The equilibrium rigidity of polyorganophosphazene molecules

Optical anisotropy and extinction angles of the molecules of polyorganophos phazenes -[P(OR)(2)=N]- (R = CH2CF3, -CH2CF2CF2H, -CH2(CF2)(3)CF2H) were st udied by the now birefringence and viscometry techniques. The experimental optical parameters and conformation characteristics of the polymers studied agree with the optical anisotropy of a monomer unit calculated by the quan tum chemistry methods. The thermodynamic rigidity parameter A = (50 +/- 5) x 10(-8) cm estimated by various methods for the macromolecules of polyorga nophosphazenes with an allowance for their backbone structure and the steri c interaction of side chains apparently corresponds to the real structure a nd observed physical properties of these molecules. Analysis of the ability of polyorganophosphazene molecules to form mesophases of various types sho ws that the mesogenic properties of these polymers are determined by strong interactions between side fluorine- containing chains, rather than by the rigid-chain backbone structure.