Primary macromolecular

Self-assembling macromolecules are particularly well suited for applications as nano- and micro-templates. Macromolecules allow control of the size and topology of the template over many decades in length scale. The simplest primary macromolecular structure which permits one to carry out these functions are diblock copolymers. The last few years have seen considerable progress in the development of methods to synthesize block polymers, some of them applicable on an industrial scale. 

The implications of the foregoing concept have profoundly influenced modern trends in polymer research. If polymers owe their differences from other compounds to the extent and arrangement of their primary valence structures, the problem of understanding them is twofold. It is necessary in the first place to provide appropriate means, both experimental and theoretical, for elucidating their macromolecular structures a[Pg.3]

The history of dendrimer chemistry can be traced to the foundations laid down by Flory [34] over fifty years ago, particularly his studies concerning macro-molecular networks and branched polymers. More than two decades after Flory s initial groundwork (1978) Vogtle et al. [28] reported the synthesis and characterization of the first example of a cascade molecule. Michael-type addition of a primary amine to acrylonitrile (the linear monomer) afforded a tertiary amine with two arms. Subsequent reduction of the nitriles afforded a new diamine, which, upon repetition of this simple synthetic sequence, provided the desired tetraamine (1, Fig. 2) thus the advent of the iterative synthetic process and the construction of branched macromolecular architectures was at hand. Further growth of Vogtle s original dendrimer was impeded due to difficulties associated with nitrile reduction, which was later circumvented [35, 36]. This procedure eventually led to DSM s commercially available polypropylene imine) dendrimers. 

The copolymer-based systems possessing the core-shell structure in solutions are known and studied rather well (see, e.g., [14-16]). These copolymers in aqueous media tend to form polymeric micelles, which are often considered as promising drug delivery nano-vehicles [ 17,18], i.e., these macromolecular systems are not only of scientific, but also of considerable applied significance. Among such systems there are interesting examples, whose properties are very similar to the properties that should be inherent in the protein-like copolymers. All of these macromolecules possess the primary structure of... 

Protein polymers based on Lys-25 were prepared by recombinant DNA (rDNA) technology and bacterial protein expression. The main advantage of this approach is the ability to directly produce high molecular weight polypeptides of exact amino acid sequence with high fidelity as required for this investigation. In contrast to conventional polymer synthesis, protein biosynthesis proceeds with near-absolute control of macromolecular architecture, i.e., size, composition, sequence, topology, and stereochemistry. Biosynthetic polyfa-amino acids) can be considered as model uniform polymers and may possess unique structures and, hence, materials properties, as a consequence of their sequence specificity [11]. Protein biosynthesis affords an opportunity to completely specify the primary structure of the polypeptide repeat and analyze the effect of sequence and structural uniformity on the properties of the protein network. 

For ultrafiltration, the macromolecular solutes and colloidal species usually have insignificant osmotic pressures. In this case, the concentration at the membrane surface (C ) can rise to the point of incipient gel precipitation, forming a dynamic secondary membrane on top of the primary structure (Figure 7). This secondary membrane can offer the major resistance to flow. 

Leukemia P388 has also been used as a primary screen to detect the antitumor activity of macromolecular conjugates. For example, Ohya et al. [213] used P388 to determine the antitumor activities of polygalactosamine immobilized 5-fluoruracil, and Zunino et al. [214] of a poly-L-aspartic acid-daunomycin conjugate. 

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