Studies on the application of matrix-assisted-laser-desorptionionisation time-of-flight mass spectrometry to the determination of chain transfer coefficients in free radical polymerization

The chain transfer coefficient (C_S) has been determined for 2-methyl-2-propanethiol (t-Bu-SH) in the solution polymerization of methyl methacrylate (MMA). Three different analytical methods were investigated. The Mayo and chain length distribution (CLD) methods yielded consistent C_s values of 0.12 and 0.13, respectively, at 60°C. A third, new approach to the evaluation of C_s values was also attempted using Matrix-Assisted-Laser-Desorption-Ionisation (MALDI) Time-Of-Flight Mass Spectrometry to analyse the end-groups of the polymer chains. The values of C_s obtained from MALDI analyses were not consistent with the other two methods and the relative intensities of the peaks with different end-groups were found to be dependent on the selection of cation.