Intercalation methods

SCHEME 2.1 The melt-intercalation method for nanocomposite preparation. 

This is the most widely used naturally occurring rubber. The literature search shows that many research groups have prepared nanocomposites based on this rubber [29-32]. Varghese and Karger-Kocsis have prepared natural rubber (NR)-based nanocomposites by melt-intercalation method, which is very useful for practical application. In their study, they have found increase in stiffness, elongation, mechanical strength, and storage modulus. Various minerals like MMT, bentonite, and hectorite have been used. 

This is a highly polar polymer and crystalline due to the presence of amide linkages. To achieve effective intercalation and exfoliation, the nanoclay has to be modified with some functional polar group. Most commonly, amino acid treatment is done for the nanoclays. Nanocomposites have been prepared using in situ polymerization [85] and melt-intercalation methods [113-117]. Crystallization behavior [118-122], mechanical [123,124], thermal, and barrier properties, and kinetic study [125,126] have been carried out. Nylon-based nanocomposites are now being produced commercially. 

An Intercalation Method Involving Dissolution and Re-coprecipitation Procedures... 

The incorporation of unmodified and organically modified montmorillonite nanoclays (namely 15A and 30B) in chlorinated polyethylene (CPE) by the solution intercalation method and their influence on mechanical properties of the nanocomposites have been studied by Kar et al. [137]. The o-MMT-embedded nanocomposites show enhanced tensile strength and Young s modulus in comparison to the nanocomposites containing the unmodified nanoclay. They have shown from and XRD analyses that organically modified clay shows better dispersion in the CPE matrix. This has been further substantiated from FTIR analysis, which proves an interaction between the CPE matrix and the clay intercalates. 

There are few reports on rubber-LDH nanocomposites in which they have been prepared mostly by solution intercalation methods and not by a conventional technique for processing rubber-based composites [102, 103]. But, the melt... 

In the weak basic solution, Ni(OH)2 is preferentially formed in the interlayer space of blmessite rather than as free Ni(OH)2 from Ni containing solution. Hydrothermal intercalation method is favored the formation of a mixed layered Ni(OH)2-manganese oxide, in which the Ni(OH)2 insertion into the bimessites is topotactic reaction. 

Organic-perovskite hybrids play an important role in the fabrication of various nanodevices as well as in elucidating their fundamental properties. Intercalation of organic components into layered perovskites can be facilitated by various techniques such as ion exchange and the exfoliation-restacking method. In addition, the electrochemical intercalation method is also favorable for intercalation of organic molecules into transition metal oxides. However, except for... 

The hexylamine-intercalation method was usually used four layered compounds were treated by the exchange of acid (IM-HNO3 with stirring for several hours at 70 °C) to form H+-type product, which was dried in air, and then suspended in the excess of hexylamine solution at room temperature and the mixture was stirred for 28 d. Hexylamine was removed by filtration and the hexylamine-expanded silicates were used immediately for the pillaring reaction in order to prevent hexylamine evaporation. 

Moreover, the intercalation method was applied to the enantioresolution of racemic alcohols. The amide derivative of cholic add, called cholamide, serves as an excellent host for enantioresolution of 2,2-dimethyl-3-hexanol among secondary aliphatic alcohols. The intercalation method gave highly effective enantioresolution of the alcohol, as in the case of the recrystallization method. For example, dioxane molecules were exchanged with the alcohol molecules in channels of the bilayers with a high enantioselectivity of 96% ee, which was close to the value (98% ee) obtained by the recrystallization method. X-ray diffraction studies proved that the host bilayer framework has an anti-parallel arrangement on the lipophilic side in the case of dioxane, while the framework has a parallel one after intercalation of the alcohol. This indicates that the intercalation accompanies a layer-reversion. Such dynamical enantioresolution confirms the effidency of the intercalation method. 

Recently, the authors of this chapter have prepared polymer/clay nanocomposites using a water-soluble hyperbranched aliphatic polyester (Bottom from Perstorp) [Decker et al., 2009]. The nanocomposites were prepared via a solution-intercalation method using deionized water as the solvent medium. The nanocomposite preparation recipe was similar to that used by Plummer et al. [2002]. There are several advantages of this system compared to many other polymer/clay nanocomposite systems. These include the fact that no surfactant is required, the polymer is amorphous, and a broad range of composites from 0 to 95 wt% can be easily prepared. This... 

Layered siUcate/polypropylene nanocomposites were prepared by melt intercalation method. Homopolymers PP alone and maleic anhydride-grafted polypropylene (PPgMA) as a compatibiUzer were used as the matrix. Clay (Na montmorillonite, MMT) particles were used to obtain silicate nano-layers within the PP matrix. Structural modification of MMT... 

The first technique to be developed was the monomer intercalation method. This chapter describes the results of studies and experiments that we conducted to characterize this method. 

Lu et al. [95] have also prepared ER fluid based on PANI-MMT nanocomposite with small particles diameter about 100-200 nm by an emulsion intercalation method. No additional surfactant is used and the aniline monomer remains excess amount in their intercalation reaction, and thus, the positive charged aniline monomer can well replace the absorbed sodium ions in interlayer of MMT. In order to further reduce the conductivity of the PANI-MMT particles prepared by the chemical oxidation of aniline in the presence of acidic dopant, the PANI-MMT particles must be immersed in NH aqueous solution. This immersed time for controlling conductivity of this nanocomposite is longer (several hours) compared with immersed time (only several minutes) of pure PANI. This may be related to the protection function of MMT layer to PANI macromolecular. The yield stress of PANI-MMT ER fluid is 7.19 kPa at 3 kV/mm, which is much higher than that of pure MMT as well as that of the mixture of PANI with clay (PANI+MMT). 

There are two primary types of qPCR the first involves the use of fluorescence reagents that are intercalated into the double-strand structure of the amplified PCR product (i.e., the intercalation method), and the other involves the use of a probe molecule that yields dual fluorescent signals (i.e., the probe method) [37]. The former is less costly than the probe method because an expensive fluorescence probe is not required. However, use of the intercalation method can also result in nonspecific amplification by intercalation of the fluorescence reagents into an undesired PCR product. Therefore, qPCR assays using the intercalation method should include a dissociation curve to examine nonspecific amplification. If double... 

Several techniques such as intercalation of polymer from solution, in-situ intercalative polymerization, melt intercalation, direct mixture of polymer and particulates, template synthesis, in-situ polymerization and solgel process, are being employed for the preparation of polmer-layered silicate nanocomposites. Among them the most common and important approaches are in-situ polymerization, solution-induced intercalation method, and melt processing method, which are briefly discussed below. 

Figure 6.7 (a) Schematic representation of the melt intercalation method, (b) Stepwise representation of the melt intercalation method [20,21],... 

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