Dielectric study of dilute solutions of poly-γ-benzyl-L-glutamate

Abstract

Apparent dipole moments, derived for two samples of poly-γ-benzyl-L-glutamate (PBLG) in three different solvents, show values essentially in agreement with the helical structure established in the solid state and suggest that the freedom of rotation of the side-chains increases with the permittivity of the solvent. For ε(solvent) >8 the backbone dipole moment only is observed. This arises in the trans-amide configuration of the amino-acid residue and agrees well with the values found for monomer amides. Direct application of equations of Guggenheim and Onsager to the evaluation of dipole moments leads to different results for the same molecule in the same solvent. After correction to a common state, the values obtained from all equations used are consistent. A comparison of the application of the Eyring and Bauer rate equations to the dielectric relaxation processes for PBLG has been made.