Anwendung neuartiger Metalsiloxid-Katalysatoren für die ringöffnende Polymerisation zyklischer Monomeren zu bioabbaubaren und biokompatiblen Polymeren

• Applicant: Dr. Clemens Krempner
• Subject Area: Preparatory and Physical Chemistry of Polymers
• Term: from 2004 to 2007
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5442552

The objective of this project is to synthesize and utilize novel metal siloxides as catalysts for the production of biodegradable and biocompatible polymers from readily available, inexpensive renewable resources. Materials of high performance having a potential for medical application (polyoxogenates, polyamides) will be made by metal assisted ring opening polymerization of cyclic monomers such as lactides, epoxides and morpholines. In this regard, novel catalysts of the general formula [(R3SiO)"M]-OR, which combine non-toxic silanol ligands with inexpensive and biological compatible metals such as Zn, Mg, Ca (or less toxic Y, La, Al) will be designed, synthesized and studied. Whereas the alkoxide group (OR) in these compounds is an initiator for the ring opening, the electron withdrawing siloxide ligand (R3SiO) significantly increases the electrophilicity of the metal. We believe this should result in enhanced activities and selectivities in comparison to related systems. To obtain active metal siloxides of sufficient stability, novel sterically encumbered silanols with pendant donor groups that can coordinate to the catalytically active metal center will be prepared by treatment of donor functionalized organolithium reagents with chlorosilanes (R2SiC12) and subsequent hydrolysis. Finally, the catalysts will be synthesized by treatment of the obtained silanols with reactive metal amides or alkoxides.

• DFG Programme: Research Fellowships
• International Connection: USA
• Cooperation Partner: Professor Dr. Malcolm H. Chisholm (†)