V.D. Pautov

Investigation of intermolecular interactions in aqueous solutions of polymers and surfactants

Polarized luminescence was used to investigate the influence of alkyl radicals of varying length on the intramolecular mobility (IMM) of the molecules of vinylpyrrolidone-vinylamine (VPVNH2) copolymers of 90−10% composition. Alkyl radicals were attached by covalent bonding through amino groups of the copolymer. A study was also made of changes in the IMM of the macromolecules of VPVNHR copolymers (R = CηH2η+1, where η = 0, 4, 8, 12, 16) in aqueous solutions on interacting with molecules of alkyl sulphates (AS) CmH2m +1OSO3Na, where m = 8, 10, 12, 14, 16 for different ratios of the interacting molecules (in moles of the monomer unit) β ≡ [AS]//[BNHR]. It was found that the number of intermolecular contacts increases on varying β from 0 to 1 (2) and that the number decreases on further increasing the amount of alkyl sulphates in solution. In the light of experimental results on the linking of acrylidine orange molecules to the VP-VNHR+AS system it was found that mainly interaction of alkyl radicals takes place in the interval β = 0–0·3.

Interaction of protein molecules with a linear polyelectrolyte in solution

The polarized luminescence method was used to analyze changes in the synamic properties of protein (lysozyme) molecules interacting with polymer chains of polymethacrylic acid in water and in water-salt solutions and participating in processes of complex formation. The irregular mode of distribution of protein molecules between polyelectrolyte chains is shown: some parts of the polymethacrylic acid are compactly filled with protein, while other parts remain unfilled. Conditions of protein-polyelectrolyte complex formation have been determined ,as well as structural particularities making for greater stability of these complexes.

Polarized luminescence as used for analyses of high frequency twisting vibrations in macromolecules

Abstract Theoretical correlations for degrees of luminescence polarization have been analysed for different models of inhibited internal rotation and twisting vibrations. It was found that average amplitudes can be determined for high-frequency twisting vibrations (HTV) in the main chain and in side radicals by means of the polarized luminescence of “labelled” macromolecules with luminescing groups (LG). The HTV amplitudes were found by comparing theoretical considerations with experimental findings. The HTV amplitudes depend on interactions between the anthracene nucleus and the macromolecular units nearest to the LG, and likewise on the length and flexibility of the side radical containing the LG. Matters relating to these correlations are discussed.

A study of the mobility of main and side chains of macromolecules by polarized luminescence

On the basis of data obtained by polarized luminescence with PMMA having luminescent groups (anthracene nuclei) introduced in tracer quantities in the main chain, in side chains with various structures or at the end of the macromolecule, the intramolecular mobility of “labelled” fragments of the polymer chain has been analysed theoretically. It has been established that, in addition to the high frequency torsional vibrational motion of small amplitude with times τh.f, which are much less than the lifetime of the excited state τθ of the luminescent groups, comparatively slow low frequency motions (rotational isomerization or a combination of jumps and vibrations) with τ1.f  τ1.g ≈ τgq and jumps of considerable amplitude are an inherent property of the side chains and end segments of macromolecules. Within the framework of a simple model of the cooperatice combined movement of the main and side chains of the polymer, τ1.f has been assessed as a function of the chemical structure of the “labelled” side chains. The results obtained may be used in analysing the effecś of the intramolecular mobility of macromolecules on their reactivity.

A study of intermolecular interaction in aqueous solutions of polymers and cationic surfactants by polarized luminescence

Abstract The interaction of cationic surfactants with carboxyl containing polymers was studied by polarized luminescence. A high sensitivity of intramolecular mobility of the polymer to the formation of intra-chain contacts with the surfactant ions was demonstrated. The interaction of surfactant and polymer results in compacting of the polymeric coil and leads to intramolecular retardation.

Structure formation in liquid crystalline polymers containing cholesterol

Abstract Polarization luminescence, spectropolarimetry, X-ray diffractometry, electron microscopy and optical microscopy were used to examine structure formation in polymers containing cholesterol and homopolymers of cholesteric ester of N-methacryloyl-ω-amino lauric acid and its copolymers with butylmethacrylate of different compositions. It was shown that in solutions of these polymers in non-polar solvents near the point of phase separation conformation transition is observed which is accompanied by the formation of a perfect intramolecular structure. A comparison of the structure and properties of polymer films, obtained from different solvents suggests that the formation of an intramolecular structure is a requisite condition of the liquid crystalline state in films.

Intramolecular mobility in network polymer systems

Abstract A study has been made crosslinked polymethacrylic acid with luminescing groups, using the polarized luminescence (PL) method. The acid with anthracene containing luminescent groups (markers) (PMAA-C-LG) was dispersed in liquid media. The luminescence polarization of these systems was investigated in relation to the viscosity of the liquid medium. Agreement was found between PL parameters of the marker for the dispersed PMAA-C-LG and for soluble linear PMAA-LG, which means that parameters of molecular mobility are reflected in the PL of dispersed polymer systems. In the analysis of PMAA-C-LG (with ethylene dimethacrylamide (2·5 mole %) as the crosslinking agent) we determined relaxation times characterizing the intramolecular mobility (IMM) of fragments of crosslinked PMAA and changes in the latter due to the ionization of carboxyl groups. Crosslinking led to a marked reduction in IMM compared with the linear PMAA-LG. In the crosslinked PMAA-C-LG as in the linear PMAA-LG a considerable cooperative increase in IMM occurs during the ionization of carboxyl groups within a narrow interval of change in the ionization degree, an interval that practically coincides with that in which a marked change in the IMM of linear PMAA occurs.

Potentiometric titration of a suspension of crosslinked polymethacrylic acid

An aqueous suspension of a macro-mesh carboxylic cationite with particles of size ∼ 0·5 μ has been prepared from methacrylic acid and ethylene dimethacrylamide (2·5 mole %). The degree of dispersity was such that methods of polarized luminescence and potentiometric titration could be used for the investigation. Ionization of the polymethacrylic acid (PMAA) chain of the ionite network is accompanied by transition from the form with crosslinking due to hydrophobic interaction to a disordered form. This transition takes place as a cooperative process, and occurrs within a narrow interval of ionization degrees (α), as in the case of soluble PMAA. Three regions corresponding to the crosslinked and disordered forms, and to the transition, are readily distinguishable on the potentiometric titration curves plotted with the coordinates pK−α and pH-log (1−α)/α. The extent to which the ionic strength of solutions influences ionization of the suspention was investigated. The experimental results apply equally to coarse particle suspensions of the studied cationite.

Intramolecular reactions in cholesterol containing polymers

Abstract Polarization luminescence has been used to study the intramolecular reactions in cholesterol containing polymers. The macromolecules have been found to be diphilic in nature and to combine polar amide and ester groups with non-polar groups, all of which determine the differing of these polymers in polar and non-polar solvents. Intramolecular structuration has been detected in non-polar solvents. The reactions which are responsible for the latter will diminish on dilution of the cholesterol containing chain units by those of a different chemical nature; this is taken as evidence of the reactions of the cholesterol groups playing an important part in the formation of the intramolecular structures.

The intramolecular mobility of poly-n-alkylmethacrylates☆

A study has been made of the intramolecular mobility (IMM) of the “comb-like” molecules of poly-n-alkylmethacrylates (PMA) with side chains containing 6, 10, 16 and 22 C atoms (for relaxation processes), the latter coming to light in the polarized luminescence of macromolecules containing anthrylacylhydroxymethane groups, and the IMM was investigated in relation to the length of side chains, solvent and temperature. It is shown that the relaxation time τω increases (IMM is reduced) with increasing length of n-aliphatic branches, which is equal to changes in the IMM of linear polymers occurring under conditions of intramolecular crosslinking. The bonding of solvent (toluene) molecules with comb molecules (PMA-10, PMA-16, PMA-22) was detected.