Polymer macromolecular structural control

It is appropriate to compare the well-known concepts of covalent bond formation in traditional organic chemistry with those that apply to classical polymer chemistry and to dendritic macromolecular chemistry. This allows one to fully appreciate the differences between the three areas in the context of structure control, in concert with issues related to terminal group and mass amplification. 

Since that time, synthetic chemists have explored numerous routes to these statistically hyperbranched macromolecular structures. They are recognized to constitute the least controlled subset of structures in the major class of dendritic polymer architecture. In theory, all polymer-forming reactions can be utilized for the synthesis of hyperbranched polymers however, in practice some reactions are more suitable than others. 

As in linear polymers, the relative influence of the molecular structure (scale of nanometers and monomers), and the macromolecular structure (crosslink density), on network properties, depends on temperature, as shown in Fig. 10.9. In the glassy state, the physical behavior is essentially controlled by cohesion and local molecular mobility, both properties being mainly under the dependence of the molecular scale structure. As expected, there are only second-order differences between linear and network polymers. Here, most of the results of polymer physics, established on linear polymers, can be used to predict the properties of thermosets. Open questions in this domain concern the local mobility (location and amplitude of the (3 transition). 

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 synthesis of well-defined macromolecular structures with controlled properties is critical for the production of advanced materials for biological and industrial applications. Inspired by nature s ability to create proteins with exquisite control, we focus on the applications of elastin and elastin-derived polymers for materials design. The elucidation of elastin biochemical, conformational and physical properties offers insight into the fabrication of novel biomaterials. As part of this review, we highlight some of the recent advances that permit the generation of customized elastin-based polymers. These developments provide an added level of control vital to the future construction of tailor-made supramolecular structures with emergent physical, mechanical and biological properties. 

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