Controlled radical polymerization of 1,1,2,2-tetrahydroperfluorodecyl acrylate by reverse iodine transfer polymerization (RITP)

Abstract

Solution polymerization of 1,1,2,2-tetrahydroperfluorodecyl acrylate initiated by 2,2′-azobis(isobutyronitrile) (AIBN) at 65°C in the presence of molecular iodine I2 has been studied. The process, called reverse iodine transfer polymerization (RITP), efficiently controls the molecular weight (determined by 1H NMR) and the structure of the polymer. For instance, a poly(1,1,2,2-tetrahydroperfluorodecyl acrylate) sample of Mn,NMR=5200gmol−1 (Mn,theoretical=5000gmol−1), with a monomer conversion of 97% was successfully prepared. The iodine end-capped structure of the polymers (A–Mn–I, where n is the mean number degree of polymerization) was further demonstrated by mass-assisted laser desorption ionization time-of-flight (MALDI-TOF). When targeting very low degrees of polymerization (e.g. DPn=5), monomer conversion reached its maximum before the end of the induction period (incomplete consumption of iodine and of the A–I adduct) leading to higher than expected molecular weights. This could be a limitation for RITP when targeting very low molecular weight oligomers (DPn<10). Finally, an efficient functionalization method was used to end-cap the PFDA polymer chains with a hydroxyl or a carboxylic acid function. The iodine atom at the chain end was displaced by 2-mercaptoethanol or 2-mercaptoacetic acid in basic media to yield the corresponding alcohol or acid.