Soft templates phase

The kinds of structures adopted by these microorganisms as well as other mineral morphologies, are the subject of increasing study as chemists look at soft templated routes to nanoscale objects. Early work in the 1990s by a team at Mobile used supramolecular micelles, lamellae and bicontinuous phases formed by amphiphiles, to assemble inorganic materials, particularly silica and alumina. A range of new... 

Soft template method by using block copolymers was reported for first time by Liang et al. [72] in 2004. After that, a significant progress on the fabrication of carbon with a well ordered mesopores was achieved [32, 73-77]. Zhao and coworkers performed a widespread study of soft template via the triblock poly (ethylene oxide) (PEO) and poly(propylene oxide) (PPO) based systems, PEO-PPO-PEO [65, 78]. Several ordered pore stmctures corresponding to various surfactant liquid crystal phases were synthesized by liquid crystal template pathway, a schematized synthesis procedure is shown in the Pig. 7.11. 

Using functional molecules as structural directors in the chemical polymerization bath can also produce polyaniline nanostructures. Such structural directors include surfactants [16-18], liquid crystals [19], polyelectrolytes (including DNA) [20,21], or complex bulky dopants [22-24]. It is believed that functional molecules can promote the formation of nanostructured soft condensed phase materials (e.g., micelles and emulsions) that can serve as soft templates for aniline polymerization (Figure 7.3). Polyelectrolytes such as polyacrylic acid, polystyrenesulfonic acid, and DNA can bind aniline monomer molecules, which can be polymerized in situ forming polyaniline nanowires along the polyelectrolyte molecules. Compared to templated syntheses, self-assembly routes are more scalable but they rely on the structural director molecules. It is also difficult to make nanostructures with small diameters (e.g., <50 nm). For example, in the dopant induced self-assembly route, very complex dopants with bulky side groups are needed to obtain nanotubes with diameters smaller than 100 nm, such as sulfonated naphthalene derivatives [23-25], fidlerenes [26], or dendrimers [27,28]. 

Pat. CN101332999 (A) C01G3/02, Method for preparing Cup or CuO hoUow sub-microspheres with particle diameter controllable by water phase soft template method, Yun Fang [CN] Jin Hu [CN] Yueping Ren [CN] Yongmei Xia [CN]. 

Till date, liquid-crystalline phases [51], colloidal particles [52], and structure-directing molecules [53[ as the soft-template have been employed to synthesize PANI nanostructures. Based on the traditional synthesis method of PANI, in particular, some simple approaches such as interfacial polymerization [54], mixed reactions [55], dilute polymerization [56] and ultrasonic irradiation [57] have also been employed to synthesize PANI. The interfacial polymerization method only allows the oxidative polymerization of aniline to take place at the interface of the organic/water phases and the product directly enters into the water phase, which could facilitate environmentally friendly processing. 

The hard-templating growth methods described before should not be confused, on the contrary, with soft-templating approaches which usually are accomplished in solution phase in the presence of free surfactant molecules which severely attend the nucleation of a new particle and the further shape development selectively and dynamically interacting with the evolving particle surface facets. 

Polymerization of the continuous phase and removal of the dispersed one, used as a soft template, lead to solid microcellular foams emulsions are powerful tools to generate hierarchical porosity when combined with lyotropic meso-phases, and various synthetic routes have been reviewed by Zhang and Cooper [104]. If silica precursors such as tetraethyl-orthosilane (TEOS) are used, the materials synthesized are called Si-(HIPE). They can possess very high porosity and very low bulk density. The void size is usually situated in the microcellular range (1-100 pm). These materials will be used as supports for a wide range of applications. 

The sterical shielding of the organocationic precursor is a crucial parameter in view of the formation of nanostructured ionosilica mesophases as it determines the ionic interactions between surfectant and precursor. The more the cationic center of the precursor is shielded, the wealcer the interactions with the structure-directing agent and the less structured the formed ionosilica hybrid materials [119]. The tendency clearly indicates that strong precursor-surfectant interactions are a crucial parameter in the synthesis of nanostructured ionosilica phases. These interactions can be modulated by both the design of the precursor and the soft template [121]. 

The approaches to polymer-stabilized copper nanomaterials can be divided into three main classes (i) the so-called polyol process (ii) soft-template processes in which the polymer is employed (either as such or in combination with other capping agents), aiming exclusively at stabilization of the Cu phases and (iii) dendrimer-encapsulation. 

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