n-Octyloxyallene homopolymerization and random copolymerization with styrene using catalyst system composed of lanthanide Schiff-base complexes and Al(i-Bu)3

The catalyst system composed of lanthanide Schiff-base complexes with 3,5-tBu₂-2-(O)C₆H₂CH=NC₆H₅]₃Ln(THF)(Ln(Salen)₃, Ln = Sc, Y, La, Nd, Sm, Gd, Yb) and triisobutyl aluminum shows high activity for n-octyloxyallene (A) homopolymerization with narrow molecular weight distribution (MWD). The influences of reaction conditions on polymerization behavior are investigated, and poly(n-octyloxyallene) has a weight average molecular weight (M _w) of 20.6 × 10³ with MWD of 1.39 and 100% yield is obtained under the optimum conditions: Al]/Y] = 50 mol/mol, A]/Y] = 100 mol/mol, with polymerization at 80 °C for 16 h in bulk. The kinetic studies of n-octyloxyallene homopolymerization indicate that the polymerization rate is first-order with respect to the monomer concentration and shows some controlled polymerization characteristics. Random copolymer of n-octyloxyallene with styrene is obtained by using the same binary catalyst system; the reactivity ratios of the comonomer determined by Kelen-Tüdös method are r _A = 1.20 and r _St = 0.35, respectively, the ratio of each segment and M _w of the resulting copolymer could be controlled by varying the feed ratio of each monomer. Determined by differential scanning calorimetry, the copolymers obtained show only one glass transition temperature, which increases gradually with the increase of styrene content in the copolymer.