Abstract Monodisperse latexes having a particle size in the range of 2 to 40 microns are prepared by seeded emulsion polymerization in microgravity. A reaction mixture containing smaller monodisperse latex seed particles, predetermined amounts of monomer, emulsifier, initiator, inhibitor and water is placed in a microgravity environment, and polymerization is initiated by heating. The reaction is allowed to continue until the seed particles grow to a predetermined size, and the resulting enlarged particles are then recovered. A plurality of particle-growing steps can be used to reach larger sizes within the stated range, with enlarged particles from the previous steps being used as seed particles for the succeeding steps. Microgravity enables preparation of particles in the stated size range by avoiding gravity-related problems of creaming and settling, and flocculation induced by mechanical shear that have precluded their preparation in a normal gravity environment.
Inventors
👤 with respect to an invention of Lovelace Alan M. Administrator of the National Aeronautics and Space Administration
👤 John W. Vanderhoff
👤 Fortunato J. Micale
👤 Mohamed S. El-Aasser
👤 Dale M. Kornfeld
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-29 15:08
CPC Classifications
C; C08; C08F; C08F291/00
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
94 words
The method of preparing a monodisperse latex having a particle size over 2 microns which comprises: (a) combining monodisperse seed particles of a polymer prepared by emulsion polymerization, predetermined amounts of monomer, an emulsifier, at least one inhibitor, a heat-decomposable initiator and water in a closed reaction vessel: (b) disposing the reaction vessel containing the resulting mixture in a microgravity environment; (c) heating the mixture above the decomposition temperature of said initiator; and (d) maintaining the mixture in microgravity at an effective polymerization temperature under mild agitation until growth of seed particles is completed.
Claim 2
Independent Claim
94 words
The method of preparing a monodisperse latex having a particle size over 2 microns which comprises: (a) combining monodisperse seed particles of a polymer prepared by emulsion polymerization, predetermined amounts of monomer, an emulsifier, at least one inhibitor, a heat-decomposable initiator and water in a closed reaction vessel: (b) disposing the reaction vessel containing the resulting mixture in a microgravity environment; (c) heating the mixture above the decomposition temperature of said initiator; and (d) maintaining the mixture in microgravity at an effective polymerization temperature under mild agitation until growth of seed particles is completed.
Claim 3
Dependent Claim
15 words
The method of claim 1 wherein said polymer is polystyrene and the monomer is styrene.
Claim 4
Dependent Claim
17 words
The method of claim 2 wherein the particle size of the seed particles is about 2 microns.
Claim 5
Dependent Claim
12 words
The method of claim 3 wherein the emulsifier is an anionic surfactant.
Claim 6
Dependent Claim
13 words
The method of claim 4 wherein the initiator is azobisisobutronitrile or benzoyl peroxide.
Claim 7
Dependent Claim
21 words
The method of claim 5 wherein the concentration of polymer and monomer in said mixture is 20 to 30 weight percent.
Claim 8
Dependent Claim
17 words
The method of claim 6 wherein said effective polymerization temperature is from 60° C. to 80° C.
Claim 9
Dependent Claim
28 words
The method of claim 1 including the additional steps of recovering the resulting enlarged particles and subjecting said particles to additional growth according to steps (a) through (d).
Claim 10
Dependent Claim
11 words
The method of claim 1 wherein said inhibitor is potassium dichromate.
Claim 11
Dependent Claim
19 words
The method of claim 9 wherein said mixture includes two inhibitors and said inhibitors are potassium dichromate and tertbutylpyrocatechol.