Current Research Projects

1. Synthesis of well defined macromolecules via living and controlled polymerizations. Block, graft and gradient copolymers. Control of chain microstructure. Functional polymers and telechelics. Radical, cationic, and anionic polymerization of alkenes and heterocyclics.
A. In the controlled radical polymerization we apply dynamic equilibration between growing radicals and dormant covalent species. The examples of dormant species are alkoxyamines (X=O-NR2) and alkyl halides (X=Cl, Br). The latter system, Atom Transfer Radical Polymerization, ATRP, is reversibly activated by transition metal salts (Y=Cu/2BPY):
 

Another process is based on the degenerative transfer:

In both systems polymers with low polydispersities as well as block, graft, gradient, periodic and hyperbranched (co)polymers have been prepared.

References

1. "Living" Radical Polymerization. I. Possibilities and Limitations.", D. Greszta, D. Mardare, K.Matyjaszewski, Macromolecules, 27, 638 (1994)
2. "Living / Controlled Radical Polymerization. Transition - Metal - Catalyzed Atom Transfer Radical Polymerization in the Presence of A Conventional Radical Initiator", J. S. Wang, K. Matyjaszewski, Macromolecules, 8, 7572 (1995)
3. "Controlled Radical Polymerization by Degenerative Transfer. The Effect of the Structure of the Transfer Agent", S. G. Gaynor, J. S. Wang, K. Matyjaszewski, Macromolecules, 8, 8051 (1995)
B. In the controlled carbocationic polymerization we apply dynamic equilibration of growing carbenium ions with dormant covalent species and onium ions:
 

References

1. "Unified Approach to Living and Non-Living Cationic Polymerization of Alkenes", K. Matyjaszewski, P. Sigwalt, Polymer International, 35, 1 (1994)
2. "Cationic Polymerization: Mechanisms, Synthesis and Applications", K. Matyjaszewski, Marcel Dekker, New York, 1996
2. Organometallic polymers. Preparation of well defined oligomers and high molecular weight polymers. Inorganic and organometallic polymers as nonlinear optical materials, photoconductors, photoresists, and precursors to ceramics. Polysilanes and polyphosphazenes
A. Polysilanes find applications as precursors to ceramics, radical initiators, specialty photoresists, nonlinear optical, photoconductive and photorefractive materials. We devloped new synthetic routes to polysilanes by sonochemical reductive coupling of dichlorosilanes, by modification reactions and by the ring opening process:

Ring opening allows preparation of polymers with controlled stereo- and regiochemistry as well as various random and block copolymers. We study new monomer synthesis and novel initiating systems to further improve control of molecular weights and tacticity of resulting polymers. We also investigate synthesis of polysilanes with novel topologies including chiral polymers.

References

1. "Sonochemical Synthesis of Polysilylenes by Reductive Coupling of Disubstituted Dichlorosilanes with Alkali Metals" K. Matyjaszewski, D. Greszta, J. Hrkach, H. K. Kim, Macromolecules, 28, 59 (1995)
2. "Ring Opening Polymerization of Cyclotetrasilanes: Microstructure and Mechanism", E. Fossum, K. Matyjaszewski, Macromolecules, 28, 1618 (1995)
B. Polyphosphazenes are very important class of polymers with inorganic backbone which exhibit various special properties and find applications as specialty biomedical materials, low temperature elastomers and fire resistant polymers. We have discovered two new synthetic approaches towards polyphosphazenes based on catalyzed polymerization of phosphoranimines:

and phosphine azides and used them successfully for the preparation of first well-defined homopolymers and various random and block copolymers. Current research is focused on new monomers and improved initiating systems for the synthesis of polyphosphazenes with controlled polydispersities, end functionalities and novel copolymers.

References

1. "Synthesis of Polyphosphazenes from Phosphoranimines and Phosphine Azides", K. Matyjaszewski, U. Franz, R. A. Montague, M. L. White, Polymer , 35, 5005 (1994)
2. "Synthesis, Isomerization and Polymerization of Mixed Phosphoranimines", M. L. White, K. Matyjaszewski, J. Polym. Sci., Polym. Chem., 34, 277 (1996)
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