Physical properties of liquid crystalline solution of once-broken rod poly(γ-benzyl L-glutamate)

Abstract

Poly(γ-benzyl L-glutamate) (PBLG) whose molecule is a straight rod in shape and a large permanent dipole moment along the rod axis and once-broken (OB)-PBLG which has two anti-parallel permanent dipoles in its molecule composed of two α-helices jointed by a flexible chain of the bifunctional initiator (trimethylenediamine) in the manner of head to head, were synthesized and the behavior of concentrated solutions were investigated. The solution of OB-PBLG formed a cholesteric liquid crystal as well as that of straight (S)-PBLG. Temperature and concentration dependency of cholesteric texture for both polymers were similar, except for OB-PBLG having a lower molecular weight, Mv < 5 × 104. Alignment of molecules in a thin cell is different for the two polymers. As dynamics of the electro-optic response, differences for the two polymers are clearly evidently. Response time of OB-PBLG is 60 to 70 times as long as that of ordinary S-PBLG under similar experimental conditions.