PMSE 108 |
| Polymerization of alpha-aminoacid-N-carboxyanhydrides is an established method for the synthesis of high molecular weight polypeptides in large quantities. The state-of-the-art NCA polymerizations are through the use of zero-valent transition metal catalysts that were developed by Deming and coworkers in the late 1990's. These metal catalysts allow the formation of polypeptides with precisely controlled molecular weights and narrow polydispersities. Parallel to the development of transition metal catalysts, there is also growing interest in developing organocatalysts for controlled organic reaction or polymerizations. NCA polymerizations initiated with classical metal-free organocatalysts such as various amino compounds, however, result in homopolypeptides or random copolypeptides with poorly controllable molecular weights and broad polydispersities. In this preprint, we report the use of hexamethyldisilazane (HMDS) for living NCA polymerizations that lead to formation of polypeptides with controlled molecular weights and narrow molecular weight distributions. At M/I = 100, HMDS mediated gamma-benzyl-glutamate NCA polymerization gave poly(gamma-benzyl-glutamate) with number average molecular weight of 21.8 kDa, which agrees perfectly with the expected polymer molecular weight (21.9 kDa). |
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Polypeptide and Protein Materials
8:00 AM-11:40 AM, Monday, August 20, 2007 Westin Boston Waterfront -- Commonwealth Blrm C, Oral
Division of Polymeric Materials: Science & Engineering |