Polymer architecture control using living polymerizations
Our interest lies in the development of cost-effective, one-pot chemistry that uses cationic, anionic, free radical, and step-growth polymerizations in an orthogonal fashion. This approach relies on a multifunctional initiator containing initiating sites for each method and has led to the synthesis of novel functional macromonomers. In living free-radical polymerization, we are investigating novel functionalized nitroxyl radicals that operate at lower temperatures and can tolerate a broad scope of monomers. In our continuing studies of GTP, we are probing control of stereochemistry and regio-chemistry using cyclopolymerization, chiral monomers and initiators.
Synthesis of bioorganic "LegoŽ" sets: A modular approach to architecture control
Naturally occurring polymers are characterized by well-defined secondary and tertiary structures. However, these structures are rare in synthetic polymers. We are developing a modular chemical approach involving catenation of well-defined biopolymer architectures such as a-helices and b-sheets, to control the structure of synthetic polymers. Each building block or "LegoŽ" set, having the desired conformation, is independently preformed and then catenated. This is expected to lead to materials of predetermined folded structures having predictable modulus induced by appropriately placed organic segments with either twofold axes or U-turns. The concept is also being applied to the synthesis of high-performance polyamides. It has enabled us to determine the fold spacing required for certain properties, such as lyotropic liquid crystallinity, to be retained.
Carbohydrate-based, environmentally benign, water-soluble polymers
This project is directed to the synthesis of architecturally welldefined, environmentally benign polymers based upon monomers derived from renewable resources. An important part of the project is the development of both solution and solid phase techniques for producing, on large scale, polymers having uniform chain lengths. ABn-type glycal monomers containing at least one free hydroxyl group will undergo self-addition to give both linear and hyperbranched polymers. Copolymers and materials with a variety of controlled surface functionalities are being prepared.
Surface modification and interfacial chemistry
Our goal in this research area involves the design and synthesis of novel self-assembling molecules (both polymeric and monomeric) that form spontaneously or can be induced to form monolayers leading to well-defined, quasi two-dimensional surfaces with appropriate placement of surface functional groups. Some of the investigations include molecular recognition in the LB subphase, organic surface reactivities, and enhancement of polymer properties through surface modifications.
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Winningham,
M. J.; Sogah, D. Y. A modular approach to polymer architecture
control via catenation of prefabricated biomolecular segments.
Polymers containing parallel beta-sheets templated by a phenoxathiin-based
reverse turn mimic. Macromolecules 1997, 30,
862.
Puts, R. D.; Sogah, D. Y. Universal multifunctional
initiator containing orthogonal reactive sites. Synthesis of
macromonomers and comb polymers using consecutive controlled
free radical and cationic ring-opening polymerizations. Macromolecules
1997, 30, 7050.
Weimer, M. W.; Scherman, O. A.; Sogah, D.
Y. Multifunctional initiators containing orthogonal sites. One-pot,
one-step, block copolymerization by simultaneous free radical
and either cationic ring-opening or anionic ring-opening polymerizations.
Macromolecules 1998, 31.
Puts, R. D.; Sogah, D. Y. Cationic ring-opening
cyclopolymerization of bis(oxazolines). Synthesis of chiral polymers
containing pendent heteromacrocycles. Macromolecules 1997,
30, 6826.
Zheng, S.; Sogah, D. Y. Highly isotactic
optically active methacrylate polymers by free radical cyclopolymerization.
Tetrahedron 1997, 53, 15469.
Puts, R. D.; Chao, J.; Sogah, D. Y. Novel
biaryl bis(oxazolines). Synthesis 1997, 431.
Puts, R. D.; Sogah, D. Y. Control of living
free radical polymerization by a new chiral nitroxide and implications
for the polymerization mechanism. Macromolecules 1996,
29, 3323.
Nakano, T., Sogah, D. Y. Toward control of
stereochemistry in GTP by a rational monomer design. Cyclopolymerization
of 2,2'-bis(methacryloylxymethyl)-1,1'-binaphthyl. J. Am.
Chem. Soc. 1995, 117, 534.
Shen, J., Sogah, D. Y. Novel alternating
copolymers of controlled sequence. Regiochemical control in aldol
group transfer polymerization of substituted (butadienyloxy)trialkylsilanes.
Macromolecules 1994, 27, 6996.
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