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The crystallization of polymers with long side chains proceeds in the form of hexagonal crystal lattice, regardless of the configuration of the backbone chain. For these polymers the ordered structure in the crystalline state as well as in the melt is typical. The tendency to form an ordered structure takes place in the solutions of branched polymers. At polymer critical concentration about 0.5 wt % the gelation process occurred. The structure and properties of gels of acrylic polymers (i.e., polycetylacrylate) in n-aliphatic alcohols (C7H15OH–C12H25OH) and hydrocarbons (C10H22–C16H34) were studied. The x-ray patterns show that all the gels have the same interplanar spacings at the wide angles which correspond to the hexagonal cell. The phase transitions and thermodynamic parameters of gel-solution transition were studied by means of x-ray and differential thermal analysis. The structure of gels in alcohols and hydrocarbons was found to be different. This difference was explained in terms of specific polymer-solvent interactions. The kinetics of supermolecular structure formation in gels was investigated using small-angle light scattering (SMAL) method. Rather good correlation between SMAL and electron microscopic data was found. Some conclusions about the character of the supermolecular structure-forming process were made and the model of gel structure was proposed.

A new approach to the synthesis of thermotropic liquid-crystalline (LC) polymers is described based on the polymerization of monomers containing various mesogenic groups attached to the backbone chain by flexible polymethylene spacer groups. Dozens of new LC polymers are described, including derivatives of polymethacryloyl L-lysine, cholesteric esters of long-chain aminocarboxylic acids, and other aromatic polymers. Phase transition temperatures, heats of fusion, and x-ray structural analysis were evaluated. Polymers exhibiting spontaneous optical anisotropy in the glasslike, elastic, and fluid states are described, and schemes of molecular packing in the LC phase are proposed. We show the possibility of realizing smectic, nematic, and cholesteric types of structures in these thermotropic LC polymers. An LC structure for various comblike copolymers not having mesogenic groups at every monomeric unit was detected. The role of specific interactions in side groups and their mobility in allowing for the LC structure are discussed, and the necessity of having particular conformations of the macromolecules is shown to provide the LC structure in films made from various solutions.

An x-ray, electron microscope, and mechanical properties study was carried out on polyethylene, isotactic polypropylene, and trans-1,4-polyisoprene (gutta-percha) with different degrees of chemical irregularity made by halogenation reaction of these regular polymers. The gradual distortion of chemical regularity causes a change in crystalline lattice parameters, degeneration of crystalline spherulitic structure, and simplification of supermolecular structures of the polymers investigated. The introduction of chemical irregularity is analogous to supercooling of a crystalline polymer with suitable change of mechanical properties and morphological forms of structures. In the case of gutta-percha, chlorination in films also favors the α to β transition within the crystalline state. It has been found that stretching of vulcanized samples of chlorogutta-percha at temperatures above its melting point proceeds with an essential change in internal energy and increase of entropy. A supposition has been made about the structure peculiarities of chlorogutta-percha which permit the appearance of such an effect. A total picture of change of different parameters and properties is given from the point of view of gradual transformation of the stereoregular polymer to an irregular amorphous one.

Block cooligomers of 2,6,7,10,11-pentapentyloxy-3-(3-acryloylpropyloxy)triphenylene and poly(tert-butyl acrylate) have been synthesized by the atom-transfer living radical polymerization. The preformed 3,6,7,10,11-pentapentyloxy-3-(3-acryloylpropyloxy)triphenylene block comprising eight monomer units was used as a macroinitiator with a fixed length, whereas the length of the poly(tert-butyl acrylate) block was varied through a change in the monomer-to-macroinitiator ratio. The microphase separation phenomenon has been established with DSC and X-ray diffraction. However, the sizes of discrete structures observed via transmission electron microscopy and atomic-force microscopy lie in the micron-size length (0.1–3.0 μm). This fact is inconsistent with the molecular characteristics of individual blocks. It is proposed that the micron-sized structural elements are not true domain structures belonging to each phase but reflect the occurrence of aggregation in solution preceding formation of thin films.

The copolymers of N,N-diethylacrylamide and ovomucoid from duck egg white (an inhibitor of proteolytic enzymes) with low critical solution temperature (LCST) have been synthesized. The behaviour of these copolymers at the point of phase transition was investigated. It was shown that the relation between LCST and physiological activity for these copolymers is a function of their composition. The increase of ovomucoid content leads to the increase of LCST. When the content of ovomucoid rises above 0.2 mol%, LCST disappears. At the same time the physiological activity of obtained copolymers decrease with increasing of N,N-diethylacrylamide content.

The orientation behavior of liquid crystal networks having the Sm CA structure stabilized by H-bonds has been studied. The mesogenic groups formed by hydrogen bonds generate a layered structure of the polymer. The hydrogen bonds are responsible for the elastic properties of the liquid crystal polymer network and the mechanism of its plastic flow above the threshold strain. The mechanical response is interpreted in terms of the mechanism of breaking and reconnecting H-bonds under stress. The local sliding of layers is possible if H-bonds are temporarily disconnected and then reconnected again to restore the LC structure. The anisotropy of the mechanical properties of the H-bonded polymer materials is observed in the monodomain LC networks.

Hydrolysis of polyacrylonitrile (PAN) was carried out in 65% HNO3 at 21 °C. The composition and structure of hydrolyzed samples (HPAN) were determined using 13C NMR spectrometry. The HPAN are multi...

A phenomenological approach has been developed to evaluate a variety of the characteristics of hydrogen bonding in poly( N -vinyl pyrrolidone) (PVP) miscible blends with short chain poly(ethylene glycol) (PEG), ranging in molecular weight from 200 to 1000 g mol −1 . The approach is based on the analysis of experimentally measured composition dependence of the negative deviations in glass transition temperature, T g , from weight-average values predicted by the Fox equation. The PVP–PEG miscibility is a result of hydrogen bonding between carbonyl groups in PVP repeat units and both terminal hydroxyls of PEG short chains. Because PEG macromolecules bear reactive hydroxyl groups only at both chain ends, the PVP–PEG complex has a network supramolecular structure. Influence of blend composition and PEG molecular weight on the mechanism of hydrogen bonding, the structure and the stoichiometry of the PVP–PEG complex have been studied. The significance of this work is two-fold. First, the validity of the approach suggested for determining the stoichiometry, network density and the thermodynamics of hydrogen-bonded complex formation in PVP–PEG systems has been confirmed by the results of independent measurements. Second, the nonequimolar stoichiometry of the hydrogen-bonded complex has been explained taking into account the counterbalancing contributions of the entropic loss caused by PEG chain immobilization by hydrogen bonding to PVP repeat units through both PEG chain-end hydroxyls, and the entropic gain due to the increase of the mobility of PVP chain segments between neighbouring hydrogen-bonded PEG crosslinks in the PVP–PEG network.

The well-known Fox equation has been modified to express the glass transition temperature, Tg, as an explicit function of the number of polymer–plasticizer hydrogen bonds in miscible poly(N-vinyl pyrrolidone) (PVP) blends with ethyl alcohol, water, short-chain poly(ethylene glycol) (PEG), and glycerol. The plasticization effect has been found to be dependent on the fraction of hydroxyl groups in the blend rather than on the plasticizer weight fractions. Negative deviations of the blend Tg from the relationship predicted with the original form of the Fox equation were shown to be in direct proportion to the number of hydroxyl groups in the plasticizer molecule. The following quantities can be evaluated based on the Tg–composition profiles: binding degree, fraction of plasticizer hydroxyl groups forming hydrogen bonds to PVP repeat units, the fraction of plasticizer molecules crosslinking the polymer units by hydrogen bonding through two or more hydroxyl groups in their molecule. The dynamics of PVP–PEG hydrogen bonding over the entire compositional range has been evaluated in terms of hydrogen-bonded network density. The stoichiometric composition of the PVP–PEG hydrogen-bonded complex, determined from the Tg–composition relationship, corresponds to the data obtained with independent methods.

For the blend melts of isotropic polysulfone (PSF) and LC polyester (PES), differing in viscosity more than 10 times, the flow curves with maxima were observed in cone and plate geometry. The low shear rate branch is located near the PSF flow curve, and the high shear rate branch is close to the PES flow curve. At high strains, the formation of the ring-like morphology of the blend sample, accompanied by appearance of maximum on flow curve, was registered. The scaling analysis of the reasons for the ring morphology formation was based on stretching of the large, low-viscous LC droplet, embedded to the high-viscous polymer matrix, in a homogeneous shear field. It was shown that, if the critical Taylor radius is not exceeded, the droplet may form the closed torus. Under strong flows, the PSF melt manifests the “spurt effect”, consisting of a drastic increase of the shear rate when the critical value of the shear stress is reached. The pattern of the blend flow curves with maxima may be explained by a vanishing PSF input to the total shear stress, inherent for blends, while the PES melt continues to be in a liquid state and, consequently, is responsible for the blend viscosity at the high shear rates. The presence of regular heterogeneities in the blend in the form of LC rings may initiate the rupture of the entanglements network of the matrix PSF (close to LC rings) under strong shear flows. The appearance of the low-viscous “cracks” at the critical shear stress will diminish the contribution of the PSF to the blends rheological response.

Some new data were obtained about alkaline hydrolysis of a polyacrylonitrile (PAN) suspension at 75°C in a water/ethanol mixture. At > 95% conversion of nitrile groups, the hydrolyzed polymer contains ≃ 20% of amidines situated in the nearest neighborhood of the amidines, poly[(sodium acrylate)-co-acrylamide] is formed having a Bernoulli distribution of units. During the initial stage of PAN cyclization of 25-97°C, very short sequences of conjugated C=N bonds are formed which are much more reactive in hydrolysis than nitrle groups. These data enable us to reconsider the mechanism of alkaline PAN hydrolysis. A corresponding reaction scheme is suggested.

The swelling capacities of alkali hydrolyzed polyacrylonitrile in water Q w and in 0.9 wt.-% NaCL aqueous solution Q s were measured. Using these data the fraction of crosslinked units is estimated to vary from 0.8 to 1.6% for different samples. The analysis of Q s dependence on Q w is proposed as a method to estimate the degree of polymer network ionization α. The α value is found to be approximately 0.36 for all samples at the degree of neutralization 0.49-0.70. This indicates that a significant part of counterions does not affect the swelling, being bound by polyions. The influence of the conditions of hydrolysis (polymer/alkali and water/ethanol ratios) on the swelling properties of the product and the nature of crosslinks are discussed. Interchain interaction of an amidine group and an acrylonitrile unit resulting in a formation of β-diketone-like structure is proposed to explain the crosslinking. Kinetic measurements were carried out to estimate the ratio of the initial rate constants for the polyacrylonitrile and polyacrylamide alkaline hydrolysis which was found to be of order 10 -1 .

The phase behaviour of blends of high-molecular weight poly(N-vinyl pyrrolidone) (PVP) with short-chain poly(ethylene glycol) (PEG) of M w =400, prepared by drying their solutions in a common solvent (ethyl alcohol), was studied using DSC. Upon heating of cool-quenched samples a single glass transition was observed, followed by an exotherm corresponding to cold crystallization of excess PEG, a melting endotherm, and an endotherm corresponding to vaporization of absorbed water. The temperatures of glass transition (Tg), PEG cold crystallization (Tc), and melting (Tm), along with the change in heat capacity (ΔCp) between the polymer's glassy and rubbery states at Tg, vary with blend composition and hydration. As a result the Tg/Tm, Tc/Tm and Tc/Tg ratios for PVP–PEG blends are functions of composition. PVP–PEG compatibility is due to H-bonding of PEG terminal hydroxyls to the carbonyls in the PVP repeating units. Large negative deviations of Tg values from the calculated weight averages, found mainly for PVP-overloaded blends, signify strong PVP–PEG interaction and free volume formation.

A mathematical simulation is presented which describes the in vitro drug delivery kinetics from hydrophilic adhesive water-soluble poly-N-vinylpyrrolidone (PVP)-polyethylene glycol (PEG) matrices of transdermal therapeutic systems (TTS) across skin-imitating hydrophobic Carbosil membranes. Propranolol is employed as the test drug. The contributions of the following physicochemical determinants to drug delivery rate control have been estimated: the drug diffusion coefficients both in the matrix and the membrane; the membrane-matrix drug partition coefficient: the drug concentration in the matrix and the membrane thickness. Drug transfer from the hydrophilic matrix across the membrane is shown to be controlled by the drug partitioning from the matrix into the membrane. The best correlation between simulation data and experimental results is obtained when the effect of membrane hydration is taken into consideration during in vitro drug release.

The optical anisotropy of poly-(1-trimethylsilyl-1 propyne) (PTMSP) molecules has been studied by flow birefringence. High positive birefringence was detected which is one order of magnitude higher than that of a polymer with a similar structure, poly-vinyltrimethylsilane (PVTMS). Semiempirical quantum-chemical calculation of the optical anisotropy of the polymer molecules under investigation was carried out. It was established that high optical anisotropy of molecules (with a low anisotropy of the monomer unit) indicates that these macromolecules exhibit high intramolecular orientational order. This is also confirmed by the correct choice of the ordered helical model in the quantum-chemical calculation of the optical anisotropy of PTMSP molecules. This model gave good quantitative agreement between the theoretical and experimental optical and geometric parameters of the macromolecules being investigated.

The main task of the theory of macromolecular reactions in polymer blends is to describe an evolution of the blend structure under the concerted action of the reaction and interdiffusion. For a polymeranalogous reaction proceeding with autoacceleration in a compatible blend, the task has been solved by methods of linear non-equilibrium thermodynamics. The set of reaction-diffusion equations derived permits to describe the blend structure in details, including the parameters characterizing compositional heterogeneity and units' distribution of the reacting chains in any local region of the blend. For incompatible blend of two homopolymers, the competition between a phase separation and the reaction of end-coupling with a formation of diblock-copolymer has been considered. The peculiarities of the processes mentioned as well as the actual problems in this field are discussed.

Peculiarities of the rheological properties of blends composed of thermoplastic polymer and polyacrylates are studied. The comparison of blends containing comb-shaped polymers of differing side-chain lengths shows that the flow mechanism changes with shortening side-group length. This leads to higher viscosity and elasticity of the combshaped component and, at the same time, results in the dramatic decrease in the blend viscosity, even at combshaped additive low content.

Peculiarities of the rheological behavior of blends composed of thermoplasts and side-chain nematic polymers have been studied. The strong role of interface interactions associated with the polymer chemical structure on the effect of rheology is shown. The influence of the nematic ordering is shown to be effective in the mechanical characteristics of blend extrudates whereas the rheology effect does not depend on the liquid crystal ordering.

The influence of crosslinking conditions (γ-radiation-induced and chemical crosslinking above and below the clearing point) on the phase behavior of a liquid-crystalline polyacrylate-based elastomer is shown and discussed. The network formation in samples γ-irradiated in the nematic phase results in an increase of the clearing point Tn-i which does not depend on the crosslinking density expressed as the ratio of weight-average molecular weight over number-average molecular weight between crosslinks Mw/Mc within a wide Mw/Mc range. The distorting action of the crosslinking agent at the same temperature leads to the opposite tendency in the change of Tn-i. Crosslinking in the isotropic phase shows a strong decrease in Tn-i.

The type of bonds responsible for the complexation of di- and polyacids with the tertiary amine β-N-dimethylamino-4-dodecyloxypropiophenone is studied by means of FTIR spectroscopy. The complexes are shown to be stable due to strong H-bonding with partial charge transfer. The characteristic composition for complexes of polyacrylic, polymethacrylic and malonic acids is calculated as 2:1 (number of carboxylic groups per number of amine molecules) whereas glutaric acid forms complexes of different composition including 1:1. The characteristic composition results from the structure of the initial acid. The structures of both the characteristic complex and “excess” acid are also discussed.

Temperature dependence of structure and properties of poly- N-alkyl-substituted acrylainides and their aqueous solutions has been studied by IR-Fourier spectroscopy technique. For poly-N-alkyl- substituted acrylamides showing lower critical solution temperature, a specific H-bonded ring structure involving alkyl amide units of a polymer and hydroxyl functions of water was discovered. A new approach to the targeted transport of physiologically active compounds was proposed. The approach involves the immobilization of these compounds on activated poly-N-alkylsubstituted acrylamides and heating the delivery site above critical temperature. It is known that the solubility of a polymer in a solvent is determined by the balance

The kinetics of drug supply described above from gel-like hydrophilic matrices of a TTS through human skin, or a polymeric membrane imitating itin vitro, are analogous to the kinetics of the release of a drug from a reservoir TTS through an attached polymeric membrane controlling the rate. Studying the kinetics of drug supply from diffusion matrices of TTS through a polymeric membrane imitating skin enables modeling of the kinetics of transdermal drug supplyin vitro andin vivo. The adequacy of such modeling is determined by the correlation between the diffusion coefficients of the drug in the membrane and skin epidermis and the distribution coefficients of the drug between skin and matrix or between membrane and matrix, which are subject to experimental determination. The transdermal supply of drug with kinetics of zero order (i.e. at a rate constant with time) may be effected from a TTS of the membrane-reservoir type containing a membrane specially controlling the rate or from a matrix TTS. In the latter case the function of the membrane controlling the rate of drug supply is fulfilled by the human skin at the point of application of the TTS, while the TTS diffusion matrix acts as a reservoir containing drug on the skin surface and limits the maximally achievable rate of drug release from the TTS to the skin according to equation 12. The competence of such an approach is occasionally questioned because of fears that the permeability of skin for a drug depends markedly on the point of application of the TTS and on the special features of the patient's skin. The effect of skin permeability at the point of application on the rate of transdermal drug supply has been studied well in [21] and a standard place for the application of a TTS may be the correct choice. The vast scope for the clinical application of the various TTS available at the present time indicates that individual variability of skin permeability is not so great and may be displayed mainly by a reduced permeability of the skin for a drug. Unlike membrane-reservoir TTS the majority of matrix TTS may be divided into portions of various size without disturbing their efficiency. This raises the possibility of continuously regulating the dose (by the area of application for TTS of this type).

A method of covalent immobilization of microorganisms (marine luminescent bacteria and yeast) in polymeric hydrogels is described. It is shown that cell immobilization leads to the creation of materials having properties of both synthetic polymers and physiologically active systems. Application of systems containing covalent immobilized yeast and photobacteria in biotechnological and other processes is proposed.

Sorbents for the removal of proteolytic enzymes from biological fluids were synthesized by immobilization of proteinase inhibitor, ovomucoid from duck egg white, in polymeric hydrogel matrix. The immobilization of the protein inhibitor modified by acryloyl chloride occurs during copolymerization of the unsaturated derivative of inhibitor with hydrophilic monomer and crosslinking agent. It was shown that the sorbent obtained possesses a high affinity for proteinases and is haemocompatible. The use of the haemosorbent for eliminating excess activated proteinase from blood is proposed.

The aggregation states of a series of comb-shaped polymers with perfluoroalkyl side chains were investigated. The main chains of the comb-shaped polymers were poly(fumarate), poly(acrylate) and poly(methacrylate). D.s.c. and w.a.x.d. measurements and p.o.m. observations over a wide temperature range showed that all the poly(fluoroalkylfumarates) (PFAF) investigated were amorphous polymers, but poly(fluoroalkylacrylate) (PFAA) and poly(fluoroalkylmethacrylate) (PFAMA) having a heptadecafluorodecyl (C 8 F 17 ) group in the side chain were in a mesomorphic state at room temperature. The type of mesophases can be most likely classified as an ordered smectic liquid crystalline (LC) structure in the Smectic B (S B ) modification for PFAA and an unordered smectic LC structure in the Smectic A (S A ) modification for PFAMA. Increasing the main chain flexibility in going from poly(fumarate) to poly(methacrylate) and poly(acrylate) enhances the probability of ordered structure formation.

The synthesis and application of hydrogel biospecific sorbents with immobilized physiologically active substances for creation of bio- and blood-compatible polymeric materials are given and discussed. The chemical nature and structure of affinic ligand, its availability and distribution in the matrix determine the action efficiency of these sorbents. A high blood-compatibility of polymers can be reached by chemical modification with several physiologically active substances acting at the different steps of thromboformation. The complex biotissue chemical modification permits the reduction of calcium and phosphorus accumulation inin vivo experiments by 10–100 times, compared with the control.

Polymers containing mesogenic groups in side and main chains of macromolecules represent liquid crystalline (LC) polymers as a special class of polymeric materials. Peculiarities of electrooptical behaviour of side-chain polymers as ferroelectric materials and optically- recording media as well as the future of LC engineering plastics based on main-chain polymers are discussed.

The kinetics of the reaction between linear and crosslinked hydrophilic copolymers carrying aldoxime- or ketoxime-pyridinium bromide groups and O,O′-diethyl-O-p-nitrophenyl phosphate has been studied in aqueous media. The reactivity of the copolymers was found to be given not only by the nucleophilic properties and basicity of the oxime group but by the substrate-binding ability of the polymer matrix as well. A kinetic scheme of solvolysis has been proposed and the rate constants of dissociation of the catalytic complex as well as of its first-order decomposition have been determined. It has been shown that oxime-containing copolymers catalyse hydrolysis of organophosphates. The rate constant of the first-order hydrolytic reaction of phosphorylated polymeric oximes has been determined and the efficiency of the catalyst has been estimated.

The ferroelectricity in the chiral smectic C phase of two comb-shaped liquid-crystalline polymers with a methacrylic main chain, phenyl benzoate side groups and chiral fragments of different types have been studied using the pulse pyroelectric method. The spontaneous polarization, pyroelectric coefficient and some relaxation times associated with two different molecular motions have been evaluated.

La reticulation radiochimique des polymeres (CH 2 CHCO 2 R) n (R=(CH 2 ) m −O−Ph−Ph−CN m=4,5,6) ne modifie pas la structure de la mesophage. L'ordre cristallin liquide et la structure de la mesophage ont une influence importante sur leur thermoelasticite

Three series of copolymers forming a cholesterol mesophase are obtained by copolymerization of nematogenic phenyl benzoate and cholesterol-containing monomers. The temperature ranges of existence of cholesterol and smectic mesophases are determined. The structure of the copolymers obtained is studied, and their optical properties are evaluated (wavelength for selective reflection of light and its dependence on temperature).

Alkaline hydrolysis of polyacrylamide (PAM) proceeds with a pronounced retardation and, under mild conditions, almost ceases near 40-50% conversion. The retardation is usually interpreted in terms of the nearest neighbor effect due to the electrostatic repulsion between -COOgroups formed and hydroxyl ions catalyzing the reaction1-4 (also a certain change of OHion activity has been considered5). Various approximate equations4-6 were used to describe the kinetics.3,4 Sawant and Morawetz2 were the first who employed correct Keller’s equations7 to describe the reaction kinetics in the framework of neighbor effect model. The equations contain three individual rate constants k0, k1, and k2 characterizing the reactivity of amide groups with 0, 1, and 2 neighboring carboxylate groups, respectively. Using polymer models (statistical copolymers acrylamide-acrylic acid of various composition), the authors2 estimated the rate constant values (k0:k1: k2 ) 1:0.11:0.013) and found that the calculated kinetic curve did not fit the experiment. Moreover, they showed that even for the maximum retarding effect k0:k1:k2 ) 1:0:0 calculations predicted a greater reaction rate than observed in their experiments. Then Sawant and Morawetz2 tried another approach. They supposed that more remote units, not only the nearest ones, also affect the reactivity of any amide group. Only one rate constant dependent on the total charge of a macromolecular coil was introduced. Following the ideas of Katchalsky et al.,8,9 they assumed that (a) the concentration of OHions near the charged coil is exponentially small in comparison with their bulk concentration and (b) the electrostatic work Wel required to bring a hydroxyl ion to any amide group of a charged reacting PAM coil (in alkaline medium) against the polyion repulsion is the same as that to remove a hydrogen ion from poly(acrylic acid) (PAA) with the same charge density. Using Mandel data on the PAA titration,10 they obtained the equation k/k0 ) exp[-2.3(0.9R + 0.6R2)] describing the rate constant dependency on a conversion degree R, where k0 is the initial rate constant of hydrolysis of uncharged PAM. The equation described well a dependency of the initial rate constants of hydrolysis of random copolymers acrylamide-acrylic acid on copolymer composition; however, “it completely failed to predict the rapid decrease of the rate of polyacrylamide hydrolysis”.2 It should be mentioned that the authors of ref 2 were aware of the fact that neither of the two alternative approaches would work. In their concluding remarks they wrote: “it is reasonable to assume that the three parameters k0, k1, k2 are also functions of the overall polymer charge”. Putting it in other words, they pointed out that the separate treatment of retarding action of the nearest and more remote units on the reaction rate could not fit experimental data. Our idea is to propose a model combining the nearest neighbor effect with the effect of a charged coil. This model demonstrates its efficiency to describe quantitatively the kinetics of PAM hydrolysis. According to ref 11 the data concerning both the reaction kinetics and units distribution in the chain formed are necessary to elucidate peculiarities of a macromolecular reaction. The only publication containing the proper information is the paper of Truong et al.3 So we used their results to test both the model of the pure neighbor effect and our model.

PVP is a highly hygroscopic amorphous polymer that is widely used in medicine as a drug-carrier, disintoxicant, blood-substituting agent and pharmaceutical excipient. In aqueous solution as many as 12 water molecules are reported to be associated with one PVP unit [1]. The PVP unit is capable of forming two H-bonds with water molecule through two unshared electron pairs at oxygen atom in carbonyl groups. Unshared p-electron pair at nitrogen atom has been shown to be never involved into H-bonding [2]. Consequently, the size of a first hydrate layer in solid polymer is limited by two water molecules associated with every PVP unit. This work focuses on eliciting the molecular mechanism of the first hydrate layer formation.

A number of problems: political, social, military, economical, technical, and ecological are interlaced intimately within the framework of the problem of chemical weapons (CW) disposal. Working out the strategy of the destruction of such supertoxic substances as chemical warfare demands considering the problem conceptually.

This chapter discusses a study analyzing the bifunctional polymeric reagents based on immobilized cholinesterases and their reactivators as piezoelectric coating for detection of the organophosphorus compounds. The development of sensoric technology for chemicals detection leads to necessity of preparation of high sensitive materials, which provide selective analytical response on the detected component in gaseous phase. In this study, as a base of reactive piezoelectric sensitive coating for detection of toxic organophosphorus compounds, the hydrophilic copolymers with coimmobilized acetylcholinesterase and nucleophilic groups reacting with poisons in neutral and slightly basic solutions were used. Hydrophilic copolymers containing acetylcholinesterase and aldoxime groups (as inhibited enzyme reactivators) were synthesized by radical polymerization, and their reactivity toward p -nitrophenylacetate and O , O ′-diethyl- O - p -nitrophenylphosphate in liquid systems was investigated. The influence of structural and physicochemical characteristics of polymeric reagents on their nucleophilic activity was studied. To regulate the ability of the sensitive coating to regeneration and to increase of the number of analytical cycles, the catalytic activity of copolymers in hydrolysis reaction was estimated, and methods of reagents' activation were suggested.

Wide-line 1 H NMR spectroscopy was used to investigate the kinetics of director rotation in the comb-shaped nematic polymer [CH 2 CH(COOR)] n (R= (CH 2 ) 4 OPhPhCN).The director rotation was found to conform to the following general features: the experimentally observed kinetics of director reorientation was interpreted in terms of the monodomain model; coefficients of rotational viscosity versus temperature plots were satisfactorily described by the Arrhenius equation with abnormally high activation energies; activation energy increased with an increase in polymer chain length; the rotational viscosity coefficient was related to polymer chain length via an exponential dependence; and an increase in temperature was accompanied by a linear increase of the exponent from 0.9 to 2.2

Influence du type de structure mesophase du polymere sur le processus d'orientation dans des champs electriques et magnetiques

The synthesis of comb-like polyacrylates and polymethacrylates with phenyl benzoate mesogenic groups is described. The LC phases formed by the polymers, the temperatures and heats of the phase transitions have been studied. The factors promoting the formation of such systems of inclined smectic mesophases are discussed.

A study was made of the viscosities of polyalkylacrylate (PA) and polyalkylmethacrylate (PMA) melts containing 4 to 18 carbon atoms in the side chain. It was shown that with an increase in the length of side branches, viscosity and any anomaly in viscosity in homologous series markedly decreases, the viscosity of polymers with the same side radical being higher for PMA, compared with PA. The activation energy of viscous flow E decreases with an increase in the length of the side radical. The maximum corresponds to the first members of the series—polymethylmethacrylate and polymethylacrylate. The value of E for polymers with long alkyl side radicals is equal to the value of E of polypropylene, in contrast to the poly-α-olefin series, for which E corresponds to E of linear polyethylene for higher homologues. It was found that PA and PMA with long side branches capable of being crystallized may flow at temperatures somewhat lower than melting point. The formation of discontinuities is a typical feature of flow curves in this case. It was shown that the formation of this discontinuity is due to the breakdown of crystalline structure of the polymer.

The effect of polymers of various structure (polycation, polyanion, comb-like neutral polymer and a comb-like polycation) on the permeability of liposomes from dipalmitoyl-phosophatidyl choline to enclosed low-molecular weight markers—6-carboxyfluorescein and 3H-glucose was studied in dependence on the pH of the medium. The greatest effect on liposome permeability was observed with a comb-like polycation—the copolymer of N-vinyl-pyrrolidone with vinyloctylamine, sharply enhancing the liberation of markers from liposomes at pH 7·0. In the presence of the polycation—poly(dimethylaminoethyl methacrylate), the permeability of liposomes with a comb-like polymer (poly(cetyl methacrylate)) introduced into the double-layer is also increased in a narrow pH range, reaching its maximum at pH 7·5.

The synthesis, structure and some properties of therrn6tropic liquid crystalline polymers with side xnesogenic groups are discussed. Approaches towards the synthesis of such systems are presented, as well as the data revealing the relationship between the molecular structure of the liquid-. crystalline polymers and the type of mesophase formed. The structure of smectic, nematic and cholesteric mesophases as well as models of chain packing in them are analyzed. The possibility to affect the strtcture of a liquid—crystalline polymer by an electric field is demonstrated. INTRODUCTION A new scientific trend related to the synthesis and study 0±' thermotropic liquid—crystalline (LC) polymers was formed and extensively developed in the field of chemistry and physics of high molecular weight compounds in the past decade (refs. 1—5). The general approach towards the synthesis of such systems is incorporation of mesogenic fragments into macromolecules with formation either of linear systems (A), or branching (comb—like) (B), when me sogenic groups are found in the side chains: where x' and x" are the lengths of flexible and rigid fragments, respectively, x0 is the distance between points of branching, • is the attachment bridge. An important role in the both cases belongs to the length of flexible fragments (spacers) linking either mesogenic groups with each other (A) or separating mesognic groups from the main chain (B). This above—mentioned pathway was the first time used in refs. (6-8) for the synthesis of LC comb— like polymers (refe. 6—7) and linear systems (ref. 8), it is currently universally adopted (ref. 5)*• Liquid—crystalline side chain polymers are obtained either by synthesis of monomers containing LC (mesogenic) groups with their subsequent homopoly— merization (Pig.la) or by copolymerization with non—mesogenic (Pig.lb) or mesogenic compounds (Fig.lc), or by attachment of molecules of low molecular weight liquid crystals to the polymer chain via polymer—analogous reactions (Pig.ld). These methods open in fact unlimited possibilities for combinations of different me sogenic fragments within macromolecules (ref. 11). Among synthesized LC comb-like polymers, those of acrylic and methacrylic series, containing various types of widespread mesogenic fragments of low— molecular weight liquid crystals (Schiff's base, cyanobiphenyl groups, *There are some other pathways of obtaining linear LC polymers when "foreign" units distorting the initial regular structure of the polymer chain are incorporated (refs. 9,10).

The intramolecular crosslinking of a polyelectrolyte by divalent metal ions has been investigated for poly-Nϵ-methacryloyl-L-lysine and copper (II) ions. It is shown that in the 4·5–11·0 pH range irreversible complex formation takes place, and is accompanied by a change in hydrodynamic properties of the macromolecules. The structure of the polymer-ligand (metal ion) complexes has been determined, and their behaviour in aqueous solutions investigated. Agreement between the results of theoretical calculations and experimental determination of change in the macromolecular coil dimensions during complexation reactions shows that the model used for theoretical calculations fits particular reactions of intramolecular crosslinking.

Phase transitions and structure of cholesterol-containing polymers, poly(cholesteryl-ω-acryloyloxyalkanoates) and poly(cholesteryl-ω-methacryloyloxyalkanoates), were examined by differential scanning calorimetry. X-ray studies and polarization microscopy. The polymers are shown to form smectic and cholesteric mesophases. Models for the packing of macromolecules in the liquid crystalline state are suggested. The cholesteric structure of the polymers is characterized by layer ordering in the arrangement of mesogenic groups. The cholesteric mesophase of the polymers was found to exhibit selective light reflection in the u.v.-region and circular dichroism.