ACYCLIC DIENE METATHESIS (ADMET) POLYMERIZATION - SYNTHESIS OF UNSATURATED POLYCARBONATES

The first acyclic diene metathesis (ADMET) polymerization of carbonate containing monomers using the molybdenum catalyst, Mo(CHCMe2Ph)(N-2,6-C6H3-i-Pr2)[OCCH3(CF3)2]2 is reported. Bis(1-hexenyl) carbonate, bis(1-pentenyl) carbonate, bis(1-butenyl) carbonate; and 4,4'-isopropylidenebis(phenyl 1-butenylcarbonate) successfully undergo ADMET homopolymerization. These polymerizations are initiated under bulk conditions and are continued in solution to produce poly(5-decenyl carbonate), poly(4-octenyl carbonate), poly(3-hexenyl carbonate), and poly(oxycarbonyloxy-1,4-phenyleneisopropylidene-1,4-phenyleneoxycarbonyl-1,6-hex-3-enylene), respectively. No metathesis activity is observed for bis(1-propenyl) carbonate due to a negative neighboring group effect. This effect involves either the coordination of the carbonyl oxygen to the metal center or simply the polarization of the double bond such that the intermediates of the metathesis process are not favored. All polymer structures were characterized by IR, H-1 NMR, and C-13 NMR spectroscopy. Number-average molecular weights were determined by end-group analysis and vapor pressure osmometry. Synthesis, characterization, and the general limitations of this polymerization are discussed.