Ring Opening Polymerization of Cyclotetrasilanes: A Versatile Route to Linear Polysilylenes.
CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF CHEMISTRY
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This paper reviews ring opening polymerization ROP of cyclotetrasilanes. The ROP of cyclotetrasilanes is an interesting and versatile method to prepare both polysilylenes homo and copolymers which cannot be prepared by other methods. First fundamentals of ROP are discussed with a special emphasis on thermodynamics and kinetics as well as chemoselectivity, regioselectivity, and stereoselectivity. Subsequently, a basis of silicon chemistry, including Si-Si bond formation and cyclosilanes, is covered. A variety of cyclotetrasilanes, MenPh8-nSi4, where n 3, 4, 5, or 6, were prepared and polymerized using silyl cuprates as initiators. The polymerization of the all-trans isomer of Me4Ph4Si4 proceeded with two inversions of configuration at both the attacked silicon atom in the ring and the newly formed reactive center resulting in a polymer with 75 heterotactic triads and 25 isotactic triads. Polymerization of the tri-, penta-, and hexamethyl derivatives proceeded with some degree of regioselectivity. jg p. 2
- Polymer Chemistry
- Organic Chemistry
- Physical Chemistry