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.

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.

With the use of light scattering and viscometry, as well as the employment of various aprotic solvents for the polymer synthesis, the molecular characteristics of two poly(amic acids), namely, poly[4,4′-bis(4″- N -phenoxy)diphenylsulfone]amic acid of 1,3-bis(3′,4-dicarboxyphenoxy)benzene and poly[4,4′-bis(4″- N -phenoxy)diphenyl]amic acid of 1,3-bis(3′,4-dicarboxyphenoxy)benzene, have been studied at various molar ratios of the starting reagents and concentrations of the polycondensation solution. The molecular masses of poly(amic acids) depend on the thermodynamic quality of a solvent which may be changed by varying the nature of the solvent, the structure of the resulting polymer, or the chemical nature of the mixture.

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.

Specific features of the supramolecular organization of moderately concentrated methyl cellulose and cyanoethyl methyl cellulose solutions in the pre-gel region are quantitatively described by the method of static scattering of polarized light using the Debye-Bueche-Stein theory. The parameters characterizing the fluctuational heterogeneity and statistical dimensions of associates, as well as the dimensions of oriented regions and the ordering of the system, depend on the amount of highly polar hydrophobic cyanoethyl groups introduced into the methyl cellulose macrochains. As this amount increases, the solutions display a tendency for increasing fluctuational heterogeneity and decreasing correlation dimensions of the associates. These structural features are due to a superposition of two processes that take place in the system: the molecular mass of the polymer decreases because of its degradation during esterification and the polymer-solvent thermodynamic affinity deteriorates because of the increasing hydrophobicity of mixed-ester macromolecules. The supramolecular orientational order and hydrophobic association processes in cyanoethyl methyl cellulose solutions are compared to the structural organization of moderately concentrated aqueous solutions of propyl methyl cellulose.

ChemInformVolume 34, Issue 10 Heterocyclic Compounds Efficient Synthesis of 1-(2-Propynyl)pyrrole. L. Brandsma, L. Brandsma Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this authorO. A. Tarasova, O. A. Tarasova Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this authorN. A. Kalinina, N. A. Kalinina Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this authorA. I. Albanov, A. I. Albanov Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this authorL. V. Klyba, L. V. Klyba Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this authorB. A. Trofimov, B. A. Trofimov Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this author L. Brandsma, L. Brandsma Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this authorO. A. Tarasova, O. A. Tarasova Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this authorN. A. Kalinina, N. A. Kalinina Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this authorA. I. Albanov, A. I. Albanov Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this authorL. V. Klyba, L. V. Klyba Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this authorB. A. Trofimov, B. A. Trofimov Utrecht Univ., NL-3584 CH Utrecht, Neth.Search for more papers by this author First published: 14 March 2003 https://doi.org/10.1002/chin.200310116Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume34, Issue10March 11, 2003 RelatedInformation

Nanostructures arising from the reduction of an ionic selenium in the presence of an anionic polyelectrolyte, poly(2-acrylamido-2-methylpropanesulfonic acid), and an anionic surfactant, sodium dodecyl sulfate, were studied for the first time using a set of optical methods (static and dynamic light scattering, polarized light scattering, flow birefringence). It was shown that the reduction of selenium ions in polymer or surfactant solutions includes two processes, namely, the formation of selenium nanoparticles with a narrow unimodal size distribution and the adsorption of organic molecules on these particles. These processes afford nanostructures characterized by high molecular mass, compact packing, and unique morphology.

The flow birefringence and polarized light scattering techniques were applied to study semidilute water-salt solutions of a high-molecular-mass (M-w = 6 x 10(6)) flexible-chain polyelectrolyte, the copolymer of 2-acrylamido-2-methylpropanesulfonic acid with acrylamide, at different ionic strengths of the medium (I = l and 0.1 mol/l). It was shown that "domain" structures with the morphology predetermined by the solution ionic strength were formed in the solutions of this copolymer. In the case of suppressed electrostatic interactions, a fluctuation network of entanglements was formed.

Evolution of the supramolecular associate structure of moderately concentrated aqueous methyl and propyl methyl cellulose solutions, as dependent on the degree of substitution by propyl groups, is studied by the polarized light scattering using the Debye-Bueche-Stein theory.

The supermolecular structure of dilute solutions of methyl cellulose in water, polyamidoimide in N-methyl-pyrrolidone, and hydroxypropyl cellulose in trifluoroacetic acid is studied by the method of polarized light scattering. The experimental data are explained in the framework of the Debye-Bicy-Stein statistic theory.

The process of structurization in solutions of H-complexes of dimethyl 3,3′,4,4′ -benzophenonetetracarboxylate with 4,4′ -diaminodiphenylmethane has been investigated in 90 % aqueous methanol in the concentration range 6 to 0.2 g L−1. Structural instability of the solutions has been found in the concentration range from 1.2 to 2 g L−1. The addition of an ionogenic substance stabilizes the solution and results in monotonic changes in the structural parameters as solution is diluted. A tendency toward variation of the extemum in the mean correlation radius of the polarizability fluctuation has been found in the concentration range 0.6-–1 g L−1, which had been observed previously for polymer systems.

The method of polarized light scatter has been used to study the structure of dilute and moderately concentrated polyamido imide solutions based on the diaminodiphenyl ether in N-methylpyrrolidone and also films prepared from the polymer in a pure solvent and mixture with a precipitant. For the comparative analysis of the structure the authors also investigated solutions of the high molecular mass fraction of PMMA and a polyamido acid in good solvents. With change in the concentration the correlation radii of the fluctuation in the polarizability of the solutions pass through a maximum explained by association processes. Passage from solution to the solid phase is accompanied by substantial increase in the values of the mean square of fluctuation in polarizability reflecting increase in the heterogeneity of the system and also by increases in the mean square optical anisotropy.

The kinetics of the chemical and dynamics of the structural conversions have been investigated at the initial stage of copolymerization of methacrylic acid with N,N′-ethylene dimethacrylate by analysing the soluble copolymers before the point of gelation and the sol fraction. The method of scatter of polarized light provided quantitative information on the structural changes in the course of the process. The features of structuring of the developing polymer networks in different conditions of synthesis are essentially determined by the energy interaction between the microgel blanks and the medium. The character of the specific interactions appearing to the copolymer influences the relationship between the processes of inter- and intramolecular crosslinking and determines the topology and properties of the network structures.

Correlation distance of polarizability fluctuations, ac, was measured by elastic light scattering in moderately concentrated solutions of polymers differing in molar mass Mw. In very dilute solutions the relationship ac→o=(R̄g2)12/√6 holds true, where (R̄g2)12) is the mean square radius of gyration of the isolated macromolecule. For flexible-chain polymers in the absence of strong intermolecular interactions the distance ac decreases with polymer concentration c because of shrinkage of swollen macromolecular coils. The dependences of 1n (ac/√Mw) on 1n c follow a single master curve for all fractions of different molar mass. On the other hand, in the presence of specific intermolecular interactions (such as hydrogen bonds), ac increases with concentration as a result of association phenomena. At a given concentration the size of associates is proportional to (Rg2)12. The character of the concentration dependence of ac is governed by the type of intermolecular interactions operative in the system.