N. P. Evlampieva

Molecular Solutions of Cellulose in Mixtures of Ionic Liquids with Pyridine

New systems suitable for determination of molecular characteristics of cellulose, mixtures of ionic liquids based on 1-n-alkyl-3-methylimidazolium with pyridine, were found. In ionic liquid-pyridine mixtures, cellulose is dispersed on the molecular level. The cellulose-ionic liquid-pyridine systems with 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium diethyl phosphate are stable in time. The dynamic viscosity and refractive index of the mixtures can be controlled by varying the ionic liquid to pyridine ratio. The viscometric and dynamooptical properties of cellulose in these mixtures were compared with those in Cadoxen.

Electrooptical and Conformational Properties of Poly(1-Trimethylsilyl-1-Propynes) with Different Chain Microstructures

The methods of the Kerr effect and solution hydrodynamics were applied to study the electrooptical and hydrodynamic properties of samples of disubstituted polyacetylenes, poly(1-trimethylsilyl-1-propynes), prepared by polymerization of 1-trimethylsilyl-1-propyne with NbCl5 and TaCl5/BuLi as catalysts. The experimental electrooptical characteristics of polymers were compared with those calculated by PM3 semiempirical quantum-chemical method.

Molecular and electrooptical characteristics of poly(1-trimethylsilyl-1-propynes) with varied chain regularity

Samples of a disubstituted polyacetylene, poly(1-trimethylsilyl-1-propyne), containing on the average 60% of cis-C=C bonds and prepared with NbCl5 as catalyst were studied by means of Kerr effect measurements in solution and molecular hydrodynamics methods. The resulting data were correlated with the properties of the sample prepared with another catalytic system, TaCl5/BuLi. Samples prepared under different catalytic conditions were found to have much different electrooptical properties. It was concluded that the TaCl5/BuLi catalyst allows preparation of polymers with longer continuous sequences of monomeric units of the same isomeric structure as compared with those obtained with NbCl5.

Methyl methacrylate polymerization in the presence of C60 (C70) and molecular characteristics of fullerene-containing poly(methyl methacrylate)

Kinetics was studied of bulk polymerization of methyl methacrylate initiated by dicyclohexyl peroxydicarbonate in the presence of tri-n-butylborane and fullerene C60 (or C70) at variable ratio initiator: fullerene. The deceleration of the polymerization in the first stage of the reaction (below 10% conversion) was established by dilatometric method that depended on the fullerene concentration and the mode of its addition to the monomer. It was shown that at similar ratios initiator: fullerene the C60 inhibited the polymerization process considerably stronger than C70. The gel-permeation chromatography revealed the widening of the molecular weight distribution of the poly(methyl methacrylates) containing C60 or C70 compared to its analog synthesized under the same conditions without fullerene. It was established that in the fullerene-containing poly(methyl methacrylates) all the framework nanospecies are linked by covalent bonds and are mostly accumulated in the low-molecular fractions. The effect of the covalently bound fullerene on the molecular characteristics of polymers were investigated by translational isothermal diffusion, high-speed sedimentation, and viscometry

Conformational properties of metathesis poly(trimethylsilylnorbornene) in solutions

The hydrodynamic and conformational properties of silicon-containing polynorbornene prepared by metathesis polymerization of 5-trimethylsilylnorbornene in the presence of Grubbs Ru carbene complex were studied by viscometry, isothermal translation diffusion, and centrifugal sedimentation. For the ten-sample homologous series of the polymer, Mark-Kuhn-Houwink relationships correlating the hydrodynamic characteristics of the molecules in toluene with their molecular weight were obtained.

Hydrodynamic and Molecular Characteristics of Poly[1-(trimethylgermyl)propyne]

Samples and fractions of a membrane-forming polymer poly[1-(-trimethylgermyl)propyne], with the molecular weight within 4 < M × 10-4 < 170 were studied in cyclohexane by methods of molecular hydrodynamics (centrifugal sedimentation, translational isothermal diffusion, and viscometry). The molecular weight dependences of the hydrodynamic characteristics were determined and analyzed. These dependences were used to estimate the equilibrium rigidities of the poly[1-(trimethylgermyl)propyne] chains. The size of the macromolecules was studied as influenced by the bulk effects. The results obtained are compared with published data for poly[1-(trimethylsilyl)propyne].