Determination of equilibrium constants for atom transfer radical polymerization
Wei Tang1, Nicolay V Tsarevsky, Krzysztof Matyjaszewski
1Center for Macromolecular Engineering, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, USA.
Journal of the American Chemical Society
|February 2, 2006
Summary
Modified Fischer
Area of Science:
- Polymer Chemistry
- Physical Chemistry
- Organic Chemistry
Background:
- Atom transfer radical polymerization (ATRP) relies on equilibrium between active and dormant species.
- Accurate determination of ATRP equilibrium constants (K(ATRP)) is crucial for controlling polymerization.
- Existing methods using Fischer's equations are limited to low conversions and K(ATRP) values.
Purpose of the Study:
- To develop and validate modified Fischer's equations for determining K(ATRP) at higher conversions.
- To accurately measure K(ATRP) for various catalysts and alkyl halides.
- To investigate the structure-reactivity relationships in ATRP.
Main Methods:
- Modified Fischer's equations incorporating changes in catalyst and initiator concentrations.
- Kinetic simulations to validate the new equations.
- UV-vis spectrometry to monitor copper species (X-Cu(II)).
- Gas chromatography (GC) to track initiator concentration.
Main Results:
- Modified equations accurately determine K(ATRP) at conversions >10% and K(ATRP) >10(-7).
- Successfully determined K(ATRP) values for several catalyst/alkyl halide systems.
- Demonstrated the effect of structural variations on ATRP component reactivity.
Conclusions:
- Modified Fischer's equations extend the applicability of equilibrium constant determination in ATRP.
- Accurate K(ATRP) values are essential for precise control over polymerization processes.
- Understanding structure-reactivity relationships aids in designing efficient ATRP systems.
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