Ionic Block Copolymers Research Articles

Tandem interactions in the self‐assembly of ionic block copolymers

AbstractThe aim of the present review is to show how the phenomena of block copolymer self‐assembly and interactions of ionic (or ionizable) groups in polymer systems can be combined to produce materials with versatile and unique behavior. In our discussion, we consider two classes of tandem interactions. First, block copolymers containing short ionic blocks and long nonionic blocks are investigated in organic media. In systems of this type, block copolymer self‐assembly and short‐range electrostatic interactions act in tandem, forming regular and highly‐stable spherical structures. Next, we consider ionic (or ionizable) block copolymers dissolved in aqueous media. In this case, block copolymer self‐assembly acts in tandem with the hydrophilic nature of the soluble blocks, resulting in a wide range of unique morphologies.

Block polyelectrolytes in aqueous environments

AbstractAnalogous to the self‐assembly of low‐molecular‐weight amphiphiles in aqueous solutions, the formation of spherical micelle‐like aggregates has been observed in systems of amphiphilic block copolymers in water. The aggregates, often called micelles due to structural similarities with surfactant associates, are found to exist above the critical micelle concentration (cmc). The micellization of amphiphilic block copolymers has been investigated using a wide range of techniques, such as size‐exclusion chromatography (SEC), static and dynamic light scattering (SLS and DLS), small‐angle x‐ray scattering (SAXS), small‐angle neutron scattering (SANS), transmission electron microscopy (TEM), viscometry, and steady‐state fluorescence spectroscopy.The present lecture is a review of recent work in our laboratory concerning the micellization of ionic block copolymers. These high‐molecular‐weight amphiphiles may contain one or more of a variety of ionic blocks, such as poly(4‐vinylpyridinium alkyl halides), poly(metal acrylates), poly(metal methacrylates) and sulfonated polystyrene. In water, such polymers are referred to as block polyelectrolytes, as they combine the colloidal behavior of block copolymers with the long‐range electrostatic interactions of polyelectrolytes. Early work in this field has been reviewed by Selb and Gallot.1

Micellization of Ionic Block Copolymers

Micellization of Ionic Block Copolymers

Micellization of Ionic Block Copolymers

Micellization of Ionic Block Copolymers

Microphase structure of block ionomers. 3. A SAXS study of the effects of architecture and chemical structure

The structure of various ionic block copolymers of ABA and AB architecture was investigated by SAXS. Polystyrene formed the B-blocks of all materials, and vinylpyridinium methyl iodide or cesium methacrylate formed the ionic A blocks. The latter were sept short and spherical ionic domains were observed. The morphology was studied as a function of the lengths of both ionic and nonionic blocks and of the methods of preparation (neutralization in different solvents, solvent casting, or compression molding). A strong correlation peak was observed, often followed by features related to shape factors for the spherical microdomains

Adsorption of ionic block copolymers: self-consistent-field analysis and scaling predictions

The adsorption of ionic diblock copolymers on an uncharged surface is investigated. One block, the «anchor», consists of N A uncharged, adsorbing A segments, whereas the «buoy» block has N B segments which carry a fixed charge and are nonadsorbing. Upon adsorption these molecules form a layer that resembles a brush of B segments. In contrast with a usual brush, however, the molecules in the adsorbed layer are in equilibrium with those in solution. Consequently, the chain density of the brush is not fixed; its value is determined by the dynamic equilibrium between polymer adsorption and desorption