Monodisperse submicron polymer particles
AssigneeInvitrogen Dynal AS
InventorsGrete Irene Modahl, Geir Fonnum, Astrid Molteberg, Silje Lien, Nini Hofslokken Kjus
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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.
Claims79
Monodisperse cross-linked polymer particles having the following characteristics:
- a substantially smooth outer surface;
- a z-average diameter of less than 1 μm;
- the particles are porous;
- and
- a coefficient of variation (CV) %, when measured by CPS disk centrifugation analysis, of less than 15%.
Monodisperse cross-linked polymer particles being a first population of polymer particles and having the following characteristics
- a substantially smooth outer surface;
- a z-average diameter of less than 1 μm;
- a coefficient of variation (CV) %, when measured by CPS disk centrifugation analysis, of less than 15%;
- and
- the swellability of a second population of polymer particles, wherein the second population of particles are reference particles produced by a known Ugelstad process and made of a comparable polymer to the first population, wherein the amount of cross-linker monomer used in the suspension polymerisation stage of the known Ugelstand process is >25% by weight of the total weight of monomers used in the suspension polymerisation stage.
Monodisperse cross-linked polymer particles, having the following characteristics:
- a z-average diameter of less than 1 μm,
- a coefficient of variation (CV) %, when measured by CPS disk centrifugation analysis, of less than 15%
- a specific surface area of from 300 to 700 m2/g when measured by gas adsorption analysis.
Monodisperse polymer particles for use as seed particles in the Ugelstad process, wherein the particles have a z-average diameter of from 50 nm to 200 nm and the polymer has a mean weight average molecular weight of more than 1,000 and less than 70,000, when measured by gel permeation chromatography.
A process for the preparation of monodisperse particles for use as Ugelstad seed particles, the process comprising an emulsion polymerisation process comprising:
- forming an aqueous dispersion comprising a vinylic monomer and a water soluble polymerisation initiator;
- and
- agitating until the commencement of particle nucleation;
- characterised in that:
- the aqueous dispersion comprises a surfactant and a chain transfer agent is added after the commencement of particle nucleation, such that the polymerisation 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.
The process of claim 54, wherein the magnetic material is a superparamagnetic material which comprises a ferrite or coated iron based or iron-nickel alloy nanoparticles.
Monodisperse magnetic polymer particles comprising a matrix polymer and magnetic crystals, the particles having a z-average diameter of less than 1 μm, and having a CV, when measured by disc centrifugation analysis, of less than 15%.
A process for the preparation of monodisperse particles comprising an Ugelstad process with more than one swelling and polymerisation stage, the Ugelstad process comprising a first pass and a final pass of the following steps (i) to (vi):
- (i) forming an aqueous dispersion comprising
- the monodisperse seed particles (first pass) or intermediate particles (final pass and optional intermediate pass),
- finely divided droplets comprising an organic compound of molecular weight below 5,000 and water solubility at 25° C. of less than 10−2 g/L, and
- an organic solvent in which the organic compound is soluble, the organic solvent being optional when the polymer forming the seed particles has an average molecular weight which corresponds to up to 50 monomer units;
- (ii) allowing the organic compound to diffuse into the monodisperse seed particles, causing the seed particles to become activated;
- (iii) removing the organic solvent, where present, from inside the seed particles, and contacting the activated seed particles or intermediate particles with an aqueous vehicle containing a monomer having a solubility in water at least 10 times that of the organic compound and, in the final pass only, a cross-linker;
- (iv) allowing the monomer and, in the final pass only, the cross-linker to diffuse into the activated seed particles or intermediate particles to form an aqueous dispersion of swollen seed particles or intermediate particles;
- and
- (v) initiating polymerisation of the monomer and, in the final pass only, the cross-linker in the swollen seed particles.
63-64. (canceled)
(canceled)
Dependencies are inferred from the claim text.