A set of hydrodynamic methods in extremely dilute solutions (determination of intrinsic viscosity [eta], translational diffusion D and flotation in a centrifugal field s) was used in the studies of conformational properties, dimensions and equilibrium rigidity of individual molecules of a series of samples of poly(3-hexylthiophene). Absolute molecular masses M-sD were determined. The Mark-Kuhn-Houwink equations for the range of M-sD from 2240 to 15 300 gmol(-1) are given. For the first time, an analysis of conformational properties and equilibrium flexibility of poly(3-hexylthiophene) molecules was carried out using the model of a statistical segment containing a twisted polymer chain. (C) 2017 Society of Chemical Industry

Conducting polymers demonstrate low solubility in organic solvents. Introducing aliphatic substituents into polymer chains improves their solubility, but may also lead to changes in conformational characteristics of macromolecules. In the present work, the studies of hydrodynamic properties and conformational characteristics of comb-shaped poly(3-hexylthiophene) with aliphatic side substituents were carried out in chloroform solutions. Conformational analysis of the studied macromolecules was performed for the first time using homologous series with a wide range of molecular weights of the polymers in dilute solutions. The hydrodynamic properties of these macromolecules were interpreted using the worm-like spherocylinder model and the straight spherocylinder model. The projection of the monomer unit in the direction of the main polymer chain lambda=50.37 nm was determined experimentally. The following parameters of poly(3-hexylthiophene) were characterized and quantified: equilibrium rigidity (Kuhn segment length) A=6.7 nm and hydrodynamic diameter of a polymer chain d=0.6 nm. (C) 2016 Wiley Periodicals, Inc.

Методами молекулярной гидродинамики (седиментация, диффузия, вискозиметрия), поляризованной люминесценции и двойного лучепреломления в потоке исследованы конформационные и релаксационные свойства образцов сополимеров N,N-диметиламиноэтилметакрилата и 2-деокси-2-метакриламидо-D-глюкозы в растворах. Получены уравнения Марка–Куна–Хаувинка и выполнена оценка длины статистического сегмента Куна при различных степенях протонирования аминогрупп. Установлена корреляция между длиной статистического сегмента Куна и внутримолекулярной подвижностью сополимеров.

The conformational and relaxation properties of N,N-dimethylaminoethyl methacrylate and 2-deoxy-2-methacrylamido-D-glucose copolymers in solutions are studied by the methods of molecular hydrodynamics (sedimentation, diffusion, viscometry), polarized luminescence, and flow birefringence. Kuhn-Mark-Houwink equations are obtained, and Kuhn statistical segment lengths at various degrees of protonation of amino groups are estimated. It is found that there is a correlation between the Kuhn statistical segment length and the intramolecular mobility of the copolymers.

Synthesized cellulose pelargonates, tridecanoates, valerates, and acetovalerates of various molecular weights are studied in chloroform, dioxane, and tetrachloroethane solutions by the methods of isothermal translational diffusion, sedimentation velocity method, flow birefringence (dynamooptical Maxwell effect), viscometry, and equilibrium electric birefringence (Kerr effect). The equilibrium polymer rigidities are determined and the role of the solvent and temperature in the formation of the conformational characteristics of the macromolecules under study is analyzed. The values of the intrinsic optical anisotropy of the monomeric units of the studied cellulose esters are experimentally determined. The contribution of the side chains to the optical anisotropy of the macromolecules of cellulose esters with aliphatic substituents is analyzed. The results obtained in this study are compared with the data on the cellulose esters with the aliphatic side substituents studied earlier. For the studied samples, the values of the longitudinal components of the monomeric unit dipoles in a nonpolar solvent are estimated.

A number of samples of poly(dodecylammonium-2-acrylamido-2-methylpropanesulfonate)-a comb-like polymer with ionically bound side chains-are obtained by the polymerization of dodecylammonium-2-acrylamido-2-methylpropanesulfonate in an aqueous medium. The samples are obtained in a wide molecular-mass range. Molecular, hydrodynamic, and optical characteristics of the samples are determined by the methods of sedimentation-diffusion analysis, viscometry, and flow birefringence in dilute polymer solutions in chloroform and dimethyl sulfoxide containing small amounts of 0.1 M LiCl. It is shown that conformational and optical characteristics based on hydrodynamic and dynamo-optic investigations agree with the data available for acrylic and methacrylic polymers with the same lengths of side groups. In other words, the character of attachment (covalent or ionic) of long side chains to the backbone has no effect on the conformational and optical characteristics of macromolecules.

Poly(N,N-dimethylaminoethyl methacrylate) macromolecules in the un-ionized and ionized states were studied by methods of molecular hydrodynamics, optics, and polarized luminescence. The conformation, relaxation, and optical parameters of the macromolecules were determined. The Mark-Kuhn-Houwink equations were obtained for the intrinsic viscosity and diffusion and sedimentation coefficients.

Samples of poly(N,N,N,N-trimethylmethacryloyloxyethylammonium) methyl sulfate prepared by suspension and bulk polymerization were studied.

Poly( N -acryloyl-11-aminoundecanoic acid) samples are synthesized in monomer solutions occurring in both micellar and nonmicellar states. It is shown that polymeric ionogenic surfactants of various molecular masses can be prepared through variation in the concentration of a polymerizable surfactant or in the ionic strength of a solution. The polymer of interest is investigated in detail via the methods of molecular hydrodynamics (viscometry, isothermal diffusion, and velocity sedimentation), dynamic light scattering, GPC, and scanning probe microscopy. The solubility of the polymer in various solvents is examined in detail, and the tendency of this polymer toward association in DMF solutions is discovered. The equilibrium rigidity of macromolecules, which is characterized by the Kuhn segment length A = 100 × 10 −8 cm, and the effective hydrodynamic radius are determined in a dioxane-cyclohexanol mixed solvent.

A thermotropic mesogenic alkylene-aromatic poly(ether ester) was prepared by phase-transfer polycondensation of the azomethine derived from 5-amino-2-phenylbenzoxazole and 3,4-dihydroxybenzaldehyde with 1,6-bis(4-chlorocarbonylphenoxy)hexane in the presence of a phase-transfer catalyst, trimethylhexadecylammonium bromide. The intramolecular orientation order parameters and the angle formed by the pendant 5-imino-2-phenylbenzoxazole substituent relative to the backbone were estimated by methods of molecular hydrodynamics and optics.

Newly prepared cellulose pelargonate samples of various molecular weights were studied in dioxane and chloroform solutions by isothermal translation diffusion, high-speed sedimentation, flow birefringence (Maxwell effect), electric birefringence (Kerr effect), and viscometry. The conformational, hydrodynamic, optical, electrooptical, and dynamic characteristics of the polymer were determined.

Various acrylic polymers in which an aspartic acid fragment with different end groups (the firstgeneration dendron) is attached to the main chain either via the amide group or the 4-aminobenzoic acid residue are studied. The synthesis of monomers and polymers with the asymmetric substitution of the aspartic fragment, in which a long hexadecyl group is situated only at the α-carboxyl group, is described. The molecular, optical, electrooptical, and conformational properties of the polymer containing the long hexadecyl group at the α-carboxyl bond and the hydrolyzed β-ester bond in the aspartic acid fragment are examined in detail. In the range M = (23−508) × 103, the Mark-Kuhn-Houwink equations [η] ∼ M 0.53 and D ∼ M −0.53 are obtained for the intrinsic viscosity and diffusion of the polymers under study in octyl alcohol. The length of the statistical Kuhn segment (120 Å), the hydrodynamic diameter of a chain (50 Å), the shear optical coefficient, and the anisotropies of the segment and monomer unit are determined. An analysis of the experimental data shows that the main optical axis of the side hexadecyl chain makes an angle of ∼54.5° with the direction of the main chain.

The molecular characteristics of cylindrical first-third generation dendrimers carrying dendrons based on L -aspartic acid are compared. It is shown that both the generation number of side dendrons and their structure determine the conformational, hydrodynamic, optical, and dipole characteristics of dendrite macromolecules. It is found that the studied class of cylindrical dendrimers is distinguished by a marked amount of intramolecular hydrogen bonds between side dendrite substituents. These bonds ensure the unusual combination of high kinetic rigidity and a compact conformation (low equilibrium rigidity) of macromolecules. The rupture of hydrogen bonds leads to an enlargement of molecular coils (an increase in equilibrium rigidity) that is accompanied by a sharp drop in kinetic rigidity.

Исследованы различные структуры акриловых полимеров, в которых фрагмент аспарагиновой кислоты с различными концевыми группами (дендрон первой генерации) присоединен к основной цепи либо через амидную группу, либо через остаток 4-аминобензойной кислоты. Описан синтез мономеров и полимеров с несимметричным замещением аспарагинового фрагмента, который только по -карбоксильной группе имеет длинную гексадецильную группу. Наиболее детально исследованы молекулярные, оптические, электрооптические и конформационные свойства полимера с длинной гексадецильной группой по -карбоксильной связи и гидролизованной -сложноэфирной связью во фрагменте аспарагиновой кислоты. В интервале М = (23–508) ? 103 для характеристической вязкости и диффузии в октиловом спирте получены уравнения Марка–Куна–Хаувинка: [ ] М 0.53 и D M-0.53. Определены длина статистического сегмента Куна (120 A), гидродинамический диаметр цепи (50 A), оптический коэффициент сдвига, анизотропии сегмента и мономерного звена. Анализ экспериментальных данных показал, что главная оптическая ось боковой гексадецильной цепочки составляет угол 54.5° относительно направления основной цепи.

Выполнен сравнительный анализ результатов систематических исследований молекулярных характеристик цилиндрических дендримеров первой–третьей генераций с дендронами на основе L-аспарагиновой кислоты. Показано, что как номер генерации боковых дендронов, так и их структура определяют конформационные, гидродинамические, оптические и дипольные характеристики дендритных макромолекул. Установлено, что специфической особенностью исследованного класса цилиндрических дендримеров является значительное количество внутримолекулярных водородных связей между боковыми дендритными заместителями. Эти связи обеспечивают необычное сочетание высокой кинетической жесткости и компактной конформации (низкая равновесная жесткость) макромолекул. Разрыв водородных связей приводит к увеличению размеров молекулярных клубков (рост равновесной жесткости), сопровождающемуся резким падением кинетической жесткости.

Acrylic polymers containing side dendrons of the third generation based on L -aspartic acid have been studied via the methods of molecular hydrodynamics, dynamic and static light-scattering, optics, and electrooptics. There are marked differences in hydrodynamic and optical properties of the macromolecules under study and previously examined polymers with side dendrons of first and second generations. In the range of degrees of polymerization from 10 to 40, these macromolecules possess an extremely low shape asymmetry. Experiments demonstrate the predominant orientation of end side dendrons along the main molecular chain. In chloroform solutions, the orientation of macromolecules in hydrodynamic and electric fields occurs according to the large-scale mechanism. In dichloroacetic acid, the hydrodynamic dimensions of macromolecules decrease, an effect that is accompanied by an increase in the kinetic flexibility of polymer chains.

Colloids of metal nanoparticles (NPs) of Au, Ag, Pd, and Pt protected by natural polymer arabinogalactan (ARB) extracted from Larix sibirica were studied. The nanocomposites were prepared by reduction of metal salts in the water solutions of ARB. We carried out dynamic (DLS) and static light scattering resonantly enhanced by the NP plasmons. The translational diffusion was examined via DLS and a polarized interferometer. The virgin ARB was shown to form aggregates in dilute aqueous solutions. The introduction of NPs reduced the size of the virgin ARB aggregates. The aggregate forms as viewed by the scanning electron microscopy support the light scattering results.

Using the methods of molecular hydrodynamics, structural-conformational studies have been performed for a number of cellulose valerate and acetovalerate samples in the molecular-mass range M = (58.1–464.3) × 10 3 and with a mean degree of substitution of 182.4 with respect to valeric acid isomers. The conformations of valerate-substituted cellulose molecules are characterized by an increased local packing density of monomer units. The molecular conformations are quantitatively described in terms of the helix formed by the succession of vectors connecting glycoside oxygens of a chain. The molecular-hydrodynamic and conformational characteristics of cellulose valerate are compared with the corresponding characteristics of cellulose myristate.

The linear dendritic polymers of the first and second generations have been investigated by the methods of flow birefringence and equilibrium and nonequilibrium electric birefringence. The side dendrons are attached to the polymer backbone through benzamide groups and contain long terminal hexyloxycarbonyl fragments. Optical, dynamic, dipolar, and conformational characteristics of the macromolecules in question have been analyzed in detail. It has been found that the macromolecules of dendritic polymers with dendrons based on L-aspartic acid possess permanent dipole moments and reorient in external electric and hydrodynamic fields according to the large-scale rotation mechanism. The introduction of rigid benzamide fragments substantially increases the equilibrium rigidity, optical anisotropy, and dipole moment of monomer units of dendritic macromolecules. The role of macro-and microform effects in the formation of optical features of the molecules under study is considered in detail.