Olefin copolymerization via controlled radical polymerization: Copolymerization of acrylate and 1-octene

The atom transfer radical copolymerization (ATRP) of methyl acrylate (MA) with 1-octene was investigated in detail. Well-controlled copolymers containing almost 25 mol % of 1-octene were obtained using ethyl 2-bromoisobutyrate (EBriB) as initiator. Narrow molar mass distributions (MMD) were obtained for the ATRP experiments. The feasibility of the ATRP copolymerizations was independent of the ligand employed. Copolymerizations carried out using 4,4'-dinonyl-2,2'-bipyridine (dNbpy) resulted in good control, with significant octene incorporation in the polymer. The lower overall percent conversion obtained for the dNbpy systems as compared to that of the PMDETA systems was attributed to the redox potential of the formed copper(I)-ligand complex. The comparable free radical (co)polymerizations (FRP) resulted in broad MMD. An increase in the fraction of the olefin in the monomer feed led to an increase in the level of incorporation of the olefin in the copolymer, at the expense of the overall percent conversion. There was a good agreement between the values of the reactivity ratios determined for the ATRP and FRP systems. The formation of the copolymer was established using matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS). From the obtained MALDI-TOF-MS spectra for the ATRP systems, several units of 1-octene were incorporated in the polymer chain, and only one pair of end groups was observed. On comparison, in the FRP systems, due to the multitude of side reactions occurring, several end groups were obtained. In general, narrow chemical composition distributions were obtained for the ATRP systems as compared to FRP.