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The ratio of the radius of gyration, obtained by static light scattering, and the hydrodynamic radius, obtained by dynamic light scattering, are routine experimental techniques for the assessment of nanoparticle shape. The potential effect of particle nonuniformity is mostly not considered. In this communication, we demonstrate that, even with medium particle nonuniformities, it is advisable to apply appropriate corrections. The values of the correction factors are offered in a diagram for various particle shapes, and two types of particle-size distributions and their widths.

IUPAC recommendations on source-based nomenclature for single-strand polymers have so far addressed its application mainly to copolymers, non-linear polymers and polymer assemblies, and within generic source-based nomenclature of polymers. In this document, rules are formulated for devising a satisfactory source-based name for a polymer, whether homopolymer or copolymer, which are as clear and rigorous as possible. Thus, the source-based system for naming polymers is presented in a totality that serves as a user-friendly alternative to the structure-based system of polymer nomenclature. In addition, because of their widespread and established use, recommendations for the use of traditional names of polymers are also elaborated.

Infekce mocových cest (IMC) mohou mit zasadni vliv na průběh a prognozu pacientů s roztrousenou sklerozou (RS). V běžne praxise s nimi denně potýkaji lekaři, kteři maji tyto pacienty v peci. Přesto stale chybi jednoznacne doporuceni, kterým by se měliurologove, neurologove a prakticti lekaři řidit. Nasledujici přehled se zabýva touto problematikou, vcetně diagnostiky a terapieIMC u pacientů s RS.

Summary The Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, provides training of young scientists, mainly from economically disadvantaged countries, in the form of a 10-month programme under the auspices of UNESCO and IUPAC named “UNESCO/IUPAC Postgraduate Course in Polymer Science”. The programme consists primarily of a research-project work under supervision by senior researchers and also of lectures, seminars and language courses. In this paper, the achievements of the 18 completed academic years of the Course are summarised, and the progress of the current run is reported. For those who become interested in the future runs, practical advice is given.

This document defines terms relating to the properties of individual macromolecules, macromolecular assemblies, polymer solutions, and amorphous bulk polymers. In the section on polymer solutions and amorphous bulk polymers, general and thermodynamic terms, dilute solutions, phase behaviour, transport properties, scattering methods, and separation methods are considered. The recommendations are a revision and expansion of the IUPAC terminology published in 1989 dealing with individual macromolecules, macromolecular assemblies, and dilute polymer solutions. New terms covering the principal theoretical and experimental developments that have occurred over the intervening years have been introduced. Polyelectrolytes are not included.

This document provides some basic rules and guidelines regarding the use and creation of abbreviations for the names of polymers. An extended list of currently used abbreviations for polymers and polymeric materials is appended.

For several decades, the relation between the contraction factor of radius of gyration for branched macromolecules, g, and that of intrinsic viscosity, g′, has been presented as g′ = ge. The value of e was assumed to be constant for branched macromolecules of a certain type, such as stars, or combs, or statistically branched macromolecules. Experimentally determined values of e, however, turn out in the majority of cases to be molecular-weight dependent. The present study shows that molecular-weight-independent values of e can be expected only for a plurality of molecules with identical architecture. By branched molecules with identical architecture we mean molecules in which with varying degree of polymerization the ratios of the degrees of polymerization of all sub-chains remain constant, irrespective of the integral degree of polymerization of individual molecules. Also, it has been demonstrated that the ratio of intrinsic viscosities of a linear and a branched polymer molecule having the same hydrodynamic volume, [η]l,V/[η]b,V

Statistical long-chain branching occurring during the free-radical polymerization of the system sodium 4-vinylbenzenesulfonate (SSNa) and N, N′-methylene-bis(acrylamide) (MBAA) in aqueous medium was studied by ¹H NMR spectroscopy and SEC. The former method yielded the degree of conversion and the content of the three monomer units in the chain, i.e., SSNa, MBAA with pendant vinyl groups, and MBAA as branching points. It was found that the number of individual monomer units per a total of 1000 monomer units does not perceivably change with the degree of conversion and only slightly increases with increasing ratio MBAA/SSNa in the feed.

In the past, aggregation and self-assembly have been associated principally with micellar and colloidal systems of molecules; however, with the advent of supramolecular chemistry, molecular self-assembly has been opened to a much wider understanding that has facilitated access to a variety of different shapes and sizes, along with the construction of new and fascinating molecular topologies. This document aims at defining more than 150 terms related to aggregation and self-assembly in the particular case of macromolecules. The list is restricted to the most commonly encountered terms.

The nonuniformities of graft (co)polymers have been analyzed using the probability generating functions and their moments. The nonuniformity is described by ratios of averages of molecular weights ...

Synthesis, characterization, and reactivity of new allyl cyclopentadienyl molybdenum(II) compounds [(η3-C3H4R1)(η5-C5H3(R2)2)Mo(CO)2] (R1 = H, COOMe; R2 = COOMe, CONHtBu) are reported. Although these compounds are structural analogues of [(η3-C3H5)(η5-Cp)Mo(CO)2], their reactivity is very different. While protonation of [(η3-C3H5)(η5-Cp)Mo(CO)2] gives a cationic cyclopentadienyl complex, the presented compounds give cationic allyl complexes [(η3-C3H4R)Mo(CO)2(NCMe)3][BF4] (R = H, COOMe) or stable cationic allyl cyclopentadienyl complexes. The theoretical calculations have shown that this behavior is a result of high affinity of the functional groups in the cyclopentadienyl ligand toward protonation.

Recommendations are given concerning the terminology relating to the structure and the morphology of crystalline polymers and the processes of polymer crystallization. They are applicable to cases where polymer crystals are a significant fraction of a system and primarily with crystal structures that are comprised of polymer chains with limited, static, or dynamic disorder. After some general definitions, terms pertaining to structural arrangements at subnanometric scales and to polymer crystal structures are defined. Terms relating to molecular conformation within polymer crystals, morphological aspects, and polymer crystallization are given in subsequent sections.

This document defines class names of polymers based on the class names of starting monomers and characteristic features of the chemical constitution of polymer molecules (macromolecules), i.e., class names that have gained general acceptance in the polymer and material literature, science and technology as well as in public. The glossary is divided into three parts: Source-based class names, which identify common classes of starting monomers such as "acrylic", "diene", "phenolic", "vinylic". Class names based on chemical structure, which identify characteristic groups in the main chains (backbones) of the polymer molecules such as (i) inter-unit groups derived from functional groups, e.g., "amide", "ester", "ether"; (ii) a specific group of atoms, e.g., "alkenylene", "siloxane", "sulfone"; (iii) ring structures, e.g., "benzimidazole", "benzoxazole", "quinoxaline". Class names based on molecular architecture, which identify mainly the overall shapes of polymer molecules through the type of their graphical representation such as "linear", "branched", "dendritic", "comb". Each part of the glossary is arranged in a non-hierarchical alphabetical order. Each entry provides: (a) the polymer class name; (b) its definition; (c) specific or generic examples including IUPAC names and a structure or graphical representation; (d) relations to other polymer classes and subclasses; (e) notes on the inclusion or exclusion of borderline cases. An alphabetical index of all class names is included.

BACKGROUND: Frequently, the unimodal shape of size-exclusion chromatography (SEC) elution curves is taken as evidence that the polymer sample being analysed contains no minority components in significant quantities. The legitimacy of this assumption, however, has never been checked systematically. RESULTS: An algorithm for the simulation of SEC elution curves of multi-component polymer systems has been developed. Using the algorithm, the shapes of the overall SEC curves with a wide range of parameters describing binary systems were generated and scanned. The crucial parameters determining the shape of the elution curves are the ratio of the molecular weights of the components, the breadth of the molecular weight distribution of the components, the mass fractions of the components and the band broadening. CONCLUSION: A detailed inspection of the curves shows that the identification of the presence of minority components in such systems from the shapes of the elution curves is more difficult then generally assumed. The absence of peak irregularities, such as minima or inflection points, widely used as a proof of absence of minority components, is a highly unreliable criterion. Copyright © 2008 Society of Chemical Industry

BACKGROUND: Number-average molecular weight, M n , is an important characteristic of synthetic polymers. One of the very few promising methods for its determination is size-exclusion chromatography (SEC) using on-line viscometric detection and assuming the validity of the universal calibration concept. RESULTS: We have examined the applicability of this approach to the characterization of statistically branched polymers using 22 copolymers of styrene and divinylbenzene as well as 3 homopolymers of divinylbenzene with various degrees of branching. SEC with three on-line detectors, i.e. concentration, light scattering and viscosity, enables us to evaluate experimental data by various computational procedures yielding M n and weight-average molecular weight, M w . Analysis of the results has shown that the universal calibration theorem has limited validity, apparently due to the dependence of the Flory viscosity function on the molecular shape, the molecular weight distribution and the expansion of molecules. CONCLUSION: For complex polymers, the universal calibration, i.e. the dependence of the product of intrinsic viscosity and molecular weight, [η]M, on elution volume, can differ in values of [η]M from those obtained for narrow molecular weight standards by 10-15%. The method studied is helpful for the determination of M n of polymers, in particular of those with very broad molecular weight distribution, such as statistically highly branched polymers.

A series of samples of linear aromatic polyester of 3-phenylglutaric acid and bisphenol A was prepared with molecular weights ranging from 14 700 to 92 700. The polymers were characterized by size exclusion chromatography with triple light-scattering, viscosity, and concentration detection. Hydrodynamic parameters of the chain were determined using the theory of Yoshizaki, Yamakawa, and Nitta modified by Bohdanecký and Netopilik. The chain parameters are a useful reference in the study of aromatic hyperbranched polyesters.

Some remarks on the light-scattering behavior of polydisperse systems and on the methods of interpreting the light-scattering curves are presented. P(θ) functions for systems of linear Gaussian and branched coils with Schulz-Zimm and generalized exponential distribution were calculated.

The importance of the refractive index increment measured after the establishment of dialysis equilibrium between the polymer solution and the mixed solvent for the evaluation of light scattering measurements from polymer solutions in multicomponent solvents is stressed. The feasibility of determination of heterogeneity in copolymer composition by light scattering can often be considerably extended by using mixed solvents. Light scattering measurements from solutions of binary polymer mixtures yield correct molecular weights of the components and parameters characterizing the thermodynamic interaction of unlike polymer molecules. In all the types of measurements discussed, information is obtained from ratios or differences of rather close values. In order to get physically meaningful data a higher experimental accuracy is required than in conventional light scattering measurements.

This paper describes a study of dilute solutions of polycaprolactam in mixed solvents TFP-H2O-LiCl with the objective of finding the most convenient solvent for determining the molecular weight of polyamides by the light-scattering method. Selective adsorption of both TFP and LiCl on the polyamide has been proved and quantitatively determined. The adsorption of TFP decreases the measured value of molecular weight, whereas that of LiCl increases it. A composition has been found (TFP-10% H2O-0.1M LiCl) in which the two effects exactly compensate. In this mixed solvent 24 fractions of hydrolytic and alkaline polycaprolactams were measured in a range Mw = 9 × 1033 to 3.5 × 105. The same solvent and m-cresol have also been selected for measuring the intrinsic viscosities and determining the constants of the Mark-Houwink equation.

This document defines terms related to the structure and processing of inorganic, polymeric, and inorganic-organic hybrid materials from precursors, through gels to solid products. It is divided into four sections - precursors, gels, solids, and processes - and the terms have been restricted to those most commonly encountered. For the sake of completeness and where they are already satisfactorily defined for the scope of this document, terms from other IUPAC publications have been used. Otherwise, the terms and their definitions have been assembled in consultation with experts in the relevant fields. The definitions are intended to assist the reader who is unfamiliar with sol-gel processing, ceramization, and related technologies and materials, and to serve as a guide to the use of standard terminology by those researching in these areas.

This document defines the terms most commonly encountered in the field of polymers containing ionizable or ionic groups and polymers containing ions. The scope of the document has been limited to organic polymers. Inorganic materials, such as certain phosphates, silicates, etc., which also may be considered ionic polymers, are excluded from the present document. The terms selected are those that are widely used in the field of polymers containing ionizable or ionic groups and polymers containing ions. Only those terms that could be defined without ambiguity are considered. The terms are listed in alphabetical order, and cross-references to definitions given in other documents are provided.

Stockmayer's classical theory of statistical branching of polymers, as modified by Thurmond and Zimm, and subsequently by Kilb, has been used to describe the evolution of the distribution of the degrees of polymerization with conversion up to the gel point in the copolymerization of a vinyl monomer with a small amount of a divinyl monomer. The weight fractions of molecules with a particular number of branch points per molecule, the averages of the degrees of polymerization of these molecules, and some other characteristics were calculated as functions of a complex variable—the branching parameter γ, including the composition of the monomer mixture, relative reactivities of the individual types of double bonds, and conversion. From these calculations, a few general conclusions on the behaviour of the model system can be drawn. The conclusions are likely to be qualitatively valid also for systems not strictly conforming to the model. Copyright © 2005 Society of Chemical Industry

The determination of the interdetector volume (IDV) in size-exclusion chromatography (SEC) of polymers with dual multiangle light-scattering/concentration detection based on the s-detection is demonstrated. By s-detection the determination is meant of local molecular mass from a known relation between molecular mass and radius of gyration, obtained from the angle dependence of the intensity of scattered light. IDV is found basing on the stipulation of equal slope of local calibrations found by the dual light-scattering/concentration detection, referred to as the w- and s-detection. As the s-detection uses just the light-scattering detector and, therefore, is independent of the value of IDV, this quantity can be found by searching for its value that gives the local calibration dependence obtained by the dual detection closest to that determined independently by the s-detection.

Migration of foreign bodies into the renal collecting system is very rare and usually concerns iatrogenically implanted objects. Migration of a foreign body from the gastrointestinal tract to the kidneys is even more rare. We present a case of migration of a wooden toothpick from the duodenum into the pelvis of the right kidney. The patient was not aware that he swallowed a toothpick; the foreign body resulted in hematuria and flank pain. The toothpick was missed during the initial computed tomography urography. Correct diagnosis was revealed by follow-up computed tomography. The toothpick was extracted endoscopically.

The evaluation of the size-exclusion chromatography (SEC) concentration elution curves by means of a calibration dependence obtained in a given SEC set for a polymer different from the polymer to be analyzed results in an error in the determination of both molecular weight and molecular-weight distribution (MWD). The problem is analyzed assuming the validity of the universal-calibration concept. The differences between the true and apparent values of molecular weight, MWD and Mw/Mn depend on and are expressed in terms of the parameters of the Mark–Houwink–Kuhn–Sakurada equation, describing the molecular-weight dependence of intrinsic viscosity, for the polymer to be analyzed and the polymer used for calibration. The differences in molecular weight and the Mw/Mn ratio are typically tens of percent and, in extreme cases, can amount up to a factor of three for molecular weight and a factor of two for the Mw/Mn ratio.

A new method for the estimation of the weight-to-number-average molecular-weight ratio, M w / M n , of polymers with a narrow molecular-weight distribution, approximated by log-normal distribution, is proposed using size-exclusion chromatography (SEC) with concentration and light-scattering detectors. From experimental data, the M w / M n ratios are calculated by two procedures: one using the concentration and light-scattering elution curve for the polymer measured, and the other based on the concentration elution curve and calibration line for a wide range of molecular masses. An iteration method has been developed making the two M w / M n ratios converge. The method was applied to a series of narrow molecular-weight distribution polystyrene standards.

The ordering of electrically conducting polyaniline particles dispersed in a non-conducting liquid, 1,2,4-trichlorobenzene, in a weak electric field (of the order V mm −1 ) has been studied. The time needed for the formation of conducting chains, depending on the applied voltage, the polyaniline concentration and the viscosity of the suspension medium, was used to calculate the effective relative electric permittivity for polyaniline, ɛ p = 4.8, responsible for the dipole-dipole interaction leading to the structure formation. Nonlinear limit current-voltage characteristics typical of electrorheological suspensions were observed. The formation of the conducting chains could be followed in an optical microscope.

Electrically conducting polyaniline particles were organized by an electric field in a liquid medium, which was subsequently polymerized to produce a polyurethane network. The changes in electrical conductivity during polymerization were recorded. The chains of conducting polyaniline particles oriented in the direction of the electric field became fixed in the polymer network. In this way, electrically anisotropic materials were produced. The conductivity in the direction parallel to the orientation was several times higher than that in the perpendicular one. The conductivity of these composite materials increases with temperature, while the electrical anisotropy decreases. The effect of electrical anisotropy is explained by simple geometric considerations.

Copolymers of aniline and p-phenylenediamine were prepared by joint chemical oxidation of these chemicals with ammonium peroxydisulphate in aqueous medium. The temperature and frequency dependences of the impedance and permittivity of copolymers were measured. The exponential dependence of resistivity on aniline content was observed.

Dissolution of polystyrene-block-poly(ethylene-co-propylene) (PS—PEP) in decane, a selective solvent for the PEP block, and dioxane, a selective solvent for the PS block, at room temperature leads to formation of metastable micellar structures, which convert into stable micelles with molar mass reduced several times after heating above ∼50°C. By comparing small-angle X-ray scattering (SAXS) and light scattering (LS) data, the following models of micellar structures are suggested: At room temperature, dissolution of PS— PEP in decane yields aggregates of micelles. These are detected by LS, while SAXS reflects the molar mass of individual micellar cores formed by PS blocks. At elevated temperature, these compound particles disaggregate and then reorganize into equilibrium micelles of reduced molar mass. Solutions of PS—PEP in dioxane at room temperature have a different character. The molar masses of the observed particles determined by SAXS are in a good agreement with LS results, so we can exclude aggregation of micelles in this solvent. Nevertheless, also here, after heat treatment, both SAXS and LS yield a molar mass that is about 5 times lower than that determined for unheated solutions. Metastable structures surviving from the solid-state morphology after dissolution in a selective solvent at room temperature may convert to classical equilibrium micelles only after heating.

Aniline was polymerized in the presence of ultrafine colloidal silica particles (hydrodynamic diameter 35 nm) in aqueous media and, given a sufficient silica concentration, colloidally stable polyaniline−silica particles were obtained. The particle size of the resulting dispersions was determined by both dynamic light scattering and disk centrifuge photosedimentometry. The typical size of these polyaniline−silica particles is in the range 300−600 nm and is insensitive to the concentration of components in the reaction mixture, temperature, or acidity of the reaction mixture. Particles produced at 0 °C are spherical and their shape becomes less defined when polymerization proceeds at 25 °C. As the silica size is increased, the composite particles become larger and their raspberry morphology more distinct. The electrical conductivity of a typical polyaniline (37.8 wt%)−silica composite is 6.1 × 10-2 S cm-1 at 25 °C. It grows with increasing temperature and does not depend on the frequency in the investigate...

Nonpolar block copolymers may be selectively multisite substituted in only one block with various functional groups, like carboxyl, hydroxy, or alkyl groups. In this way, block copolymers with unusual structures are easily accessible. The degree of substitution in the functionalized blocks may be controlled in a wide range and copolymers with various concentrations of substituents arise. The procedure of functionalization involves selective multisite metalation of the block copolymer by Superbase, made from 3-(lithiomethyl)heptane and potassium tert-pentoxide, and subsequent reaction of the metalated copolymer with an electrophile. Hydrophilic−hydrophobic block copolymers prepared by this method were investigated with regard to formation of micellar solutions in aqueous media.

The effect of the chemical-composition heterogeneity of flexible-chain binary copolymers on their separation in size-exclusion chromatography (SEC) was theoretically examined. The two-parameter theory of polymer solutions was engaged to estimate the coil size. The variation in molecular weight is shown for copolymer molecules which differ in the ratio of the two constituent monomeric units but have the same coil size and, therefore, are eluted at the same elution volume. The result was applied to a theoretical case of analysis of copolymers, the composition and molecular-weight distributions of which are given by theoretical functions. If the refractive index increments of homopolymers whose units constitute the copolymer are equal or close to each other, the influence of the chemical heterogeneity on the experimental data is below the experimentally detectable limit. A significant error in the determination of the molecular-weight averages can occur only if the difference in the refractive index increments exceeds physically reasonable limits.

The forms of polyaniline, viz. pernigraniline, emeraldine and leucoemeraldine, their mutual transformations and their roles in the chemical polymerization of aniline, are discussed. Absorption spectra of its various protonated forms and corresponding bases are reported. A simple reaction scheme is proposed to account for the colour and acidity changes during polymerization.

The chemical oxidation of aniline to polyaniline has been monitored by colour and acidity changes during dispersion polymerization. A small amount of various p-phenylenediamines or benzidine was found to accelerate the formation of polyaniline. The ability of such compounds to form cation radicals upon oxidation allows them to act as mediators in electron-transfer processes. Related chemicals, e.g. o-phenylenediamine, had little effect on polymerization, while m-phenylenediamine caused its retardation.

Optical absorption spectra of polyaniline dispersions in aqueous media have been investigated. Two absorption bands located at 340 and 610 nm are found for blue polyaniline base in ammonia solutions. The spectra of alkalized dispersions are close to those observed for polyaniline base in N-methylpyrrolidone solution (maxima at 332 and 638 nm), but the position of the maxima depends on the nature of the alkali. In the acidic region, three distinct absorption bands of the green protonated polyaniline are observed at 350, 430 and 810 nm. The spectroscopic response to change of pH is fast but additional slow changes occur and may extend for hours when close to neutral media. The absorption coefficient of polyaniline in 1 M hydrochloric acid for a local maximum between 380 and 420 nm is estimated as ϵ=31 500 ± 1700 cm2 per gram of polyaniline hydrochloride. Spectroscopy is used to follow up the dispersion polymerization of aniline. After an induction period, a fast polymerization takes place and the originally colourless solution turns blue. A subsequent change of colour to green indicates termination of polymerization.

Stable aqueous dispersions of polyaniline (PANI) have been prepared using an underivatized poly(vinyl alcohol-co-acetate) (PVAL) as a steric stabilizer. Investigation of aqueous PANI dispersions by scanning electron microscopy and light scattering revealed that oxidative polymerization of aniline in the presence of PVAL results in the formation of spherical particles. Their size does not depend on the concentration of aniline in the polymerizing system but the uniformity of the particles seems to be improved as the aniline concentration is increased at least up to a certain limit. Electron absorption spectroscopy study of PANI dispersions made it possible to follow the changes of PANI on both molecular and supermolecular levels. When the initial concentration of aniline in the polymerizing system was ca 2 wt% (at a concentration of PVAL from 2 to 10 wt%), electrical conductivity of free standing films cast from dispersions reached 10−1S/cm.

Phase behavior of a hydrogenated styrene/isoprene diblock copolymer in a dimethylformamide/methylcyclohexane demixing-solvent pair has been studied. At a fixed copolymer concentration (1% w/v), the scheme of phase behavior (temperature vs. mixed-solvent composition) of the system has been found to be complex, with several areas where various supramolecular structures are spontaneously formed. In a particular area of the scheme, a multistep demixing-solvent fractionation of the copolymer has been performed. The resulting fractions have been characterized and the data used to construct integral distribution functions of copolymer molar mass and copolymer composition. These functions have been compared with those obtained by a previously reported light-scattering characterization of the whole, unfractionated, nonhydrogenated precursor of the copolymer © 1993 John Wiley & Sons, Inc.

Brechungsindexinkremente der Copolymeren von N-Phenylmaleimid mit Styrol, Methylmethacrylat und Acrylnitril sowie der entsprechenden Homopolymeren wurden in verschiedenen Losungsmitteln bei 536 nm und 25°C gemessen. Die Brechungsindexinkremente der Copolymeren mit Styrol und Methylmethacrylat zeigten in allen verwendeten Losungsmitteln positive Abweichungen von der fur die meisten Copolymeren ublichen Additivitat. Dies wurde durch unabhangige Mesungen der partiellen spezifischen Volumina bestatigt. Mogliche Ursachen der Nichtadditivitat werden erortert. Refractive index increments of copolymers of N-phenyl maleimide with styrene, methyl methacrylate and acrylonitrile, and of the corresponding homopolymers were measured in different solvents at 536 nm and 25°C. In contrast to the usually observed behaviour, the refractive index increments of the copolymers with styrene and methyl methacrylate exhibit positive deviations from additivity in all solvents used. This result was confirmed by independent measurements of the partial specific volumes. Possible reasons for nonadditivity are discussed.

Micellization of di- and triblock copolymers, poly(methacrylic acid)-block-polystyrene and poly(methacrylic acid)-block-polystyrene-block-poly(methacrylic acid), varying in molecular weight and composition, has been studied by static and dynamic light scattering, and sedimentation velocity. Micelles with polystyrene cores were prepared in water-dioxane mixtures, rich in dioxane, and transferred into water-rich mixtures, water, and aqueous buffers via stepwise dialysis. It has been shown that, in dioxane-rich mixtures, the micellar system was in dynamic equilibrium, while in water-rich solvents, water, and aqueous buffers the micellization equilibrium was frozen and micelles behaved like autonomus particles. Under certain conditions, micelles were accompanied by independent large particles. This phenomenon, known from other micellar systems as an "anomalous micellization", is discussed.

Polystyrene-block-poly(ethylene-co-propylene) solutions in decane have been investigated by dynamic and static light scattering. The dissolution of the diblock copolymer in a solvent, which is selective of aliphatic blocks, yields well-defined metastable micellar structures. These structures are converted into equilibrium micelles on heating and change into frozen micelles when cooled. A similar pattern is observed also in dioxane, which is a selective solvent for polystyrene blocks.

Methyl methacrylate was polymerized in an aqueous medium in the presence of gelatin using potassium persulfate as initiator. The dispersion mode of polymerization, when the monomer is completely miscible with water, was investigated and compared with an emulsion process, which proceeds at higher monomer concentration. Spherical and relatively uniform polymer particles were formed. Macroscopic precipitation of polymer is prevented by combination of the steric stabilization by grafted gelatin and of repulsive electrostatic interactions from the initiator residues attached to the particle surface. Static and dynamic light scattering have been used to determine the molar mass (molar mass of the whole dispersion particle, MwD ∼ 108-109 g mol−1) and hydrodynamic radius (RhD ∼ 50-120 nm) of the particles. The number of particles per unit volume does not depend on overall monomer concentration, and it is higher, and therefore the particle size is smaller, than that observed for the soapless emulsion polymerization. The addition of gelatin may be thus used to modify the particle size. Acrylonitrile dispersions were prepared under similar conditions. Unlike methyl methacrylate, this monomer does not swell the polymer particles. While poly(methyl methacrylate) particles are spherical and relatively uniform, the polyacrylonitrile dispersions consist of polydisperse aggregates of tiny polymer particles.

Several series of polyaniline dispersions were prepared by oxidative polymerization of aniline in aqueous medium. Ammonium persulfate was used as an oxidizing agent and poly(vinyl alcohol) as a steric stabilizer of dispersions. The amount of dispersion particles, their size and uniformity, and the fraction of the steric stabilizer attached to the particles were determined in dependence on the concentration of the individual components and on temperature. The properties of resulting dispersions are controlled mainly by the concentration of the oxidizing agent and by the polyaniline/stabilizer ratio

The synthesis of branched poly(methyl methacrylate) is described. The method used is based on an anionic technique with initiation by enolate ions. details of product characterization are included.

The reaction of vanadocene dichloride with sodium arsenate gives Cp(2)V(O(2)AsO(2)H). This compound was identified on the basis of the super-hyperfine coupling observed in the solution EPR spectrum. The effect of substitution was studied on the ring-substituted and ansa-bridged compounds.

When selective solvents are used for the dissolution of block copolymers, their solid-state structure may be partly preserved in solution. At room temperature, polystyrene- block -poly(ethylene- co -propylene) dissolves in decane, a selective solvent for the aliphatic block, to form a solution of metastable micellar structures with polystyrene core. These convert to stable micelles at elevated temperature; the molar mass of the micelles is reduced several times after the heat treatment. The change of the structure is explained by the existence of a frozen state of the micellar core at room temperature. A possible connection with the glass transition of the core is discussed. Static and dynamic light scattering, small-angle X-ray scattering, differential scanning calorimetry and viscometry have been used to characterize equilibrium and non-equilibrium micelles. A pronounced mutual interaction of micelles has been observed by light scattering even at a concentration as low as 5 × 10 −4 g cm −3 . The concept of sticky chains is introduced to explain the association of the micellar shells. The behaviour of micelles in another selective solvent, diisopropylether, is simpler, both effects observed in decane being absent.