Multilayer films of organic compounds on solid surfaces have been studied for more than 60 years because they allow fabrication of multicomposite molecular assemblies of tailored architecture. However, both the Langmuir-Blodgett technique and chemisorption from solution can be used only with certain classes of molecules. An alternative approach—fabrication of multilayers by consecutive adsorption of polyanions and polycations—is far more general and has been extended to other materials such as proteins or colloids. Because polymers are typically flexible molecules, the resulting superlattice architectures are somewhat fuzzy structures, but the absence of crystallinity in these films is expected to be beneficial for many potential applications.

https://science.sciencemag.org/content/sci/277/5330/1232.full.pdf

Fuzzy Nanoassemblies: Toward Layered Polymeric Multicomposites

Application of the pople-santry-segal CNDO method to the cyclopropylcarbinyl and cyclobutyl cation and to bicyclobutane

An anionic and a cationic bipolar amphiphile containing rigid biphenyl cores were synthesized. The compounds were dissolved in a mixture of dimethylsulfoxide (DMSO) and water and pure water, respectively. When a solid substrate with a positively charged planar surface is immersed in the solution containing the negatively charged bipolar amphiphile, a monolayer of the amphiphile is adsorbed and due to its bipolar structure the surface charge is reversed. After rinsing in pure water the substrate is immersed in the solution containing the positively charged bipolar amphiphile. Again a monolayer is adsorbed but now the original surface charge is restored. By repeating both steps in a cyclic fashion alternating multilayer assemblies of both compounds are obtained. It is demonstrated that multilayer films, composed of at least 35 consecutively alternating layers, which corresponds to a total film thickness of 170 nm can be assembled.

Buildup of ultrathin multilayer films by a self-assembly process, 1 consecutive adsorption of anionic and cationic bipolar amphiphiles on charged surfaces

Photopolymerization of polymer-coated solid substrates with linearly polarized light is shown to induce an anisotropic, uniaxial orientation of polymer molecules. The linearly photopolymerized (LPP) layers exhibit UV dichroism and optical anisotropy. The resulting anisotropic dispersive surface interaction forces are shown to align adjacent liquid crystals parallel. A qualitative microscopic model is presented. The new LPP-alignment technique allows to generate homogeneous LC-director pattern with different azimuthal director angles on the same substrate requiring no mechanical treatment. The use of LPP substrates in liquid crystal displays (LCDs) is shown to enable to combine different electrooptical effects-such as twisted nematic (TN) and parallel configurations-in the same hybrid LCD. Besides from high-contrast LPP-aligned TN-LCDs, LPP-aligned supertwisted nematic (STN)-LCDs exhibiting steep transmission-voltage characteristics are presented.

https://iopscience.iop.org/article/10.1143/JJAP.31.2155/pdf

Surface-Induced Parallel Alignment of Liquid Crystals by Linearly Polymerized Photopolymers

https://escholarship.org/content/qt6nx7k5zw/qt6nx7k5zw.pdf?t=qlup1r

Lipidomics reveals a remarkable diversity of lipids in human plasma

Thermodynamic and static properties of liquid crystals

Covalently attached organic monolayers on semiconductor surfaces

Molecular symmetry in mitochondrial cardiolipins.

Order-related properties of some nematic liquids

This paper examines the utility of four newly proposed positive resists whose processing combines electron-beam-induced degradation of certain polymers and, subsequently, in situ fractionation according to molecular weight. Positive-resist action in four systems formulated on this concept has been demonstrated. Typical sensitivity in electron-beam exposure is 10-4 coulomb/cm2. Two resists exhibit resolution better than 1 micron. One resist investigated in detail yields extremely clean edges in electron-beam exposure, is resistant to hydrofluoric acid etching baths, and appears otherwise applicable to the fabrication of circuit elements of submicron size.

Ivan Haller

Papers

Thermodynamic and static properties of liquid crystals

Covalently attached organic monolayers on semiconductor surfaces

Molecular symmetry in mitochondrial cardiolipins.

Order-related properties of some nematic liquids

High-resolution positive resists for electron-beam exposure