Flow birefringence in solutions of rigid chain polynaphthoylene imidoquinazoline

Abstract

The optical and conformational properties of polynaphthoylene imidoquinazoline molecules, consisting of rigid arimide fragments joined by simple bonds are studied by flow birefringence and viscosity methods. Modern theories of the dynamooptical properties of worm-like chains are used to show that in sulphuric and sulphonic acids they have a worm-like chain conformation with a low degree of coiling: persistence length a = (800 ± 200) Å, optical anisotropy of a unit of length β = 26 × 10 −17 cm 2. The value of a obtained is almost double the corresponding assessment a = 300 A ̊ for the para-aromatic analogue, poly- n-benzamide, which is associated with the presence in the chain of the latter of an amide group, which permits deformation.