Self-assembly structures polymers

Due to its unique chemical composition and structure, DNA can interact with a plethora of chemical structures via numerous types of bonds. This property ultimately defines the ability of DNA fragments to serve as the building blocks in the complex three-dimensional self-assembled structures. Following we Ust four major types of polymer/DNA interactions that can lead to formation of supramolecular structures ... 

Self-assembled structures can be closed if all the potential binding sites are utilized, or open if they are not. Closed assemblies have a definite geometry and stoichiometry, while open assemblies exist as mixtures of oligomers or polymers of varying stoichiometry. In addition, the self-assembled structure can be classified as cooperative if the multiple binding interactions reinforce each other to yield enhanced stability, or trivial if the binding interactions do not cooperate in the... 

The size-exclusion and ion-exchange properties of zeolites have been exploited to cause electroactive species to align at a zeolite—water interface (233—235). The zeolite thus acts as a template for the self-organization of electron transfer (ET) chains that may find function as biomimetic photosynthetic systems, current rectifiers, and photodiodes. An example is the three subunit ET chain comprising Fe(CN )g anion (which is charge-excluded from the anionic zeolite pore structure), Os( bipyridine (which is an interfacial cation due to size exclusion of the bipyridine ligand), and an intrazeolite cation (trimethylamino)methylferrocene+ (F+ ). A cationic polymer bound to the (CN)6 anion holds the self-assembled structure at an... 

An interesting approach to the design of biomaterials and biologically inspired materials is to combine the best features of synthetic and biological polymers into copolymers (Klok, 2005 Vandermeulen and Klok, 2004). Thus, peptide sequences may be used to create self-assembled structural motifs at the nanoscale, most commonly [3-sheets or a-helices, while the... 

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-... 

Generally, these pre-self-assembled structural motives are often found in the final polymer materials. 

Fig. 3 Self-assembled structure of BTC (a) and CTC (b) supramolecular polymers (R alkyl group). Adapted with permission from [34]...

With the exception of the last example we have mainly dealt with supramolecular assemblies and structures of polymers which are formed by dispersion interaction forces so far. Self-assembly of polymers by more specific interactions, which justifies the denotation as supramolecular complexes is still limited in number and mostly poorly defined. 

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... 

In addition to lipid-like molecules, polymers can also form self-assembling particulates [8]. As expected, the amphiphilic polymers do form polymeric micelles with polar part orienting towards the surface of the particle and the hydrophobic part orienting towards the core of the particle. Also, in this case, different complicated self-assembled structures can be tailored by using block copolymers with regular blocks of monomer units but, only the simpler ones have been investigated so far in the context of drug delivery. 

Biological systems provide numerous examples of self-assembled objects. Owing to the relatively weak interactions involved, a self-assembled structure is much more sensitive and responsive to its environment than a more rigid structure held together by covalent bonds. Unlike processes involving simple surfactants, polymers, and nanoparticles, self-assembly processes in biological systems are usually directional and functional and often lead to the formation of extremely complex structures. For example, the three-dimensional structure adopted by a protein in solution is critical to the protein s function, and this structure is determined by both strong (covalent) and weak... 

Recent advances in polymer chemistry have yielded better control over the architecture and polydispersivity of simple polymers, polymer-conjugates and block copolymers such that they can be efficiently produced and can spontaneously form sterically stabilized, nanoscale, self-assembling structures with macrophage evading properties. ... 

Mixtures of two homopolymers (A and B) and their corresponding diblock copolymer (A-B) are polymeric counterparts of mixtures of water, oil and surfactant. The immiscible nature between water and oil is also observed in polymer blends due to the fact that most polymers are immiscible in each other. The addition of diblock copolymers into blends of homopolymers has effects similar to adding surfactants into water-oil mixtures. The resulting reduction in interfacial tension and formation of the preferred interfacial curvature yield a variety of self-assembled structures. 

Many examples of self-assembly do not involve reactions but involve merely the alignment of molecules among and between phases. Add a detergent to a mixture of oil and water. The detergent migrates to the oil-water interface. When the interface is saturated, the excess detergent forms nanoscale aggregates known as micelles. More complicated self-assembled structures can result when polymer mixtures are... 

Understanding the crystal growth mechanisms of these solution-processable polymers is required to control the self-assembled structure during film formation. Most studies on solution-deposited semiconducting polymer thin films for OTFTs pertain to PATs [6,10,15,23,24,27,30,35,36,44,46-48,51-81]. The key factors affecting self-assembly of these polymers during solution processing are as follows ... 

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