Amphiphilic block copolymers ionic

Amphiphilic Block Copolymers with One Ionic Block in Aqueous Solution... 

Block copolymer micelles with a polyelectrolyte corona are a very important class of colloidal particles in aqueous medium and are often referred to as polyelectrolyte block copolymer micelles. The micellization behavior of these charged micelles has been very recently reviewed by Riess [14] and FOrster et al. [15]. A brief overview of the topic will therefore be presented in what follows. Amphiphilic block copolymers consisting of one hydrophobic block linked to one ionic block will only be discussed in this section. Blocks copolymers containing one hydrophilic block and one ionic block will be discussed in Sect. 4.3. 

Hence, this observation provided the bridge between the classical surfactants and amphiphilic block copolymers. The versatility of these amphiphiles is based not only on the ability to change the size of the head-group, but also on the possibility of chemically modifying of the dendritic head-group. Carboxylic acid terminated dendritic amphiphiles were prepared that exhibited a pH dependent aggregation behaviour due to the zwitter-ionic nature of their head-groups... 

Finally, amphiphilic graft copolymers will be reviewed and compared to the linear block copolymer structures of the same composition and it will be shown that micellization depends not only on composition, pH, and ionic strength, but also significantly on the topology of the polymer molecule. 

Let us assume that for a conventional surfactant the hydrophobic chain (e.g. an alkyl chain) and the hydrophilic group (e.g. a non-ionic oligo(ethylene glycol) chain) is continuously lengthened. Then we have a continuous transition from a monomeric amphiphile to an AB block copolymer. Similarly, ABA or multiblock copolymers can be realized according to Figure 5, D. These block copolymers show interesting properties in solution as well as in bulk. They are extensively reviewed by Riess(29). 

Kim, J.M. Han, Y.J. Chmelka, B.F. Stucky, G.D. One-step synthesis of ordered mesocomposites with non-ionic amphiphilic block copolymers implications of isoelectric point, hydrolysis rate and fluoride. Chem. Commun. 2000,24, 2437-2438. 

Another improvement of the solubilisation has been accomplished by adding short amphiphilic block copolymers in low concentration (see Section 4.2 for details). Briefly, these polymers have a polyethylene-propylene hydrophobic block and a polyethylene oxide head group and are thus similar to the ethoxylated non-ionic surfactants to which these are added. The main difference is that the two blocks of the amphiphilic polymer are several times larger than the corresponding low molecular weight surfactant. The role of these polymers is to increase the reach of the amphiphilic layer such that it extends deeper into both the oil and the aqueous phase in accordance with Winsor s premise. As a consequence, they are found to notably increase solubilisation [50]. As seen in Fig. 3.9(c), these additives could be called amphiphilic linkers since they act upon both sides of the interface. 

In the case of ordered mesoporous oxides, the templating relies on supramolecular arrays micellar systems formed by surfactants or block copolymers. Surfactants consist of a hydrophihc part, for example, ionic, nonionic, zwitterionic or polymeric groups, often called the head, and a hydrophobic part, the tail, for example, alkyl or polymeric chains. This amphiphiUc character enables surfactant molecules to associate in supramolecular micellar arrays. Single amphiphile molecules tend to associate into aggregates in aqueous solution due to hydrophobic effects. Above a given critical concentration of amphiphiles, called the critical micelle concentration (CMC), formation of an assembly, such as a spherical micelle, is favored. These micellar nanometric aggregates may be structured with different shapes (spherical or cylindrical micelles, layered structures, etc. Fig. 9.8 Reference 70). The formation of micelles. 

Self-Assembled Structures of Amphiphilic Ionic Block Copolymers Theory, Self-Consistent Field Modeling and Experiment... 

Abstract We present an overview of statistical thermodynamic theories that describe the self-assembly of amphiphilic ionic/hydrophobic diblock copolymers in dilute solution. Block copolymers with both strongly and weakly dissociating (pH-sensitive) ionic blocks are considered. We focus mostly on structural and morphological transitions that occur in self-assembled aggregates as a response to varied environmental conditions (ionic strength and pH in the solution). Analytical theory is complemented by a numerical self-consistent field approach. Theoretical predictions are compared to selected experimental data on micellization of ionic/hydrophobic diblock copolymers in aqueous solutions. 

Self-Assembled Structures of Amphiphilic Ionic Block Copolymers... 

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