Claims
- 1. A method of preparing uniformly-shaped, porous, round beads having an average diameter below 2 microns comprising the steps of:
- copolymerizing a polymerizable mixture of an amino- or hydroxy-substituted acrylic monomer and a minor amount of a polyunsaturated cross-linking agent in aqueous medium containing 0.05 to 5% by weight of an aqueous soluble polyether by applying high energy radiation to the mixture; and
- recovering said beads.
- 2. A method according to claim 1 in which the polyether is a polyalkylene oxide having a molecular weight from 300,000 to 10,000,000 and is present in the polymerizable mixture in an amount from 0.2 to 2% by weight.
- 3. A method according to claim 2 in which the polyether is a polymer of ethylene oxide, propylene oxide or mixtures thereof and the molecular weight is from 400,000 to 6,000,000.
- 4. A method according to claim 2 in which polymerization is conducted at a temperature from -70.degree. C to reflux and at least 80% of the beads produced have a diameter of no more than 2 microns.
- 5. A method according to claim 1 in which the polymerization is conducted at a temperature of 0.degree. to 70.degree. C with application of 0.05 to 1.0 megarads of radiation to the mixture from a cobalt gamma source.
- 6. A method according to claim 2 in which the acrylic monomer is selected from a hydroxy substituted acrylate, an amino substituted acrylate, or mixtures thereof.
- 7. A method according to claim 6 in which the monomer is selected from compounds of the formula: ##STR3## where R.sup.1 is hydrogen or lower alkyl of 1-8 carbon atoms, R.sup.2 is alkylene of 1-12 carbon atoms, Z is OH or ##STR4## where R.sup.3 or R.sup.4 are H, lower alkyl of 1-10 carbon atoms or lower alkoxy of 1-10 carbon atoms.
- 8. A method according to claim 7 in which the monomer is selected from hydroxyethylmethacrylate, hydroxypropylmethacrylate, dimethylaminoethylmethacrylate and 2-aminoethylmethacrylate.
- 9. A method according to claim 6 in which the polymerizable mixture contains 1-35 weight percent based on said acrylic monomer of a comonomer selected from a lower alkyl methacrylate, acrylic acid, methacrylic acid, styrene or vinyl toluene.
- 10. A method according to claim 6 in which the cross-linking agent is present in the polymerizable mixture in an amount from 0.1 to 30% and is a liquid polyunsaturated compound.
- 11. A method according to claim 10 in which the cross-linking agent is a low molecular weight liquid polyvinyl diene or triene compound.
- 12. A method according to claim 11 in which the cross-linking agent is selected from ethylene dimethacrylate, divinyl benzene, trimethylol propane trimethacrylate, and N,N'-methylene-bis-acrylamide.
- 13. A method according to claim 7 in which the monomer is hydroxyethylmethacrylate.
Parent Case Info
This is a division of application Ser. No. 434,124, filed Jan. 17, 1974.
ORIGIN OF THE INVENTION
The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 83-568 (72 Stat. 435; 42 USC 2457).
US Referenced Citations (3)
Divisions (1)
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Number |
Date |
Country |
Parent |
434124 |
Jan 1974 |
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