Composite magnetic beads
US5834121A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jan 16, 1996 |
| Grant date | Nov 10, 1998 |
| Priority date | — |
| Expiry date | Jan 16, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2998
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
This invention provides a novel composite magnetic bead and a method for making the composite magnetic bead. The composite magnetic bead is comprised of a matrix formed from vinyl monomers throughout which is distributed primary beads, each primary bead of which is a magnetizable metal oxide encapsulated in a rigid polymeric coating. The matrix structure allows the composite magnetic bead to swell in organic solvents without loss of the intermeshed primary beads. Further, the matrix can be functionalized to allow the covalent bonding of sites useful for organic syntheses. The composite magnetic beads are made utilizing a core-shell polymerization techinque under conditions which preserve the oxidation state of the magnetizable metal oxide in the primary particles. In one embodiment, primary beads, each having a hydrophobic exterior surface, are dispersed in an inert solvent with a vinyl monomer and a crosslinking agent for that monomer to form a dispersed phase. The dispersed phase is mixed into an aqueous solvent-dispersing agent phase and stirred until the desired droplet size is achieved, then polymerization is initiated. After removal of the solvent and unreacted components, th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.