Hierarchial self-assembly

Abstract This chapter gives an overview of the research on the self-assembly of amorphous block copolymers at different levels of hierarchy. Besides the influence of composition and topology on the morphologies of block copolymers with linear, cyclic and branched topologies blends of block copolymers with low molecular weight components, other polymers or block copolymers and nanoparticles will also be presented. 

Organoclay materials with higher-order organization can also be prepared by template-directed methods involving self-assembled supramolecular structures. In this approach, preformed organic architectures in the form of tubes, fibers, hollow shells, gyroids, helicoids, and so on are transferred into hybrid materials exhibiting structural hierarchy, complex form and ordered mesoporosity [47-55]. For example,... 

During the course of the article, we will present evidence that the histones constitute part of a self-assembly system (Section IV). In the absence of DNA they retain the information to interact with each other to form a hierarchy of structures with dimensions, periodicities, and intermolecular contacts, compatible with what is known about the protein core of chromatin. This strongly suggests that histone-histone interactions have a fundamental role in chromatin structure. 

Steinbeig, M.S. (1970). Does differential adhesion govern self-assembly processes in histogenesis Equilibrium configurations and the emergence of a hierarchy among populations of embryonic cells. J. Exp. Zool. 173,395-434. 

Self-assembly can comprise a number of hierarchical levels, j. The lifetime of each self-assembled stage (x) is inversely proportional to its position in the hierarchy, thus the highest stages are much longer lived than the stages below them, i.e. Xj Xj.j. 

The self-assembly of small molecules into complex material based on a multitude of different noncovalent interactions, such as hydrogen bonding, ionic interactions, hydrophobicity and metal coordination, has been established over the last century [2, 30, 38, 44-49]. In this context, the real power of self-assembly becomes evident when not only multiple noncovalent interactions but also multiple levels of self-assembly occur within the same small molecule system. These multiple tiers of self-organizational hierarchy can yield highly complex structures with sec-... 

With a decade of experience, I have brought together seven papers with a scope limited to self-assembly of peptides, but covering key issues for advancing materials research into product development. The patent literature activity is typically an indicator of commercial interest and application space. Chapter 1 covers in some detail, but without being comprehensive, what self-assembled peptides may bring in terms of material applications. Chapters 2 and 3 explain the underlying principles of peptide self-assembly and how experiment can be used to model the hierarchy of structure formation. Typically, the work on peptides requires a tailored molecular... 

In our studies of the open-framework zinc oxalates, we have recently isolated monomeric, dimeric, ID linear chain, 2D layer, and 3D structures by the reaction of amine oxalates with Zn2+ ions,21 suggesting thereby that the presence of a hierarchy of structures is not unique to the phosphates alone. We believe that the evidence provided by our studies for the existence of an Aufbau principle of open-framework complex structures is of considerable significance. Many other complex inorganic structures are also likely to be formed by similar building-up processes, involving basic building units and self-assembly. 

Biology and organic chemistry are replete with examples of self-assembly. Examples include lipid bilayers, the DNA duplex, proteins in their correctly folded forms, self-assembled monolayers, and crystals. In MESA, we extend ideas abstracted from molecular recognition - shape recognition, chirality, directional interactions, hierarchy of bonds, and hydrophobicity - to the mesoscale. 

A great variety of self-assembled supramolecular structures can be found in supramolecular gels . Association of low molecular weight compounds in a topologically defined way yields long fibres with often well defined diameters [420], An amazing variety of very complex superstructures has been described, i.e. rods and tubes formed from concentric or would up lamellae, helices, or braid-like structures. In all cases we can assume a hierarchy of superstructures which ultimately link the molecular structure to the nanoscopic assembly. However, this has only been investigated in detail in a few cases so far. 

Fig. 21A-C. Electron microscopic graph of a structure hierarchy over three organization levels [108] prepared with the aid of microcontact-printing and self-assembly A microcontact sample (d=15 pm) B macroporous structirre (d=200 nm) C mesoporous structure (d=2 nm)...

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