Ring-Opening Polymerization of Cyclic Esters and Carbonates with (Thio)urea/Cyclopropenimine Organocatalytic Systems.

Autor: Morodo R; Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States., Dumas DM; Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States., Zhang J; Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States., Lui KH; Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States., Hurst PJ; Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States., Bosio R; IBM Almaden Research Center, San Jose, California 95120, United States., Campos LM; Department of Chemistry, Columbia University, New York, New York 10027, United States., Park NH; IBM Almaden Research Center, San Jose, California 95120, United States., Waymouth RM; Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States., Hedrick JL; IBM Almaden Research Center, San Jose, California 95120, United States.
Jazyk: angličtina
Zdroj: ACS macro letters [ACS Macro Lett] 2024 Jan 22, pp. 181-188. Date of Electronic Publication: 2024 Jan 22.
DOI: 10.1021/acsmacrolett.3c00716
Abstrakt: Organocatalyzed ring-opening polymerization is a powerful tool for the synthesis of a variety of functional, readily degradable polyesters and polycarbonates. We report the use of (thio)ureas in combination with cyclopropenimine bases as a unique catalyst for the polymerization of cyclic esters and carbonates with a large span of reactivities. Methodologies of exceptionally effective and selective cocatalyst combinations were devised to produce polyesters and polycarbonates with narrow dispersities ( Đ = 1.01-1.10). Correlations of the p K a of the various ureas and cyclopropenimine bases revealed the critical importance of matching the p K a of the two cocatalysts to achieve the most efficient polymerization conditions. It was found that promoting strong H-bonding interactions with a noncompetitive organic solvent, such as CH 2 Cl 2 , enabled greatly increased polymerization rates. The stereoselective polymerization of rac -lactide afforded stereoblock poly(lactides) that crystallize as stereocomplexes, as confirmed by wide-angle X-ray scattering.
Databáze: MEDLINE
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