Structure and Properties of the Cholesteric Blue Phases

Johnson, D.L.; Flack, J.; Crooker, P. P.

doi:10.1103/physrevlett.45.641

Cited by 158 publications

(72 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, the BP lattice cell contracts as the temperature increases, resulting in a gradual color change of the BP (43). This effect can be described by multiplying the magnitude of the original blue phase wave vector by a red shift, r s .…”

Section: Resultsmentioning

confidence: 99%

Blue-phase liquid crystal droplets

Martínez‐González

Zhou

Rahimi

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Blue phases of liquid crystals represent unique ordered states of matter in which arrays of defects are organized into striking patterns. Most studies of blue phases to date have focused on bulk properties. In this work, we present a systematic study of blue phases confined into spherical droplets. It is found that, in addition to the so-called blue phases I and II, several new morphologies arise under confinement, with a complexity that increases with the chirality of the medium and with a nature that can be altered by surface anchoring. Through a combination of simulations and experiments, it is also found that one can control the wavelength at which blue-phase droplets absorb light by manipulating either their size or the strength of the anchoring, thereby providing a liquid-state analog of nanoparticles, where dimensions are used to control absorbance or emission. The results presented in this work also suggest that there are conditions where confinement increases the range of stability of blue phases, thereby providing intriguing prospects for applications.blue phases | chiral liquid crystals | droplets | confinement B lue phases of liquid crystals (LCs) are characterized by a local director field that forms double-twisted cylinders, arranged into defect regions that are periodically repeated in space (1, 2). The symmetry properties of blue phases (BPs) have attracted considerable attention, as have their potential applications in a wide range of technologies (3-7). Theoretical and computational studies of the bulk structure and dynamics of BPs have helped elucidate their nature (1, 8, 9-15) in considerable detail. In the bulk, however, BPs are only found in a narrow range of temperature, between the cholesteric and the isotropic phases (1-6, 10-18), thereby placing limits on their practical utility. Recent efforts have therefore focused on increasing their stability over wider ranges of temperature and chirality, for example through addition of nanoparticles (19, 20, 21-23), polymers (24-26), or by manipulating their flexoelectricity (14).Confined chiral liquid crystals are of interest for applications in optical devices (27)(28)(29)(30)(31). Simulations of chiral LCs in channels have shown that their defect structure can be manipulated through confinement, thereby raising intriguing prospects for technology (32)(33)(34)(35). Chiral LC droplets have also been studied both numerically (36-38) and experimentally (39,40). More recent, intriguing simulations of planar chiral droplets with strong anchoring by Seč et al. (41) have examined their phase behavior as a function of chirality. In particular, it was reported that the twist bipolar structure (BS) is stable in the low chirality regime, whereas the radial spherical structure (RSS) is preferred at high chirality. The BS state has a cylindrical symmetry, where the director field is uniform along the symmetry axis of the droplet and rotates in the perpendicular direction forming bent cholesteric layers. In the RSS state, the director field also forms curved ...

show abstract

Section: Resultsmentioning

confidence: 99%

Blue-phase liquid crystal droplets

Martínez‐González

Zhou

Rahimi

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Nevertheless, the high-chirality (single spatial frequency) limit, which was initially treated exclusively Shtrikman 1979, 1980a, b), is evidently inconsistent with a large number of the early experimental findings detailed in section 3: in particular, the appearance of more than one cubic structure (Bergmann and Stegemeyer 1979a); the red shift of the primary reflection (Bergmann et al 1979); the observation of a second strong Bragg reflection for both BPI and BPII (Goldberg and Schnur 1970, Meiboom and Sammon 1980, Johnson et al 1980, indicating as shown below that neither has an O5 structure; and even more definitely the polarised light studies (Flack and Crooker 1981), which found the second Bragg line strongly sensitive to the sense of input light. The last result seems to rule out the O5 symmetry for which the c = 2 reflection is polarisationindependent in the back direction (see below).…”

Section: Theory Versus Experiment: Higher Harmonicsmentioning

confidence: 96%

The liquid-crystalline blue phases

Seideman

1990

Rep. Prog. Phys.

View full text Add to dashboard Cite

show abstract

“…Generally, in BPs circularly polar ized light of wavelength /.hki is selectively reflected at different lattice planes (/? k I) of a cubic structure (normal incidence) [7]:…”

Section: Electric Field Effects In the Bp Imentioning

confidence: 99%

“…they exhibit no birefringence [2,3]. From this result a cubic BP structure has been derived [4,5] which was evidenced by observation of Bragg-type light scattering [6,7] and growing liquid single crystals belonging to cubic crystal classes [8,9].…”

Section: Introductionmentioning

confidence: 99%