Since poly (γ-benzyl L-glutamate)(PBLG) in helix conformation has a large permanent dipole moment along the helical axis, the response to dc or low frequency ac field is dominated by backbone contribution, while under medium frequency ac field, the backbone contribution vanishes and the contribution of polar gropes in side chain remains. In the present work, the dielectric deformation for PBLG solution (Mw:64000, 0.18V/V in 1,1,2-trichloroethane) was studied with ac electric field (10〜1kHz; 200〜720V_<p-p>/cm) applied. With the starting homeotropic boundary condition, the breakdown of macroscopic homogeneity leads to develop periodic bands parallel to the field direction with applying the field in plane. The dependencies of band spacing and the alignment direction of director on the field strength and frequency were qualitatively investigated.
