Non-functional derivatives of polymethylsilsesquioxane (PMSSQ) dendrimers of first to fourth generation were synthesized for the first time using combination of divergent and convergent synthetic approaches. Obtaining of non-functional derivatives allowed investigating their properties not only in solution, but also in the bulk. While having practically identical chemical composition with linear polydimethylsiloxanes, PMSSQ dendrimers demonstrated increased density, a significant increase in the viscous flow energy, an absence of crystallization, and a gradual increase in the glass transition temperature with the generation.

Михаил Валентинович Ковальчук (к 70-летию со дня рождения), Велихов Е.П., Ильгисонис В.И., Камболов М.А., Каневский В.М., Кропачев Н.М., Кудрявцев Н.Н., Матвеев В.А., Нарайкин О.С., Панченко В.Я., Садовничий В.А., Стриханов М.Н., Фейгин Л.А.

Михаил Валентинович Ковальчук (к шестидесятилетию со дня рождения), Аксенов В.Л., Алфимов М.В., Велихов Е.П., Желудева С.И., Каган Ю.М., Киселев Н.А., Кулипанов Г.Н., Осипьян Ю.А., Румянцев А.Ю., Скринский А.Н., Фейгин Л.А., Черноплеков Н.А.

The conditions of the deposition of the mixed cellulose acetovalerate ester Langmuir–Blodgett (LB) films are studied. The structure of films is examined by X-ray and electron diffraction methods, and atomic force microscopy. It was shown that LB films reveal the Y-type layer structure. A comparison between the macromolecule packing in LB films and macrofilms (bulk) was done. Modeling of the cellulose acetovalerate mono- and multilayer organization on the basis of the π–A isotherms and structural data was realized.

The theory of linear models is suggested for quantification of parameters’ significance in application to reflectivity data. Determination of the ultimate complexity of the model for real neutron reflectivity data by Ti/TiO2 film as well as influence of experimental limitations on the number of reliably restored parameters for Langmuir–Blodgett multilayer is considered.

Monolayers of 14-H-perfluorotetradecane-1-carbonic acid (PFTDA) at the air-water interface with different metal cations (K +, Cd+2, Cu2+, A13+, Fe3+) dissolved in a water subphase were studied. The dependence of the surface pressure P(A) and the jump of the surface potential ΔV on the area per molecule A in the monolayer were studied. Some compression isotherms of the PFTDA monolayers within a wide surface pressure range obey the equation of state P(A−A0) =kTn, where Ao is the effective area of interaction of the molecules in the monolayer, n = 1 − 4 and it depends on the interaction of the polar groups with one another or with the cations of the subphase. On the whole, this is the evidence of a weak cohesive interaction between the hydrophobic radicals in the monolayer.

Neutron and X-ray reflectivity measurements are used to characterize Langmuir—Blodgett films composed of 20 bilayers of barium stearate. To facilitate contrast for neutron measurements, molecules with deuterated aliphatic tails were used for the depostion of every odd-numbered bilayer. Model fitting of both data sets yields values of the following: the bilayer thickness, the area per molecule, the ratio of undissociated carboxylic acid groups to Ba salts, and the degree of mixing between neighboring bilayers (30%) ocurring on deposition. Structural changes of the film during temperature annealing at 66°C were studied. Interlayer diffusion, evaporation of matter, and distortion were observed. Quantitative parameters of these processes were calculated using two complementary approaches — modeling and Bragg peak analysis based on general ideas about film structure. In particular, interdiffusion reduces the intensities of different Bragg peaks differently, depending on the operative mode of interdiffusion. After 90 min of annealing, complete mixing of deuterated and hydrogenated aliphatic chains was achieved. At that time, 35% of the film had evaporated. This amount is very close to the content of undissociated acid groups.

X-ray and neutron reflectivity is now a powerful tool for investigating density profiles of thin films. Combined X-ray and neutron reflectivity measurements are used to characterize Langmuir-Blodgett films of barium stearate. To facilitate contrast for neutron measurements, molecules with deuterated aliphatic tails were used for the deposition of every-odd numbered bilayer. Model fitting of both data sets permitted to present the structure of the film.The electron diffraction in transmission and reflection geometry was successfully used for studying the structure of thin Langmuir-Blodgett films formed by amphiphilic molecules.Structural changes of the film during temperature annealing at 66 degrees C (below the melting temperature) were studied by neutron reflectivity. Interlayer diffusion, evaporation of matter, and distortion were observed.Comparative analysis of high energy electron diffraction patterns from Langmuir-Blodgett films of Cd and Pb stearates shows: there is the correlation of structure ordering with the subphase composition.The monolayer of fatty acid and Langmuir-Blodgett films of Pb salts of fatty acids have been successfully used as an ordered substrate for the growing of oriented nanocrystals of inorganic semiconductor compound - PbS.

LB films of Cd- and Pb-stearates are studied by electron diffraction in reflection and transmission modes. The low e-beam radiation resistance and structure disorder are revealed in CdSt2 films obtained on the surface of CdCl2-solution. The films of CdSt2 and PbSt2 obtained on the surface of Me(NO3)2 solutions are high ordered and stable under the electron beam. The origin of this phenomena is discussed.

The behaviour of the monolayer of cellulose triester of myristic and acetic acids on a water surface has been studied. The surface pressure-area (π-A) isotherm curves of the monolayer of triester had a plateau region. The cyclic π-A curve measurements, i.e. the cycles of compression and successive expansion of the monolayer, showed that the structural change in the monolayer under compression was non-reversible. The multilayers prepared by Langmuir-Schaefer method at different surface pressure provided X-ray diffraction patterns, which suggested that they had a Y-type packing. Studies of the relationship between the structure of the Langmuir-Blodgett films and the surface pressure for film deposition revealed that a change in the orientation of cellulose triester molecules was caused by compression of the monolayer.

Polymer molecules of cellulose acetomyristat (CAM) with different degrees of substitution (γ) on acyl groups of myristic and acetic acids were synthesized and their crystals were investigated by X-ray diffraction methods to choose a proper γ for fabrication of well-packed LB films. It was shown that there is a possibility of fabricating CAM LB films in which one-third of the long side chains is changed into different functional groups: drugs (for medical purposes), light sensitive compounds (for micro electronics) or others.

Langmuir-Blodgett films of two mixed cadmium fatty acid salts were deposited and investigated by small-angle X-ray scattering. For one of the systems investigated (a mixture of stearic and behenic acids) it was found that for a 1:1 ratio, the lattice spacing corresponds to the sum of stearic and behenic acid salts, while, for any other ratio, the X-ray patterns contained two systems of reflections, each of them corresponding to one of the pure acid salts (49.0 angstrom and 58.5 angstrom, respectively). The other system investigated (a mixture of behenic and palmitic acid salts) gave a completely different result: a single phase was present for any molar ratio of compounds and the lattice spacing varied with the molar ratio itself.

Langmuir-Blodgett films of lead and cadmium stearate were treated by exposure to H2S atmosphere. Such treatment lead to formation of CdS and PbS particles and protonation of stearic acid head-groups. The process was studied by small-angle X-ray scattering. The reaction was shown to be completed after 5 hours of treatment.