POLYMERIZATION OF p-DIETHYNYLBENZENE INITIATED BY Ni(C≡CC6H4C≡CH)2(PPH3)2
摘要
Homogeneous polymerization ofp-diethynylbenzene initiated by nickel acetylide Ni(C≡CC6H4C≡CH)2(PPh3)2 has been investigated in terms of different solvents, addition agents, atmosphere gases, catalyst concentrations, monomer concentrations and polymerization temperatures. The yield and catalytic efficiency approach 88% and 11.1 kg polymer/mol Ni, respectively, under the optimum conditions: [cat] = 0.01 mol/L, [M] = 1.0 mol/L, NEt3/cat (mol ratio) = 3～5, 1,4dioxane/toluene (volume ratio) = 1 and T = 25℃ for 5 h. The polymerization rate equation can be expressed as Rp = kp[M][cat]2, where kp = 0.47 L2 * mol-2 * S-1 (25 ℃ ). The overall polymerization activation energy was found to be 203 kJ * mol-1. Poly(p-diethynylbenzene) so obtained is soluble in THF, CHCl3 and toluene with weight-average molecular weights as high as 27, 100 and a rich-trans extended π-conjugated polyene chain structure with pendent groups of p-C6H4C≡CH.