Static and dynamic light scattering on aligned solution of root like polymer

Abstract

Static and dynamic light scattering are described on well-aligned nematic solutions of the rodlike poly(1.4-phenylene-2.6-benzobisthiazole) (PBT). The data are used to discuss the Frank elastic constants Kμ for curvature distortions and the corresponding distortion viscosities ημ (μ = S for splay, T for twist, and B for bend). Data were obtained on a PBT at three concentrations over the range 1.1 < Ψ/ΨNI < 2 where Ψ is the polymer volume fraction and ΨNI the value of Ψ required to form the nematic phase. The data show that ηB/KB < ηT/KT, as expected, but do not give the pronounced dependence of on ηB/KB on Ψ predicted for rodlike chains. Possible explanations for the observed behavior are discussed.