Dispersions containing living radicals
View Patent ↗A dispersion of polymer particles, the particle containing, on average, one or more living radicals each, the radicals not being chemically protected. Further disclosed is a free radical polymerization process resulting in a dispersion containing polymer particles having on average one or more living radicals. The process involves carefully regulating the polymerization conditions to produce small size particles under monomer-starved conditions containing, on average, more than one living radical in every particle. These living polymer radicals can be further reacted to form polymers with a controlled architecture.
1. A process for producing a polymer having a controlled architecture in a reactor comprising:
a) forming a first stage stable polymer dispersion by polymerizing one or more monomers in a dispersion medium under monomer-starved conditions using a source of free radicals to initiate polymerization and optionally using a surfactant, stabilizer, or dispersant to stabilize the polymer dispersion and without using a chemical polymerization control agent or capping agent wherein said particles contain an average of at least one living radical per particle; and
b) adding additional monomer to the first stage dispersion in one or more stages to extend the pre-existing polymer chains by reaction of the additional monomer with the living radicals; and
c) optionally adding one or more initiators comprising initiator molecules in one or more steps to the dispersion.
2. The process of claim 1 , wherein the initiator is added during step (a).
3. The process of claim 1 , wherein the initiator is added during step (b).
4. The process of claim 1 , wherein the initiator is added during steps (a) and (b).
5. The process of claim 1 , wherein the number of initiator molecules are in the range of 0.001 to 10,000 times the number of polymer particles present in the reactor.
6. The process of claim 5 , wherein the number of initiator molecules are in the range of 0.01 to 1000 times the number of polymer particles present in the reactor.
7. The process of claim 6 , wherein the number of initiator molecules are in the range of 0.1 to 1000 times the number of polymer particles present in the reactor.
8. The process of claim 1 wherein said dispersing medium is water.
9. The process of claim 1 wherein said first stage dispersion is formed by regulating said particle size, monomer and/or solvent concentration within said particle.
10. The process of claim 1 wherein said source of free radical generating agent is a water-soluble initiator.
11. The process of claim 1 further comprising adding, following step (b) and optionally step (c), at least one additional monomer in at least one additional stage to the said dispersion polymer having living, trapped radicals.
12. The process of claim 1 wherein the additional monomer in step (b) and/or subsequent stages comprises the same monomer as in the first stage polymerization.
13. The process of claim 1 wherein the additional monomer in step (b) or in any subsequent stages comprises at least one monomer which is different than the first stage monomer, resulting in a block copolymer.
14. The process of claim 1 wherein the additional monomer in step (b) or in any subsequent stages comprises at least one monomer which is different than the first stage monomer, resulting in a graft copolymer.
15. The process of claim 1 wherein the additional monomer in step (b) or in any subsequent stages comprises at least one monomer which is different than the first stage monomer, resulting in a mixture of block and graft copolymers.
16. The process of claim 1 wherein said copolymer is highly branched or hyperbranched.
17. The process of claim 1 wherein said dispersion medium is an admixture of two or more liquids.
18. The process of claim 1 wherein said stabilizer is a colloid.
19. The process of claim 1 wherein said surfactant is a non-ionic surfactant.
20. The process of claim 13 wherein said block copolymer is a pure block copolymer.
21. The process of claim 13 wherein said block copolymer is a tapered block copolymer.
22. The process of claim 1 wherein said first stage monomer and said second stage monomer comprise at least one hydrophobic monomer and at least one hydrophilic monomer.