Initiator for surface-based polymerization and use thereof
Disclosed are polymerization initiators as may be utilized for addition of polymers to a substrate surface. The initiators are azo-based initiators that include multi-functionality through addition of multiple anchoring agents to an inner azo group. Disclosed polymerization initiators can be utilized to form high density and high molecular weight polymers on a surface such as a particulate surface. Formed materials can be beneficial in one embodiment in fracking applications, providing composite proppant/polymer materials that can prevent leakage of polymers from a subterranean geologic formation.
1. A composite particle comprising a polymerization initiator bonded to a surface of a particle, the polymerization initiator comprising an azo-group comprising a first and second end, a first anchoring agent and a second anchoring agent, the first and second anchoring agents being bonded to the first and second ends, respectively, of the azo-group, at least one of the first and second anchoring agents being bonded to the surface of the particle.
2. The composite particle of claim 1 , the polymerization initiator having the general structure of:
X 1 —R 1 -A 1 -N═N-A 2 -R 2 —X 2
in which
A 1 and A 2 are the same as or different from one another and each comprise an attachment group,
R 1 and R 2 are the same as or different from one another and each comprise a linkage group,
X 1 and X 2 are the same as or different from one another and each comprise the first and second anchoring agents, respectively.
3. The composite particle of claim 2 , wherein A 1 and A 2 have the general structure:
in which
R 3 and R 4 independently comprise H, CN, CH 3 , COOR 6 (R 6 ═H or alkyl), or C 2 H 5 ; and
R 5 is an alkyl group.
4. The composite particle of claim 2 , wherein R 1 and R 2 independently comprise a carbonyl-containing linkage, an amine-containing linkage, a thiol-containing linkage, a phosphonate linkage, an epoxy linkage, an alkene-containing linkage, or are a bond.
5. The composite particle of claim 2 , wherein X 1 and X 2 each independently comprise a thiol group, a phosphonate group, or a halogen.
6. The composite particle of claim 1 , wherein at least one of the first and second anchoring agents are bonded to the surface via thiozoline reactivity.
7. The composite particle of claim 1 , wherein at least one of the first and second anchoring agents are bonded to the surface via succinimide reactivity.
8. The composite particle of claim 1 , wherein both the first and second anchoring agents are bonded to the surface of the particle.
9. The composite particle of claim 1 , wherein the particle comprises natural or synthetic clay, inorganic metal oxide, latex, or organic materials.
10. The composite particle of claim 1 , wherein the particle comprises silica.
11. The composite particle of claim 1 , wherein the particle is a proppant particulate substrate.
12. A method for forming a composite particle comprising a particle and a polymer at the surface of the polymer, the method comprising:
bonding a polymerization initiator at a surface of the particle, the polymerization initiator comprising an azo-group comprising a first and second end, a first anchoring agent and a second anchoring agent, the first and second anchoring agents being bonded to the first and second ends, respectively, of the azo-group, at least one of the first and second anchoring agents being bonded to the surface of the particle; and
bonding the polymer to the surface of the particle via the polymerization initiator.
13. The method of claim 12 , wherein the polymer is bonded to the surface of the particle via a “grafting from” process.
14. The method of claim 12 , wherein the polymer is bonded to the surface of the particle via a “grafting to” process.
15. The method of claim 12 , wherein the polymerization initiator has the general structure of:
X 1 —R 1 -A 1 -N═N-A 2 -R 2 —X 2
in which
A 1 and A 2 are the same as or different from one another and each comprise an attachment group,
R 1 and R 2 are the same as or different from one another and each comprise a linkage group,
X 1 and X 2 are the same as or different from one another and each comprise the first and second anchoring agents, respectively.
16. The method of claim 15 , wherein A 1 and A 2 have the general structure:
in which
R 3 and R 4 independently comprise H, CN, CH 3 , COOR 6 (R 6 ═H or alkyl), or C 2 H 5 ; and
R 5 is an alkyl group.
17. The method of claim 15 , wherein R 1 and R 2 independently comprise a carbonyl-containing linkage, an amine-containing linkage, a thiol-containing linkage, a phosphonate linkage, an epoxy linkage, an alkene-containing linkage, or are a bond.
18. The method of claim 15 , wherein X 1 and X 2 each independently comprise a thiol group, a phosphonate group, or a halogen.
19. The method of claim 12 , comprising bonding at least one of the first and second anchoring agents to the surface via thiozoline reactivity or via succinimide reactivity.
20. The method of claim 12 , comprising bonding the polymerization initiator to the surface via both the first and second anchoring agents.