Polymerization of p-diethynylbenzene initiated by Ni(C equivalent to CC6H4C equivalent to CH)(2)(PPH3)(2)

Homogeneous polymerization of p-diethynylbenzene initiated by nickel acetyl ide Ni(C equivalent to CC6H4C equivalent to CH)(2)(PPh3)(2) has been invest igated in terms of different solvents, addition agents, atmosphere gases, c atalyst concentrations, monomer concentrations and polymerization temperatu res. The yield and catalytic efficiency approach 88% and 11.1 kg polymer/mo l Ni, respectively, under the optimum conditions: [cat] = 0.01 mol/L, [M] = 1.0 mol/L, NEt3/cat (mol ratio) = 3 similar to5, 1,4-dioxane/toluene (volu me ratio) = 1 and T = 25 degreesC for 5 h. The polymerization rate equation can be expressed as R-p = k(p)[M][cat](2), where k(p)= 0.47 L-2 . mol(-2) S-1 (25 degreesC). The overall polymerization activation energy was found t o be 203 kJ . mol(-1). Poly(p-diethynylbenzene) so obtained is soluble in T HF, CHCl3 and toluene with weight-average molecular weights as high as 27, 100 and a rich-trans extended pi -conjugated polyene chain structure with p endent groups of p-C6H4C equivalent to CH.