THERMAL, FERROELECTRIC AND DIELECTRIC STUDIES ON TWO DISTINCT STRUCTURAL ISOMERS: A FIELD INDUCED TRANSITION IN PSEUDO-NEMATIC PHASE

Abstract

The thermal and ferroelectric properties of a novel series comprising of two distinct ferroelectric structural isomers, (S)-1,4 – diphenylene bis (2-chloro-3- (4 – dodecyloxyphenyl)-propionate) (DCDP-1) and (S)-1,3 – diphenylene bis (2-chloro-3- (4 – dodecyloxyphenyl)-propionate) (DCDP-2), are studied by polarizing thermal microscopy (TM), differential scanning calorimetry (DSC), spontaneous polarization (P_S), response times (τ), viscosity (η) and dielectric techniques. The thermal studies imply these isomers exhibit altogether different thermal and phase behaviour. The comparative ferroelectric investigations infer an increment in the magnitude of P_S(three fold) and a wide ferroelectric thermal range in DCDP-2 compound. Further, the detailed ferroelectric studies on DCDP-2 compound reveal the occurrence of spontaneous polarization, for the first time, in the threaded nematic like phase (here after this phase is referred as pseudo-nematic). A detailed investigation confirming the existence of a field-induced transition (FiT) from pseudo-nematic to nematic phase is achieved through spontaneous polarization and dielectric studies.

Key Words:

• DCDP-1
• DCDP-2
• FiT
• pseudo-nematic