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SP–PLP–EPR Investigations into the Chain‐Length‐Dependent Termination of Methyl Methacrylate Bulk Polymerization
Author(s) -
Barth Johannes,
Buback Michael
Publication year - 2009
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/marc.200900335
Subject(s) - microsecond , polymerization , radical , electron paramagnetic resonance , exponent , activation energy , methyl methacrylate , radical polymerization , kinetics , materials science , power law , polymer chemistry , chemistry , analytical chemistry (journal) , nuclear magnetic resonance , polymer , physics , optics , organic chemistry , linguistics , philosophy , statistics , mathematics , quantum mechanics
Termination kinetics of methyl methacrylate (MMA) bulk polymerization has been studied via the single pulsed laser polymerization–electron paramagnetic resonance method. MMA‐ d 8 has been investigated to enhance the signal‐to‐noise quality of microsecond time‐resolved measurement of radical concentration. Chain‐length‐dependent termination rate coefficients of radicals of identical size, k t i , i , are reported for 5–70 °C and up to i = 100. k t i , idecreases according to the power‐law expression $k_{\rm t}^{i,i} = k_{\rm t}^{{\rm 1,1}} \cdot i^{ - \alpha }$ . At 5 °C, k t for two MMA radicals of chain‐length unity is k t 1,1 = (5.8 ± 1.3) · 10 8 L · mol −1 · s −1 . The associated activation energy and power‐law exponent are: E A ( k t 1,1 ) ≈ 9 ± 2 kJ · mol −1 and α ≈ 0.63 ± 0.15, respectively.