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Research Interests
My research group is interested in the common ground shared by polymer,
organic, and materials chemistry and we are involved in the design,
synthesis, and characterization of polymer-based organic materials.
Polymer physics provides a framework for understanding the basics of
copolymer self-assembly in the bulk and in solution and this knowledge,
in turn, suggests concepts for the design of novel polymers and copolymers
that will organize into predictable arrangements on the nanometer scale.
Such assemblies, many inspired by biological systems, are predicted
to exhibit novel properties in a range of possible applications.
The combination of living anionic, free radical, and cationic polymerization
methods can provide access to many possible polymeric structures, and
many techniques of organic chemistry are applicable to the modification
of these polymers for the preparation of an even larger variety of materials.
We use these techniques to realize specifically designed polymeric architectures.
Synthesis of these materials is the major focus of the research program,
and students will gain experience in many synthetic techniques. A number
of techniques for characterization of new materials by established methods
(i.e., small-angle scattering, electron microscopy, etc.) at both the
molecular level and at longer length scales are also used.
Representative research projects being undertaken are outlined below.
Each primarily involves the use of living/controlled free radical polymerization
techniques in combination with initiator and/or monomer synthesis for
the creation of novel polymers that should exhibit interesting self-assembly
behavior in solution and in bulk.
1. Stimulus-Induced Morphological Transformation of Ternary
Copolymer Micelles: The micellar form which amphiphilic block
copolymers adopt in water is strongly governed by the relative volumes
of the hydrophobic and hydrophilic blocks. The preparation of triblock
copolymers with the hydrophilic and hydrophobic end blocks typical of
amphiphilic block copolymers, but with a central block which exhibits
condition-dependent water-solubility, will be targeted. Adjustment of
the hydrophilic-hydrophobic balance in these polymeric systems should
lead to interesting stimulus-induced changes in micellar form, which
will be studied by techniques such as light scattering and small-angle
x-ray scattering.
2. Incorporation of Metallic Nanoparticles into Polymeric Matrices:
In collaboration with Dave Glueck at Dartmouth, multiblock copolymers wherein different blocks
and utilized to specifically stabilize the formation of ordered arrays
of nanoparticles composed of different metals are being prepared. Related polymers are being explored with collaborators at Brookhaven National Laboratory.
3. New Alkoxyamines for Controlled Free Radical Polymerization:
We are investigating the preparation of new alkoxyamines by reaction
of nitrosoalkanes with carbon-centered radicals as outlined below. New
functional alkoxyamines are being designed for the preparation of end-functional
polymers.
Selected
Publications
- Sundararaman,
A.; Stephan, T.; Grubbs, R. B. “Reversible Restructuring of
Aqueous Block Copolymer Assemblies through Stimulus-Induced Changes
in Amphiphilicity.” J. Am. Chem. Soc. 2008,
130, 12264-12265. (link)
- Grubbs, R. B.
“Roles of Polymer Ligands in Nanoparticle Stabilization.”
Polymer Reviews 2007, 47, 197-215. (link)
- Sessions, L. B.; Cohen, B. R.; Grubbs, R. B. “Alkyne-Functional
Polymers through Sonogashira Coupling to Poly(4-Bromostyrene).”
Macromolecules 2007, 40, 1926-1933.
(link)
- Xia, Q.; Grubbs,
R. B. “In Situ Generation of Nitroxide from Alkoxyamines for
Controlled Acrylate Polymerization.” J. Polym. Sci., Part
A: Polym. Chem. 2006, 44, 5128-5136.
(link)
- Aubrecht, K.
B.; Grubbs, R. B. "Synthesis and Characterization of Thermoresponsive
Amphiphilic Block Copolymers Incorporating a Poly(Ethylene oxide-stat-Propylene
oxide) Block." J. Polym. Sci., Part A: Polym. Chem. 2005,
43, 5156-5167. (link)
- Grubbs, R. B.
"Hybrid Metal-Polymer Composites from Functional Block Copolymers."
J. Polym. Sci., Part A: Polym. Chem. 2005, 43,
4323-4336. (link)
- Wegrzyn, J.
K.; Stephan, T.; Lau, R. N.; Grubbs, R. B. "Preparation of poly(ethylene
oxide)-block-polyisoprene by nitroxide-mediated free radical polymerization
from PEO macroinitiators." J. Polym. Sci., Part A: Polym.
Chem. 2005, 43, 2977-2984.(link)
- Sessions, L.
B.; Mîinea, L. A.; Ericson, K. D.; Glueck, D. S.; Grubbs, R.
B. "Alkyne-functional Homopolymers and Block Copolymers through
Nitroxide-Mediated Free Radical Polymerization of 4-(Phenylethynyl)styrene."
Macromolecules 2005, 2116-2121. (link)
- Grubbs, R. B.;
Wegrzyn, J. K.; Xia, Q. "One-step synthesis of alkoxyamines for
nitroxide-mediated radical polymerization." Chem. Comm. 2005,
80-82. (link)
- Mîinea,
L. A.; Sessions, L. B.; Ericson, K. D.; Glueck, D. S.; Grubbs, R.
B. "Phenylethynylstyrene-Cobalt Carbonyl Block Copolymer Composites."
Macromolecules 2004, 37, 8967-8972. (link)
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