Ring-Opening Metathesis Copolymerizations

Well-defined diblock and triblock copolymers (pdi = 1.08-1.14) were first prepared by ring-opening metathesis polymerization by sequential monomer addition of norbor-nene, dicyclopentadiene and benzonorbor- 

---

Sinner and Buchmeiser developed a less typical approach to monolithic columns [58,59]. They used ring-opening metathesis copolymerization of nor-born-2-ene and l,4,4a,5,8,8a-hexahydro-l,4,5,8-exo,endo-dimethanonaphtha-... 

Fig. 2 a - d. Scanning electron micrographs of the inner part of the norborn-2-ene monolith prepared by ring-opening metathesis copolymerization (Reprinted with permission from [58], Copyright 2000 American Chemical Society)... 

Jeon et al. have recently reported on ring-opening metathesis copolymerizations of cyclooctene and the PGSS-norbornylene monomer performed with Grubbs s catalyst. Random copolymers were then formed and fully charac-... 

Figure 19.10 Structure of initiators used for alternating ring-opening metathesis copolymerization.

Yong and S wager [181] reported ring-opening metathesis copolymerizations of calixarene containing monomers with cyclooctene and norbomene to yield high molecular weight transparent elastic polymers. 

It is noteworthy that polymers of practical interest that exhibit a globular shape and unsymmetrical faces of the Janus-type architecture, not easy to make by conventional methods [89, 90], can be prepared by sequential ring-opening metathesis copolymerization of two different norbomenyl macromonomers. To this end, sequential polymerization of co-norbomyl polystyrene and a-norbornyl-poly(ethylene oxide) macromonomers in the presence of the Schrock initiator Mo(NAr)(ChrBu)(OC(CH3)(CF3)2)2 produced poly[polystyrene xycarbonyl-norbornene)-b-poly(ethylene oxide) xymethylene-norbomene)] block copolymer (122) in high yield [88] [Eq. (54)]. 

Finally, copolymers containing polyethylene backbone and polystyryl grafts, (124), have been manufactured by ring-opening metathesis copolymerization of cycloalkenes like cyclooctene with co-norbornenyl macromonomers in the presence of the molybdenum carbene initiator Mo(NAr)(CHrBu)(OC(CH3)(CF3)2)2 [92] [Eq. (56)]. 

Thom-Csanyi, E., Hohnk, H.D., and Pflug, K.P. (1993) Ring-opening metathesis copolymerization of cyclopentene and [2.2] paracyclophane-l,9-diene UV-Vis-spectroscopic determination of sequence-length distribution of p-pheny-lenevinylene units. Journal of Molecular Catalysis, 84,253. 

Figure 10 Synthesis of POSS-norbornyl macromers and their ring-opening metathesis copolymerization.

Ring-opening metathesis copolymerizations of cyclooctene and norbomyl-POSS were performed with Grubbs s catalyst, RuCl2(=CHPh)(PCy3)2 (Fig. 11). Reduction of these copolymers afforded poly(ethylene-co-norbomyl-POSS) copolymers, which have properties similar to those of the poly(ethylene-co-norbomylethyl-POSS) prepared by direct copolymerization of ethylene with no bomyl-POSS, described above. Poly(cyclooctene-co-norbornylethyl-POSS) copolymers with 0,12,23,31,45, and 56 wt % POSS (0,1.39,3.06,4.62, 7.96, and 11.9 mol %) had melting temperatures of 46°C, 43°C, 38°C, 36°C, 33°C, and 30°C, respectively. Their heat of fusion values (J/g) are 56,45,36,28, 24, and 19, respectively. This decrease in both melting temperatures and heat of fusion values as more POSS is incorporated shows that the random POSS moieties disrupted crystallinity. No Tg was observed for these copolymers, presumably because of their semicrystalline nature. 

---