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Organocuprates as initiators for the polymerization of methyl methacrylate in THF
Author(s) -
Dimonie Mihai,
Mardare Daniela,
Coca Simion,
HogenEsch Thieo E.,
Zöller Joachim
Publication year - 1993
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19930670114
Subject(s) - polymerization , chemistry , activation energy , polymer chemistry , methyl methacrylate , exothermic reaction , lithium (medication) , ion , kinetic energy , organic chemistry , polymer , physics , quantum mechanics , medicine , endocrinology
Several types of lithium organocuprates (I) e.g. R 2 CuLi, RR'CuLi, R 3 CuLi 2 , R 2 CuLi 2 X (X‐ CN, SCN), were prepared and used as polymerization initiators for methyl methacrylate in THF at temperatures ranging from −30 to +20 * C. Polymerization initiated by a mixed homocuprate, e.g. lithium n‐butyl (thien‐2‐yl)cuprate was studied in more detail. Kinetic measurements indicated an overall large (−4 to −14 kcal) apparent negative activation energy of polymerization in the −30 + +20 * C temperature range. The reaction was shown to have a kinetic order of about 1.5 with respect to initiator concentration. Conductance measurements indicate that the equivalent conductance increases with initiator concentration in the 10 −2 + 10 −1 M range indicating the formation of multiple ions formed by intermolecular association. The data are consistent with a polymerization involving aggregated ion pairs of as yet undetermined composition. The negative activation energy is tentatively interpreted as due to the exothermic formation of aggregates existing as highly solvated ion pairs.