Barth, J.; Buback, M.
SP-PLP-EPR Investigations into the Chain-Length-Dependent Termination of Methyl Methacrylate Bulk Polymerization
Macromolecular Rapid Communications 2009, 30, 1805-1811.
 

Termination kinetics of methyl methacrylate (MMA) bulk polymerization has been studied via the single pulsed laser polymerization-electron paramagnetic resonance method. MMA-d₈ 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,i decreases according to the power-law expression k_t^i,i = k_t^1,1 · i ^-α. At 5 °C, k_t for two MMA radicals of chain-length unity is k_t^1,1 = (5.8 ± 1.3) · 10⁸ 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 0.63 ± 0.15, respectively.