End‐functional poly(methyl methacrylate)s via group transfer polymerization

Hydroxyl‐, amine‐, and lactone‐end‐functional poly(methyl methacrylate)s (PMMA) were prepared with controlled molecular weights and Mw/Mn = 1.06–1.19 via group transfer polymerization. This was achieved by the electrophilic termination of silyl ketene acetal ended PMMAs with benzaldehyde, N‐trimethylsilyl benzaldimine, and 5,6‐dihydro‐2H‐pyran‐2‐one, respectively. The number‐average degree of functionalization, as determined by NMR/SEC, was in the range of 0.70–0.85. A Lewis acid was used for terminating silyl ketene acetal ended PMMA with N‐trimethylsilyl benzaldimine, whereas tetra‐n‐butyl ammonium bibenzoate was used in the case of benzaldehyde and 5,6‐dihydro‐2H‐pyran‐2‐one. MALDI‐TOF MS analysis of the end‐functional polymers indicated the competing formation of cyclic end groups due to a back‐biting reaction along with end‐functional PMMAs.