CHED 684 |
| Fluorenyllithium, formed by treatment of fluorene with a strong base such as lithium diisopropylamide, was able to initiate the anionic polymerization of methyl methacrylate (MMA), as expected. Therefore, a similar procedure was implemented with 9-bromofluorene as the initiator; this reaction scheme was intended to deprotonate the 9-carbon while retaining the C-Br bond, which could then be utilized in atom transfer radical polymerization (ATRP) of styrene. The resulting polymer would be a polystyrene-block-poy(methyl methacrylate) with fluorene at the junction. It was found, however, that dominant side reactions preclude such a pathway: for example, upon reaction with a base, the halogen-substituted fluorenyl anions spontaneously undergo C-X cleavage, leading to an unsaturated fluorene dimer. Another fluorene-based initiator, 9-(2,2,6,6-tetramethyl-4-hydroxypiperidinyloxy)fluorene, was prepared from 9-bromofluorene. This compound, though found to successfully initiate the nitroxide-mediated polymerization (NMP) of styrene, has thus far failed as an anionic initiator of MMA when deprotonation is attempted. |
|
Undergraduate Research Poster Session: Polymer Chemistry
11:00 AM-1:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Poster
Division of Chemical Education |