Types of Self-assembled Structures

We have a specific interest in the self-assembled structures formed by poly(ferrocenylsilane) block copolymers, such as poly(ferrocenyldimethylsilane-Z -dimethyl-siloxane) (PFS-PDMS) and (ferrocenyldimethylsilane-Z>-isoprene) (PFS-PI). The PFS block contains an iron atom in the main chain repeat unit. These polymers are particularly promising for novel applications, since they can be used as charge-transport materials and, by pyrolysis, as precursors to ferromagnetic ceramics [4-6], Moreover, they can by synthesized with a very narrow molar mass distribution, with excellent control over chain length and composition [7], An important feature of PFS is that the polymers bearing two methyl groups on the silane unit are crystalline, whereas polymers with two different substituents on each silane (methyl, ethyl methyl, phenyl) are atactic and remain amorphous. This feature of the polymer composition has a strong influence on the type of self assembled structures that these poly-... 

Hager, M., Olsson, U. and Holmberg, K. (2004) A nucleophilic substitution reaction performed in different types of self-assembly structures. Langmuir, 20, 6107-6115. 

Thus, the transition from a V-shaped to star-shaped amphiphiles greatly affects the type of self-assembled structures that are formed. As the arms are not able to associate... 

Polymerisable surfactants constitute another important area of polymerisation in disperse media. Over the past fifteen years, a number of studies have been made of surfactant assemblages possessing a polymerisable group. The aim of these studies is to fix the structure of the initial assemblages in such a way as to obtain stable aggregates with controllable size, rigidity and permeability. These systems could be applied where the non-polymerisable assemblages had proven inadequate as a result of their limited lifetime. The studies concerned two types of self-assembled structures vesicles and micellar systems. 

Microemulsions, isotropic liquid mixtures of oU, water, and surfactant, frequently in combination with a cosurfactant, were stable. In the binary systems (water/ surfactant or oil/surfactant), different types of self-assembled structures can be formed, providing excellent templating systems to synthesize monodispersed nanocrystals with controllable size and morphology [28]. Recently, imidazolium-based ILs had been explored and used as solvents of the iimer phase, or continuous... 

Woolfson and Mahmoud have classified the routes to preparation of decorated self-assembling peptide materials [53] as (1) co-assembly, where the functional part is already attached to a self-assembling component prior to assembly, and (2) postassembly, where a non-functionahsed self-assembled structure is modified by covalent or non-covalent means. This discussion adheres to this classification. A third route, beyond the scope of this review, is the use of structured peptides as templates for inorganic materials. Section 4.1 discusses functionalised self-assemblies formed from co-assembly-type approaches, while post-assembly modifications of self-assembled structures are considered in Sect. 4.2. 

Caspar and Klug distinguished two fundamental types of self-assembly processes (a) True self-assembly—a series of reactions relying on the propensity of subunits to condense and form assembled structures strictly as a result of the information encoded in the architecture of the components, (b) Template-directed assembly—a process depending on the presence of a separate template that imparts structural constraints on the pathway for constructing the final assembled structure. 

Although not strictly LB films, there are other types of self-assembled films containing Q-state MCs that resemble LB films. One example involves the self-assembly of the amphiphile DTG into an organized film by slow evaporation of solvent from a dispersion of the amphiphile (40). The structure of the cast film has the head-... 

Our efforts in the self-assembly of three-dimensional (3D) arrays (Table 4.4) evolved to answer three questions first, and perhaps most importantly, how does one assemble in three dimensions Here, assembly in 3D refers to self-assembly that does not take place at an interface, but rather in the bulk of a liquid. Second, what sorts of 3D structure can be self-assembled at the mesoscale Rods, crystals, and sheets certainly, but what about spirals, sponges, or ropes Third, how small are the dimensions to which this type of self-assembly can be scaled For some of the applications of 3D structures in optics that we envision, it is desirable to have a method to make 3D arrays of l-(xm-sized objects. 

This section briefly discusses the use of self-assembly in the designed synthesis of coordination compounds having higher structures. The different types of self-assembly are reviewed, along with factors which influence them. Certain well-known synthetic strategies are also described. 

Recent studies by Lin and co-workers [63] have shown that not only the fatty acid composition influences the kind and ratio of carbonyls formed during heating of lipids, but also the structure of the reaction medium. The type of self-assembly stmcture had a significant influence on reaction yields. Egg phosphatidylcholin, which forms a lamellar phase together with water, generated significantly more 41 than phosphatidylethanolamine which adopts a different nanostructure, namely a reversed hexagonal structure. 

Different other attractive way to modify the active electrode of amperometric sensors, besides deposition of polymers or electropolymerization, is formation of self-assembled structures, e.g., self-assembled monolayers (SAM) on solid supports 88 89 or bilayer lipid membranes (BLM) on various types of support.90 Both types of theses structures can either induce selectivity of sensor to particular analytes and... 

Several terminologies were created to describe the composition of self-assembled structures and therefore also of the self-assembly process. Slang s assembly descriptor terminology involves treating the assembly components as linear (L), or angular (A), and then listing the numbers and types of each constituent with superscripts to describe their respective topicities. An assembly, such as the square shown in Fig. 4 is therefore assigned the descriptor because it consists of four... 

A similar type of self-assembly has been observed in 2,2, 5,5 -tetramethyldi-stibole [21, 22]. The molecular tectons are aligned in chains with a colinear Sb-Sb- - -Sb-Sb sequence, 4. Note that the arsenic analog contains discrete molecules in the crystal with no secondary supramolecular structure. 

Structural characterized examples of metal cluster complexes with the same type of self-assembly are H30s3(C0)9(/<3-CC00H), 47 [112] and HRu3(CO)io-(/i-SCH2COOH), 48 [113]. All three types of metal complex typify the close structural analogy between organometallic and organic carboxylic acids. 

In most cases the different constituent blocks are incompatible, giving rise to intramolecular phase separation, but the chemical connectivity restricts the special dimension of phase segregation to the nanoscale. As a result, at sufficiently high molecular weight, monodisperse block copolymers form a rich variety of self-assembled structures or an array of periodic nanostructures with a periodicity of 10-100 nm, commonly referred to as microphase-separated structures. By changing the relative composition, the compatibility between the component polymers, and the architecture of the copolymer molecules, the size and type of nanostructures can be precisely controlled [1-6]. 

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