Chemistry Biology Physiology archive

Oxides-2,3 with Vinyl Monomers

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Using the free-radical copolymerization of l-(vinyloxyalkoxy)propylene oxides-2,3 with vinyl monomers, it was established that the process is activated by the low-activity l-(vinyloxyalkoxy)propylene oxides-2,3. An increase in the content of the latter comonomers in the initial monomer mixture leads to a rise in the rate of copolymerization and in the conversion of a more active comonomer.

Authors: Raskulova T.V., Moskaleva O.N., Volkova L.I., Kanitskaya L.V., Khaliullin A.K.,

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A Fractal Variant of the Mark-Kuhn-Houwink Equation

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The possibility of deriving the Mark-Kuhn-Houwink equation in terms of the fractal analysis concepts was shown. The constant K_η in this equation was found to depend on the fractal dimension D and the molecular mass of the monomer unit characterizing the macromolecular coil structure and the chemical structure of a polymer, respectively.

Authors: Kozlov G.V., Dolbin I.V.,

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Rapid Microwave Irradiation-Induced Synthesis of New Optically Active Poly(amidoimides) Based on Aromatic Diamines and N,N'-(Pyromellitoyl)bis(L-phenylalanine) Dichloroanhydride

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The reaction of pyromellitic dianhydride with L-phenylalanine in an AcOH: Py (3:2) mixture produced imidodicarboxylic acid N,N'-(pyromellitoyl)bis(L-phenylalanine) with a quantitative yield, the treatment of which by thionyl chloride yielded corresponding dichloroanhydride. The polycondensation of this dichloroanhydride with a number of aromatic diamines was carried out in a microwave oven in the presence of a small amount of o-cresol. The process was complete during 12 min and led to the formation of optically active poly(amidoimides) (η_red = 0.27-0.41 dl/g) with a good yield. Some characteristics of the synthesized polymers are discussed.

Authors: Mallakpour Shadpour E., Hajipour Abdol-Reza, Habibi Sakineh,

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Thermodynamic Properties of l,2,3-Poly(trichlorobutadiene) in the Temperature Range 0-340 К

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For l,2,3-poly(trichlorobutadiene), the temperature dependence of heat capacity in the 7-340 К range was studied by adiabatic vacuum calorimetry with an error of 0.2%. The relaxation transitions occurring in this polymer in the 200-340 К range were revealed, and their thermodynamic characteristics were determined; the thermodynamic functions C° (7), H°(Ty-H°(0), S°(T), and G°(Ty-H°(0) for the range 0-340 K, as well as the standard entropy of polymer formation from simple substances at 298.15 К ΔS_f, were calculated.

Authors: Bykova T.A., Lebedev B.V.,

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Elibrary: https://elibrary.ru/item.asp?id=43791406

Electromagnetoplastic Effect in Amorphous Poly(methyl methacrylate)

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A joint effect of a static magnetic field and an alternating field on the plasticity of PMMA was revealed. The experimental data obtained suggest that the previously discovered effects of a pulse magnetic field on the plasticity of linear amorphous polymers are due to the combined action of a vortex electric field and the magnetic field.

Authors: Morgunov R.B., Golovin Yu. I., Yakunin D.V., Trofimova I.N.,

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Elibrary: https://elibrary.ru/item.asp?id=43791407

Thermodynamics of Poly[5,5-difluoro-6,6-bis(trifluoromethyl)norbomene] and Poly[5,5,6-trifluoro-6-(heptafluoropropoxy)norbomene] in the 0-340 К Range

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Using the data of precision adiabatic vacuum calorimetry, the temperature dependences of the heat capacities of poly[5,5-difluoro-6,6-Ws(trifluoromethyl)norbomene] and poly[5,5,6-trifluoro-6-(heptafluoro-propoxy)norbomene] in the 6-340 К range were mostly studied with an error of about 0.2%. It was determined that poly[5,5,6-trifluoro-6-(heptafluoropropoxy)norbomene] undergoes a relaxation transition in the range from 10 to 15 К which is apparently related to the activation of the vibrational motion of heptafluoropropoxy groups. Based on the C° =f(T) data, the thermodynamic functions of the polymers of interest in the glassy state were calculated in the range 0-340 K. The temperature dependences of the heat capacity of the studied polymers and the metathesis poly(norbomene) (for comparison) were analyzed in terms of the Tarasov heat capacity theory developed for chain structures.

Authors: Markin A.V., Lebedev B.V., Smirnova N.N., Bespalova N.B., FinkeVshtein E. Sh.,

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The Formation of Lyotropic Mesophase in Aqueous Solutions of the Sodium Salt of Cellulose Acetate Sulfate

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Aqueous solutions of the sodium salt of cellulose acetate sulfate are shown to be isotropic at concentrations below 42 wt %, biphasic in the concentration range 42-52 wt % in which the isotropic phase-anisotropic phase transition is partially accomplished, and liquid-crystalline at a concentration of higher 52 wt %. The anisotropic phase is represented by different ordered supramolecular structures such as individual spherulites, spherulite ribbons, fingerprint structures, and other more complex entities. Rheological curves typical of LC systems were recorded; the corresponding concentration and temperature dependences of shear viscosity also prove the existence of an LC state in aqueous solutions of the cellulose acetate sulfate sodium salt. The critical concentration corresponding to the transition of the sodium salt of cellulose acetate sulfate to the LC state at 293-323 К was estimated at 52-52.5 wt %.

Authors: Grinshpan D.D., Tsygankova N.G., Tret’yakova S.M., Savitskaya T.A.,

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Elibrary: https://elibrary.ru/item.asp?id=43791409