Radical Terpolymerization of Organoarsenic Homocycle, Phenylacetylene, and Vinyl or Butadienyl Monomers

Abstract

The free radical terpolymerization of pentamethylcyclopentaarsine (cyclo-(MA)5), phenylacetylene (PA), and various vinyl monomers in toluene is described. The terpolymerization of cyclo-(MA)5, PA, and styrene (St) in the molar ratio 1:5:5 with a catalytic amount of AIBN at 60 °C for 8 h provided a polymer in 38% yield after reprecipitation. The terpolymer was soluble in common organic solvents such as tetrahydrofuran, chloroform, benzene, and toluene. In the GPC analysis (chloroform, PSt standards), the terpolymer showed a single peak, and the number-average molecular weight was estimated to be 10 200. The structure of the terpolymer obtained was compared with those of poly(vinylene−arsine) and polystyrene by use of 1H NMR and 13C NMR and found to have two block units, [poly(MA-alt-PA)−poly(St)]. The integral ratio of the peak area in the 1H NMR spectrum revealed the terpolymer composition, MA:PA:St = 1:0.99:0.56. The terpolymer showed fluorescence properties attributable to the n−π* transition in the poly(MA-alt-PA) block. The terpolymerization of cyclo-(MA)5, PA, and St in various feed ratios was carried out in the presence of AIBN to yield the terpolymers which possessed poly(MA-alt-PA) and poly(St) blocks with various compositions. The terpolymer with the higher content of St unit exhibited a more blue-shifted emission peak. The radical terpolymerization of methyl methacrylate (MMA) with cyclo-(MA)5 and PA also yielded the corresponding terpolymer with a poly(MA-alt-PA) unit and a poly(MMA) unit, while the terpolymerization employing vinyl acetate (VA) as a vinyl monomer produced poly(vinylene−arsine) with no VA segment. The radical reaction of 2,3-dimethyl-1,3-butadiene (DB) with cyclo-(AsMe)5 and PA formed a different type of terpolymer which had alternating sequences of AsMe and PA or DB, e.g., [(MA-PA)−(MA-DB)]n.