Aluminosilicates nanocomposites

Tunney. J.J. Detellier, C. Aluminosilicate nanocomposite materials. Poly(ethylene glycol)- kaolinite intercalates. Chem. Mater. 1996, 8. 927-935. 

The maleated polypropylenes also play an important role in the preparation of thermoplastic aluminosilicate nanocomposites [45]. This could become another important outlet if this technology is more widely adopted. 

In recent years, many anionic polymers have been interleaved into LDH to form a new class of LDH-polymer nanohybrids, in which the LDH hydroxide layer and polymer anion layer alternate this topic has been reviewed by Leroux and Besse (14). LDH compounds have been added to neutral polymer as additives or fillers to improve the properties of polymeric materials, such as thermal stability, flammability, mechanical strength, and hardness. The delamination of LDH into single hydroxide layers offers a route to a new kind of polymer-LDH nanocomposite, analogous to the polymer-aluminosilicate nanocomposites extensively studied since the mid 1990s. We review these three classes next. 

The entrapment-type nanocomposites can be prepared from zeolites and they are of two types zeolite-inorganic and zeolite-organic. Zeolite crystals are three-dimensionally linked network structures of aluminosilicate, aluminophosphate (ALPO), and silicoaluminophosphate (SAPO) composition and are porous, the pores being in the range of 2.8 to 10 A. Many of the highly siliceous, ALPO, and SAPO zeolites have been synthesized using organic templates such as tetrapropyl... 

Pillared interlayered clays (PILC) can be regarded as nanocomposites, in which oxide particles of nano- and subnanometer scales are incorporated into the interlayer space of two-dimensional aluminosilicates [1]. In recent years, much attention has been focused on this new type of materials with large heights of pillars, because they provide larger pores in comparison to conventional zeolites. Smectites pillared with transition metal oxides (e.g. Cr, Fe, Ti) are of particular interest because the incorporated phases have themselves catalytic properties. Such solids are claimed to possess a remarkable activity in a notable number of reactions [2,3]. 

Microporous materials with regular pore architectures comprise wonderfully complex structures and compositions. Their fascinating properties, such as ion-exchange, separation, and catalysis, and their roles as hosts in nanocomposite materials, are essentially determined by their unique structural characters, such as the size of the pore window, the accessible void space, the dimensionality of the channel system, and the numbers and sites of cations, etc. Traditionally, the term zeolite refers to a crystalline aluminosilicate or silica polymorph based on comer-sharing TO4 (T = Si and Al) tetrahedra forming a three-dimensional four-connected framework with uniformly sized pores of molecular dimensions. Nowadays, a diverse range of zeolite-related microporous materials with novel open-framework stmctures have been discovered. The framework atoms of microporous materials have expanded to cover most of the elements in the periodic table. For the structural chemistry aspect of our discussions, the second key component of the book, we have a chapter (Chapter 2) to introduce the structural characteristics of zeolites and related microporous materials. 

The wide assortment of polymer systans (polypropylene, poly(methyl methacrylate) [PMMA], polyepoxide, polystyrol, PC, etc.) is used as a polymeric matrix for nanocomposites production (Ray and Okamoto 2003). The most well-known fillers of polymeric matrix are nanoparticles (silica, metal, and other organic and inorganic particles), layered materials (graphite, layered aluminosilicates, and other layered minerals), and fibrous materials (nanofibers and nanotubes) (Thostenson et al. 2005). Nanocomposite polymer materials containing metal or metal oxide particles attract growing interest due to their specific combination of physical and electric properties (Rozenberg and Tenne 2008, Zezin et al. 2010). Nanocomposites on the base of layered materials... 

Both the nanocomposites prepared by in-situ polymerization of 2-ethnyl-pyridine (2Epy) in the presence of a layered aluminosilicate such as Ca + -... 

The formation of filaments of PANI was also achieved using MCM-41 as a template [86,87]. MCM-41 is a synthetic aluminosilicate, with hexagonal arrays of holes ca. 3.0 nm in size. Nanocomposites of PANI-MCM-41 were synthesized by exposure of MCM-41 containing ions of Cu (II) or Fe (III) to vapors of aniline [88]. The adsorption of aniline... 

Figure 8.8 Polarized absorption spectra of PEPy-C18/saponite 32-bilayer films obtained by irradiating (a) s-polarized light and (b) p-p>olarized light (incidence angle 0=8CP). (Reprinted with permission from Chemistry of Materials, Ordered Multilayer Nanocomposites Prepared by Electrostatic Layer-by-Layer Assembly between Aluminosilicate Nanoplatelets and Susbtituted Ionic Polyacetylenes by D. W. Kim, A. Blumstein, J. Kumar et al., 14, 9. Copyright (2002) ACS)...

D.W. Kim, A. Blumstein, J. Kumar, L.A. Samuelson, B. Kang, and C. Sung. Ordered multilayer nanocomposites prepared by electrostatic layer-by-layer assembly between aluminosilicate nanoplatelets and substituted ionic polyacetylenes, Chem. Mater., 14, 3925 3929... 

Although both natural and synthetic aluminosilicates have long been reported to be effective free radical initiators for the aqueous polymerization of vinylic monomers [248-251], their utilization in nanocomposite materials was reported only recently. 

A new composite material was introduced in 1987 with the discovery of a nylon-6/clay hybrid (NCH) [201]. The hybrid was prepared by the in situ thermal polymerization of s-caprolactam with 8% or less montmorillonite, the clay material containing 1-nm thick exfoliated aluminosilicate layers. It exhibited a truly nanometer-sized composite of nylon-6 and layered aluminosilicate. Figure 2.14 depicts conceptually the NCH synthesis and its fine structure. The NCH exhibited high modulus, high strength, and good gas-barrier properties. The unique and superior properties led to the commercialization of NCH. It has also created a new class of nanocomposites and worldwide interest. 

Chitosan/day nanocomposites represent an innovative and promising class of materials. Potential biomedical applications of chitosan/clay nanocomposites include the intercalation of cationic chitosan in the expandable aluminosilicate structure of the clay is expected to affect the binding of cationic drugs by anionic clay the solubility of chitosan at the low pH of gastric fluid may decrease the premature release of drugs in the gastric environment ... 

The ratio of silicon, aluminum, and oxygen (Si Al 0) at the very surface of the exposed nylon 6 nanocomposite is 22.96% 9.14% 60.2%, which is 2.5 1 6.5. This ratio corresponds well to that generally anticipated for low-magnesium montmorillonite (2.3 1 6.8, (Ai3.5Mgo.5)Si802o(OH)4 (5)). This further indicates a thin layer of aluminosilicate covers the surface of the oxygen plasma treated nanocomposite film. 

Since the initial absorption (i.e. color) of the nanocomposite increases with montmorillonite addition, future investigations should focus on examining synthetic aluminosilicates that do not contain isomorphic substitution from transition metals such as Fe. Alternative types of inorganic fillers include laponite, fluorohectorite or synthetic silicic acids (31). Note that the UV exposure is not only an on-orbit concern, but will drastically affect life-cycle and long-term environment stability and performance of nanocomposites used in external terrestrial environments. 

Three different types of nanomaterials, based on their dimensional characteristics, are generally used to prepare polymer nanocomposites. These include nanomaterials with only one dimension in the nanometre range (e.g. nano-clay), those with two dimensions in the nanometre scale (e.g. carbon nanotubes) and those that have all three dimensions in the nanometre scale (e.g. spherical silver nanoparticles), as stated earlier. Thus nanosize thin layered aluminosilicates or nanoclays, layer double hydroxide (LDH), a large number of nanoparticles of metals and their oxides, carbon nanotubes and cellulose nanofibres are used as nanomaterials in the preparation of vegetable oil-based polymer nanocomposites. 

Transmission electron micrographs of PP nanocomposites. The dark lines represent the cross sections of aluminosilicates. (Reproduced from Mittal, V., /. Thermoplast. Compos. Mater., 20,575,2007.)... 

Pramanik, M., Srivastava, S. K., Samantaray, B. K., and Bowmick, A. K. 2003. EVA/clay nanocomposite by solution blending Effect of aluminosilicate layers on mechanical and thermal properties. Macromolecular Research 11 260-266. 

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