Near-continuous isotropic – nematic transition in compressed rod-like liquid crystal based nanocolloid

Łoś, Jerzy; Drozd-Rzoska, Aleksandra; Rzoska, Sylwester J.; Starzonek, Szymon; Czupryński, K.; Mukherjee, Prabir K.

doi:10.1016/j.molliq.2023.121844

Cited by 4 publications

(16 citation statements)

References 64 publications

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“…Worth recalling are also polarized microscopy observations in 5CB-based nanocolloids, which is a nematogenic compound with density and viscosity similar to MBBA. Tests were carried out in the ‘horizontal’ and ‘vertical’ arrangements, confirming the above conclusions [ 32 , 33 ].…”

Section: Methodssupporting

confidence: 61%

“…Consequently, the dielectric constant within fluctuations is qualitatively lower than for the ‘non-ordered’ surroundings:

. On approaching the I–N transition, the contribution from the volume related to fluctuations finally dominates, and the following crossover occurs [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]:

in agreement with Equation (2).…”

Section: Introductionsupporting

confidence: 67%

“…Recent studies of nCB and nOCB liquid crystalline compounds showed that adding BaTiO 3 nanoparticles (

) can create a unique endogenic permanent orientation of rod-like LC molecules in bulk [ 30 , 31 , 32 , 33 ]. It is reached without any strong external field (electric, magnetic).…”

Section: Resultsmentioning

confidence: 99%

“…Studies were carried out for nanocolloids with nanoparticle concentrations of 0.05%, 0.1%, 05%, and 1% weight (mass) fractions. Our experience shows that significant nanoparticle sedimentation can occur at concentrations above 1% in such systems [ 32 , 33 ]. It can be avoided by introducing a macromolecular surfactant [ 8 , 9 , 10 ], but it significantly distorts the dielectric response by introducing the molecular admixture, which can also lead to a shift in the clearing temperature ([ 7 ] and refs therein).…”

Section: Methodsmentioning

confidence: 99%

“…Subsequent research reports showed the analogous pretransitional anomalies in nanocolloids based on rod-like LC with solid–nematic–isotropic mesomorphism (in pentylcyanobiphenyl (5CB) + NPs) or solid (S)–smectic A (SmA)–nematic (N)–isotropic (I), in undecylcyanobiphenyl (11CB + NPs), and octyloxycyanobiphenyl (8OCB + NPs) [ 27 , 28 , 29 , 30 , 31 , 32 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

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The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4′–butylaniline with Transverse Permanent Dipole Moment and BaTiO3 Nanoparticles

Drozd-Rzoska,

Łoś,

Rzoska

2024

Nanomaterials

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The report presents static, low-frequency, and dynamic dielectric properties in the isotropic liquid, nematic, and solid phases of MBBA and related nanocolloids with paraelectric BaTiO3 nanoparticles (spherical, d = 50 nm). MBBA (4-methoxybenzylidene-4′–butylaniline) is a liquid crystalline compound with a permanent dipole moment transverse to the long molecular axis. The distortions-sensitive analysis of the dielectric constant revealed its hidden pretransitional anomaly, strongly influenced by the addition of nanoparticles. The evolution of the dielectric constant in the nematic phase shows the split into two regions, with the crossover coinciding with the standard melting temperature. The ‘universal’ exponential-type behavior of the low-frequency contribution to the real part of the dielectric permittivity is found. The critical-like pretransitional behavior in the solid phase is also evidenced. This is explained by linking the Lipovsky model to the Mossotti catastrophe concept under quasi-negative pressure conditions. The explicit preference for the ‘critical-like’ evolution of the apparent activation enthalpy is worth stressing for dynamics. Finally, the long-range, ‘critical-like’ behavior of the dissipation factor (D = tgδ), covering the isotropic liquid and nematic phases, is shown.

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Section: Methodssupporting

confidence: 61%

“…Consequently, the dielectric constant within fluctuations is qualitatively lower than for the ‘non-ordered’ surroundings:

. On approaching the I–N transition, the contribution from the volume related to fluctuations finally dominates, and the following crossover occurs [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]:

in agreement with Equation (2).…”

Section: Introductionsupporting

confidence: 67%

“…Recent studies of nCB and nOCB liquid crystalline compounds showed that adding BaTiO 3 nanoparticles (

) can create a unique endogenic permanent orientation of rod-like LC molecules in bulk [ 30 , 31 , 32 , 33 ]. It is reached without any strong external field (electric, magnetic).…”

Section: Resultsmentioning

confidence: 99%