Evolution of molecular weight distributions in the catalytic chain transfer polymerization of methyl methacrylate up to high monomer conversions

Abstract

The evolution of molecular weight distributions (MWDs) with monomer conversion in the catalytic chain transfer (CCT) polymerization of methyl methacrylate at 60 °C is investigated by simulation (via the program package PREDICI®) and experiment. A Co(III)‐based complex is used as the precursor for the CCT agent, which is formed in situ by initiator‐derived (2,2′‐azobisisobutyronitrile) radicals to yield the catalytically active Co(II) species. The small shifts seen in the MWD toward lower molecular weights with increasing monomer conversion are shown to be of the same order of magnitude as the associated changes in the MWD in non‐CCT controlled free‐radical polymerization, indicating that no significant change in the MWD with monomer conversion is associated with the CCT process. These results are compared to the evolution of MWDs in conventional chain transfer polymerizations with thiols as transfer agents. A clear shift toward higher molecular weights is seen with increasing monomer conversion, indicating disparate rates of thiol and monomer consumption. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3303–3312, 2000

High‐conversion catalytic chain transfer polymerization of methyl methacrylate

“…Heuts et al22 recently also reported a slight decrease in molecular weight in the terpolymerization of styrene, MMA, and 2‐hydroxyethyl methacrylate, but it is very hard to interpret these data in a straightforward way, as the presence of three monomers considerably complicates the system. Kowollik et al20 reported an experimentally determined decrease of 45% in M w going from 10 to 100% conversion. Simulations showed that such a decrease corresponds to what is expected when the Co(II) concentration remains unchanged and monomer is consumed 20.…”

Degradation of Poly(methyl methacrylate) Model Compounds Under Extreme Environmental Conditions

“…In addition to being an industrially significant polymer and a major component of poly(acrylic) or poly(methacrylic) surface coatings, pMMA possesses two further advantages. Firstly, it has excellent ionisability in ESI‐MS and secondly, low molecular weight compounds with terminal vinyl bonds (which can easily be hydrogenated for saturated pMMA) can be easily synthesised via catalytic chain transfer (CCT) polymerisation (Scheme ) 51–55…”

Macromonomer Chain Growth in the Radical Polymerization of MMA by Cobalt(II) Catalyzed Chain Transfer

“…[4,5] This article reports on the observation that the average degree of polymerization (DP n ) increases as the conversion increases in the cobalt(II) mediated CCT process during radical polymerization of methyl methacrylate (MMA) in benzene, which is opposite to the change in DP n associated with a mechanism involving only Equation (1)-(3). Living character of the macromonomers in the cobalt(II) porphyrin mediated CCT process is illustrated by the observed chain growth.…”