For the first time, multilayer graphene films on quartz glass were obtained by carbonization of the Langmuir-Blodgett films of polyimide. On the Raman spectra of the carbonized polyimide films, the G, D bands and a wide band in the region of 2300–3200 cm-1 were observed. Using the method of transmission microscopy, it was shown that films consist of “stacks” of layers with a interlayers distance of 0.36 nm. The surface resistance of films 5 nm thick was 1.2±0.2 kOmega, and the transmittance was 87% at lambda=550 nm. In the infrared region of the spectrum, the transmittance was 97%, and in the UV region 70-80%.

Multigraphene films have been for the first time obtained on the surface of quartz glass via carbonization of polyimide Langmuir–Blodgett films. The Raman spectra of the films show bands G and D and a broad band at 2300–3200 cm –1 , which are characteristic of graphite-like films. The transmission electron microscopy demonstrated that the films are constituted by “stacks” of layers spaced by 0.36 nm. The surface resistance of the 5-nm-thick films was 1.2 ± 0.2 kΩ, and the transmittance was 87% at λ = 550 nm. The transmittance was 97% in the IR part of the spectrum and 70–80% in the UV part.

Методом электроформования растворов полиамидокислоты на основе диангидрида 3,3 ,4,4 -дифенил тетракарбоновой кислоты и о-толидина в смеси растворителей N,N-диметилацетамид-бензол получены нановолокна диаметром от 100 до 300 нм. Термическая обработка нановолокнистого материала из полиамидокислоты приводит к образованию нановолокон ароматического полиимида диаметром от 100 до 200 нм. Температура начала терморазложения полиимидных нановолокон в атмосфере аргона составляет 537 °С. Методом сканирующей электронной микроскопии показано, что материал на основе нановолокон из ароматического полиимида сохраняет эластические свойства вплоть до температуры жидкого азота. Полученный материал характеризуется отсутствием цитотоксичности - фибробласты человека, культивируемые на нем, обладают высокой пролиферативной активностью.

Nanofibers with a diameter of 100–300 nm are obtained by electroformation of solutions of polyamide acid based on 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride and o-toluidine in an N,N-dimethylacetamide/ benzene solvent mixture. Thermal treatment of nanofibrous polyamide acid material leads to the formation of nanofibers of aromatic polyimide with a diameter of 100–200 nm. The temperature of the beginning of thermal decomposition of polyimide nanofibers in an argon atmosphere is 537°C. SEM images show that the material based on aromatic polyimide nanofibers preserves its elastic properties even at the temperature of liquid nitrogen. The obtained material is characterized by the absence of cytotoxicity: human fibroblasts cultivated on it are characterized by high proliferative activity.

High quality single crystal SiC films were prepared by carbonization of polyimide Langmuir-Blodgett films on Si substrate. The films formed after annealing of the polyimide films at 1000°C, 1100°C, 1200°C were studied by Fourier transform-infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, transmission electon microscopy (TEM), transmission electron diffraction (TED), and scanning electron microscopy (SEM). XRD study and HRTEM cross-section revealed that the crystalline SiC film begins to grow on Si (111) substrate at 1000°C. According to the HRTEM cross-section image five planes in 3C-SiC (111) film are aligned with four Si(111) planes at the SiC/Si interface. It was shown the SiC films (35 nm) grown on Si(111) at 1200°C have mainly cubic 3C-SiC structure with a little presence of hexagonal polytypes. Only 3C-SiC films (30 nm) were formed on Si (100) substrate at the same temperature. It was shown the SiC films (30-35 nm) are able to cover the voids in Si substrate with size up to 10 μm.

The structure of Langmuir-Blodgett (LB) films formed from solutions of comblike N,N-dimethylhexadecylammonium polyamic-acid salt on the basis of the dianhydride of 3,3′,4,4′-diphenyl-tetracarboxylic acid and o-tolidine is studied by the AFM method. The structural organization of dilute solutions of the amphiphilic polyimide prepolymer in mixed solvents (DMAA-dioxane, DMAA-benzene, and MP-benzene) is studied by the method of polarized light scattering. The statistical structural parameters of the solutions are calculated using Debye-Stein theory. It is shown that the dimensions of ordered scattering formations depend on the chemical nature of the mixed solvent components. The parameters, characterizing the structure of the prepolymer solutions in various solvents, are compared. The dependence of the surface morphology of the LB films on the structural organization of the initial prepolymer solutions is revealed.

Continuous decrease of the feature size of transistors in modern integrated circuits (ICs) constrains thickness of auxiliary dielectric layers in interconnects because of their relatively high dielectric constant, which reduces the efficiency of low-k material integration. Dielectric materials used today as barrier or etch-stop layers are usually SiN (k ∼ 7.0) and SiCN (k ∼ 4.8), which k-value significantly exceeds that of recent ultra low-k materials (k < 2.2). In our work we have investigated thin films of rigid-chain polyimide (PI) with a k-value of about 3.2-3.3. This film was deposited using a Langmuir-Blodgett (LB) technique and can be as thin as several monolayers. The intermolecular interaction of densely packed precursor macromolecules within a monolayer formed at the water-air interface makes it possible to avoid penetration of precursor material inside the pores. The latter peculiarity of the deposition process results in a pore sealing effect using a 4 nm PI film.

The Langmuir monolayers and Langmuir-Blodgett films of a comb-like polyimide prepolymer (the rigid-chain polyamic acid alkylamine salt bearing multichains of tertiary amine) were studied. The supramolecular structures of the monolayers and Langmuir-Blodgett films of polyamic acid salts were characterized and a way for the surpamolecular structure to form was proposed based on an analysis of the surface pressure-area isotherms of monolayers on the water surface, investigations of the conditions of monolayer deposition onto solid substrates, and studies of the structures and surface morphology of Langmuir-Blodgett films.

The structure of mixed amide solvents used for the preparation of polyimide Langmuir-Blodgett films and the structural organization of water, on which nanofilms are formed, have been studied by polarized light scattering. Fluctuation supramolecular structures are found to exist in water and in its mixtures with amide solvents, and the dimensions of the structures are comparable with the light wavelength. When a mixture contains more than 20 vol % water, associates show microanisotropic properties. In snowmelt water, the dimensions of associates are larger than those in distilled water. In the DMAA-water mixture, the dimensions of supramolecular structures are virtually independent of composition.

The effect of biaxial orientation on the mechanical properties and supramolecular structure of the films based on rigid-chain polyimides and copolyimides was studied. The films were oriented in two different ways: by hot drawing and by cold drawing at the prepolymer stage and the subsequent cyclization according to the specified temperature regime. It was shown that the curing of the precursor films after their preliminary biaxial drawing is accompanied by self-orientation, although its degree is well below that after uniaxial drawing under the same conditions. As compared with homopolyimide films, the films based on rigid-chain copolyimide exhibit a lower tendency toward orientation under biaxial drawing. The reasons for such behavior are discussed.

The surface structure of a three-layer Langmuir-Blodgett film of comblike rigid-chain polyimide prepolymer (polyamic acid alkylammonium salt) has been studied by atomic force microscopy (AFM). The AFM data reveal the presence of supramolecular formations consisting of two-dimensional domains in which aliphatic chains of the prepolymer macromolecules are oriented perpendicularly to the substrate. A mechanism responsible for the supramolecular structure formation in the film is proposed.

Structural organization is studied for dilute solutions of the comblike N,N-dimethylhexadecylammonium salt of polyamic acid based on 3,3′,4,4′-diphenyltetracarboxylic dianhydride and o-tolidine by the method of polarized light scattering in mixed dimethylacetamide-benzene and N-methylpyrrolidone-benzene solvents. The statistical structural parameters of the solutions are calculated according to the Debye-Stein theory. The dimensions of ordered scattering fluctuation-type formations are shown to be much greater than the molecular dimensions and to depend on the chemical nature and composition of the mixed solvent. At polymer concentrations below 0.2 g/dl, the corresponding concentration dependences of the statistical structural parameters are characterized by extreme patterns for all systems under study.

Atomic-force microscopy, reflectometry, and ellipsometry were applied to analysis of ultrathin films (3.3–13.6 nm) of a rigid-chain polyimide, formed on the surface of a silicon substrate by thermal imidization of Langmuir-Blodgett films of polyamido acid derived from 3,3′,4,4′-diphenyltetracarboxylic acid and ortho-tolidine.

The structures have been analyzed of the monolayers of comblike precursor polymers of polyimides and mixed cellulose esters formed at the water/air interface and of the Langmuir-Blodgett films obtained by transfer of these condensed monolayers onto solid substrates. The important factors that ensure the structure control and supramolecular organization of these monolayers and films are established.

An ultrathin polyimide membrane network has been formed for the first time on a metal grid matrix using the Langmuir-Blodgett method. The ratio of the membrane thickness to the grid mesh reaches 1: 1000.

During storage under normal climatic conditions for 10-20 years, the changes in mechanical characteristics, thermal stability parameters, glass transition temperature, and density were studied for films based on various thermally stable polyimides and copolyimides prepared by different methods. High stability of the properties is observed for films prepared by the methods of thermal and thermochemical cyclization, whereas the products of heterogeneous chemical cyclization of polyamic acids are characterized. by low stability. The reasons for the observed instability of the properties of such materials are discussed.

Rigid-chain polymers are capable of spontaneous uniaxial molecular orientation without any action of external forces. This process accompanies thermal cyclization of prestretched poly(amido acid) films. The kinetics of this process is studied, and the activation energy of self-orientation is estimated.

The structure of dilute solutions of comblike N,N-dimethylhexadecylammonium salts of polyamic acids made from 3,3',4,4'-biphenyltetacarboxylic dianhydride and o-tolidine was studied by the polarized-light scattering technique. Experiments were carried out in the mixed solvent DMAA-dioxane with compositions close to polymer precipitation. Using the Debye-Stein statistical theory, the structural parameters characterizing the supramolecular structure were calculated. It was shown that the sizes of scattering entities substantially exceed the molecular dimensions and increase as the polymer molecular mass and the proportion of DMAA in the solvent blend increase. These entities are fluctuating in nature. There is a certain concentration at which the course of concentration dependence of structural parameters changes. This concentration increases with a decrease in the polymer molecular mass, which is probably due to the involvement of the mechanisms of intermolecular interaction between main- and side-chain segments of comblike salt macromolecules.