Nature of smectic A*-C* phase transitions in a series of ferroelectric liquid crystals with little smectic layer shrinkage

We review results of a high resolution systematic study of the specific heat for alkyl-cyanobiphenyl liquid crystals confined to the 0.2µm diameter cylindrical pores Anopore membranes. The nematic director alignment at the pore wall is varied from homeotropic to tangential by pore surface treatment. Several phenomena are uncovered by these studies which probed the weakly first order nematic to isotropic, the continuous smectic-A to nematic and the first order smectic-A to isotropic phase transitions. The specific heat is strongly dependent on the nematic director configuration, and confinement effects are remarkably distinct according to the order of the phase transition. The influence of elastic distortions and surface ordering and disordering effects are evident. Despite considerable departures from bulk behavior with regards to specific heat peaks size, rounding and width, and transition temperature shifts, a bulk-like critical behavior appears to be retained. The formation of smectic translational order within the pores is hindered for those liquid crystals that also possess a nematic phase. The average scalar order parameter temperature dependence is extracted from the specific heat results using a simplified Landau-de Gennes type of model, and is shown to be consistent with nuclear magnetic resonance results.

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Smectic-A–smectic-C–smectic-C*multicritical point in ferroelectric liquid crystals

Physical Review Letters ◽

10.1103/physrevlett.72.3558 ◽

1994 ◽

Vol 72 (22) ◽

pp. 3558-3561 ◽

Cited By ~ 14

Author(s):

Shankar B. Rananavare ◽

V. G. K. M. Pisipati ◽

E. W. Wong

Keyword(s):

Liquid Crystals ◽

Multicritical Point ◽

Ferroelectric Liquid Crystals ◽

Smectic A ◽

Smectic C

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Ferroelectric Liquid Crystals - Properties of the Smectic C Phase and the Smectic A Phase of Compounds with High Spontaneous Polarization

Berichte der Bunsengesellschaft für physikalische Chemie ◽

10.1002/bbpc.19870910921 ◽

1987 ◽

Vol 91 (9) ◽

pp. 925-929 ◽

Cited By ~ 11

Author(s):

Ch. Bahr ◽

G. Heppke

Keyword(s):

Liquid Crystals ◽

Spontaneous Polarization ◽

Ferroelectric Liquid Crystals ◽

Smectic A ◽

Smectic C ◽

Smectic A Phase

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Experimental and computational (DFT) studies on induced orthogonal smectic A∗ phase in hydrogen-bonded ferroelectric liquid crystals

International Journal of Modern Physics B ◽

10.1142/s0217979218502235 ◽

2018 ◽

Vol 32 (21) ◽

pp. 1850223 ◽

Cited By ~ 2

Author(s):

P. Subhasri ◽

R. Jayaprakasam ◽

V. N. Vijayakumar

Keyword(s):

Liquid Crystals ◽

Molecular Orbital ◽

Density Functional ◽

Liquid Crystalline ◽

Proton Acceptor ◽

Dft Studies ◽

Ferroelectric Liquid Crystals ◽

Smectic A ◽

Present Complex ◽

Hydrogen Bonded

Hydrogen-bonded ferroelectric liquid crystals (HBFLC) are designed and synthesized from nonmesogenic chiral proton donor compound of (R)-([Formula: see text])-Methylsuccinic acid (MSA) and mesogenic proton acceptor compound of 4-undecyloxybenzoic acid (11OBA) in a different mole ratio. Intermolecular hydrogen bonds (H-bond) between the nonmesogenic and mesogenic compounds have been confirmed through experimental Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) computational studies. The steric hindrance and inductive effects of the present complex and its influence on the structure are discussed. A rich phase polymorphism in the liquid crystalline complex has been studied using polarizing optical microscope (POM) and differential scanning calorimetry (DSC). The chiral phases observed in the present complex are due to the presence of lone pair (n) to anti-bonding ([Formula: see text]) transition symmetry which is validated by DFT studies. A noteworthy observation of induced smectic A[Formula: see text](Sm A[Formula: see text]) by quenching of traditional phase (nematic) has been identified and the reason for the same has been discussed by DFT studies. The unusual phase order of Sm A[Formula: see text], smectic C[Formula: see text](Sm C[Formula: see text]) and smectic G[Formula: see text][Formula: see text](Sm G[Formula: see text]) mesogenic phases are observed. The other liquid crystalline parameters are evaluated by experimental and theoretical calculations and the same has been compared. Increased tilt angle in liquid crystal (LC) molecules has been theoretically analyzed by natural bond orbital (NBO) studies. Stability of the HBFLC phases and its origination mechanism have been discussed with the help of highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO–LUMO) energies.

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