Claims
- 1. A composition consisting essentially of uniformly shaped, hydrophilic, swellable, porous, round beads, at least 80% having a uniform diameter from less than to 2 microns and being the cross-linked polymer of an acrylic monomer containing an hydroxy or amino group and of the formula: ##EQU3## 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 ##EQU4##
- where R.sup.3 or R.sup.4 are H, lower alkyl or lower alkoxy, and 0. 1 to 30 weight percent of a liquid diene or triene cross-linking agent.
- 2. A composition according to claim 1 in which the monomer is selected from hydroxyethylmethacrylate, hydroxypropylmethacrylate, dimethylaminoethylmethacrylate, and 2-aminoethylmethacrylate.
- 3. A composition according to claim 1 in which the beads contain 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.
- 4. A composition according to claim 1 in which the cross-linking agent is a low molecular weight liquid polyvinyl diene or triene compound.
- 5. A composition according to claim 4 in which the cross-linking agent is selected from ethylene dimethacrylate, divinyl benzene, trimethylol propane trimethacrylate, and N,N'-methylene-bis-acrylamide.
- 6. A composition according to claim 1 in which the monomer is hydroxyethylmethacrylate.
- 7. A composition according to claim 6 in which the cross-linking agent is ethylene dimethacrylate present in an amount of about 1.5% by weight.
- 8. A composition according to claim 1 in which at least 90% of the beads have a uniform diameter between 0.001 to 2 microns.
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)