Reverse Iodine Transfer Polymerization (RITP) of Methyl Methacrylate

Abstract

The polymerization of methyl methacrylate (MMA) initiated by 2,2‘-azobis(isobutyronitrile) (AIBN) as radical initiator in the presence of iodine (I2) was studied at different temperatures (T = 70 °C and 80 °C). This process, called reverse iodine transfer polymerization (RITP), is based on the direct reaction of radicals with molecular iodine. RITP efficiently controls the molecular weight (determined by size exclusion chromatography, SEC) and the structure of the polymer chains (confirmed by 1H and 13C NMR spectroscopy). For instance, PMMA samples of Mn,SEC = 2300 g mol-1 and polydispersity index PDI = Mw/Mn = 1.5 (Mn,theoretical = 2300 g mol-1), Mn,SEC = 4600 g mol-1 and PDI = 1.6 (Mn,theoretical = 4700 g mol-1), Mn,SEC = 9600 g mol-1 and PDI = 1.6 (Mn,theoretical = 10 000 g mol-1), and Mn,SEC = 19 200 g mol-1 and PDI = 1.5 (Mn,theoretical = 18400 g mol-1) were successfully prepared by RITP. The polymerization was followed by on-line 1H NMR spectroscopy, and the conversion of iodine was followed by titr...