Fullerene C6 0 Aggregates in Polymethyl Methacrylate Films

The structure of aggregates of fullerene C_{6 0} introduced into films of radical polymethyl methacrylate in the stage of solution preparation was studied by wide-angle X-ray diffraction.     

Anomalies of Glass Transition: Manifestation in fullerene core polystyrene stars

Segmental dynamics around T_g in the 4- and 6-arm fullerene (C₆₀) core star-like polystyrenes with different preset arm lengths was studied by DSC as compared to that in the linear PS and PS/C₆₀ blend. The anomalies in glass transition behavior were found for the stars including both suppression and facilitation of segmental motion, and pronounced dynamic heterogeneity within a transition range. The results are interpreted in terms of breakdown of intermolecular cooperativity of segmental motions and PS-C₆₀ interactions.This revised version was published online in November 2005 with corrections to the Cover Date.     

Rheological Behavior of Poly(vinylpyrrolidone)/Fullerene C60 Complexes in Aqueous Medium

Aqueous solutions of complexes formed between poly(vinylpyrrolidone) (PVP), as a matrix polymer, and fullerene C₆₀ were investigated. The effect of the external hydrodynamic field on the supermolecular assemblies formed by the complexes was analyzed. Despite the low content in the complexes (1.5 mass%), fullerene significantly modified the viscosity of aqueous PVP. Thus, the dynamic viscosity of the PVP/C₆₀ complexes grew faster than that of the pure PVP upon increasing the PVP/C₆₀ concentration. The difference in viscosities is especially pronounced for semidilute solutions. As a possible explanation, it is assumed that fullerenes act as crosslinks, in addition to the physical entanglements of the PVP macromolecules, which appear in the vicinity of the crossover concentration. Shear flow corresponding to the high shear rates destroyed fullerene‐induced intermolecular crosslinks in PVP/C₆₀ solutions.     

Analyzing the adsorption of blood plasma components by means of fullerene-containing silica gels and NMR spectroscopy in solids

The results from studying the adsorption of blood plasma components (e.g., protein, triglycerides, cholesterol, and lipoproteins of low and high density) using silica gels modified with fullerene molecules (in the form of C₆₀ or the hydroxylated form of C₆₀(OH) _x ) and subjected to hydration (or, alternatively, dehydration) are presented. The conditions for preparing adsorbents that allow us to control the adsorption capacity of silica gel and the selectivity of adsorption toward the components of blood plasma, are revealed. The nature and strength of the interactions of the introduced components (fullerene molecules and water) with functional groups on the silica surface are studied by means of solid state NMR spectroscopy (NMR-SS). Conclusions regarding the nature of the centers that control adsorption are drawn on the basis of NMR-SS spectra in combination with direct measurements of adsorption. The interaction of the oxygen of the hydroxyl group of silica gel with fullerene, leading to the formation of electron-donor complexes of C₆₀-H, C₆₀-OH, or C₆₀-OSi type, is demonstrated by the observed changes in the NMR-SS spectra of silica gels in the presence of fullerene.     

Complexation in Water-Soluble Systems Poly-N-vinylpyrrolidone-Fullerene C60

Complexes of fullerene C_{6 0} with poly-N-vinylpyrrolidone were prepared by various procedures in the presence of additional agents in solution (systems C_{6 0}-poly-N-vinylpyrrolidone and ternary system C_{6 0}-tetraphenylporphyrin-poly-N-vinylpyrrolidone) and in the solid phase (C_{6 0}-polyvinylpyrrolidone and C_{6 0}-KBr-poly-N-vinylpyrrolidone). Formation of a donor-acceptor bond in the system C_{6 0}-poly-N-vinylpyrrolidone was studied by ¹³C NMR. The conditions under which the ternary complex C_{6 0}-tetraphenylporphyrin-poly-N-vinylpyrrolidone with fullerene content varied from 1 to 5 wt % can be obtained were found.     

Specifics of light scattering in solutions of fullerene-containing polymers

The molecular mass and hydrodynamic dimensions of molecules of two fullerene-containing polymers which differ in the preparation procedure and the mode of fullerene C₆₀ binding were determined by means of static and dynamic light scattering and transport techniques (diffusion, sedimentation, gel permeation chromatography). It was established that the molecular masses of polymeric C₆₀ derivatives determined by means of static light scattering are substantially above those measured by means of the transport techniques. Using as an example a polystyrene specimen containing 6.2 wt % C₆₀ prepared according to the widespread technique of solvent evaporation from a mutual fullerene and polymer solution, it was shown that the multicomponent nature, the compositional inhomogeneity, and a lack of coincidence in the signs of refractive index increments for structurally different components of fullerene-containing polymers may cause anomalies in the intensity of light scattering by solutions of these compounds.     

Calorimetric Properties of Different Kinds of Polymers Containing C60 Fullerene

Transformations of polymers containing C60 fullerene: poly-N-vinylpyrrolidone with the complex and covalent-graft structure, polyphenylene oxide with the complex structure, and polyethylene glycol and polystyrene with beam structure, were studied by differential scanning microcalorimetry. The observed effects were assigned to the change in nanofragmentary topology on heating.     

Adsorption of midmolecular peptides by fullerene modified silica gel

The adsorption properties of raw and processed silica gels and of silica gels modified with fullerene (fullerene-silica gel nanosystems) toward serum midmolecular peptides of ischemic origin were examined. A high adsorption capacity of the nanosorbents was found. The influence of fullerenes on the condition of silica gel was studied by solid-state NMR, and an increase in the silanol fraction at the adsorbent surface was demonstrated. It was shown that presence of fullerene C₆₀ in nanosorbents enables oxidation reaction of the adsorbed peptides, i.e., sorption of metabolites.