Polymer micelles self-assembling process

By covalent linkage of different types of molecules it is possible to obtain materials with novel properties that are different from those of the parent compounds. Examples of such materials are block-copolymers, soaps, or lipids which can self-assemble into periodic geometries with long-range order. Due to their amphiphilic character, these molecules tend to micellize and to phase-separate on the nanometer scale. By this self-assembly process the fabrication of new na-noscopic devices is possible, such as the micellization of diblock-co-polymers for the organization of nanometer-sized particles of metals or semiconductors [72 - 74]. The micelle formation is a dynamic process, which depends on a number of factors like solvent, temperature, and concentration. Synthesis of micelles which are independent of all of these factors via appropriately functionalized dendrimers which form unimolecular micelles is a straightforward strategy. In... 

It is also possible to prepare chiral PANI by in situ polymerisation with CSA, and in this case the reaction can afford chiral nanotubes [63]. The optically active materials contain nanotubes with 80 to 200 nm outer diameter and an internal diameter of between 20 and 40 nm, as revealed through microscopy images. A self-assembly process was proposed in which anilinium cations and CSA anions form micelles which act as templates for the growing polymer chains. Nanotubes are also formed when (R)- or (S)-2-pyrrolidone-... 

Polyanions and polycations can co-react in aqueous solution to form polyelectrolyte complexes via a process closely linked to self-assembly processes [47]. Despite progresses in the field of (inter-) polyelectrolyte complexes [47] (IPEC from Gohy et al. [48], block ionomer complexes BIC from Kabanov et al. [49], polyion complex PIC from Kataoka and colleagues [50, 51], and complex coacervate core micelles C3M from Cohen Stuart and colleagues [52], understanding of more complex structures such as polyplexes (polyelectrolyte complexes of DNA and polycations) [53] is rather limited [54]. It has also to be considered that the behavior of cationic polymers in the presence of DNA and their complexes can be unpredictable, particularly in physiological environments due to the presence of other polyelectrolytes (i.e., proteins and enzymes) and variations in pH, etc. 

The versatile nature of the self-assembly process allows for design of the chemical nature of the polymer micelles which permits fine-tuning of the material properties, shapes, and sizes. For example, the core composition can be varied to include glassy, crystalline, and fluid-Uke materials, hydrolyzed to produce an entirely hydrophilic structure, or fully degraded and removed to afford a solvent-filled... 

Both of the above templated methods are often referred to as hard template methods, as template dimensions are well-defined, pre-formed, and hence robust. In contrast to the former are the so-called soft templates. There, self-assembly processes are responsible for the formation of spatially defined geometric structures (the soft template) around which the polymer tube is then formed. Reverse rod-shaped micelles are a typical example around which polymeric tubes can be formed. Removal of the soft template releases the nanotubular structure. 

Cyclic polymers should be an excellent substrate for the preparation of invertible unimolecular micelles (Figure 2). Traditional micelles are formed in solution as a thermodynamic minima resulting from the self-assembly of surfactant type amphiphilic molecules. Because of this self-assembly process, they are subject to two significant limitations ... 

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