Liquid Crystal Codendrimers with a Statistical Distribution of Phenolic and Mesogenic Groups: Behavior as Langmuir and Langmuir−Blodgett Films

Abstract

The first series of carbosilane liquid crystal codendrimers with groups of different polarity has been synthesized. The chemical structure of the newly synthesized materials and the composition of the codendrimers were studied by NMR spectroscopy and MALDI-TOF MS. It was found that the codendrimers tend to form stable Langmuir films at the air-water surface. The influence of composition and generation number on surface pressure-surface area isotherms and film stability was studied. Brewster angle microscopy confirmed the different phase behavior for monolayers of different codendrimer composition and generation number. It was found that side groups of fifth-generation codendrimers do not segregate, unlike those of lower generations. Langmuir-Blodgett films on solid substrates were obtained by the vertical dipping method. X-ray diffraction showed that the codendrimers with 75% of hydrophobic mesogenic terminal groups formed ordered layers parallel to the substrate.

Temperature dependence of the structure of a carbosilane dendrimer with terminal cyanobiphenyl groups: Molecular-dynamics simulation

“…Calculations were performed for the fourth gener ation carbosilane dendrimer with terminal cyanobi phenyl groups (64 groups) that were linked to the den drimer through short aliphatic spacers (-СН 2 -) 5 . Figure 1 shows the structural formula of the studied dendrimer.…”

“…A dendrimer is a regular treelike macromolecule that exhibits some unique properties, which are used in various domains of polymer chemistry, biology, and medicine [1][2][3]. There are a great number of studies concerning carbosilane dendrimers with ter minal mesogenic groups [4][5][6][7][8][9][10][11][12][13][14][15]. Usually, these stud ies focus on the analysis of the LC states of the den drimer melt that are generated by terminal mesogenic groups [4][5][6][7][8][9][10][11][12].…”

Pulse Programming of Resistive States of a Benzothieno[3,2‐B][1]‐Benzothiophene‐Based Organic Memristive Device with High Endurance

“…Long aliphatic spacers in the O(Si‐Und‐BTBT‐Hex) 2 dimer molecule increase its solubility in organic solvents, which plays an important role in the manufacturing of electronic devices by solution processing. [ 40 ] In addition, due to its molecular structure, the siloxane dimer O(Si‐Und‐BTBT‐Hex) 2 has good film‐forming properties, and the central disiloxane group contributes to the correct self‐organization of the molecule on the water surface for subsequent transfer of the monolayer to the solid support using Langmuir–Blodgett or Langmuir–Schaefer techniques, [ 41,42 ] frequently used for the realization of organic systems with nanometer resolution. However, the possibility of the fabrication of memristive devices based on this siloxane dimer has not yet been investigated.…”

Formation of Two-Dimensional Network of Organic Charge-Transfer Complexes at the Air–Water Interface

“…Two-dimensional (2D) ordering of organic molecules in the form of a fishing net has generated intense research interest in both fundamental and applied physical sciences . Although 2D polymers and graphene are the most prominent members of this class of materials, several molecular and supramolecular assemblies at the air–water interface can also form such intriguing 2D structures. − A single 2D molecular layer offers a plethora of scientific interest starting from self-interaction between molecules to their relative orientations and interaction of the layer with water and other aqueous solutes. − Temperature-dependent orientation and pH-dependent studies have been carried out thoroughly for such 2D systems . Charge-transfer (C-T) complexes of donor and acceptor molecules are of considerable importance to develop basic understanding and for novel device development. − Here, we report a study on the formation of a 2D network of a C-T complex at the air–water interface in the form of a Langmuir monolayer.…”