cs9b00095_si_002.mov (1.29 MB)
Single-Polymer–Particle Growth Kinetics with Molecular Catalyst Speciation and Single-Turnover Imaging
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posted on 2019-03-04, 00:00 authored by Quinn
T. Easter, Antonio Garcia, Suzanne A. BlumThe dynamics of the
local environments surrounding molecular polymerization
catalysts plausibly impact turnover kinetics, but the impact of and
nature of such dynamics have previously been obscured by ensemble
averaging. With Grubbs’ second generation ruthenium metathesis
catalyst and a precipitation polymerization system, studies at the
single-particle and -turnover level establish that (1) an inverse
correlation exists between rate and duration of single-polymer–particle
growth of aggregates, consistent with a local environment density
model for the time-variable kinetics; (2) cross-linking additives
produced a small, but detectible, reduction in overall monomer incorporation;
(3) total ruthenium quantity within the polymer particles (as characterized
by energy dispersive X-ray spectroscopy) is differentiable from the
quantity that is catalytically active (as characterized by in situ
fluorescence microscopy), providing catalyst speciation information;
and (4) time-resolved enyne metathesis reactions can be imaged, corresponding
to single turnovers at individual molecular catalysts during polymer
growth under synthetically relevant conditions. These findings identify
and characterize reactivity distributions likely arising from the
dynamics of local environments. As such, these data provide reactivity
information that is unavailable through traditional ensemble analytical
methods that obscure this type of information through averaging.
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dynamicenvironment density modelpolymerization catalystsprecipitation polymerization systemcatalyst speciation informationenergy dispersive X-ray spectroscopyMolecular Catalyst Speciationgeneration ruthenium metathesis catalystreactivity informationimpact turnover kineticspolymer growthtime-variable kineticsturnover levelreactivity distributionsSingle-Turnover Imagingmonomer incorporationruthenium quantityensemblepolymer particles
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