Stereoselective Ring-Opening Metathesis Polymerization by New Mo, W-based Catalysts-Development of Crystalline Hydrogenated Poly (endo-dicyclopentadiene)

The properties of the tactic hydrogenated ring-opened poly (endo-dicyclopentadiene)s and features of the molybdenum and the tungsten oxo/imido/phenolate catalyzed stereoselective ring-opening metathesis polymerizations (ROMP) were studied. Oxomolybdenum (VI) bis ((R) - (+)-5,5',6,6'-Me(4)-3,3'-t-Bu(2)-biphenolate) promoted cis-, iso-selective ROMP of endo-dicyclopentadiene (DCP) (cis = 85%, m/r = 95/5), whereas W (= NPh)Cl(4)center dot Et(2)O promoted cis-, syndio-selective ROMP (cis = 93%, m/r = 20/80). Both tactic hydrogenated poly (DCP)s were shown to be crystalline polymers by means of DSC, WAXD and TEM measurements. In contrast, atactic hydrogenated poly (DCP) was an amorphous polymer. The crystallization rate of the syndiotactic hydrogenated poly (DCP) was significantly higher than that of the isotactic polymer. Stereoselective ROMPs of norbornene and tetracyclododecene were also investigated. A stereoblock copolymer, hydrogenated poly (syndio-DCP-block-ata-DCP), was successfully prepared by catalytic block copolymerization method and its properties were also determined.