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1.
Lebedev B. V. Kulagina T. G. Smirnova N. N. Shifrina Z. B. Averina M. S. Rusanov A. L. 《Journal of Thermal Analysis and Calorimetry》2003,74(3):735-748
In an adiabatic vacuum calorimeter, the temperature dependence of the heat capacity C
p of phenylated polyphenylene and initial comonomer 1,4-bis(2,4,5-triphenylcyclopentadienone-3-yl)benzene was studied between
6 and 340 K with an uncertainty of about 0.2%. In a calorimeter with a static bomb and an isothermal shield their energies
of combustion DUcomb were measured. From the experimental data, the thermodynamic functions C
p
0 (T), H
0(T)-H
0(0), S
0(T)-S0(0), G
0(T)-H
0(0) were calculated from 0 to 340 K, and standard enthalpies of combustion ΔH
comb
0 and thermodynamic parameters of formation-enthalpies ΔH
f
0, entropies ΔH
f
0, Gibbs functions ΔG
f
0 - of the substances studied were estimated at T=298.15 K at standard pressure. The results were used to calculate the thermodynamic characteristics (ΔH
f
0 ,ΔS
f
0, ΔG
f
0) of phenylated polyphenylene synthesis in the range from 0 to 340 K.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
N. N. Smirnova Yu. A. Zakharova A. V. Markin N. V. Kuchkina E. Yu. Yuzik-Klimova Z. B. Shifrina 《Russian Chemical Bulletin》2013,62(10):2258-2262
The temperature dependences of heat capacity C ○ p = f(T) of hard poly(phenylene-pyridyl) dendrimers of the first and the second generations based on 1,3,5-triethynylbenzene were studied over the temperature range from 7–180 to 455–470 K for the first time. Over the range 290–350 K, the relaxation transition supposedly caused by sample devitrification was detected and characterized for the dendrimer of the first generation. The experimental results were used to calculate the standard thermodynamic functions, namely, heat capacity, enthalpy, entropy, and change in the Gibbs energy on heating. The standard entropy of formation of the compounds under study was determined at T = 298.15 K. The qualitative and quantitative dependences of the thermodynamic properties of the poly(phenylene-pyridyl) dendrimers on their composition and structure were revealed by comparison of the determined parameters with similar data for the earlier studied dendrimers of this series. 相似文献
3.
4.
N. N. Smirnova A. V. Markin Yu. A. Zakharova N. V. Kuchkina A. L. Rusanov Z. B. Shifrina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(4):548-553
The temperature dependence of heat capacity C p o = f (T) of second generation hard poly(phenylene-pyridyl) dendrimer (G2-24Py) was measured by a adiabatic vacuum calorimeter over the temperature range 6–320 K for the first time. The experimental results were used to calculate the standard thermodynamic functions: heat capacity C p o (T), enthalpy H o(T)–H o(0), entropy S o(T)–S o(0) and Gibbs function G o(T)–H o(0) over the range from T → 0 K to 320 K. The standard entropy of formation at T = 298.15 K of G2-24Py was calculated. The low-temperature heat capacity was analyzed based on Debye’s heat capacity theory of solids. Fractal treatment of the heat capacity was performed and the values of the temperature characteristics and fractal dimension D were determined. Some conclusions regarding structure topology are given. 相似文献
5.
N. A. Belov O. Yu. Sanfirova Z. B. Shifrina Yu. P. Yampolskii 《Polymer Science Series A》2010,52(5):490-495
A fourth-generation rigid-chain pyridine-containing polyphenylene dendrimer is studied by inverse gas chromatography. Two
types of sorbates are investigated: C7-C11
n-alkanes and C6H6-C6H5C5H11 alkylbenzenes. In the range 35−150°C, specific retention volumes of the indicated sorbates are measured and their solubility
coefficients are calculated. It is shown that aliphatic sorbates exhibit reduced solubility coefficients in the aromatic dendrimer
compared to those observed for aliphatic polymers and the earlier studied carbosilane dendrimer. At the same time, alkylbenzenes
are characterized by enhanced solubility coefficients and this effect is more pronounced for the first members of the homologous
series. An analysis of excess partial molar thermodynamic functions shows that π-electron interactions in the dendrimer and
among dendrimer and aromatic sorbates are responsible for the thermodynamic properties of the dendrimer under study. 相似文献
6.
M. V. Zhiryakova N. V. Kuchkina Z. B. Shifrina V. A. Izumrudov 《Polymer Science Series A》2011,53(8):698-706
The affinities of two anionic pyrenyl probes for pyridinium high-molecular-mass cations of different topologies—poly(N-ethyl-4-vinylpyridinium bromide) and a water-soluble poly(pyridylphenylene) dendrimer—are studied by the method of fluorescence
quenching. The hydrophilic probe carrying three sulfonate groups in a molecule more efficiently interacts with a flexible
highly charged linear polycation throughout the studied pH range. The binding of the dendrimer with a relatively hydrophobic
probe containing a single carboxyl group is improved by acidification of solutions, and it becomes dominant in weakly acidic
solutions. The interaction of DNA with the dendrimer containing the hydrophobic probe has no effect on the formation of the
dendriplex and leads to displacement of only a small fraction of the bound probe into solution. Our model studies demonstrate
that dual-action dendrimer carriers capable of simultaneous delivery of genetic material and hydrophobic drugs to target cells
can be created. 相似文献
7.
8.
9.
V. A. Izumrudov N. V. Kuchkina A. L. Rusanov Z. B. Shifrina 《Polymer Science Series A》2009,51(3):229-241
Cationic water-soluble dendrimers have been prepared by the alkylation of pyridyl groups in polypyridylphenylene dendrimers of the first four generations, and their interaction with a polymethacrylate anion has been studied. The stability of polyelectrolyte complexes in aqueoussaline solutions has been studied by fluorimetric titration with the use of the pyrenyl-tagged polyanion, and it has been shown that the stability of these complexes significantly increases with the dendrimer generation number and the content of hydrophobic phenylene groups. Based on sedimentation analysis and turbidimetric titration, it is inferred that a significant part of charged groups of dendrimers are inaccessible to interaction with the polyanion and that water-soluble nonstoichiometric polyelectrolyte complexes develop in mixtures of higher generation dendrimers. Modeling results of this study may be useful for designing efficient cationic dendrimer carriers of genetic material and hydrophobic physiologically active compounds. 相似文献
10.
N. N. Smirnova A. V. Markin Ya. S. Samosudova T. A. Bykova Z. B. Shifrina E. S. Serkova N. V. Kuchkina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(2):226-231
The thermodynamic properties of amorphous polyphenylquinoxaline in the temperature range of 6 to 570 K are studied via precision adiabatic vacuum calorimetry and differential scanning calorimetry. The thermodynamic characteristics of glass transition are determined. Standard thermodynamic functions C°p, H°(T) ? H°(0), S°(Т) ? S°(0), and G°(T) ? H°(0) in the range of T → 0 to 570 K and the standard entropy of formation at T = 298.15 K are calculated. The low-temperature (T ≤ 50 K) heat capacity is analyzed using a multifractal model for the processing of heat capacity, fractal dimension D values are determined, and conclusions on the topological structure of the compound are drawn. 相似文献