Hydrodynamic and dynamo-optical properties of poly(1,3-phenylene-1,3,4-oxadiazole) molecules in sulphuric acid

Translational diffusion of the macromolecules, intrinsic viscosity and flow birefringence induced in dilute solutions of poly(1,3-phenylene-1,3,4-oxad iazole) (PMOD) in cone. sulphuric acid has been investigated. Molecular-wei ght dependences of hydrodynamic and dynamo-optical properties are establish ed over the M range from 8.1 x 10(3) to 87 x 10(3). Experimental data agree well with the theories developed for translational friction and intrinsic viscosity of the wormlike chains with the following molecular parameters: m ass pet chain unit M-L = 22.7 Dalton/Angstrom, the Kuhn segment length A = 59+/-4 Angstrom, the chain diameter d = 4 +/- 1.5 Angstrom. Hindrance to in tramolecular rotation is characterized by the parameter sigma = 1.7. The sh ear optical coefficient was found to be approximately 1.7 times lower the v alue of that obtained in the same solvent for the para-phenylene isomer of this polymer, being in good agreement with higher equilibrium flexibility o f the PMOD molecule chains in solutions as determined herein from the hydro dynamic data. (C) 1999 Elsevier Science Ltd. All rights reserved.