad seed particles, the process comprising an emulsion polymerization process comprising:
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forming an aqueous dispersion comprising a vinylic monomer and a water soluble polymerization initiator; and agitating until the dispersion becomes visibly cloudy, wherein the aqueous dispersion comprises a surfactant and a chain transfer agent is added after the dispersion becomes visibly cloudy, such that the polymerization forms monodisperse seed particles having a z-average diameter of from 50 nm to 200 nm and, when measured by gel permeation chromatography, the polymer has a mean weight average molecular weight of more than 1,000 and less than 70,000. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification