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Polymerizability of cycloalkenes in a living ring‐opening metathesis polymerization initiated by Schrock complexes, 1. Effect of the solvent on the polymerization kinetics
Author(s) -
Cazalis Chrystelle,
Héroguez Valérie,
Fontanille Michel
Publication year - 2000
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/(sici)1521-3935(20000501)201:8<869::aid-macp869>3.0.co;2-z
Subject(s) - polymer chemistry , ring opening metathesis polymerisation , polymerization , metathesis , kinetics , chemistry , acyclic diene metathesis , solvent , organic chemistry , polymer , physics , quantum mechanics
The solvent influence was studied on the polymerizability of norbornene, whereby a Mo‐based Schrock complex was used as the initiator due to its ability to generate a persistent active center. The polymerizations were performed in solvents of differing coordinating power with the aim to look at their effect on the reactivity of the system. Cyclohexane, toluene, and tetrahydrofuran (THF) were chosen as solvents taking into account that cyclohexane has only a diluent effect whereas both toluene and THF should be able to coordinate to the complex. The competitive binding character of both monomer and solvent was established from kinetic data for ring‐opening metathesis polymerization (ROMP) performed in pure and mixed solvents (cyclohexane/THF). Independent of the solvent, first‐order kinetics with respect to the initiator suggest that most organometallic species form monosite propagating species. The kinetic order with respect to the monomer depends on the THF concentration of the reaction medium; the kinetic order is equal to one in pure THF and zero in pure cyclohexane. To explain this behavior, a kinetic scheme of the polymerization process is proposed, considering that the actual active species are monomer‐bonded metala‐alkylidenes. The respective equilibrium constants of monomer and of THF complexation to alkylidenic species were estimated showing the stronger binding of norbornene compared to that of THF and the strong influence on the polymerization kinetics.