V. P. Sklizkova

Study of the supramolecular structure formation of comb-like polyimide precursor Langmuir-Blodgett films

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.

Formation of Langmuir-Blodgett films in solutions of comblike polymers

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.

Investigation of the role of the pyrimidine ring in the main chain of polyamido acids and polyimides. 1. Supermolecular structure of polypyromellitimides based on 2,5-bis(p-aminophenyl)pyrimidine and its carbocyclic analog 4,4′-diaminoterphenyl

A detailed comparative study of polypyromellitamido acids and polyimides based on 2,5-bis(paminophenyl)pyrimidine and 4,4′-diaminoterphenyl was conducted to determine the role of the nitrogencontaining pyrimidine ring in the main chain of the polymers. A model of the layer packing of polyimide chains in crystalline regions was proposed based on the data from x-ray structural analysis and quantum chemical calculations. The existence of tilted packing caused by partial displacement of the solvent molecules bound to the pyrimidine ring of the neighboring macromolecule with higher basicity in pyrimidine-containing polymers was hypothesized.

A model of supermolecular structure of stiff-chain polyimide copolymers and composites☆

Abstract Microstructure and molecular packing in stiff-chain polyimide copolymers and composites of various composition was studied by PMR, X-ray diffraction, and also by calculating the diffraction patterns for model systems. Copolymers of different microheterogeneity were synthesized; it is shown how to characterize the microheterogeneity in the stage of poly(amic acid) by means of PMR and in the polyimide stage by means of X-ray diffraction measurements. A generalized model has been proposed for the domain structure of polyimide copolymers and composites, which shows the latter to be molecular composites and elucidates the reasons underlying the improvement of physico-mechanical over those of homopolymers.

Supramolecular structure formation of Langmuir-Blodgett films of comblike precursor and polyimide

The surface structure of Langmuir-Blodgett films of a comblike polyimide precursor—a rigid-chain polyamic acid alkylamine salt bearing multichains of tertiary amine—and films of the corresponding polyimide were studied by atomic force microscopy (AFM). An analysis of the images of the surface of three-layer films revealed a domain structure. It was found that the Langmuir-Blodgett film formation of the precursor occurs as a result of the layer-by-layer deposition of two-dimensional domains (composed of polyamic acid salt molecules on the water surface) onto a substrate. The formation of domains in a monolayer is associated with the chemical structure of the precursor, to be more precise, with the rigidity of the main chain and the presence of closely spaced aliphatic side chains in the polymer chain, whose total cross-section area is close to the surface area of the projection onto the plane of the repeating unit of the main chain. Polyimide films inherit the domain structure of the precursor films; the inhomogeneity of the film thickness substantially decreases, whereas the domain size and character of their distribution in the film remain unchanged.

X-ray and electron diffraction study of polyimide LB films

Abstract The fabrication of polyimide LB films was carried out via two stages. The structure of polyimide LB films was studied by X-ray small-angle scattering and electron diffraction methods. It was shown that the macromolecules were packed into an orthorhombic lattice with unit cell parameters: a = 0.631, b = 0.397, c = 3.2 nm.

Initial stages of structurization in dilute solutions of polyamic acids and polyimides

Abstract By means of IR spectroscopy, light scattering, and X-ray diffraction, strong intermolecular interactions have been found to exist in dilute solutions (at concentrations c ⩾ 0·5%) of polyamic acids and of soluble polyimides in amidic solvents.

Effect of the structural organization of polyamic-acid salt solutions on the morphology of Langmuir Monolayers of the prepolymer

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.

Equilibrium rigidity of macromolecules of poly(4,4′-phenylene)pyromellitamido acid☆

From the value of the intrinsic viscosity in θ conditions and from the value of reduced dynamic birefringence the authors determine the equilibrium rigidity of non-hinge macromolecules of poly(4,4′-phenylene)pyromellitamido acid. They obtain the size of the statistical segment A=(60±10) × 10−10 which is twice the size of the segment of the macromolecules of poly(4,4′-oxydiphenylene)pyromellitamido acid similar in structure but with hinge articulation.