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Anionic polymerization of methyl methacrylate using tetrakis[tris(dimethylamino)phosphoranylidenamino] phosphonium (P 5 + ) as counterion in tetrahydrofuran
Author(s) -
Baskaran Durairaj,
Müller Axel H. E.
Publication year - 2000
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/(sici)1521-3927(20000401)21:7<390::aid-marc390>3.0.co;2-b
Subject(s) - phosphonium , counterion , tetrahydrofuran , polymer chemistry , polymerization , chemistry , anionic addition polymerization , tris , degree of polymerization , methyl methacrylate , metathesis , phosphonium salt , salt (chemistry) , organic chemistry , ion , polymer , biochemistry , solvent
A novel metal‐free initiator, i.e. the salt of the tetrakis[tris(dimethylamino)phosphoranylidenamino]phosphonium (P 5 + ) cation with the 1,1‐diphenylhexyl (DPH – ) anion was prepared by cation metathesis. It initiates a very fast and controlled anionic polymerization of methyl methacrylate in THF. Kinetic investigations between –20 and +20°C using a flow tube reactor provide nearly linear first‐order time‐conversion plots with half‐lives below 0.1 s, a linear dependence of the number‐average degree of polymerization, and rather narrow molecular weight distributions ( M w / M n ≈ 1.2). 13 C NMR measurements on a model of the active chain end (the P 5 + salt of ethyl isobutyrate) in THF‐ d 8 show 15 and 25 ppm upfield shifts of the α ‐carbon compared to the dimers and tetramers of the lithium ester enolate, respectively, indicating a non‐aggregated structure and an increased charge density on the α ‐carbon.