Kerr effect in solutions of carbosilane dendrimers with terminal mesogenic groups

Ryumtsev, E. I.; Evlampieva, N. P.; Лезов, А. В.; Ponomarenko, S.A.; Boiko, N. I.; Шибаев, В. П.

doi:10.1080/026782998205985

Cited by 21 publications

(4 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[61] Likewise, the electro-optical properties, e.g., electric birefringence (Kerr-effect) and dielectric polarization, of the first generation LC Si-based dendrimers 93a± 93c in diluted CCl 4 solutions were studied. [65] It was found that the dielectric polarization is proportional to the second power of the electric field in accordance with the Kerr-law. It is characteristic that the electric birefringence of solutions containing the LC dendrimers is principally defined by the electro-optical properties of the end-grafted mesogenic entities oriented in the electric field independently of the main chain.…”

Section: Silicon-based Dendrimers Containing Si±o±si Sub-unitsmentioning

confidence: 70%

“…It is characteristic that the electric birefringence of solutions containing the LC dendrimers is principally defined by the electro-optical properties of the end-grafted mesogenic entities oriented in the electric field independently of the main chain. [65] Even the structure of the fifth generation LC dendrimer 94, bearing 128 terminally bound mesogenic cyanobiphenyl groups, was studied and revealed unusual phase behavior: at 25 C it forms a laminar, smectic A phase, which undergoes an in-plane ordering above 40 C. [66,67] One explanation for this behavior is the tendency to create columns of molecules, which are probably arranged perpendicularly to the layers. [67] However, above 121 C the material starts to transform into another, more disordered mesophase, which presumably is a hexagonal columnar phase.…”

Section: Silicon-based Dendrimers Containing Si±o±si Sub-unitsmentioning

confidence: 99%

See 1 more Smart Citation

Siloxane and Carbosiloxane Based Dendrimers: Synthesis, Reaction Chemistry, and Potential Applications

Lang

Lühmann

2001

Adv. Mater.

View full text Add to dashboard Cite

This article focuses on recent developments made in the field of siloxane and carbosiloxane dendrimers with the silicon atoms as the branching (1 → 2, 1 → 3, or 1 → 4) points. It attempts to treat in a comprehensive way the divergent growth method for the synthesis of Si–O‐ and Si–O–C‐based dendrimers, including their reaction chemistry, their theoretical and physical descriptions, as well as their potential applications in the area of materials science.

show abstract

Section: Silicon-based Dendrimers Containing Si±o±si Sub-unitsmentioning

confidence: 70%

Section: Silicon-based Dendrimers Containing Si±o±si Sub-unitsmentioning

confidence: 99%

Siloxane and Carbosiloxane Based Dendrimers: Synthesis, Reaction Chemistry, and Potential Applications

Lang

Lühmann

2001

Adv. Mater.

View full text Add to dashboard Cite

show abstract

“…From this point of view, it is very important to establish the main features of their phase behavior including (i) the influence of generation number (responsible for dimensions and molecular weight of dendrimers), (ii) the spacer length between the mesogenic units and the dendritic matrix, and (iii) the chemical nature of the terminal mesogenic groups. The effect of mesogen type on the properties of first-generation LC dendrimers in bulk and in dilute solutions was presented in previous works. 4a, Influence of spacer length was estimated elsewhere. , This work presents a systematic study of the role of generation number on the thermal properties of carbosilane LC dendrimers. It was stimulated by the fact that the effect of generation number on mesophase formation has not been clearly distinguished yet 5a.…”

Section: Introductionmentioning

confidence: 91%

Carbosilane Liquid Crystalline Dendrimers: From Molecular Architecture to Supramolecular Nanostructures

et al. 2000

View full text Add to dashboard Cite

A systematic study of the influence of generation number on the phase behavior of LC dendrimers is presented. For this purpose, phase behaviors and structures of first to fifth generations of liquid crystalline (LC) carbosilane dendrimers with 8, 16, 32, 64, and 128 terminal cyanobiphenyl groups were investigated. Investigation of thermal behavior of the LC dendrimers by means of polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction experiments reveals smectic-type mesophases over a wide temperature region. It is shown that with increasing generation number the isotropization temperature increases whereas the enthalpy of this phase transition decreases. The strongest influence of spherical molecular architecture on the phase behavior of the LC dendrimers appears at high generations. In the case of LC dendrimer of the fifth generation, it leads to the formation of two levels of a structural organization. This dendrimer forms different supramolecular nanostructures of columnar type in addition to smectic-like arrangement of mesogenic groups. Possible structures of all mesophases formed are discussed.

show abstract

“…The study of hydrodynamic and electro-optical properties of dilute solutions of LC dendrimers clearly showed the dual nature of such compounds . According to their hydrodynamic properties, LC dendrimers are similar to solid, impermeable particles.…”

Section: Introductionmentioning

confidence: 99%

Order and Dynamics of a Liquid Crystalline Dendrimer by Means of ²H NMR Spectroscopy

et al. 2008

View full text Add to dashboard Cite

A complete Deuterium NMR study performed on partially deuterated liquid crystalline carbosilane dendrimer is here reported. The dendrimer under investigation shows a SmA phase in a large temperature range from 381 to 293 K, and its mesophasic properties have been previously determined. However, in this work the occurrence of a biphasic region between the isotropic and SmA phases has been put in evidence. The orientational order of the dendrimer, labeled on its lateral mesogenic units, is here evaluated in the whole temperature range by means of (2)H NMR, revealing a peculiar trend at low temperatures (T < 326 K). This aspect has been further investigated by a detailed analysis of the (2)H NMR spectral features, such as the quadrupolar splitting, the line shape, and the line-width, as a function of temperature. In the context of a detailed NMR analysis, relaxation times (T(1) and T(2)) have also been measured, pointing out a slowing down of the dynamics by decreasing the temperature, which determines from one side the spectral changes observed in the NMR spectra, on the other the observation of a minimum in the T(1).

show abstract

Kerr effect in solutions of carbosilane dendrimers with terminal mesogenic groups

Cited by 21 publications

References 5 publications

Siloxane and Carbosiloxane Based Dendrimers: Synthesis, Reaction Chemistry, and Potential Applications

Siloxane and Carbosiloxane Based Dendrimers: Synthesis, Reaction Chemistry, and Potential Applications

Carbosilane Liquid Crystalline Dendrimers: From Molecular Architecture to Supramolecular Nanostructures

Order and Dynamics of a Liquid Crystalline Dendrimer by Means of ²H NMR Spectroscopy

Contact Info

Product

Resources

About

Kerr effect in solutions of carbosilane dendrimers with terminal mesogenic groups

Cited by 21 publications

References 5 publications

Siloxane and Carbosiloxane Based Dendrimers: Synthesis, Reaction Chemistry, and Potential Applications

Siloxane and Carbosiloxane Based Dendrimers: Synthesis, Reaction Chemistry, and Potential Applications

Carbosilane Liquid Crystalline Dendrimers: From Molecular Architecture to Supramolecular Nanostructures

Order and Dynamics of a Liquid Crystalline Dendrimer by Means of 2H NMR Spectroscopy

Contact Info

Product

Resources

About

Order and Dynamics of a Liquid Crystalline Dendrimer by Means of ²H NMR Spectroscopy