Transition Phenomena in Poly(diacetylene) Solutions Studied by Electric Birefringence Measurements

Abstract

An external electric field induces strong birefringence in solutions of poly(diacetylenes) when they are in the red (low temperature) form. The transient behaviour and the field‐strength dependence of the steady‐state birefringence reveal that the orientation of particles is predominantly due to a permanent dipole moment rather than to the anisotropy of polarizability. The estimated permanent dipole moments are in the order of tenthousand Debye units, this order of magnitude being incompatible with single macromolecules. Thus the view that aggregated particles are formed at low temperatures is supported by our experiments.

First experimental evidence of a giant permanent electric-dipole moment in cellulose nanocrystals

“…Transient electric birefringence (TEB) is one of the most common methods used to probe the electric properties of colloids. It has been widely applied to many colloidal systems and has given quantitative information on the rotational diffusion, size and polarization properties of elongated particles [18][19][20][21]. The response to a pulsed electric field also gives information on the nature of the polarization mechanism.…”

“…In principle, information about a permanent dipole could also be obtained from inverted-pulse experiments [25]. This approach allowed experimental detection of surprisingly high permanent electric-dipole moments in poly(diacetylene) solutions (about 10 4 Debye) [21]. Colloidal nanorods bearing only induced dipoles will not be sensitive to the sign change of the electric field whereas those having a permanent dipole contribution will tend to reverse their orientation when the electric-field direction is reversed.…”