Synthesis and Crystallization of Precision ADMET Polyolefins Containing Halogens

Abstract

We report the synthesis and characterization of a series of precision polyethylene (PE) structures containing either a fluorine, chlorine, or bromine on each and every 19th carbon. The use of ADMET polymerization chemistry allows unprecedented control in the synthesis of these halogen containing PE derivatives, and results in the first bromine containing polyolefin with a precisely defined primary structure. Polymerization with Grubbs' first generation catalyst followed by hydrogenation by diimide reduction or Wilkinson's catalyst leads to these precise structures, which have been characterized by 1H NMR, solution and solid state 13C NMR, solid state 19F NMR, IR, elemental analysis, TGA, DSC, AFM, and WAXD. The TGA data, coupled with elemental analysis, supply definitive proof of the structural composition through the observed thermal decomposition and release of exact masses of HX (X = F, Cl, or Br). In reference to analogous random copolymers, these precisely substituted polymers display sharper WAXD di...