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Title: Cyclopropenimine superbases: Competitive initiation processes in lactide polymerization

Cyclopropenimine superbases were employed in this study to catalyze the ring-opening polymerization of lactide. Polymerization occurred readily in the presence and absence of alcohol initiators. Polymerizations in the absence of alcohol initiators revealed a competitive initiation mechanism involving deprotonation of lactide by the cyclopropenimine to generate an enolate. NMR and MALDI-TOF analysis of the poly(lactides) generated from cyclopropenimines in the absence of alcohol initiators showed acylated lactide and hydroxyl end groups. Finally, model studies and comparative experiments with guanidine and phosphazene catalysts revealed the subtle influence of the nature of the superbase on competitive initiation processes.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [1]
  1. Stanford Univ., Stanford, CA (United States)
  2. Columbia Univ., New York, NY (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
ACS Macro Letters
Additional Journal Information:
Journal Volume: 4; Journal Issue: 8; Journal ID: ISSN 2161-1653
Publisher:
American Chemical Society (ACS)
Research Org:
Stanford Univ., CA (United States); Columbia Univ., New York, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1345046