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Kinetic Investigations of Cu‐Mediated ATRP in Aqueous Solution
Author(s) -
Smolne Sebastian,
Buback Michael
Publication year - 2015
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201400589
Subject(s) - chemistry , aqueous solution , monomer , dispersity , polymer chemistry , ethylene glycol , atom transfer radical polymerization , dissociation (chemistry) , solvent , polymerization , reaction rate constant , copolymer , kinetics , polymer , organic chemistry , physics , quantum mechanics
Cu‐mediated atom‐transfer radical polymerization (ATRP) is studied via on‐line vis/NIR spectroscopy in an aqueous solution of a monomer‐free model system, with CuBr/2,2′‐bipyridine acting as the catalyst, and 2‐hydroxyethyl 2‐bromoisobutyrate as the initiator, at a pressure of up to 2000 bar. Excess NaBr is added to avoid the water‐assisted dissociation of the Br–Cu(II)/L bond. The activation–deactivation equilibrium constant, K model , is measured at different compositions of the water–poly(ethylene glycol) dimethylether (PEO) solvent mixture, in which PEO mimics a water‐soluble monomer. K model increases by about three orders of magnitude in passing from a PEO to a water environment. The change in K model is essentially due to the effect on the activation rate coefficient. Kinetic analysis of the model system upon variation of NaBr concentration in conjunction with predici simulations shows that the NaBr content has no significant impact on the activation and deactivation rate coefficients and thus on K model , but on dispersity and on the degree of chain‐end functionality.