Quasi liquid crystals

Spiropyrans have been incorporated as photochromic moieties into many polymers [4,67]. Krongauz and his co-workers [68-72] have extended this work to include several types of SCLC polymers. Small molecule LC materials containing a spiropyran moiety have not yet been reported, presumably because typical spiropyrans are not sufficiently elongated. The covalent attachment of spiropyrans to rodlike mesogenic groups does afford quasi liquid crystals compounds with unusual metastable mesophases [4]. However, these compounds do not show LC... 

F. P. Shvartsman and V. A. Krongauz, Quasi-liquid crystals of thermochromic spiropyrans. A material intermediate between supercooled liquids and mesophases, J. Phys. Chem., 88, 6448-6453 (1984). 

Figure 4.10. Kuroda s model explaining the repeated Habitus change of snow crystals [23]. Shaded areas are crystals dotted areas are QLLs (quasi-liquid layers).

The simplest way to classify nanomaterials used in combination with liquid crystal materials or the liquid crystalline state is by using their shape. Three shape families of nanomaterials have emerged as the most popular, and sorted from the highest to the lowest frequency of appearance in published studies these are zero-dimensional (quasi-spherical) nanoparticles, one-dimensional (rod or wirelike) nanomaterials such as nanorods, nanotubes, or nanowires, and two-dimensional (disc-like) nanomaterials such as nanosheets, nanoplatelets, or nanodiscs. 

The nematic phase has unquestionably been the go-to phase to study and understand the major driving forces that govern interactions between suspended, quasi-spherical nanoparticles and liquid crystal molecules or mixtures. We credit this to three important factors (1) early experimental studies [288, 289] based on the foundation of de Gennes very early work on ferronematics [121], (2) the availability of nematic liquid crystals including room temperature and wide temperature... 

In comparison to nematic liquid crystals, examples of smectic liquid crystals doped with quasi-spherical nanoparticles became more elusive over the last few years. This is surprising especially considering recent work by Smalyukh et al., who found that nanoscale dispersion (based on /V-vinyl-2-pyrrolidone-capped gold nanoparticles with 14 nm diameter) in a thermotropic smectic liquid crystal (8CB) are potentially much more stable than dispersions of nanoparticles in nematics [367]. 

The nanocrystals of such type form in various liquid media, such as organic solution [77, 81] or the softened quasi-liquid glass [82, 83], where there are no steric hindrances for the growth of equilibrium crystals without surface defects. At the same time, barriers for aggregation of clusters or atoms to metal nanocrystals in solid system that arises during the cryochemical solid-state synthesis favor the formation of crystals with structural defects,... 

The diagram in figure 2 contains at least one phase such that its existence has been noted only recently (Brostow, W. Dziemianowicz, T.S., Hess, M., Saboe, Jr., S.H. Liquid Crystals, submitted), namely the quasi-liquid (q-1). This is the material which was in the amorphous state below its glass transition Tg, but now is in the temperature range between Tg and the melting transition. Thus, q-1 can undergo crystallization - the so-called "cold crystallization" - in distinction to an ordinary liquid which cannot. 

A MECHANISM FOR PHOTOCHEMICAL REACTIONS IN THE QUASI-LIQUID LAYER OF SNOW CRYSTALS IN POLAR REGIONS... 

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