HYDRODYNAMIC PROPERTIES AND CONFORMATIONS OF META-ISOMER AND PARA-ISOMER OF POLY(PHENYLENEOXADIAZOLE) IN SULFURIC-ACID

The hydrodynamic properties of poly[2,5-(1,3-phenylene)-1,3,4-oxadiazo le] with M = (8.1-87) x 10(3)) and poly[2,5-(1,4-phenylene)-1,3,4-oxad iazol with M = (2.7-114) x 10(3)) were studied in 96% H2SO4 at 26 degr ees C. The molecular mass dependences of the intrinsic viscosity [eta] and the translational diffusion coefficient D were revealed. It was s hown that the experimental data are well described by the theories of translational friction and characteristic viscosity of wormlike chains for the following conformational parameters of poly[2,5-(1,3-phenylen e)-1,3,4-oxadiazole] and poly[2,5-(1,4-phenylene)-1,3,4-oxadioxazole] macromolecules: the mass per chain length unit M-L = 22.7 and 19.7 Ang strom(-1) and the Kuhn segment length A = 59 +/- 4 and 81 +/- 5 Angstr om, respectively; the number of monomer units in a segment s = 9.3, an d the hydrodynamic diameter of a molecular chain d = 4 +/- 2 Angstrom. The mechanisms of flexibility of a macromolecular chain in solution w ere analyzed. It was found that the hindrance of rotation around singl e bonds in a molecular chain is characterized by parameter sigma = 1.3 -1.7.