Poly(vinyl pyrrolidone)—C70 complexes in aqueous solutions

Properties of casting solutions and ultrafiltration membranes based on fullerene-polyamide nanocomposites

“…The static methods, which affect the solution structure very slightly, clearly indicate the existence of intermolecular associates [7,10,11]. Dynamic methods such as liquid chromatography, viscometry, sedimentation, and birefringence in flow characterize only individual macromolecules since intermolecular associates existing in solution are destructed by velocity gradients during the experiments [4,7,10,12,14,15]. The change in polymer properties after modification by fullerene was demonstrated very clearly in the cases of poly(vinylpyrrolidone) (PVP)/fullerene and polystyrene (PS)/fullerene complexes.…”

“…The change in polymer properties after modification by fullerene was demonstrated very clearly in the cases of poly(vinylpyrrolidone) (PVP)/fullerene and polystyrene (PS)/fullerene complexes. Properties of water-soluble PVP/" 60 or PVP/" 70 complexes were studied in detail [7,[10][11][12]15]. The light scattering investigation showed that the sizes of intermolecular associates were one or two orders of magnitude higher than those of PVP molecules; the diameter of associate increased with increasing fullerene content in the complex.…”

“…Dynamic methods using controlled velocity gradients are of particular interest. For instance, sedimentation [12] and rheological [17] experiments with aqueous solutions of PVP/C 60 complexes and birefringence in flow experiments using PVP/C 70 solutions [10] showed that increase in velocity gradient leads to the destruction of the clusters (even to the appearance of pristine polymer at the velocity gradient of 5700 s -1 [12]). The destruction of covalent bonds in the PVP chains took place at the velocity gradient of 3000 s -1 in dilute aqueous solutions [18].…”

Delivery of fullerene-containing complexes via microgel swelling and shear-induced release

“…One is to chemically modify fullerene by grafting-on water-soluble groups, for example, carboxylic groups, followed by synthesis of pendant fullerene polymers (Sun et al, 1999), or to synthesise polymer-fullerene "derivatives" with polyacrylic or methacrylic acids (Yang, J., Li, L., Wanf, 2003;Ravi et al, 2005), poly(ethylene oxide) (Song et al, 2003), synthetic polypeptides (Higashi et al, 2006) or ampholytic block-polymers (Dai et al, 2004). The second way is to prepare polymer-fullerene "complexes", not involving fullerene chemical modification, like inclusion complexes with cyclodextrines or calixarenes (Williams et al, 1994;Takekuma et al, 2000;Murthy and Geckeler, 2001;Filippone et al, 2002) or charge-transfer complexes via donor-acceptor interaction, as with poly(vinylpyrrolidone) (PVP) (Zgonnik et al, 1996;Vinogradova et al, 1998;Reznikov et al, 2000;Ungurenasu and Airinei, 2000;Tarassova et al, 2003) or poly(vinylcaprolactam) . Any of the aqueous solutions cited above can be used as a solvent of a hydrophilic polymer network, if fullerene has to be delivered and released in a controlled way.…”

Effect of Centrifugal Field upon Hydrodynamic Characteristics of Fullerene C60and Poly(N-vinylpyrrolidone) Complex in Aqueous Solutions

“…[3][4][5] Investigation of fullerene C 60 and C 70 complexes with poly(Nvinylpyrrolidone) (PVP) by static (LS) and dynamic (DLS) lightscattering methods revealed that large, relatively stable intermolecular structures, which are referred to as clusters or domains, are formed in their dilute solutions, which can be detected even at very small dilutions. [5][6][7][8][9][10][11] Molar masses M w of clusters obtained by the light-scattering method are one to two orders of magnitude greater than those of matrix polymers used for complex preparation. Cluster molar mass (MM) and size depend on the polymer and solvent nature, fullerene content, fullerene type, and the MM of the polymer.…”