BLOCK COPOLYMERIZATION OF ALKOXYALLENES WITH PHENYLALLENE BY THE LIVING COORDINATION SYSTEM WITH PI-ALLYLNICKEL CATALYST

The block copolymerization of alkoxyallenes (2a; n-octyloxyallene and 2b; n-butoxyallene) with phenylallene (3) was carried out by [(pi-ally l)NiOCOCF3](2) (1) in toluene by the sequential addition of the two mo nomers. In spite of rather different polymerizability between 2 and 3 (i.e., 2 has ca. 70 times larger kinetic coefficient than 3), block co polymers having narrow molecular weight distributions were obtained su ccessfully by controlling the reactivity of the propagating end with t he additives such as triphenylphosphine (PPh3) and copper(I) iodide. I n the case of the copolymerization of 3 with 2, the addition of PPh3 w as effective for the control of the polymerization step of 2. The bloc k copolymers with controlled segment length and narrow molecular weigh t distributions (M-W/M-n < 1.08) were obtained almost quantitatively. Conversely, when the copolymerization was started from 2, the control of the first stage required PPh3 as a ligand of the initiator which in terrupt the second polymerization of 3. However, block copolymers with narrow molecular weight distributions (M-W/M-n < 1.03) were obtained simply by adding copper (I) iodide in the polymerization stage of 3.