120
M. Jasiurkowska-Delaporte
Abbreviations
5P-EtFLEt-P5
2,7-Bis(4-pentylphenyl)-9,9-diethyl-9H-fluorene
5P-Am*FLAm*P5 S,S-2,7-bis(4-pentylphenyl)-9,9-dimethylbutyl-9H-fluorene
BBOA
4-N-butyloxybenzylidene-4
-n
-octylaniline
BDS
Broadband dielectric spectroscopy
CONDIS
Conformationally disordered crystals
DSC
Differential scanning calorimetry
GN
Glass of nematic phase
GN*
Glass of chiral nematic phase
HN
Havriliak–Negami
Is
Isotropic state
LCs
Liquid crystals
POM
Polarizing optical microscopy
N
Nematic
N*
Chiral nematic
ODIC
Orientationally disordered crystal
SmB
Smectic B
VFT
Vogel–Fulcher–Tammann
1 Introduction
Owing to their remarkable optical and physical properties, liquid crystals (LCs)
have attracted great attention from both academia and industry. In addition to their
widespread use in displays and electrically driven optical switches, LCs have also
found novel applications in a range of areas, including medicine [1–3], pharmacy [4]
and sensing [5]. The simplest, and the most commonly used, form of LC is the nematic
phase (N), in which molecules tend to align in a single direction. However, a chiral or
choresteric form also exists (N*), comprising both an orientational molecular order
and a spontaneous macroscopic helical superstructure with a twist axis orthogonal
to the local director. As the temperature decreases, many thermotropic LCs form
smectic phases which display layered structures that can be classified according to
the degree of molecular order (A, B, E, F, G, etc.).
On cooling, LCs have been shown to form vitreous states characterized by partial
ordering; such states differ from those of amorphous materials, such as “conventional” glasses. Calorimetric studies by Sorai and Seki [6] first identified vitrification
of the nematic phase; following this, a glass-forming ability was reported for various
smectic phases, including smectic G (SmG) [7], smectic B (SmB) [8, 9] and smectic
E (SmE) [10–12]. BDS studies have indicated that cold crystallization can take place
after softening the glass upon heating [13]; this was identified for the first time for
M. Jasiurkowska-Delaporte
Abbreviations
5P-EtFLEt-P5
2,7-Bis(4-pentylphenyl)-9,9-diethyl-9H-fluorene
5P-Am*FLAm*P5 S,S-2,7-bis(4-pentylphenyl)-9,9-dimethylbutyl-9H-fluorene
BBOA
4-N-butyloxybenzylidene-4
-n
-octylaniline
BDS
Broadband dielectric spectroscopy
CONDIS
Conformationally disordered crystals
DSC
Differential scanning calorimetry
GN
Glass of nematic phase
GN*
Glass of chiral nematic phase
HN
Havriliak–Negami
Is
Isotropic state
LCs
Liquid crystals
POM
Polarizing optical microscopy
N
Nematic
N*
Chiral nematic
ODIC
Orientationally disordered crystal
SmB
Smectic B
VFT
Vogel–Fulcher–Tammann
1 Introduction
Owing to their remarkable optical and physical properties, liquid crystals (LCs)
have attracted great attention from both academia and industry. In addition to their
widespread use in displays and electrically driven optical switches, LCs have also
found novel applications in a range of areas, including medicine [1–3], pharmacy [4]
and sensing [5]. The simplest, and the most commonly used, form of LC is the nematic
phase (N), in which molecules tend to align in a single direction. However, a chiral or
choresteric form also exists (N*), comprising both an orientational molecular order
and a spontaneous macroscopic helical superstructure with a twist axis orthogonal
to the local director. As the temperature decreases, many thermotropic LCs form
smectic phases which display layered structures that can be classified according to
the degree of molecular order (A, B, E, F, G, etc.).
On cooling, LCs have been shown to form vitreous states characterized by partial
ordering; such states differ from those of amorphous materials, such as “conventional” glasses. Calorimetric studies by Sorai and Seki [6] first identified vitrification
of the nematic phase; following this, a glass-forming ability was reported for various
smectic phases, including smectic G (SmG) [7], smectic B (SmB) [8, 9] and smectic
E (SmE) [10–12]. BDS studies have indicated that cold crystallization can take place
after softening the glass upon heating [13]; this was identified for the first time for