Vinyl acetate living radical polymerization mediated by cobalt porphyrins: Kinetic-mechanistic studies
Journal
Polymer Chemistry
Journal Volume
5
Journal Issue
12
Pages
3867-3875
Date Issued
2014
Author(s)
Abstract
Radical polymerization of vinyl acetate (VAc) in the presence of cobalt(ii) tetramesitylporphyrin, CoII(TMP), as a mediator was performed in a series of solvent environments. Cobalt porphyrin was observed to mediate an effective living radical polymerization reaction of vinyl acetate in bulk as shown by the linear increase in molecular weight with conversion, relatively narrow molecular weight distributions (Mw/Mn = 1.24-1.34), and molecular weights close to the theoretical value up to moderately high monomer conversions (?70%). The levels of deviation for the observed PVAc molecular weights from the theoretical values varied with the choice of solvent medium, which suggests that the control of vinyl acetate radical polymerization was affected by chain transfer to the solvent. Non-coordinating solvents influence the polymerization rate primarily by different propagation rate constants (kp). Pyridine coordination with dormant organo-cobalt(iii) increases the dissociation constant and changes the dominant polymerization process from degenerative transfer to reversible termination. ? 2014 the Partner Organisations.
Other Subjects
Atom transfer radical polymerization;Dissociation;Free radical polymerization;Living polymerization;Molecular weight;Porphyrins;Rate constants;Solvents;Degenerative transfer;Dissociation constant;Living radical polymerization;Narrow molecular weight distributions;Polymerization process;Polymerization rates;Propagation rate constant;Solvent environments;Cobalt
Type
journal article