Zdenek Tuzar

Solvents and Self-Organization of Polymers

Overview of Polymer Micelles Z. Tuzar. Equilibrium and Nonequilibrium Polymer Micelles P. Munk. Block Copolymers: Syntheses, Colloidal Properties and Application Possibilities of Micellar Systems G. Riess, G. Hurtrez. Micellization of Ionic Block Copolymers in Three Dimensions M. Moffitt, et al. Micellization of Block Copolymers in Two Dimensions C.J. Clarke. Site Specific Drug-Carriers: Polymeric Micelles as High Potential Vehicles for Biologically Active Molecules S. Cammas, K. Kataoka. Experimental Results on Hydrophobe Release E. Arca. Solubilization of Hydrophobic Substances by Block Copolymer Micelles in Aqueous Solutions R. Nagarajan. Monte Carlo Simulations of Self-Assembly in Macromolecular Systems T. Halilogu, W.L. Mattice. Self-Assemblies in Ion-Containing Polymers A.R. Khokhlov, O.E. Philippova. Equilibrium Structure of Ionizable Polymer Brushes E. Zhulina. Structure and Interactions in Tethered Chains A.P. Gast. Block Copolymer Self-Assembly at Surfaces: Structure and Properties M. Tirrell. Copolymer Micelles in Aqueous Media Z. Tuzar. The Structure of Telechelic Associating Polymers in Water A. Yekta, et al. Unimolecular Micelles of Hydrophobically Modified Polyelectrolytes Y. Morishima. Thermally Induced Phase Separation of Poly(Ethoxy-Ethyl- Vinyl Ether) Studied by the Fluorescence Method J. Horinaka, et al. Classical Methods for the Study of Block Copolymer Micelles P. Munk. Development of Synchrotron SAXS/Diffraction Instrumentation B. Chu. Structure and Dynamics of Polymers by Synchrotron SAXS B. Chu. From the Ruler to the Sextant: Dipole-Dipole Electronic Energy Transfer as a Tool for Probing Polymer Conformation and Morphology A. Yekta, M.A. Winnik. Use of Fluorescence Methods to Characterize the Interior of Polymer Micelles S.E. Webber. Fluorescence Depolarization Method to Study Polymer Chain Dynamics M. Yamamoto, et al.

Dynamics of solutions of triblock copolymers in a selective solvent: Effect of varying copolymer concentration

We have used static and dynamic light scattering and pulsed field gradient NMR to study the effect of varying concentration on the dynamics of the triblock copolymer, polystyrene block poly(ethylene, butylene) block polystyrene (PS-PEB-PS), dissolved in n-heptane, a selective solvent for the middle block. The correlation function for a dilute solution with c = 0.49 % (w/v) corresponds to the translational diffusion of micelles. At intermediate concentrations [1.1 ≤ c ≤ 2.6 % (w/v)], the correlation functions can be fitted to the sum of a single exponential and stretched exponential functions. The slower mode is due to the diffusion of polydisperse clusters formed by random association of triblock copolymer molecules and the faster one again represents micelles. A complex behavior is observed in the semidilute region [4.0 ≤ c ≤ 6.9 % (w/v)]. Three dynamic processes can be extracted from the correlation function: (i) The fast diffusive mode is the collective diffusion mode in the physical gel, (ii) the middle, relaxational mode, is probably due to the local movement of insoluble domains trapped in the network of the physical gel, and (iii) the slow diffusive mode implies the existence of large-scale inhomogeneities in the system.

Study on the aggregation of teicoplanin

The aggregation of teicoplanin was studied in four solutions: 0.06 M phosphate buffers pH 4.3 and 6.3, both with and without 10% (v/v) of acetonitrile. Conductometry, capillary electrophoresis, cyclic voltammetry, and static light scattering were employed to determine the critical micelle concentration (CMC) of teicoplanin. Dynamic light scattering was used to give an additional information on the size and the size distribution of the particles formed. While the CMC was found in solutions without acetonitrile, attempts to detect any CMC failed in solutions containing acetonitrile. The results point out to different solvating mechanism in solutions with and without acetonitrile, leading to two different schemes of association.

Micellization of a Novel Type of Hydrophilic/Hydrophobic Block Copolymers

Abstract Hydrophilic/hydrophobic block copolymers, which consist of hydrophilic blocks containing carboxylated polystyrene or poly(4-methylstyrene) chains, resist micellization by routine procedures. Micellization may be achieved in the presence of tris (2-hydroxyethyl)amine (THEA). Apparently, in a THF/water mixture. THEA with carboxyls forms tight ionic pairs that are quite hydrophilic and keep the micelles in solution. The resulting micelles could be transferred into water, aqueous LiCl, and THEA buffer solutions. They were characterized by static and dynamic light scattering and their properties were shown to conform to a typical behavior expected for micellar solutions.

Nanosize Aggregates of Block Copolymers of Styrene and Hydrogenated Butadiene in Water

Abstract Three-block copolymer polystyrene-block-hydrogenated polybutadiene-block-poly-styrene forms micelles with aliphatic cores and polystyrene shells in dioxane. When a solution of these micelles with an appropriate stabilizer (e.g., a block copolymer of ethylene oxide and propylene oxide) is injected into excess water, a stable dispersion results. The resulting particles have a hydrodynamic radius around 55 nm and particle molecular weight is hundreds of millions. The mechanism of the particle formation and their structures are discussed.

A New Technique of Solubilization of Nanosized Hydrophobic Materials in Aqueous Media

Injection of solutions containing molecularly dissolved copolymer polystyrene-block-poly(methacrylic acid) (SA) in dioxane produced block copolymer micelles of this hydrophobic/hydrophilic copolymer in water. When the SA solution in dioxane also contained block copolymer micelles of polystyrene-block-hydrogenated polybutadiene block-polystyrene (Kraton), the product was three-layered (onion) micelles with polystyrene forming the middle layer. The molecular solutions of SA and homopolystyrene in dioxane led to micelle-like particles in which the solubilized polystyrene was kept in water solution by the shell-forming SA molecules. Mechanisms of the processes involved were discussed.