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Лезов, А. В.; Melnikov, A. V.; Polushina, G. E.; Antonov, E. A.; Novitskaya, M. E.; Boiko, N. I.; Ponomarenko, Sergei A.; Rebrov, E. A.; Shibaev, Valéry; Ryumtsev, E. I.; Muzafarov, А. М.

doi:10.1023/a:1012924607136

Cited by 18 publications

(20 citation statements)

References 3 publications

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“…After substi tution of the partial specific volume for co PPGs, we arrive at [η] sph ≈ 1.3 cm 3 /g. This estimate is somewhat smaller than the intrinsic viscosity for the lowest molecular mass PPG sample ( [38][39][40] rather than for hyperbranched polymers. For the latter polymers, [η]/[η] sph is usually above 1-5 [17].…”

Section: R 3 Geh : Net 3 or R 3 Gehmentioning

confidence: 75%

Structural and conformational properties of hyperbranched copolymers based on perfluorinated germanium hydrides

et al. 2012

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Two series of hyperbranched copolymers based on perfluorinated germanium hydrides of various topological structures are studied in dilute chloroform solutions by the methods of molecular hydrodynamics and optics. The first series is composed of copolymers with various molecular masses (from 2.3 × 10 4 to 31 × 10 4 ) that contain rigid linear chains between branching points and various amounts of branching points in cascades of the dendritic fragment, while the second series is comprised of copolymers that, at close branch ing degrees, on average, are characterized by a looser structure owing to a large amount of linear units at the periphery of macromolecules with M = (2.5 × 10 4 )-(23 × 10 4 ). Macromolecules of the studied polymers have compact dimensions and a high density of the polymer substance; their shape asymmetry is low. In terms of these characteristics, they approach dendrimers. At a fixed molecular mass, the copolymers with a loose structure have higher dimensions of macromolecules and higher intrinsic viscosities.

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Section: R 3 Geh : Net 3 or R 3 Gehmentioning

confidence: 75%

Structural and conformational properties of hyperbranched copolymers based on perfluorinated germanium hydrides

et al. 2012

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“…The behavior of polyelectrolyte complexes formed by synthetic polypeptides and oppositely charged sur factant ions in weakly polar organic solvents was stud ied in [29,30,[33][34][35].…”

Section: K Mmentioning

confidence: 99%

“…The equilibrium rigidity of the PG-surfactant complex in chloroform А = 7 nm is a factor of ~15 smaller than that of PBG molecules in the helical conformation [32]. The non stoichiometric PL-surfactant complex in the same solvents occurs in the form of α helices and assumes the rodlike conformation [33].…”

Section: K Mmentioning

confidence: 99%

“…The present review summarizes the data on the equilibrium properties and kinetics of electric birefrin gence in solutions of DNA, RNA, and polypeptides. The behavior of complexes of DNA and polypeptides with oppositely charged surfactants in organic media is considered in [29][30][31][32][33][34][35][36][37][38][39]. An approach to description of electro optical and dynamic properties of polyelec trolyte complexes is suggested.…”

Section: Introductionmentioning

confidence: 99%

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Electro-optics of solutions of biopolymers and their complexes

Лезов

Polushina

2012

Polym. Sci. Ser. A

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The review summarizes the results of electric birefringence studies of the molecular properties of biopolymers and their complexes. The application of alternating electric fields makes it possible to study the kinetics of orientation of DNA, RNA, and polypeptide molecules in diluted solutions. An analysis of molec ular mass dependences of relaxation times of biopolymer molecules in terms of the rotational friction theory is used to determine the equilibrium rigidity of macromolecules characterized by Kuhn segment length A. For DNA molecules in buffer solutions with a low ionic strength, the value of A derived from electro optical mea surements is 114 nm. The high sensitivity of electric birefringence to changes in the secondary and tertiary structures of biopolymers ensures its use for the analysis of sequence curvature in short fragments of DNA and for investigation of transitions between different tertiary structures of RNA. The study of electro optical bire fringence in solutions of complexes of DNA and polypeptides with oppositely charged ions of surfactants makes it possible to gain insight into their conformational properties in organic solvents. The stoichiometric complexes of DNA in chloroform occur in the compact globular state, whereas the conformation of com plexes formed by various polypeptides depends on their composition and may vary from rodlike to coiled. Electric birefringence in solutions of biopolymer complexes is associated with the orientation of molecules that is due to the external field induced dipole moment that appears as a result of a small displacement of ions along the contour of polyion chains. The time of reaching the induced dipole moment is equal to or greater than the time of orientational relaxation of the complex as a whole.

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“…1-5 Unusual molecular topology of these systems that are prone to microsegregation and self assembling with the formation of a complicated hierarchy of supramo lecular structures evoked increased interest in studying the structure formation processes of these compounds in dilute solutions 6 and in the solid phase. 7 Undoubtedly, substantial information on the structure of LC dendrimers could be obtained by the study of their thin films prepared by the Langmuir-Blodgett method (LB films).…”

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confidence: 99%

Structure of carbosilane amphiphilic liquid-crystalline codendrimers in bulk and in thin (Langmuir) films

et al. 2008

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Amphiphilic carbosilane liquid crystalline codendrimers with terminal mesogenic butoxy benzoate and phenolic groups have been synthesized for the first time. The structures and compositions of the synthesized codendrimers were characterized by NMR spectroscopy. The data from polarization optical microscopy, differential scanning calorimetry, and small angle X ray scattering demonstrated that all codendrimers possessed mesomorphic properties. They form thin (Langmuir) films at the water-air interface. The surface pressure-surface area isotherms were plotted. The Langmuir-Blodgett films of different thicknesses were obtained by the vertical dipping method on the solid substrate. The film structures were studied by grazing incidence X ray diffraction analysis.The studies of liquid crystalline (LC) dendrimers had long ago attracted attention of researchers working in the areas of both high molecular weight compounds and liquid crystals. 1-5 Unusual molecular topology of these systems that are prone to microsegregation and self assembling with the formation of a complicated hierarchy of supramo lecular structures evoked increased interest in studying the structure formation processes of these compounds in dilute solutions 6 and in the solid phase. 7 Undoubtedly, substantial information on the structure of LC dendrimers could be obtained by the study of their thin films prepared by the Langmuir-Blodgett method (LB films).However, to use this procedure, one needs, as a rule, amphiphilic molecules capable of specific orientation on the water surface with the polar groups arranged in the aqueous phase and nonpolar groups, in the organic phase. Carbosilane dendrimers, which have been studied in de tail in our previous works, 1,2,7 do not meet, unfortunately, these requirements. Therefore, we concentrated our attention on the synthesis of amphiphilic carbosilane LC codendrimers of the first, third, and fifth generations containing different ratios of hydrophilic (phenolic YOH) and hydrophobic (butoxybenzoate, Y´OBu) mesogenic groups (Fig. 1).As can be seen from Fig. 1, a dendrite molecule with random distribution of mesogenic and phenolic terminal fragments, in essence, is a biphilic codendrimer in which heterogeneous terminal groups are chemically bound to the carbosilane matrix through the aliphatic spacers con sisting of ten methylene units.It should be mentioned that the number of previously synthesized and studied codendrimers is rather small, although many LC dendrimers were described. 8,9The following tasks were set in the present work:(1) to develop a method for the synthesis of the LC codendrimers based on the carbosilane dendritic matrix;(2) to study the influence of the composition and gen eration number of the synthesized codendrimers on the formation of the LC structures;(3) to reveal the possibility of formation of the thin LB films from the synthesized LC codendrimers and to study their structures. Results and DiscussionSynthesis of codendrimers. We have developed a gen eral approach to the synthesis of amphi...

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Cited by 18 publications

References 3 publications

Structural and conformational properties of hyperbranched copolymers based on perfluorinated germanium hydrides

Structural and conformational properties of hyperbranched copolymers based on perfluorinated germanium hydrides

Electro-optics of solutions of biopolymers and their complexes

Structure of carbosilane amphiphilic liquid-crystalline codendrimers in bulk and in thin (Langmuir) films

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