Hydrodynamic,optical, and electrooptical properties of macromolecules of third-generation cylindrical dendrimers in chloroform and dichloroacetic acid

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.     

Synthesis and molecular properties of polymers with asymmetrically substituted side dendrons based on <Emphasis Type="Italic">L</Emphasis>-aspartic acid

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.     

Chitosan and its derivatives in extensional and shear flows

Allylchitosan and propylchitosan with different degrees of substitution were prepared on the basis of chitosan from shrimp chitin. The dynamics of semidilute electrolytic polymer solutions of chitosan derivatives in acetic acid was studied by measuring birefringence in extensional and shear flows and by means of viscometry. The optical shear coefficient and critical velocity gradients corresponding to the loss of stability of the macromolecular coil in extensional flow were found. The chain relaxation times depending on the polyelectrolyte concentration and ionic strength of solution were determined.     

Dynamics of Propyl Chitosan Solutions in Longitudinal and Shear Modes

Low-substituted chitosan was synthesized from shrimp chitin. The effect of the ionic strength on the dynamics of acetic acid solutions of propyl chitosan in longitudinal and shear modes was studied. The dynamic characteristics of these solutions under the action of hydrodynamic fields were estimated.     

Dynamic birefringence in solutions of poly (naphthoyleneimide benzimidazole) in different stages of hydrolytic thermal degradation

Flow birefringence (FB) has been investigated in solutions of products of hydrolytic degradation of poly(naphthoyleneimide benzimidazole) (PNIB) in 96% sulphuric acid PNIB solutions have previously been subjected to heating at various temperatures from 65 to 120°C and then investigated at 22°C by FB and viscometry. A monotonic decrease in intrinsic viscosity and the molecular weightM of thermal degradation products with increasing degradation temperature was detected. At the same time, the shear optical coefficients in series of products with decreasingM first increases and then, at treatment temperatures exceeding 90°C, decreases with decreasing [ν] in accordance with decreasingM of the product. Possible reasons for the detected anomaly have been discussed.     

Heat-Resistant Polyfunctional Materials for Microelectronics: Hydrodynamic,Optical, and Conformational Properties of Si-Containing Poly(<Emphasis Type="Italic">ortho</Emphasis>-Hydroxy Amide)

Polycondensation of a mixture of diamines, 3,3'-dihydroxy-4,4'-diaminodiphenylmethane and bis-(3-aminopropyl)dimethylsiloxane taken in a 3: 2 molar ratio, with isophthaloyl chloride was used to synthesize a silicon-containing poly(ortho-hydroxyamide) POA-Si exhibiting an increased adhesion to such substrates as Si, SiO₂, quartz, glass, and glass-ceramics. The polymer was separated by the fractional precipitation method into seven fractions and its polydispersity was evaluated. The degree of intramolecular orientation ordering (Kuhn segment) was determined and Mark–Kuhn–Houwink equations were derived, which can be used to determine the molecular masses of the newly synthesized samples.     

Synthesis,hydrodynamic, and conformational properties of poly(<Emphasis Type="Italic">N</Emphasis>-acryloyl-11-aminoundecanoic acid) in solutions

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.     

Synthesis and study of poly(N,N,N,N-trimethylmethacryloyloxyethylammonium) methyl sulfate in longitudinal and shear flows

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

Synthesis and conformation properties of alkylene-aromatic poly(ether esters) with nonlinear hetaryl-containing mesogenic fragments in the backbone

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.     

Synthesis and molecular properties of new poly(naphthalene-1, 3, 4-oxadiazole)s

Poly[(1, 4-naphthalene)-2, 5-diyl-1, 3, 4-oxadiazole] and poly[(2, 6-naphthalene)-2, 5-diyl-1, 3, 4-oxadiazole] have been synthesized and investigated in conc. H₂SO₄, by the flow birefringence method, in comparison with poly[(1, 4-phenylene)-2, 5-diyl-1, 3, 4-oxadiazole]. Changes in conformation parameters and optical anisotropy of a chain unit induced by incorporation of the naphthalene groups into the macromolecule backbone have been evaluated.